@article{guo_zhao_shu_lee_sun_ren_song_2023, title={A Novel Analytical Explicit Method to Calculate Formed Wheel and Tooth Flank of Involute Gears in Profile Grinding Process}, volume={145}, ISSN={["1528-8935"]}, DOI={10.1115/1.4056925}, abstractNote={
 To ensure the machining accuracy of gears, the tooth flanks are formed by profile grinding technology. In the profile grinding process, the calculation of wheels using the information of gears named as the forward-calculation process and obtaining gears based on wheels (the backward-calculation process) traditionally adopt numerical ways. It is always time-consuming. To conquer these drawbacks, this paper presents an analytical method. For the forward-calculation process, the tooth flank is expressed in the form of an extended straight-line surface which can be taken as the generating line moving along the helix curve. The normal vector for an arbitrary point on the generating line is the same. Using this characteristic, the contacting curve can be explicitly gained as the function of only one parameter. Similarly, in the backward-calculation process, the formed wheel is expressed by a cross-section rotating about its axis. For this type of surface, the guide curve is a circle and the normal vectors of points on the guideline insects with the axis at the same point. Taking advantage of this principle, the contacting curve can be analytically expressed by only one unknown parameter. To verify the validity of the proposed method, some examples and experiment are performed. The results show that the presented method is correct. Compared with the numerical method, the calculation speed is improved by 15 times. Compared with the practical grinding wheel and the practical gear, the maximum errors are 0.18 mm and 0.0099 mm respectively.}, number={6}, journal={JOURNAL OF MANUFACTURING SCIENCE AND ENGINEERING-TRANSACTIONS OF THE ASME}, author={Guo, Qiang and Zhao, Weisen and Shu, Changlin and Lee, Yuan-Shin and Sun, Yuwen and Ren, Lei and Song, Mingzhe}, year={2023}, month={Jun} }
 @article{ho_lee_ho_lin_tung_lee_2023, title={Assessment of glass-to-glass welding by USP lasers with machine learning approaches}, volume={35}, ISSN={["2213-8463"]}, DOI={10.1016/j.mfglet.2023.08.003}, abstractNote={Glass welding using ultra-short pulsed (USP) lasers has become one of the promising technologies in the past decades. With appropriate settings of parameters, USP lasers can provide many advantages for glass welding. However, there is still a lack of studies focused on predictions and relationships between successful welding and its correlates by machine learning models from glass welding experimental data, causing no guidance when implementing such experiments in the laboratory. In this study, we report the results of glass welding using a femtosecond laser system. The welding conditions (i.e., success or failure) under different process parameters such as focal position, power, and the other four parameters are analyzed by Neural Network (NN), Logistic Regression (LR), and Classification and Regression Tree (CART). The prediction accuracies of the models are from 84.3% to 97.3%. In other words, the process parameters can be applied to similar experiments to enhance the success rate of glass welding using USP lasers. Therefore, this study can fill the gap of lacking analytical results on predictions and relationships between successful welding and its process parameters in glass welding using USP lasers.}, journal={MANUFACTURING LETTERS}, author={Ho, Yi-Mo and Lee, Cheng-Hsun and Ho, Jeng-Rong and Lin, Chih-Kuang and Tung, Pi-Cheng and Lee, Yuan-Shin}, year={2023}, month={Aug}, pages={160–165} }
 @article{wang_cai_gong_lee_2022, title={Design and 3D printing of waveguide-based ultrasonic longitudinal-torsional transducers for medical needle insertion}, volume={344}, ISSN={["1873-3069"]}, DOI={10.1016/j.sna.2022.113706}, abstractNote={This paper presents a new waveguide-based longitudinal-torsional (L&T) ultrasonic transducer. For synchronization of both the longitudinal and the torsional vibrations, a new circular array of helical structures was designed and developed. The array of helical structures is used as an effective waveguide to constrain the wave propagations to achieve harmonic longitudinal-torsional vibration. Analytical modeling of the new design is presented for synchronous L&T vibration conversion. A finite element (FE) analysis was used to optimize the geometric design of the new L&T transducer. The new design was fabricated using a selective laser melting (SLM) additive manufacturing (AM) process. Lab experiments were conducted to measure the impedance and vibration performance of the novel fabricated transducers and validate the L&T transducer design. The results show that the new waveguide-based transducer is promising to deliver synchronized L&T vibration with high vibrational power efficiency. The new L&T ultrasonic transducer can be developed for a vibratory needle insertion device, effectively reducing insertion force and bending.}, journal={SENSORS AND ACTUATORS A-PHYSICAL}, author={Wang, Yi and Cai, Yi and Gong, Hu and Lee, Yuan-Shin}, year={2022}, month={Sep} }
 @article{wang_cai_lee_2021, title={Design and Development of Longitudinal and Torsional Ultrasonic Vibration-assisted Needle Insertion Device for Medical Applications}, volume={19}, url={https://doi.org/10.14733/cadaps.2022.797-811}, DOI={10.14733/cadaps.2022.797-811}, abstractNote={Automated feature recognition (AFR) makes it possible to abstract semantic information from neutral CAD models.In an earlier work, we proposed an AFR method for aerospace sheet metal (ASM) parts.In this new work, that method's implementation as an AFR prototype is outlined and the differences between the prototype and the original proposal are pointed out.Then, streamlined data structures are described and explained.They are used to organize the B rep elements extracted from the ASM parts' STEP models, classify and enhance them, and structure the features recognized from the STEP models.Next, a few examples of the algorithms that are implemented in the prototype to manipulate the B rep elements and recognize features are represented and explained.The details of the algorithms are presented in the appendices.To validate the AFR method and verify its correct implementation, a collection of 26 real-world ASM parts was used to create CAD models that were subsequently converted to STEP models.The STEP models were processed to recognize their features, and the results show perfect accuracy.A few of the output feature files are presented in detail.Our results confirm great potential for further AFR method development for rather specialized domains of application.}, number={4}, journal={Computer-Aided Design and Applications}, publisher={CAD Solutions, LLC}, author={Wang, Yi and Cai, Yi and Lee, Yuan-Shin}, year={2021}, month={Nov}, pages={797–811} }
 @article{guo_zhang_lee_yang_jiang_feng_2020, title={Study on the stability for non-uniform helix angle tools in the milling process}, volume={37}, ISSN={["2168-1023"]}, DOI={10.1080/21681015.2020.1802621}, abstractNote={ABSTRACT Uniform helix angle tools cannot effectively suppress the chatter in the high machining process. Consequently, cutters with non-uniform helix and pitch angles are more and more common in various milling operations. To suppress the regeneration chatter, it is crucial to study the stable behavior of the tools. Therefore, this paper considers the relationship between the pitch angle and the chatter stability defined by the regeneration factor (RF). Further, the governing equation of the machining system with non-uniform helix angle cutters is formulated. Based on this model, the Enhanced Multistage Homotopy Perturbation Method (EMHPM) is used to compute the stability lobes. To validate the theory in this paper, the stability lobes are predicted and compared with the results in the literature. The results show that the rational helix and pitch angle cutters exhibit increases stability in the milling process.}, number={8}, journal={JOURNAL OF INDUSTRIAL AND PRODUCTION ENGINEERING}, author={Guo, Qiang and Zhang, Ming-Yang and Lee, Yuan-Shin and Yang, Zhi-Bo and Jiang, Yan and Feng, Cong-Hui}, year={2020}, month={Nov}, pages={387–393} }
 @article{sun_sun_lee_2019, title={A Gouge-Free Tool Axis Reorientation Method for Kinematics Compliant Avoidance of Singularity in 5-Axis Machining}, volume={141}, ISSN={["1528-8935"]}, DOI={10.1115/1.4043266}, abstractNote={Abstract}, number={5}, journal={JOURNAL OF MANUFACTURING SCIENCE AND ENGINEERING-TRANSACTIONS OF THE ASME}, author={Sun, Shuoxue and Sun, Yuwen and Lee, Yuan-Shin}, year={2019}, month={May} }
 @article{xu_xu_sun_lee_zhao_2019, title={A Method of Generating Spiral Tool Path for Direct Three-Axis Computer Numerical Control Machining of Measured Cloud of Point}, volume={19}, ISSN={["1944-7078"]}, DOI={10.1115/1.4043532}, abstractNote={Smooth continuous spiral tool paths are preferable for computer numerical control (CNC) machining due to their good kinematic and dynamic characteristics. This paper presents a new method to generate spiral tool paths for the direct three-axis CNC machining of the measured cloud of point. In the proposed method, inspired by the Archimedean spiral passing through the radial lines in a circle, 3D radial curves on the cloud of point are introduced, and how to construct the radial curves on the complex cloud of point is discussed in detail and then a practical and effective radial curve construction method of integrating boundary extraction, region triangulation, mesh mapping, and point projection is proposed. On the basis of the radial curves, the spiral tool path can be generated nicely by interpolating the radial curves using a spiral curve. Besides, the method of identifying and eliminating the overcuts and undercuts in the spiral tool path resulting from the interpolation error is also presented for good surface quality. Finally, several examples are given to validate the proposed method and to show its potential in practical applications when quality parametric models and mesh models are not available.}, number={4}, journal={JOURNAL OF COMPUTING AND INFORMATION SCIENCE IN ENGINEERING}, author={Xu, Jinting and Xu, Longkun and Sun, Yuwen and Lee, Yuan-Shin and Zhao, Jibin}, year={2019}, month={Dec} }
 @article{sun_chen_jia_lee_guo_2019, title={Jerk-limited feedrate scheduling and optimization for five-axis machining using new piecewise linear programming approach}, volume={62}, ISSN={["1869-1900"]}, DOI={10.1007/s11431-018-9404-9}, number={7}, journal={SCIENCE CHINA-TECHNOLOGICAL SCIENCES}, author={Sun, YuWen and Chen, ManSen and Jia, JinJie and Lee, Yuan-Shin and Guo, DongMing}, year={2019}, month={Jul}, pages={1067–1081} }
 @article{jones_lee_moore_2019, title={Parametric study for asymmetric flexure hinge design for tissue cutting}, volume={233}, ISSN={["2041-2975"]}, url={https://doi.org/10.1177/0954405418774587}, DOI={10.1177/0954405418774587}, abstractNote={ This article presents empirical stiffness equations for a novel compliant needle mechanism that will aid in ultrasonic tissue cutting. Needles are an often used medical tool that cut tissue with minimal damage. Ultrasonic vibrational cutting has been shown to reduce insertion forces necessary to cut, thus minimizing deflections of the tissue and needle. A previous study has demonstrated that coupling this ultrasonic vibration with a compliant hinge generates a transverse cutting motion. This work explores the compliant hinge design and presents empirical stiffness equations that can be used to model the needles compliant motion. The empirical model prediction, when compared to experimental findings, is shown to have an average error less than 8% when the distance between the hinges is kept within 1.68 times the thickness of the hinges. With these equations it will be possible to optimize the compliant needle design for tissue cutting. }, number={4}, journal={PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART B-JOURNAL OF ENGINEERING MANUFACTURE}, publisher={SAGE Publications}, author={Jones, Justin A. and Lee, Yuan-Shin and Moore, Jason Z.}, year={2019}, month={Mar}, pages={1302–1309} }
 @article{sun_sun_xu_lee_2018, title={Iso-Planar Feed Vector-Fields-Based Streamline Tool Path Generation for Five-Axis Compound Surface Machining With Torus-End Cutters}, volume={140}, ISSN={["1528-8935"]}, DOI={10.1115/1.4039653}, abstractNote={This paper presents a new vector-field-based streamline smoothing method in the parametric space and a tool orientation optimization technique for five-axis machining of complex compound surfaces with torus-end cutters. Iso-planar tool path is widely used in the machining of various types of surfaces, especially for the compound surface with multiple patches, but the operations of intersecting the compound surface with a series of planes have depended considerably on the complicated optimization methods. Instead of intersecting the surface directly with planes, a novel and effective tool path smoothing method is presented, based on the iso-planar feed vector fields, for five-axis milling of a compound surface with torus-end cutters. The iso-planar feed vector field in the parametric domain is first constructed in the form of stream function that is used to generate the candidate streamlines for tool path generation. Then, a G1 blending algorithm is proposed to blend the vector fields within the adjacent parametric domains to ensure smooth transition of cross-border streamlines. Based on the smoothened streamlines in the parametric domains, pathlines along with their correspondent side sizes are selected as desirable tool paths. Concerning a high performance machining, detailed computational techniques to determine the tool axis orientation are also presented to ensure, at each cutter contact (CC) point, the torus-end cutter touches the part surface closely without gouging. Both the computational results and machined examples are demonstrated for verification and validation of the proposed methods.}, number={7}, journal={JOURNAL OF MANUFACTURING SCIENCE AND ENGINEERING-TRANSACTIONS OF THE ASME}, author={Sun, Shuoxue and Sun, Yuwen and Xu, Jinting and Lee, Yuan-Shin}, year={2018}, month={Jul} }
 @article{barnett_lee_moore_2018, title={Needle geometry effect on vibration tissue cutting}, volume={232}, ISSN={["2041-2975"]}, DOI={10.1177/0954405416654188}, abstractNote={ Needle vibration tissue cutting is a method that has been shown to reduce tissue cutting force and thereby improve needle position accuracy inside the body. Needle accuracy is crucial for minimally invasive needle operations such as the radiation cancer treatment of brachytherapy. This article uniquely determines the importance of needle geometry in minimizing cutting force in needle vibration tissue cutting. This article also determines how vibration specifically affects cutting force. This new information was found by performing needle cutting experiments with five varying conical tipped needles being inserted into ex vivo bovine liver as well as a polyurethane sheet at varying vibratory amplitudes and frequencies. Results show that applying vibration to sharper needles greatly reduced the insertion force by up to 67%, where the blunter needles saw diminishing benefits. The tissue phantom experiments showed that vibration reduced the force needed to propagate the created crack but showed no improvement over the initial puncture force. This greater understanding of needle vibration tissue cutting can lead to improved needle geometry designs that work with vibration to reduce tissue cutting force. }, number={5}, journal={PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART B-JOURNAL OF ENGINEERING MANUFACTURE}, author={Barnett, Andrew C. and Lee, Yuan-Shin and Moore, Jason Z.}, year={2018}, month={Apr}, pages={827–837} }
 @article{xu_hou_sun_lee_2018, title={PLSP based layered contour generation from point cloud for additive manufacturing}, volume={49}, ISSN={["1879-2537"]}, DOI={10.1016/j.rcim.2017.05.006}, abstractNote={This paper presents a new Planar Least-Squares Projection (PLSP) method to accurately construct the layered contours directly from the point cloud for additive manufacturing. With the rapid development of 3D measuring technology, the dense and accurate point cloud, which can represent more accurate geometry information of a physical object than before, has been readily available. Additive manufacturing based directly on such point cloud is considered to be a promising alternative for fabricating the complex parts, but it requires the research on effective processing methods of the point set surface. In this paper, the presented PLSP method addresses this technical challenge for additive manufacturing. Mathematical modeling and processing of point cloud are presented to identify projections and construct accurate layered contours by considering both the least-square projection errors and projection distance selection criteria from measured point cloud. Technique of assigning new set of weights on measure scattered point cloud is discussed to achieve accurate layered contour development. The presented PLSP method with the new weight function and the consideration of point cloud deviation distances in sliced contour development is able to avoid the occurrence of the wrong projection that many other current methods suffer from. Technique of integrating the presented PLSP with the boundary point sequence curve (PSC) method is also discussed in this paper to eliminate contour development errors by considering the similarity in shape and closeness in distance for the ideal layered contours. Since this presented method does not involve the non- linear optimization, it is mathematically robust, and it can ensure the constructed layered contours lie accurately on the underlying nominal surface, and also has the ability of recognizing and processing the multi-contours on a common slicing plane. Both computational and experimental results based on the presented method are presented for validation.}, journal={ROBOTICS AND COMPUTER-INTEGRATED MANUFACTURING}, author={Xu, Jinting and Hou, Wenbin and Sun, Yuwen and Lee, Yuan-Shin}, year={2018}, month={Feb}, pages={1–12} }
 @article{xu_ji_sun_lee_2018, title={Spiral Tool Path Generation Method on Mesh Surfaces Guided by Radial Curves}, volume={140}, ISSN={["1528-8935"]}, DOI={10.1115/1.4039918}, abstractNote={This paper presents a new spiral smoothing method to generate smooth curved tool paths directly on mesh surfaces. Spiral tool paths are preferable for computer numerical control (CNC) milling, especially for high-speed machining. At present, most spiral tool path generation methods aim mainly for pocketing, and a few methods for machining complex surface also suffer from some inherent problems, such as selection of projecting direction, preprocessing of complex offset contours, easily affected by the mesh or mesh deformation. To address the limitations, a new spiral tool path method is proposed, in which the radial curves play a key role as the guiding curves for spiral tool path generation. The radial curve is defined as one on the mesh surface that connects smoothly one point on the mesh surface and its boundary. To reduce the complexity of constructing the radial curves directly on the mesh surface, the mesh surface is first mapped onto a circular region. In this region, the radial lines, starting from the center, are planned and then mapped inversely onto the mesh surface, thereby forming the desired radial curves. By traversing these radial curves using the proposed linear interpolation method, a polyline spiral is generated, and then, the unfavorable overcuts and undercuts are identified and eliminated by supplementing additional spiral points. Spline-based technique of rounding the corners is also discussed to smooth the polyline spiral, thereby obtaining a smooth continuous spiral tool path. This method is able to not only greatly simplify the construction of radial curves and spiral tool path but also to have the ability of processing and smoothing complex surfaces. Experimental results are presented to validate the proposed method.}, number={7}, journal={JOURNAL OF MANUFACTURING SCIENCE AND ENGINEERING-TRANSACTIONS OF THE ASME}, author={Xu, Jinting and Ji, Yukun and Sun, Yuwen and Lee, Yuan-Shin}, year={2018}, month={Jul} }
 @article{cai_moore_lee_2018, title={Vibration Study of Novel Compliant Needle used for Vibration-assisted Needle Insertion}, volume={16}, url={https://doi.org/10.14733/cadaps.2019.742-754}, DOI={10.14733/cadaps.2019.742-754}, abstractNote={Needles are among the most widely used medical devices, and their placement accuracy significantly affects the effectiveness of a treatment and the success or precision of a diagnosis. Vibration-assisted needle insertion is a dynamic insertion technique which can improve needle insertion accuracy by reducing the insertion force. This paper presents the vibration analysis of a novel compliant needle design for vibration-assisted insertion in medical applications. The needle design is featured by its 4-bevel needle tip and micro-slots on the needle shaft. Harmonic analysis was applied to reveal the relationship between slot location and transverse vibration amplitude, and an empirical method was developed to determine the slot locations which lead to maximum and minimum transverse amplitudes. The results were evaluated and validated by actual amplitude measurement of selected needle prototypes. Insertion experiment into tissue phantom was then conducted using these prototypes to investigate how transverse vibration amplitude affect insertion force. It was found that adding transverses vibration of small amplitude to axial vibration had the best outcome. This paper provides useful practical guidelines for design and optimization of needles for vibration-assisted insertion in medical applications and for improvement of insertion accuracy.}, number={4}, journal={Computer-Aided Design and Applications}, publisher={CAD Solutions, LLC}, author={Cai, Yi and Moore, Jason and Lee, Yuan-Shin}, year={2018}, month={Nov}, pages={742–754} }
 @article{angrish_starly_lee_cohen_2017, title={A flexible data schema and system architecture for the virtualization of manufacturing machines (VMM)}, volume={45}, ISSN={0278-6125}, url={http://dx.doi.org/10.1016/J.JMSY.2017.10.003}, DOI={10.1016/J.JMSY.2017.10.003}, abstractNote={Abstract Future factories will feature strong integration of physical machines and cyber-enabled software, working seamlessly to improve manufacturing production efficiency. In these digitally enabled and network connected factories, each physical machine on the shop floor can have its ‘virtual twin’ available in cyberspace. This ‘virtual twin’ is populated with data streaming in from the physical machines to represent a near real-time as-is state of the machine in cyberspace. This results in the virtualization of a machine resource to external factory manufacturing systems. This paper describes how streaming data can be stored in a scalable and flexible document schema based database such as MongoDB, a data store that makes up the virtual twin system. We present an architecture, which allows third-party integration of software apps to interface with the virtual manufacturing machines. We evaluate our database schema against query statements and provide examples of how third-party apps can interface with manufacturing machines using the VMM middleware. Finally, we discuss an operating system architecture for VMMs across the manufacturing cyberspace, which necessitates command and control of various virtualized manufacturing machines, opening new possibilities in cyber-physical systems in manufacturing.}, journal={Journal of Manufacturing Systems}, publisher={Elsevier BV}, author={Angrish, Atin and Starly, Binil and Lee, Yuan-Shin and Cohen, Paul H.}, year={2017}, month={Oct}, pages={236–247} }
 @article{qin_dong_lee_2017, title={AC-pulse modulated electrohydrodynamic jet printing and electroless copper deposition for conductive microscale patterning on flexible insulating substrates}, volume={43}, ISSN={["1879-2537"]}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000385603000021&KeyUID=WOS:000385603000021}, DOI={10.1016/j.rcim.2015.09.010}, abstractNote={This paper presents a novel micro-manufacturing method for fabrication of electrical features and patterns on highly insulating substrates and flexible substrates based on high-resolution AC-pulse modulated electrohydrodynamic jet (e-jet) printing of silver nanoink as seed layer followed by electroless copper deposition. Traditional ink jet printing method is limited in printing resolution which is determined by dimension of printing nozzle and dimension of droplets. Traditional e-jet printing has the disadvantage of residual charge problem especially for highly insulating substrates which cannot dredge remained charge of printed droplets, resulting in distorted electrostatic field and low printing controllability. Meanwhile, for printing of liquid phase ink, feature resolution contradicts with the required thickness, which is a key factor of conductivity of printed patterns. In this paper, a novel AC-modulated e-jet printing technique is applied to neutralize charges on substrates by switching polarity of consequent droplets for direct printing of high-resolution conductive silver patterns on insulating substrates. Electroless copper deposition is introduced in the fabrication process to solve the thickness problem of the resulting features. Variables of fabrication process, including amplitude and frequency of AC-pulsed voltage, plotting speed, curing temperature, number of layers, concentration of solution for copper growth, were identified to achieve reliable and conductive printed patterns. Sub-20 µm silver tracks with resistivity about 3.16 times of bulk silver were successfully fabricated. We demonstrated that ac-pulse modulated e-jet printing followed by electroless copper deposition can produce high resolution conductive patterns with improved thickness on insulating substrates and flexible substrates, which can be applied to direct printing and micro scale patterning for flexible electronics and wearable devices applications.}, journal={ROBOTICS AND COMPUTER-INTEGRATED MANUFACTURING}, author={Qin, Hantang and Dong, Jingyan and Lee, Yuan-Shin}, year={2017}, month={Feb}, pages={179–187} }
 @inproceedings{jones_lee_moore_2017, title={Asymmetric flexure hinge for compliant vibrational tissue cutting}, DOI={10.1115/msec2017-2850}, abstractNote={This work investigates the compliance of a novel flexure hinge mechanism for tissue cutting. This hinge is to be used with ultrasonic axial vibration to induce transverse displacement. This transverse motion can aid in reducing tissue cutting force as well as possible target deflection by reducing the parallel tissue cutting force. The finite element method, FEM, is used to evaluate several flexural hinge designs to develop empirical equations for the compliance in the axial, transverse, and rotational directions. To generate appreciable transverse motion from an axially applied ultrasonic vibration an asymmetric flexural hinge is needed. In order to design an asymmetric complaint mechanism to fully take advantage of the transverse cutting motion the compliance with respect to geometry was explored. The ratio of thickness, length, and distance between the hinges were iterated while end loads were applied to derive the compliance equations. The empirical models are presented for each design study. It is shown that the rotational stiffness is the dominating factor of the stiffness matrix. It is also shown that the relationship between the rotational stiffness and the distance between hinges forms a piecewise equation. This is due to notch elements spaced close to each other can be modeled as a lumped element while notch elements spaced further apart need to be independently modeled.}, booktitle={Proceedings of the ASME 12th International Manufacturing Science and Engineering Conference - 2017, vol 4}, author={Jones, J. A. and Lee, Yuan-Shin and Moore, J. Z.}, year={2017} }
 @article{qin_wei_dong_lee_2017, title={Direct Printing and Electrical Characterization of Conductive Micro-Silver Tracks by Alternating Current-Pulse Modulated Electrohydrodynamic Jet Printing}, volume={139}, ISSN={["1528-8935"]}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000393881400008&KeyUID=WOS:000393881400008}, DOI={10.1115/1.4033903}, abstractNote={In this paper, a rapid prototyping method for fabrication of highly conductive micropatterns on insulating substrates was developed and evaluated. Sub-20 μm microstructures were printed on flexible insulating substrates using alternating current (AC) modulated electrohydrodynamic jet (e-jet) printing. The presented technique resolved the challenge of current rapid prototyping methods in terms of limited resolution and conductivity for microelectronic components for flexible electronics. Significant variables of fabrication process, including voltage, plotting speeds, curing temperature, and multilayer effect, were investigated to achieve reliable printing of silver tracks. Sub-20 μm silver tracks were successfully fabricated with resistivity about three times than bulk silver on flexible substrates, which indicates the potential applications of electrohydrodynamic printing in flexible electronics and medical applications, such as lab-on-chip systems.}, number={2}, journal={JOURNAL OF MANUFACTURING SCIENCE AND ENGINEERING-TRANSACTIONS OF THE ASME}, author={Qin, Hantang and Wei, Chuang and Dong, Jingyan and Lee, Yuan-Shin}, year={2017}, month={Feb} }
 @article{qin_dong_lee_2017, title={Fabrication and electrical characterization of multi-layer capacitive touch sensors on flexible substrates by additive e-jet printing}, volume={28}, ISSN={["1526-6125"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85020067130&partnerID=MN8TOARS}, DOI={10.1016/j.jmapro.2017.04.015}, abstractNote={Current consumer electronics, in particular touch displays and flexible electronics, were limited by the properties of existing commercial transparent conductor materials used as electrodes both in flat panel display and capacitive touch sensors. In this paper, an alternative fabrication technique using silver nanoink that can be used for rapid prototyping of high-resolution electrode arrays to replace indium tin oxide (ITO) for flexible electronics was presented. By direct printing silver nanoparticles on flexible substrates, capacitive touch sensors were fabricated onto polyethylene terephthalate (PET) film. Experiments were conducted to study the feasibility of electrohydrodynamic inkjet printing (e-jet printing) of high-resolution electrodes for touch sensors. Sensitivity of sub-20 μm capacitance sensor array was investigated in the study for droplet and humidity detection applications. The rapid prototyping method makes a significant impact in enabling simultaneously (1) customized and flexible touch sensors, (2) cost-effective manufacturing, and (3) high resolution and good sensitivity. The presented techniques can be used for the on-demand fabrication of customized conductive patterns for flexible and wearable electronics.}, journal={JOURNAL OF MANUFACTURING PROCESSES}, author={Qin, Hantang and Dong, Jingyan and Lee, Yuan-Shin}, year={2017}, month={Aug}, pages={479–485} }
 @article{cai_moore_lee_2017, title={Novel surgical needle design and manufacturing for vibratory-assisted insertion in medical applications}, volume={14}, ISSN={1686-4360}, url={http://dx.doi.org/10.1080/16864360.2017.1287759}, DOI={10.1080/16864360.2017.1287759}, abstractNote={ABSTRACTThis paper presents a novel design of solid surgical needle featured by its 4-bevel tip and shaft slots with the aim to further explore the potential of vibratory needle insertion for medical applications. The design philosophy was discussed, and a new way of using electric discharging machining (EDM) is introduced for fabricating the new needle design. Two sets of needle prototypes with different geometry parameters were fabricated and used for insertion into porcine skin with ultrasonic vibration. Modal analysis was conducted for the needles under the given vibration condition. The results showed that the needle design could reduce the puncture force by 14.5% at maximum than the 12.2% of control. The reduction of puncture force was found to be related to the axial displacement or the combination of axial and transverse displacement. The effects of geometry parameters on transverse displacement were also discussed. The presented new design and manufacturing techniques can be used for surgical too...}, number={6}, journal={Computer-Aided Design and Applications}, publisher={CAD Solutions, LLC}, author={Cai, Yi and Moore, Jason and Lee, Yuan-Shin}, year={2017}, month={Apr}, pages={833–843} }
 @article{zhang_starly_cai_cohen_lee_2017, title={Particle learning in online tool wear diagnosis and prognosis}, volume={28}, ISSN={["1526-6125"]}, DOI={10.1016/j.jmapro.2017.04.012}, abstractNote={Automated Tool condition monitoring is critical in intelligent manufacturing to improve both productivity and sustainability of manufacturing operations. Estimation of tool wear in real-time for critical machining operations can improve part quality and reduce scrap rates. This paper proposes a probabilistic method based on a Particle Learning (PL) approach by building a linear system transition function whose parameters are updated through online in-process observations of the machining process. By applying PL, the method helps to avoid developing a complex closed form formulation for a specific tool wear model. It increases the robustness of the algorithm and reduces the time complexity of computation. The application of the PL approach is tested using experiments performed on a milling machine. We have demonstrated one-step and two-step look ahead tool wear state prediction using online indirect measurements obtained from vibration signals. Additionally, the study also estimates remaining useful life (RUL) of the cutting tool inserts.}, journal={JOURNAL OF MANUFACTURING PROCESSES}, author={Zhang, Jianlei and Starly, Binil and Cai, Yi and Cohen, Paul H. and Lee, Yuan-Shin}, year={2017}, month={Aug}, pages={457–463} }
 @article{cai_starly_cohen_lee_2017, title={Sensor Data and Information Fusion to Construct Digital-twins Virtual Machine Tools for Cyber-physical Manufacturing}, volume={10}, ISSN={2351-9789}, url={http://dx.doi.org/10.1016/J.PROMFG.2017.07.094}, DOI={10.1016/J.PROMFG.2017.07.094}, abstractNote={This paper presents sensor data integration and information fusion to build “digital-twins” virtual machine tools for cyber-physical manufacturing. Virtual machine tools are useful for simulating machine tools’ capabilities in a safe and cost-effective way, but it is challenging to accurately emulate the behavior of the physical tools. When a physical machine tool breaks down or malfunctions, engineers can always go back to check the digital traces of the “digital-twins” virtual machine for diagnosis and prognosis. This paper presents an integration of manufacturing data and sensory data into developing “digital-twins” virtual machine tools to improve their accountability and capabilities for cyber-physical manufacturing. The sensory data are used to extract the machining characteristics profiles of a digital-twins machine tool, with which the tool can better reflect the actual status of its physical counterpart in its various applications. In this paper, techniques are discussed for deploying sensors to capture machine-specific features, and analytical techniques of data and information fusion are presented for modeling and developing “digital-twins” virtual machine tools. Example of developing the digital-twins of a 3-axis vertical milling machine is presented to demonstrate the concept of modeling and building a digital-twins virtual machine tool for cyber-physical manufacturing. The presented technique can be used as a building block for cyber-physic manufacturing development.}, journal={Procedia Manufacturing}, publisher={Elsevier BV}, author={Cai, Yi and Starly, Binil and Cohen, Paul and Lee, Yuan-Shin}, year={2017}, pages={1031–1042} }
 @article{singh_angrish_barkley_starly_lee_cohen_2017, title={Streaming Machine Generated Data to Enable a Third-Party Ecosystem of Digital Manufacturing Apps}, volume={10}, ISSN={2351-9789}, url={http://dx.doi.org/10.1016/J.PROMFG.2017.07.093}, DOI={10.1016/J.PROMFG.2017.07.093}, abstractNote={The digital factory of the future will be driven by the integration of physical smart machine tools and cyber-enabled software, working seamlessly to increase manufacturing intelligence, flexibility, agility and production efficiency. The objective of this study is develop and demonstrate a middleware software architecture to interface physical machines on a shop floor with client manufacturing applications. We have connected both legacy and modern ‘smart’ machines to a highly scalable database capable of storing streaming time-series data generated by on-board sensors and machine controllers. Three client applications were developed to demonstrate the mechanism through which third-party apps can be written without direct physical communications with machines on the shop-floor. The first, is an application that resides within the Digital Manufacturing Commons (DMC) which demonstrates the ability to query data from any physical machine on the floor; the 2nd application demonstrates a python app which compares digital product data with machine generated data; and the 3rd application demonstrates building a LabView app built to interface with the middleware service. This proposed architecture enables an ecosystem of smart manufacturing applications to be built and deployed on the shop-floor through open-sourced software and hardware devices thereby reducing cost of manufacturing software development.}, journal={Procedia Manufacturing}, publisher={Elsevier BV}, author={Singh, Shaurabh and Angrish, Atin and Barkley, James and Starly, Binil and Lee, Yuan-Shin and Cohen, Paul}, year={2017}, pages={1020–1030} }
 @article{cai_moore_lee_2017, title={Thin-slots Machining of Compliant Needles for Vibration-assisted Medical Insertion}, volume={10}, ISSN={2351-9789}, url={http://dx.doi.org/10.1016/J.PROMFG.2017.07.012}, DOI={10.1016/J.PROMFG.2017.07.012}, abstractNote={This paper presents a geometric analysis modeling and control of micro-slots manufacturing for compliant needles fabrication and biomedical applications. In medical applications, the insertion accuracy of medical needles is closely related with the insertion forces encountered during the relative motion between needle and tissue. This paper presents a new design of compliant needle featured by 4-bevel tip and shaft slots for vibratory needle insertion, whose capability in reducing insertion force has been demonstrated in our earlier works. The effects of the design variables of the slots on needle tip vibration pattern are studied using harmonic analysis with a focus on slot width and slot depth. This paper presents a method of using harmonic analysis to identify the effects of the design variables of the slots on needle tip vibration pattern with a focus on slot width and slot depth. Based on the analysis results, an analytical model is presented and validated for accurate calculation of slot depth in the EDM-based (electrical discharge machining) fabrication process. To use slot width to fine tune the tip vibration, a methodology involving additional electrode motions after initial slot cutting is proposed to increase slot width. This paper provides practical design and manufacturing guidance for vibration-assisted medical insertion devices. Examples and experimental results are presented in the paper for demonstration and validation. The presented geometric analysis model and manufacturing techniques can be used for micro-slots fabrication and biomedical applications.}, journal={Procedia Manufacturing}, publisher={Elsevier BV}, author={Cai, Yi and Moore, Jason Z. and Lee, Yuan-Shin}, year={2017}, pages={392–406} }
 @article{barnett_jones_lee_moore_2016, title={Compliant Needle Vibration Cutting of Soft Tissue}, volume={138}, ISSN={["1528-8935"]}, DOI={10.1115/1.4033690}, abstractNote={This work investigates the performance of a novel compliant needle for cutting tissue. The novel cutting geometry transfers axial vibration to transverse motion at the tip. The cutting edge of the geometry is defined in terms of the time-dependent inclination and rake angle. Finite element analysis was performed to determine the compliant geometry effect on the axial vibration modes of the needles. An ultrasonic transducer is used to apply the axial vibration. An ultrasonic horn was developed to increase the amplitude of vibration. Experiments were performed to determine the effectiveness of the compliant needle geometry. The motion of the compliant needle is measured with a stereomicroscope. The two compliant geometries developed transverse motion of 4.5 μm and 16.0 μm. The control needle with fixed geometry developed no measured transverse motion. The insertion force was recorded for two different compliant geometries and a control geometry inserted into a polyurethane sheet. The puncture force of the control needle with applied vibration and the two compliant needles was up to 29.5% lower than the control insertion without applied vibration. The compliant needles reduced the friction force up to 71.0%. The significant reduction of the friction force is explained by the compliant needles' ability to create a larger crack in the material because of their transverse motion.}, number={11}, journal={JOURNAL OF MANUFACTURING SCIENCE AND ENGINEERING-TRANSACTIONS OF THE ASME}, author={Barnett, Andrew C. and Jones, Justin A. and Lee, Yuan-Shin and Moore, Jason Z.}, year={2016}, month={Nov} }
 @inproceedings{qin_cai_dong_lee_2016, title={Direct printing of capacitive touch sensors on flexible substrates by additive e-jet printing with silver nanoinks}, volume={139}, DOI={10.1115/msec2016-8740}, abstractNote={In this paper, techniques of direct printing of capacitive touch sensors on flexible substrates are presented. Capacitive touch sensors were fabricated by using electrohydrodynamic inkjet (E-jet) printing onto flexible substrates. Touch pad sensors can be achieved with optimized design of silver nanoink tracks. An analytical model was developed to predict touch pad capacitance, and experiments were conducted to study the effects of sensor design (e.g. number of electrodes, electrode length, and electrode distance) on the capacitance of printed coplanar capacitance touch sensors. Details of the fabrication techniques were developed to enable rapid prototype flexible sensors with simple structure and good sensitivity. The presented techniques can be used for the on-demand fabrication of different conductive patterns for flexible electronics with high-resolution and good transparency.}, number={3}, booktitle={Proceedings of the ASME 11th International Manufacturing Science and Engineering Conference, 2016, vol 1}, author={Qin, H. T. and Cai, Y. and Dong, Jingyan and Lee, Yuan-Shin}, year={2016} }
 @article{barnett_lee_moore_2016, title={Fracture Mechanics Model of Needle Cutting Tissue}, volume={138}, ISSN={["1528-8935"]}, DOI={10.1115/1.4030374}, abstractNote={This work develops a needle insertion force model based on fracture mechanics, which incorporates the fracture toughness, shear modulus, and friction force of the needle and tissue. Ex vivo tissue experiments were performed to determine these mechanical tissue properties. A double insertion of the needle into the tissue was utilized to determine the fracture toughness. The shear modulus was found by applying an Ogden fit to the stress–strain curve of the tissue achieved through tension experiments. The frictional force was measured by inserting the needle through precut tissue. Results show that the force model predicts within 0.2 N of experimental needle insertion force and the fracture toughness is primarily affected by the needle diameter and needle edge geometry. On average, the tearing force was found to account for 61% of the total insertion force, the spreading force to account for 18%, and the friction force to account for the remaining 21%.}, number={1}, journal={JOURNAL OF MANUFACTURING SCIENCE AND ENGINEERING-TRANSACTIONS OF THE ASME}, author={Barnett, Andrew C. and Lee, Yuan-Shin and Moore, Jason Z.}, year={2016}, month={Jan} }
 @inproceedings{cai_moore_lee_2016, title={Intricate geometric design and manufacturing on vibration-assisted needles for medical applications}, DOI={10.1115/msec2016-8743}, abstractNote={This paper presents a unique design of solid surgical needle featured by its 4-plane bevel tip and shaft slots with the aim to further explore the potential of vibratory needle insertion for medical applications. The design philosophy of the needle was introduced. To overcome the challenging issues faced in fabricating the designed needles, a non-traditional manufacturing process using electric discharging machining (EDM) for the tip and slots is presented. Two important parameters for needle cutting edges, the inclination angle and the included angle, were derived from the two fabrication variables of the bevel angle and the interval angle. Needle prototypes of the proposed design were fabricated with different geometries, and they are used to conduct several different experiments. In the first experiment, the needles were inserted into tissue phantom, and the friction slope was chosen as the performance criterion. In the second experiment, the testing medium was skin-mimicking polyurethane sheet, and the puncture force and depth were used to evaluate the performance. In both experiments, different vibration conditions of frequency-amplitude combinations (250Hz-5μm, 250Hz-50μm and 1500Hz-5μm) were applied in terms of frequency and amplitude. The preliminary results showed both weakness and potentials of the proposed design, and indicated the necessity for more experiments. Experiments and results to validate the presented method are also presented. The design and manufacturing techniques presented in this paper can be used for the design and development of surgical needles and cutters for engineering and medical applications.}, booktitle={Proceedings of the ASME 11th International Manufacturing Science and Engineering Conference, 2016, vol 2}, author={Cai, Y. and Moore, J. and Lee, Yuan-Shin}, year={2016} }
 @inproceedings{kong_lee_2015, title={Analytical modeling of ultrasonic vibration assisted drilling of bones for medical surgical applications}, DOI={10.1115/msec2015-9488}, abstractNote={This paper presents a new analytical modeling of ultrasonic vibration assisted drilling of bones for medical surgery operations. Due to the heterogeneous bone structure and the uneven bone surface, bone surgery cutting suffers from inaccuracy and difficulty in high precision bone surgery cutting. In this paper, a new method of ultrasonic vibration assisted drilling is proposed for bone surgery cutting. An analytical force modeling is presented for ultrasonic vibration assisted bone drilling. Experimental result validates the analytical modeling presented in the paper. Preliminary testing result also shows a significant improvement of drilling accuracy based on the proposed ultrasonic vibration assisted bone drilling. The proposed cutting techniques can be used in bone cutting surgery to increase the accuracy of born drilling position and reduce trauma damage of bone and surrounding soft tissues.}, booktitle={Proceedings of the ASME 10th International Manufacturing Science and Engineering Conference, 2015, vol 2}, author={Kong, F. X. and Lee, Yuan-Shin}, year={2015} }
 @article{wei_qin_chiu_lee_dong_2015, title={Drop-on-demand E-jet printing of continuous interconnects with AC-pulse modulation on highly insulating substrates}, volume={37}, ISSN={["1878-6642"]}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000367698200008&KeyUID=WOS:000367698200008}, DOI={10.1016/j.jmsy.2014.07.005}, abstractNote={In this paper, we present a novel AC-pulse modulated electrohydrodynamic (EHD) jet printing technology that enables high resolution fabrication of electrical features and interconnects using the silver nanoink on highly insulating substrates. In traditional EHD jet printing, the remained charge of the printed droplets changes the electrostatic field distribution and interrupts the follow-on printing behavior, especially for highly insulating substrates having a slow charge decay rate. In this paper, a modulated AC-pulsed voltage was used for the EHD jet printing process that can alternate the charge polarity of the consequent droplets to neutralize the residue charge on the substrate. The effect of the residue charge is minimized, which enables high resolution printing of continuous patterns. With three printing parameters (e.g. pulse frequency, voltage, and duration), the EHD jet printing speed and droplet size can be controlled independently. We demonstrated that AC-pulse modulated EHD jet printing can overcome the charge accumulation challenge on highly insulating substrates, and investigated the variables of fabrication process to achieve reliable jet printing of conductive silver tracks.}, journal={JOURNAL OF MANUFACTURING SYSTEMS}, author={Wei, Chuang and Qin, Hantang and Chiu, Chia-Pin and Lee, Yuan-Shin and Dong, Jingyan}, year={2015}, month={Oct}, pages={505–510} }
 @article{qin_dong_lee_2015, title={ELECTROHYDRODYNAMIC JET PRINTING OF SILVER SEEDS: MICRO SCALE PATTERNING BY ELECTROLESS COPPER DEPOSITION}, ISBN={["978-0-7918-5682-6"]}, DOI={10.1115/msec2015-9487}, abstractNote={The paper describes a new method for micro scale patterning of highly conductive features on flexible and flat surfaces. The method uses electrohydrodynamic jet printing to deposit silver seeds on-demand that serve as catalysts for subsequent electroless deposition of copper. The electroless deposition of copper on substrates occurred only where silver seeds exist. In the study, ethylenediaminetetraacetic acid (EDTA) and triethanolamine (TEA) were used as chelating agents, and formaldehyde as reducing agent. Copper growth rate and resistivity were investigated using microscopic and profilometer to determine optimal concentration of each agents in reaction solution. The results indicated that EDTA significantly affects copper growth rate, playing an important role in complexing, while TEA in the dual-complexing system will balance deposition rate and stability of solution. Optimal temperature and time for copper deposition on silver nanoparticles were also discussed in the study. The techniques of activating substrates by selective printing and electroless metallization was successfully used to pattern on glass, and flexible polymer films, and both flat and curved substrates were used. The proposed technique was also capable of fabricating metal structures on flexible substrates with excellent conductivity. Metal filaments with resistivity four times bulk copper and thickness up to 15μm were demonstrated in the research.}, journal={PROCEEDINGS OF THE ASME 10TH INTERNATIONAL MANUFACTURING SCIENCE AND ENGINEERING CONFERENCE, 2015, VOL 1}, author={Qin, Hantang and Dong, Jingyan and Lee, Yuan-Shin}, year={2015} }
 @article{qin_wei_dong_lee_2014, title={DIRECT FABRICATION OF HIGHLY CONDUCTIVE MICRO SILVER TRACKS USING ELECTROHYDRODYNAMIC JET PRINTING FOR SUB-20 mu M MICRO-MANUFACTURING}, volume={2}, ISBN={["978-0-7918-4581-3"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84908429027&partnerID=MN8TOARS}, DOI={10.1115/msec2014-4163}, abstractNote={This paper presents a direct fabrication method of highly conductive silver tracks with sub-20 μm microstructures on glass substrate by using electrohydrodynamic jet printing (EHDJP) with alternative current (AC) voltage. Traditional ink jet printing fabrication approaches are limited in the achievable resolution. EHDJP has been used in directly printing by generating a fine jet through a large electrical potential between nozzle and substrate. When charge accumulates on the ink meniscus at the nozzle, a fine jet down to nano scale can be generated. In the paper, we successfully applied EHDJP for fabrication of highly conductive silver tracks using AC voltage. It was the first time that sub-20 μm silver tracks were demonstrated and printed with resistivity about 3.16 times than bulk silver. The variables of fabrication process were investigated to achieve reliable jet printing of conductive silver tracks. The topography of printed tracks was characterized and verified in the study. The presented technique can be used for micro-manufacturing of three-dimensional microstructures and biomedical device fabrications.}, journal={PROCEEDINGS OF THE ASME 9TH INTERNATIONAL MANUFACTURING SCIENCE AND ENGINEERING CONFERENCE, 2014, VOL 2}, author={Qin, Hantang and Wei, Chuang and Dong, Jingyan and Lee, Yuan-Shin}, year={2014} }
 @article{kaber_tupler_clamann_gil_zhu_swangnetr_jeon_zhang_qin_ma_et al._2014, title={Evaluation of an Augmented Virtual Reality and Haptic Control Interface for Psychomotor Training}, volume={26}, ISSN={["1949-3614"]}, DOI={10.1080/10400435.2013.800923}, abstractNote={This study investigated the design of a virtual reality (VR) simulation integrating a haptic control interface for motor skill training. Twenty-four healthy participants were tested and trained in standardized psychomotor control tasks using native and VR forms with their nondominant hands in order to identify VR design features that might serve to accelerate motor learning. The study was also intended to make preliminary observations on the degree of specific motor skill development that can be achieved with a VR-based haptic simulation. Results revealed significant improvements in test performance following training for the VR with augmented haptic features with insignificant findings for the native task and VR with basic haptic features. Although performance during training was consistently better with the native task, a correspondence between the VR training and test task interfaces led to greater improvement in test performance as reported by a difference between baseline and post-test scores. These findings support use of VR-based haptic simulations of standardized psychomotor tests for motor skill training, including visual and haptic enhancements for effective pattern recognition and discrete movement of objects. The results may serve as an applicable guide for design of future haptic VR features.}, number={1}, journal={ASSISTIVE TECHNOLOGY}, author={Kaber, David and Tupler, Larry A. and Clamann, Michael and Gil, Guk-Ho and Zhu, Biwen and Swangnetr, Manida and Jeon, Wooram and Zhang, Yu and Qin, Xiaofeng and Ma, Wenqi and et al.}, year={2014}, pages={51–60} }
 @article{wei_qin_ramirez-iglesias_chiu_lee_dong_2014, title={High-resolution ac-pulse modulated electrohydrodynamic jet printing on highly insulating substrates}, volume={24}, ISSN={["1361-6439"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84897548526&partnerID=MN8TOARS}, DOI={10.1088/0960-1317/24/4/045010}, abstractNote={This paper presents a new high-resolution ac-pulse modulated electrohydrodynamic (EHD)-jet printing technology on highly insulating substrates for drop-on-demand fabrication of electrical features and interconnects using silver nanoink. In traditional EHD-jet printing, the remained charge of the printed droplets changes the electrostatic field distribution and interrupts the follow-on printing behavior, especially for highly insulating substrates which have slow charge decay rates. The residue charge makes the control of EHD-jet printing very challenging for high-resolution continuous features. In this paper, by using modulated ac-pulsed voltage, the EHD-jet printing process switches the charge polarity of the consequent droplets to neutralize the charge on the substrate. The effect of the residue charge is minimized, which enables high-resolution printing of continuous patterns. Moreover, by modulating the pulse frequency, voltage, and duration, the EHD-jet printing behavior can be controlled with respect to printing speed/frequency and droplet size. Printing frequency is directly controlled by the pulse frequency, and the droplet dimension is controlled by the voltage and the duration of the pulse. We demonstrated that ac-pulse modulated EHD-jet printing can overcome the long-predicated charge accumulation problem on highly insulating substrates, and potentially be applied to many flexible electronics applications.}, number={4}, journal={JOURNAL OF MICROMECHANICS AND MICROENGINEERING}, author={Wei, Chuang and Qin, Hantang and Ramirez-Iglesias, Nakaira A. and Chiu, Chia-Pin and Lee, Yuan-shin and Dong, Jingyan}, year={2014}, month={Apr} }
 @inbook{kim_cho_kim_lee_kim_2014, place={Cham, Switzerland}, series={Lecture Notes in Computer Science}, title={How Similar Are Quasi-, Regular, and Delaunay Triangulations in ℝ3?}, ISBN={9783319091280 9783319091297}, ISSN={0302-9743 1611-3349}, url={http://dx.doi.org/10.1007/978-3-319-09129-7_29}, DOI={10.1007/978-3-319-09129-7_29}, abstractNote={Voronoi diagrams and quasi-triangulations are powerful for solving spatial problems among spherical particles with different radii. However, a quasi-triangulation can be a non-simplicial complex due to anomaly conditions. While quasi-triangulation is straightforward to use when it is a simplicial complex, it may not seem so if it is not. In this paper, we report the experimental statistics of showing the phenomena related with two fundamental issues: i) How frequently anomalies occur in the quasi-triangulation of the arrangement of spherical atoms in ℝ3 and ii) how much similar or dissimilar the three related structures (i.e., the quasi-triangulation, the regular triangulation, and the Delaunay triangulation of an atomic arrangements) are. The observations from the experiments are as follows: i) Anomalies occur extremely rarely in molecular structures and occur very rarely even in random sphere sets, and ii) the three dual structures of a given set of spheres are not similar.}, booktitle={Computational Science and Its Applications – ICCSA 2014}, publisher={Springer International Publishing}, author={Kim, Donguk and Cho, Youngsong and Kim, Jae-Kwan and Lee, Yuan-Shin and Kim, Deok-Soo}, editor={Murgante, B.Editor}, year={2014}, pages={381–393}, collection={Lecture Notes in Computer Science} }
 @inbook{lee_qin_prim_cai_2013, place={Singapore}, title={Data and Information Fusion for Bio-Medical Design and Bio-Manufacturing Systems}, ISBN={9789814451970 9789814451987}, url={http://dx.doi.org/10.1007/978-981-4451-98-7_177}, DOI={10.1007/978-981-4451-98-7_177}, booktitle={Proceedings of the Institute of Industrial Engineers Asian Conference 2013}, publisher={Springer}, author={Lee, Yuan-Shin and Qin, Xiaofeng and Prim, Peter and Cai, Yi}, editor={Lin, Y.K. and Tsao, Y.C. and Lin, S.W.Editors}, year={2013}, pages={1513–1520} }
 @article{nguyen_choi_lee_han_2013, title={Optimal design of a new 3D haptic gripper for telemanipulation, featuring magnetorheological fluid brakes}, volume={22}, ISSN={0964-1726 1361-665X}, url={http://dx.doi.org/10.1088/0964-1726/22/1/015009}, DOI={10.1088/0964-1726/22/1/015009}, abstractNote={In this research work, a new configuration of a 3D haptic gripper for telemanipulation is proposed and optimally designed. The proposed haptic gripper, featuring three magnetorheological fluid brakes (MRBs), reflects the rolling torque, the grasping force and the approach force from the slave manipulator to the master operator. After describing the operational principle of the haptic gripper, an optimal design of the MRBs for the gripper is performed. The purpose of the optimization problem is to find the most compact MRB that can provide a required braking torque/force to the master operator while the off-state torque/force is kept as small as possible. In the optimal design, different types of MRBs and different MR fluids (MRFs) are considered. In order to obtain the optimal solution of the MRBs, an optimization approach based on finite element analysis (FEA) integrated with an optimization tool is used. The optimal solutions of the MRBs are then obtained and the optimized MRBs for the haptic gripper are identified. In addition, discussions on the optimal solutions and performance of the optimized MRBs are given.}, number={1}, journal={Smart Materials and Structures}, publisher={IOP Publishing}, author={Nguyen, Q H and Choi, S B and Lee, Y S and Han, M S}, year={2013}, pages={015009} }
 @inproceedings{kim_narayan_lee_2012, title={Analytical modeling and excimer laser micromachining of microchannel for medical devices development}, DOI={10.1115/imece2010-40985}, abstractNote={In this paper, an analytical modeling of microchannel design and manufacturing with excimer laser micromachining is presented for medical devices development. Micro/Nano fabrication methods have made possible the creation of extremely tiny structures and systems which cannot be generated using traditional manufacturing processes. Current fabrication methods of microchannels generally require serial fabrication processes including a masking process. To overcome the drawbacks of current methods, we propose to use excimer laser micromachining to directly create microfluidic structures. Parametric study of laser machining was conducted before fabrication of microfluidic systems on polyethylene. An analytic modeling of the laser micromachining is presented to predict the machined microstructures and the surface finish. The liquid flow was visualized and studied using fluorescent dye and the velocity was measured to compare liquid behavior in each channel. The presented techniques can be used for the design and manufacturing of micro-scale medical devices development.}, booktitle={Proceedings of the ASME International Mechanical Engineering Congress and Exposition 2010, vol 3, pts A and B}, author={Kim, E. and Narayan, R. J. and Lee, Yuan-Shin}, year={2012}, pages={1037–1047} }
 @article{kaber_li_clamann_lee_2012, title={Investigating Human Performance in a Virtual Reality Haptic Simulator as Influenced by Fidelity and System Latency}, volume={42}, ISSN={["1558-2426"]}, DOI={10.1109/tsmca.2012.2201466}, abstractNote={The objective of this study was to demonstrate the utility of an established model of human motor behavior for assessing the fidelity of a virtual reality (VR) and haptic-based simulation for fine motor task performance. This study was also to serve as a basis for formulating general performance-based simulator-design guidelines toward balancing perceived realism with simulator limitations, such as latency resulting from graphic and haptic renderings. A low-fidelity surgical simulator was developed as an example VR for study, and user performance was tested in a simplified tissue-cutting task using a virtual scalpel. The observed aspect of the simulation included a discrete-movement task under different system-lag conditions and settings of task difficulty. Results revealed user performance in the VR to conform with Fitts' law of motor behavior and for performance to degrade with increasing task difficulty and system time lag. In general, the findings of this work support predictions on human performance under various simulator-design conditions using an established model of motor-control behavior and formulation of human-performance-based simulator-design principles.}, number={6}, journal={IEEE TRANSACTIONS ON SYSTEMS MAN AND CYBERNETICS PART A-SYSTEMS AND HUMANS}, author={Kaber, David B. and Li, Yingjie and Clamann, Michael and Lee, Yuan-Shin}, year={2012}, month={Nov}, pages={1562–1566} }
 @inproceedings{wongwiwat_narayan_lee_2012, title={Laser micromachining modeling and laser machined surface errors prediction for biomedical applications}, DOI={10.1115/msec2012-7370}, abstractNote={This paper presents an analytical modeling and laser micromachining technique of microchannel and micro-structures for bio-devices manufacturing and biomedical applications. The ablation of the laser micromachining with direct-write method has been modeled and simulated for micro-channels or microstructures in bio-devices microfabrication. In this paper, the analytical model was adapted from the linear function for beam propagation in our previous research by using the Gaussian function to improve modeling accuracy. Basically, the new laser ablation model based on Gaussian distribution, beam propagation modeling and Beer’s law were used to formulate and model the laser ablation phenomenon. After the simulation with MATLAB programming, the actual experiment on laser micromachining has been conducted to compare the simulated results with the actual ones. Finally, the purposed modeling technique can be applied in the surface error analysis and biomedical applications. The example case in this paper showed how the modeling could solve the complex phenomenon of the overlapping in laser micromachining.}, booktitle={Proceedings of the ASME International Manufacturing Science and Engineering Conference, 2012}, author={Wongwiwat, P. and Narayan, R. J. and Lee, Yuan-Shin}, year={2012}, pages={59–68} }
 @article{park_cho_chung_lee_jeon_2012, title={Modeling and grinding large sculptured surface by robotic digitization}, volume={26}, ISSN={1738-494X 1976-3824}, url={http://dx.doi.org/10.1007/S12206-012-0520-6}, DOI={10.1007/S12206-012-0520-6}, number={7}, journal={Journal of Mechanical Science and Technology}, publisher={Springer Science and Business Media LLC}, author={Park, J. W. and Cho, H. U. and Chung, C. W. and Lee, Y. S. and Jeon, D. J.}, year={2012}, month={Jul}, pages={2087–2091} }
 @inproceedings{wongwiwat_narayan_lee_2011, title={Improving biocompatibily of laser micromachined silicon wafer by surface coating with poly(ethylene glycol) diacrylate and diamond-like carbon for biomedical devices}, DOI={10.1115/msec2010-34283}, abstractNote={This paper presents a study of laser micromachining and the effect of the micromachined regions on the biocompatibility in the protein adsorption for medical devices applications. From the study, the surface roughness on the micromachined area promoted the protein adsorption so it probably causes the thrombus formation for the application in the cardiovascular or blood related devices. In contrast, this incident can enhance the cell promotion that is helpful for the biomedical implant MEMS devices. To modify the surface property in biocompatibility, both Diamond-like carbon (DLC) coating and Poly ethylene glycol diacrylate (PEGDA), the protein resistant and biocompatible materials, were proposed in this research. The UV lithography for coating PEGDA and Pulse laser deposition for coating DLC on the laser micromachined substrates were applied while the coated substrates were biocompatibility tested with the Bovine Serum Albumin (BSA) to observe the protein adsorption. To image the quantity of adsorption, the fluorescein labeled BSA was used for fluorescent microscope to clearly image the reflective light. This study proposed a good opportunity for major novel techniques such as laser micromachining, PLD and UV lithography in developing and prototyping biocompatible MEMS devices.}, booktitle={Proceedings of the ASME International Manufacturing Science and Engineering Conference 2010, vol 2}, author={Wongwiwat, P. and Narayan, R. J. and Lee, Yuan-Shin}, year={2011}, pages={273–280} }
 @article{lin_narayan_lee_2010, title={Hybrid client–server architecture and control techniques for collaborative product development using haptic interfaces}, volume={61}, ISSN={0166-3615}, url={http://dx.doi.org/10.1016/j.compind.2009.07.004}, DOI={10.1016/j.compind.2009.07.004}, abstractNote={In this paper, a collaborative product development and prototyping framework is proposed by using distributed haptic interfaces along with deformable objects modeling. Collaborative Virtual Environment (CVE) is a promising technique for industrial product development and virtual prototyping. Network control problems such as network traffic and network delay in communication have greatly limited collaborative virtual environment applications. The problems become more difficult when high-update-rate haptic interfaces and computation intensive deformable objects modeling are integrated into CVEs for intuitive manipulation and enhanced realism. A hybrid network architecture is proposed to balance the computational burden of haptic rendering and deformable object simulation. Adaptive artificial time compensation is used to reduce the time discrepancy between the server and the client. Interpolation and extrapolation approaches are used to synchronize graphic and haptic data transmitted over the network. The proposed techniques can be used for collaborative product development, virtual assembly, remote product simulation and other collaborative virtual environments where both haptic interfaces and deformable object models are involved.}, number={1}, journal={Computers in Industry}, publisher={Elsevier BV}, author={Lin, Shiyong and Narayan, Roger J. and Lee, Yuan-Shin}, year={2010}, month={Jan}, pages={83–96} }
 @article{doraiswamy_crombez_shen_lee_narayan_2010, title={Inkjet Printing of Cyanoacrylate Adhesive}, volume={86}, ISSN={0021-8464 1545-5823}, url={http://dx.doi.org/10.1080/00218460903417651}, DOI={10.1080/00218460903417651}, abstractNote={In this study, we have demonstrated the use of piezoelectric inkjet printing to fabricate microscale patterns of Vetbond® n-butyl cyanoacrylate tissue adhesive. Optical microscopy, atomic force microscopy, nanoindentation, and a cell viability assay were used to examine the structural, mechanical, and biological properties of microscale cyanoacrylate patterns. The ability to rapidly fabricate microscale patterns of medical and veterinary adhesives will enable reduced bond lines between tissues, improved tissue integrity, and reduced toxicity. We envision that piezoelectric inkjet deposition of cyanoacrylates and other medical adhesives may be used to enhance wound repair in microvascular surgery.}, number={1}, journal={The Journal of Adhesion}, publisher={Informa UK Limited}, author={Doraiswamy, Anand and Crombez, Rene and Shen, Weidian and Lee, Yuan-Shin and Narayan, Roger J.}, year={2010}, month={Jan}, pages={1–9} }
 @article{doraiswamy_crombez_shen_lee_narayan_2010, title={Microscale Patterning of Two-Component Biomedical Hydrogel}, volume={86}, ISSN={0021-8464 1545-5823}, url={http://dx.doi.org/10.1080/00218460903417875}, DOI={10.1080/00218460903417875}, abstractNote={In this study, piezoelectric inkjet technology was used for microscale patterning of a two-component medical hydrogel (sold under the registered trademark Coseal®). A MEMS-based piezoelectric actuator was used to control the flow of polyethylene glycol in a sodium phosphate/sodium carbonate solution through inkjet nozzles. A hydrogen chloride solution was subsequently used to cross-link the polyethylene glycol material. Optical microscopy, scanning electron microscopy, atomic force microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and nanoindentation studies were performed to examine the structural, chemical, and mechanical properties of the inkjetted hydrogel material. Scanning electron micrographs revealed that the inkjetted material exhibited randomly oriented cross-linked networks. Fourier transform infrared spectroscopy revealed that the piezoelectric inkjet technology technique did not alter chemical bonding in the material. Piezoelectric inkjet printing of medical hydrogels may improve wound repair in next generation eye surgery, fracture fixation, and wound closure devices.}, number={1}, journal={The Journal of Adhesion}, publisher={Informa UK Limited}, author={Doraiswamy, Anand and Crombez, Rene and Shen, Weidian and Lee, Yuan-Shin and Narayan, Roger J.}, year={2010}, month={Jan}, pages={62–71} }
 @article{boehm_gittard_byrne_doraiswamy_wilker_dunaway_crombez_shen_lee_narayan_2010, title={Piezoelectric inkjet printing of medical adhesives and sealants}, volume={62}, ISSN={1047-4838 1543-1851}, url={http://dx.doi.org/10.1007/S11837-010-0109-4}, DOI={10.1007/s11837-010-0109-4}, number={7}, journal={JOM}, publisher={Springer Science and Business Media LLC}, author={Boehm, Ryan D. and Gittard, Shaun D. and Byrne, Jacqueline M. H. and Doraiswamy, Anand and Wilker, Jonathan J. and Dunaway, Timothy M. and Crombez, Rene and Shen, Weidian and Lee, Yuan-Shin and Narayan, Roger J.}, year={2010}, month={Jul}, pages={56–60} }
 @article{miller_aggarwal_doraiswamy_lin_lee_narayan_2009, title={Laser micromachining for biomedical applications}, volume={61}, ISSN={["1047-4838"]}, DOI={10.1007/s11837-009-0130-7}, number={9}, journal={JOM}, author={Miller, Philip R. and Aggarwal, Ravi and Doraiswamy, Anand and Lin, Yi Jen and Lee, Yuan-Shin and Narayan, Roger J.}, year={2009}, month={Sep}, pages={35–40} }
 @article{chiou_lee_2007, title={Five-Axis High Speed Machining of Sculptured Surfaces by Surface-Based NURBS Path Interpolation}, volume={4}, ISSN={1686-4360}, url={http://dx.doi.org/10.1080/16864360.2007.10738498}, DOI={10.1080/16864360.2007.10738498}, abstractNote={AbstractThis paper presents a new surface-based NURBS path interpolation for 5-axis high speed machining (HSM) of sculptured surfaces. Detailed formulation of the new time-parameter NURBS path interpolation is proposed to convert the NURBS part surface into time-variable parameterized tool paths for 5-axis sculptured surface machining. Based on the machine configurations, the surfacebased NURBS path interpolation directly derives the pivot point location and the spindle orientation to control the machine motion. With the proposed new method, the traditional chordal and linearization deviation errors in 5-axis NC machining can be reduced. Computer implementations and illustrative examples are also presented in this paper. The presented techniques can be used in the CAD/CAM systems and the NC controllers for 5-axis high speed machining of sculptured surfaces.}, number={5}, journal={Computer-Aided Design and Applications}, publisher={CAD Solutions, LLC}, author={Chiou, John C. J. and Lee, Yuan-Shin}, year={2007}, month={Jan}, pages={639–648} }
 @article{lin_lee_narayan_2007, title={Snapping algorithm and heterogeneous bio-tissues modeling for medical surgical simulation and product prototyping}, volume={2}, ISSN={1745-2759 1745-2767}, url={http://dx.doi.org/10.1080/17452750701487941}, DOI={10.1080/17452750701487941}, abstractNote={This paper presents a novel technique for modeling soft biological tissues as well as the development of an innovative interface for bio-manufacturing and medical applications. Heterogeneous deformable models may be used to represent the actual internal structures of deformable biological objects, which possess multiple components and non-uniform material properties. Both heterogeneous deformable object modeling and accurate haptic rendering can greatly enhance the realism and fidelity of virtual reality environments. In this paper, a tri-ray node snapping algorithm is proposed to generate a volumetric heterogeneous deformable model from a set of object interface surfaces between different materials. A constrained local static integration method is presented for simulating deformation and accurate force-feedback based on the material properties of a heterogeneous structure. Biological soft tissue modeling is used as an example to demonstrate the proposed techniques. By integrating the heterogeneous deformable model into a virtual environment, users can both observe different materials inside a deformable object as well as interact with it by touching the deformable object using a haptic device. The presented techniques can be used for surgical simulation, bio-product design, bio-manufacturing, and medical applications.}, number={2}, journal={Virtual and Physical Prototyping}, publisher={Informa UK Limited}, author={Lin, Shiyong and Lee, Yuan-Shin and Narayan, Roger J.}, year={2007}, month={Jun}, pages={89–101} }
 @article{lai-yuen_lee_2006, title={Interactive Computer-Aided Design for Molecular Docking and Assembly}, volume={3}, ISSN={1686-4360}, url={http://dx.doi.org/10.1080/16864360.2006.10738423}, DOI={10.1080/16864360.2006.10738423}, abstractNote={AbstractThis paper presents a computer-aided design system for molecular docking and nanoscale assembly. A lab-built 5-DOF (degree of freedom) haptic device and the driving computational engine have been developed to provide force-torque feedback to the users for computer-aided molecular design (CAMD). The developed haptic force-torque feedback will enable researchers to visualize, touch, manipulate and assemble molecules in a virtual environment. The presented techniques can be used in the computer-aided molecular design to provide the researchers a realtime tool to better understand molecular interactions and to evaluate possible pharmaceutical drugs and nanoscale devices. Computer implementation and illustrative examples are also presented in this paper.}, number={6}, journal={Computer-Aided Design and Applications}, publisher={CAD Solutions, LLC}, author={Lai-Yuen, Susana K. and Lee, Yuan-Shin}, year={2006}, month={Jan}, pages={701–709} }
 @article{lee_chiou_2006, title={Swept Tool Envelope and Machining Potential Field for 5-Axis Sculptured Surface Machining}, volume={3}, ISSN={1686-4360}, url={http://dx.doi.org/10.1080/16864360.2006.10738428}, DOI={10.1080/16864360.2006.10738428}, abstractNote={This paper presents the machining potential field (MPF) and the explicit solutions of swept envelopes for 5-axis sculptured surface machining. The properties of the swept envelopes are analyzed. The results help us realize the geometric matching in tool-tip machining and understand the geometric machinability in tool-side machining. The complement of the swept envelope, which represents the in-process workpiece, is also addressed. It finally presents the swept envelope applications in tool orientation determination, machining interference avoidance, and run-time simulation. When a solid object moves, it creates a three-dimensional swept volume. This swept volume defines a space where is ever occupied by the object during its motion. Anything inside this occupied space is collided with the object, while anything outside the space is collision-free. The swept envelope defines the boundary between the collision and collision-free space. Therefore, the swept envelope plays an important role in a wide variety of geometric applications such as geometric construction, robot workspace configuration, and collision detection (1, 2). Swept envelope computation is usually difficult because of the nonlinearity of the problem. It is generally impossible to obtain closed form expressions for the swept envelope created by objects with arbitrary geometric shapes (1, 3). Fortunately the majority of tool geometry for robots and NC machining is axial symmetry and defined by surfaces of revolution. These tools usually can be decomposed into geometric primitives, such as spheres, tori, cylinders, and cones (4). Due to their simplicity, the swept envelopes of the geometric primitives can be easily determined and explicitly presented. The swept envelopes of the original tools can then be integrated by the swept envelopes of their primitives (5). This paper details the determination of the swept envelope of axial symmetric tools, and its applications. It first analyzes tool geometry and its decomposition of geometric primitives. Then it discusses the tool position and the tool motion. Based on the tool geometry and motion, the explicit solution of the swept envelope is derived. It further analyzes the properties of the swept envelope. The results deduce us how to match the tools with the part geometry, and reveals the machinability of the geometry. The construction of the complement of the swept envelope is also discussed. After illustrating examples in computer applications, we conclude in the final section.}, number={6}, journal={Computer-Aided Design and Applications}, publisher={CAD Solutions, LLC}, author={Lee, Yuan-Shin and Chiou, John C. J.}, year={2006}, month={Jan}, pages={751–760} }
 @article{ren_lai-yuen_lee_2006, title={Virtual prototyping and manufacturing planning by using tri-dexel models and haptic force feedback}, volume={1}, ISSN={1745-2759 1745-2767}, url={http://dx.doi.org/10.1080/17452750500283590}, DOI={10.1080/17452750500283590}, abstractNote={This paper presents a new method of using the tri-dexel volumetric models and a haptics force feedback for virtual prototyping and manufacturing planning. In the proposed method, the initial polyhedral surface model is converted to a tri-dexel volumetric model by using a depth-peeling dexelization algorithm. In the virtual prototyping process, the tri-dexel volumetric model is updated by the swept volume of a moving cutter via a haptic force feedback interface device. A collision detection algorithm is proposed for the virtual sculpting and the pencil-cut planning with real-time haptic force feedback to the users. Tool paths are generated for machining the virtual sculpted parts via the simulation and verification on a virtual CNC machine tool before they are actually machined. Computer implementation and practical examples are also presented in this paper. The proposed method enables the haptic-aided virtual prototyping and manufacturing planning of complex surface parts.}, number={1}, journal={Virtual and Physical Prototyping}, publisher={Informa UK Limited}, author={Ren, Yongfu and Lai-Yuen, Susana K. and Lee, Yuan-Shin}, year={2006}, month={Mar}, pages={3–18} }
 @article{zhu_lee_2005, title={A Visibility Sphere Marching algorithm of constructing polyhedral models for haptic sculpting and product prototyping}, volume={21}, ISSN={["1879-2537"]}, DOI={10.1016/j.rcim.2004.05.002}, abstractNote={This paper presents a Visibility Sphere Marching algorithm of constructing polyhedral models from Dexel volume models for haptic virtual sculpting. Dexel volume models are used as the in-process models representation during interactive modification in a haptic virtual sculpting system. The stock material represented in a Dexel volume model is sculpted into a designed model using a developed haptic sculpting system. The sculpted Dexel volume models are converted to polyhedral surface models in STL format by the proposed visibility sphere marching algorithm. The conversion turns out to be an interesting and challenging problem. The proposed visibility sphere marching algorithm consists of three sub-algorithms: (i) roof and floor covering, (ii) wall-building, and (iii) hole-filling algorithms. The polyhedral surface models converted from the Dexel volume models can then be input to and processed by available computer-aided manufacturing (CAM) or rapid prototyping systems. The presented technique can be used in virtual sculpting, CAD/CAM, numerically controlled machining verification and rapid prototyping.}, number={1}, journal={ROBOTICS AND COMPUTER-INTEGRATED MANUFACTURING}, author={Zhu, WH and Lee, YS}, year={2005}, month={Feb}, pages={19–36} }
 @article{wang_zhang_wang_lee_lu_wang_2005, title={Cutting on triangle mesh: Local model-based haptic display for dental preparation surgery simulation}, volume={11}, DOI={10.1109/tvcg.2005.97}, abstractNote={A new method to realize stable and realistic cutting simulation using an impedance display haptic device and microcomputer is presented in this paper. Material removal or cutting simulation is a critical task in dental preparation surgery simulation. In this paper, a piecewise contact force model is proposed to approximately describe the cutting process. Challenging issues of minimizing the difference between the cutting simulation and haptic contact simulation are analyzed. The proposed contact-based simulation method is developed for a one-dimensional cutting task and can be expanded to three-dimensional cases. Local model-based multirate simulation cutting architecture is proposed and force control of the haptic device is decoupled from the cutting simulation loop, which can both ensure high fidelity of dynamical simulation as well as maintain stability of the haptic device. The cutting operation is realized using spherical and cylindrical shaped tools. An experiment based on the Phantom desktop proves that fidelity in one-dimensional cutting can be realized and stability in three-dimensional cutting can be ensured using the force-filtering method.}, number={6}, journal={IEEE Transactions on Visualization and Computer Graphics}, author={Wang, D. and Zhang, Y. R. and Wang, Y. H. and Lee, Yuan-Shin and Lu, P. J. and Wang, Y.}, year={2005}, pages={671–683} }
 @article{ren_zhu_lee_2005, title={Material side tracing and curve refinement for pencil-cut machining of complex polyhedral models}, volume={37}, ISSN={["1879-2685"]}, DOI={10.1016/j.cad.2004.10.003}, abstractNote={In this paper, a new Material-Side-Tracing method and a pencil-cut curve refinement technique are proposed for 3-axis pencil-cut path generation. Pencil-cut machining has been used to remove remaining material at highly curved regions or corners after the finishing process. Procedures of evaluating and extracting valid pencil-cut points are developed by taking practical cases into account. With the strategy of using material-side information in the tracing process, smooth and clean pencil-cut curves can be generated even if the actual adjacent pencil-cut curves are very close. A technique of pencil-cut curve refinement is presented to overcome the limitation due to the discrete CL-net intervals, and the smooth pencil-cut paths are made complete at sharp corners. Computer implementation and practical examples are also presented in this paper. The proposed techniques can be used in the CAD/CAM systems to generate pencil-cut paths for machining complex polyhedral models.}, number={10}, journal={COMPUTER-AIDED DESIGN}, author={Ren, YF and Zhu, WH and Lee, YS}, year={2005}, month={Sep}, pages={1015–1026} }
 @article{chiou_lee_2005, title={Optimal tool orientation for five-axis tool-end machining by swept envelope approach}, volume={127}, ISSN={["1528-8935"]}, DOI={10.1115/1.2035698}, abstractNote={This paper presents a swept envelope approach to determining the optimal tool orientation for five-axis tool-end machining. The swept profile of the cutter is determined based on the tool motion. By analyzing the swept profile against the part geometry, four types of machining errors (local gouge, side gouge, rear gouge, and global collision) are identified. The tool orientation is then corrected to avoid such errors. The cutter’s swept envelope is further constructed by integrating the intermediate swept profiles, and can be applied to NC simulation and verification. This paper analyzes the properties of the swept profile of a general cutter in five-axis tool-end machining. The relation of the swept profile, the part geometry, the tool motion, and the machining errors is developed. Therefore, the error sources can be detected early and prevented during tool path planning. The analytical results indicate that the optimal tool orientation occurs when the curvature of the cutter’s swept profile matches with the curvature of the local part surface. In addition, the optimal cutting direction generally follows the minimum curvature direction. Computer illustrations and example demonstrations are shown in this paper. The results reveal the developed method can accurately determine the optimal tool orientation and efficiently avoid machining errors for five-axis tool-end machining.}, number={4}, journal={JOURNAL OF MANUFACTURING SCIENCE AND ENGINEERING-TRANSACTIONS OF THE ASME}, author={Chiou, JCJ and Lee, YS}, year={2005}, month={Nov}, pages={810–818} }
 @article{ren_yau_lee_2004, title={Clean-up tool path generation by contraction tool method for machining complex polyhedral models}, volume={54}, ISSN={["1872-6194"]}, DOI={10.1016/j.compind.2003.09.003}, abstractNote={In high performance machining, multiple cutters of different sizes are used for roughing, finishing and clean-up cutting. In this paper, a contraction tool method is proposed to detect gouging and generate clean-up tool paths for machining complex polyhedral models. The proposed contraction tool method utilizes a series of intermediate virtual cutters to search for clean-up boundaries and construct the clean-up tool paths. The constructed clean-up tool paths consist of a set of clean-up CL-curves traced by the intermediate virtual cutters. The techniques presented in this paper can be used in CAD/CAM systems to automatically identify the clean-up regions of polyhedral models and to generate clean-up tool paths. Computer implementation and practical examples are also presented in this paper.}, number={1}, journal={COMPUTERS IN INDUSTRY}, author={Ren, YF and Yau, HT and Lee, YS}, year={2004}, month={May}, pages={17–33} }
 @article{zhu_lee_2004, title={Dexel-based force-torque rendering and volume updating for 5-DOF haptic product prototyping and virtual sculpting}, volume={55}, ISSN={["1872-6194"]}, DOI={10.1016/j.compind.2004.07.003}, abstractNote={This paper presents new techniques of Dexel-based force–torque rendering and volume-updating for haptic virtual sculpting of complex surfaces with a developed 5-DOF (degree of freedom) haptic interface. In the proposed methodology, 5-axis tool motion and analytical tool swept volume are formulated for updating the virtual stock material, which is represented with the Dexel volume model. Based on the tool motion analysis, a Dexel-based collision detection method and a force–torque feedback algorithm are proposed for virtual sculpting. A lab-built 5-DOF force–torque output haptic interface system is developed for the proposed haptic sculpting system. With the proposed methodology, a user can virtually sculpt a volume stock to get an intuitive design by using the haptic interface. From the haptic sculpting system, both the corresponding tool motion of the creative process and the sculpted model can be recorded and output. The output STL models of the haptic sculpting system can be processed for machining planning. Based on the proposed techniques, hardware and software implementation of the haptic sculpting system as well as the illustrative examples are also presented in this paper.}, number={2}, journal={COMPUTERS IN INDUSTRY}, author={Zhu, WH and Lee, YS}, year={2004}, month={Oct}, pages={125–145} }
 @article{ren_lee_2004, title={Explicit Free-form Curve Interpolation and Error Analysis for NC Machining of Complex Surface Models}, volume={1}, ISSN={1686-4360}, url={http://dx.doi.org/10.1080/16864360.2004.10738264}, DOI={10.1080/16864360.2004.10738264}, abstractNote={AbstractThis This paper presents an explicit solution approach to calculate the exact maximal interpolation errors for cubic free-form curves and the offset curves. To solve the maximal interpolation errors, the exact locations of the maximal error points are found by solving polynomial functions explicitly. Compared with conventional approaches, the proposed interpolation method ensures interpolation accuracy and generates fewer interpolation points for free-form curves and their offset curves. The proposed method can be used for high-accuracy curve interpolation and NC tool-path generation in CAD/CAM systems. Computer implementation and practical examples are also presented in this paper.}, number={1-4}, journal={Computer-Aided Design and Applications}, publisher={CAD Solutions, LLC}, author={Ren, Yongfu and Lee, Yuan-Shin}, year={2004}, month={Jan}, pages={243–250} }
 @article{zhu_lee_2004, title={Five-axis pencil-cut planning and virtual prototyping with 5-DOF haptic interface}, volume={36}, ISSN={["1879-2685"]}, DOI={10.1016/j.cad.2004.01.013}, abstractNote={In this paper, techniques of 5-axis pencil-cut machining planning with a 5-DOF (degree of freedom) output haptic interface are presented. Detailed techniques of haptic rendering and tool interference avoidance are discussed for haptic-aided 5-axis pencil-cut tool path generation. Five-axis tool path planning has attracted great attention in CAD/CAM and NC machining. For efficient machining of complex surfaces, pencil-cut uses relatively smaller tools to remove the remaining material at corners or highly curved regions that are inaccessible with larger tools. As a critical problem for 5-axis pencil-cut tool path planning, the tasks of tool orientation determination and tool collision avoidance are achieved with a developed 5-DOF haptic interface. A Two-phase rendering approach is proposed for haptic rendering and force-torque feedback calculation with haptic interface. A Dexel-based volume modeling method is developed for global tool interference avoidance with surrounding components in a 5-axis machining environment. Hardware and software implementation of the haptic pencil-cut system with practical examples are also presented in this paper. The presented technique can be used for CAD/CAM, 5-axis machining planning and virtual prototyping.}, number={13}, journal={COMPUTER-AIDED DESIGN}, author={Zhu, WH and Lee, YS}, year={2004}, month={Nov}, pages={1295–1307} }
 @article{yau_chuang_lee_2004, title={Numerical control machining of triangulated sculptured surfaces in a stereo lithography format with a generalized cutter}, volume={42}, ISSN={["1366-588X"]}, DOI={10.1080/00207540410001671651}, abstractNote={A unified approach to the generation of numerical control tool paths for triangulated sculptured surfaces in a stereo lithography format using a generalized cutter is presented. This is important because the use of a stereo lithography format for representing a computer-aided design model has been widely accepted in industry for quite some time. It is not only just because of an application such as rapid prototyping (RP), which specifically requires the use of it, but also it is due to the fact that complex stereo lithography models can now be created directly by the digitization and reverse engineering process. Although many computer-aided design/computer-aided manufacturing software systems support the translator of stereo lithography files, only a few papers have addressed the issue of numerical control machining directly from a stereo lithography file. A general computing algorithm to generate tool paths by using a generalized automatically programmed tools cutter is presented. It is general in the sense that it can be applied to various cutters including ball, flat and fillet end-mills. To reduce the computation time, an efficient method for the region query of a tessellated mesh is also presented. Simulations as well as real machining examples are given to illustrate the effectiveness of the proposed method.}, number={13}, journal={INTERNATIONAL JOURNAL OF PRODUCTION RESEARCH}, author={Yau, HT and Chuang, CM and Lee, YS}, year={2004}, month={Jul}, pages={2573–2598} }
 @article{joneja_weifeng_lee_2003, title={Greedy tool heuristic approach to rough milling of complex shaped pockets}, volume={35}, ISSN={["0740-817X"]}, DOI={10.1080/07408170390227532}, number={10}, journal={IIE TRANSACTIONS}, author={Joneja, A and Weifeng, Y and Lee, YS}, year={2003}, month={Oct}, pages={953–963} }
 @article{yoon_pottmann_lee_2003, title={Locally optimal cutting positions for 5-axis sculptured surface machining}, volume={35}, ISSN={["1879-2685"]}, DOI={10.1016/S0010-4485(01)00176-2}, abstractNote={The paper presents a local condition for collision-free 5-axis milling of sculptured surfaces. We consider cutter positions, which guarantee local gouging avoidance. This can replace concepts such as ‘cutting profile’ or ‘effective cutting shape’ which are of approximate nature. Based on second order approximations of the machined strip width, we also present locally optimal cutting positions for cutting directions.}, number={1}, journal={COMPUTER-AIDED DESIGN}, author={Yoon, JH and Pottmann, H and Lee, YS}, year={2003}, month={Jan}, pages={69–81} }
 @article{jun_cha_lee_2003, title={Optimizing tool orientations for 5-axis machining by configuration-space search method}, volume={35}, ISSN={["0010-4485"]}, DOI={10.1016/S0010-4485(02)00077-5}, abstractNote={This paper presents a methodology and algorithms of optimizing and smoothing the tool orientation control for 5-axis sculptured surface machining. A searching method in the machining configuration space (C-space) is proposed to find the optimal tool orientation by considering the local gouging, rear gouging and global tool collision in machining. Based on the machined surface error analysis, a boundary search method is developed first to find a set of feasible tool orientations in the C-space to eliminate gouging and collision. By using the minimum cusp height as the objective function, we first determine the locally optimal tool orientation in the C-space to minimize the machined surface error. Considering the adjacent part geometry and the alternative feasible tool orientations in the C-space, tool orientations are then globally optimized and smoothed to minimize the dramatic change of tool orientation during machining. The developed method can be used to automate the planning and programming of tool path generation for high performance 5-axis sculptured surface machining. Computer implementation and examples are also provided in the paper.}, number={6}, journal={COMPUTER-AIDED DESIGN}, author={Jun, CS and Cha, K and Lee, YS}, year={2003}, month={May}, pages={549–566} }
 @article{chiou_lee_2002, title={A machining potential field approach to tool path generation for multi-axis sculptured surface machining}, volume={34}, ISSN={["0010-4485"]}, DOI={10.1016/S0010-4485(01)00102-6}, abstractNote={This paper presents a machining potential field (MPF) method to generate tool paths for multi-axis sculptured surface machining. A machining potential field is constructed by considering both the part geometry and the cutter geometry to represent the machining-oriented information on the part surface for machining planning. The largest feasible machining strip width and the optimal cutting direction at a surface point can be found on the constructed machining potential field. The tool paths can be generated by following the optimal cutting direction. Compared to the traditional iso-parametric and iso-planar path generation methods, the generated MPF multi-axis tool paths can achieve better surface finish with shorter machining time. Feasible cutter sizes and cutter orientations can also be determined by using the MPF method. The developed techniques can be used to automate the multi-axis tool path generation and to improve the machining efficiency of sculptured surface machining.}, number={5}, journal={COMPUTER-AIDED DESIGN}, author={Chiou, CJ and Lee, YS}, year={2002}, month={Apr}, pages={357–371} }
 @article{koc_lee_2002, title={Adaptive ruled layers approximation of STL models and multiaxis machining applications for rapid prototyping}, volume={21}, ISSN={["0278-6125"]}, DOI={10.1016/S0278-6125(02)80159-5}, abstractNote={This paper presents a new method of generating adaptive ruled layers for rapid prototyping (RP) processing of complex parts. To increase the accuracy and reduce the build time, an adaptive ruled layer approximation of the stereolithography (STL) models and multiaxis path planning for rapid prototyping are proposed. In this paper, a new method of constructing ruled layers from slicing STL points is developed to approximate the STL models with better surface accuracy. A technique of surface error analysis is presented to find the maximum errors at different layers of RP parts. By finding the RP surface errors, adaptive ruled layers are generated for the RP process of the STL CAD models. Using the constructed ruled layers of the STL models, the multiaxis material removal process is integrated with traditional RP processes to achieve better surface accuracy and to reduce the total RP build time. Computer implementation and illustrative examples are presented.}, number={3}, journal={JOURNAL OF MANUFACTURING SYSTEMS}, author={Koc, B and Lee, YS}, year={2002}, pages={153–166} }
 @article{kloypayan_lee_2002, title={Material engagement analysis of different endmills for adaptive feedrate control in milling processes}, volume={47}, ISSN={["0166-3615"]}, DOI={10.1016/S0166-3615(01)00136-1}, abstractNote={This paper presents a technique for analyzing the material removal volume when a tool moves in linear, circular, or parametric curved motions. Tool motions of different types of endmilling cutters are considered in this study. By studying the relationship between the cutter geometry and the tool motion, the material removal rates of different cutters are analyzed. The adaptive feedrate can be determined to maintain a constant cutting load. The technique developed in this research can be used for tool path generation in CAD/CAM systems for 2.5D NC machining.}, number={1}, journal={COMPUTERS IN INDUSTRY}, author={Kloypayan, J and Lee, YS}, year={2002}, month={Jan}, pages={55–76} }
 @article{koc_lee_2002, title={Non-uniform offsetting and hollowing objects by using biarcs fitting for rapid prototyping processes}, volume={47}, ISSN={["0166-3615"]}, DOI={10.1016/S0166-3615(01)00141-5}, abstractNote={This paper presents a new method of using non-uniform offsetting and biarcs fitting to hollow out solid objects or thick walls to speed up the part building processes on rapid prototyping (RP) systems. Building a hollowed prototype instead of a solid part can significantly reduce the material consumption and the build time. A rapid prototyped part with constant wall thickness is important for many different applications of rapid prototyping. To provide the correct offset wall thickness, we develop a non-uniform offsetting method and an averaged surface normals method to find the correct offset contours of the stereolithography (STL) models. Detailed algorithms are presented to eliminate self-intersections, loops and irregularities of the offsetting contours. Biarcs fitting is used to generate smooth cross-section boundaries and offset contours for RP processes. Implementation results show that the developed techniques can generate smoothed slicing contours with accuracy for rapid prototyping without suffering from handling the huge number of linear segments of the traditional methods.}, number={1}, journal={COMPUTERS IN INDUSTRY}, author={Koc, B and Lee, YS}, year={2002}, month={Jan}, pages={1–23} }
 @article{chiou_lee_2002, title={Swept surface determination for five-axis numerical control machining}, volume={42}, DOI={10.1016/S0890-6955(02)00110-4}, abstractNote={This paper presents a closed-form solution of the swept profile of a generalized cutter in five-axis numerical control (NC) machining. The machine configurations and tool movements defined in NC programs are considered to model the true machine tool trajectory, which includes the linearly translational and rotational movements. Based on the machine tool trajectory and the cutter geometry, the cutter’s instantaneous swept profile is determined. By integrating the intermediate swept profiles, the cutter’s swept envelope can be constructed and applied to NC verification. The proposed method provides the explicit solution of the swept profile of a generalized cutter, which is important but not possible in the existing methods for five-axis NC verification. The computer implementations show that the approach developed is superior to the traditional methods.}, number={14}, journal={International Journal of Machine Tools & Manufacture}, author={Chiou, C. J. and Lee, Yuan-Shin}, year={2002}, pages={1497–1507} }
 @inbook{fang_chiu_lee_2000, title={Optimal planning of parallel machining operation}, booktitle={Handbook of computational intelligence in design and manufacturing}, publisher={CRC Press}, author={Fang, S.-C. and Chiu, N. C. and Lee, Y. S.}, year={2000} }
 @article{lee_ma_jegadesh_2000, title={Rolling-ball method and contour marching approach to identifying critical regions for complex surface machining}, volume={41}, ISSN={["0166-3615"]}, DOI={10.1016/S0166-3615(99)00042-1}, abstractNote={This paper presents a surface analysis method that includes a rolling-ball algorithm and a contour marching algorithm for identifying the critical regions that are unfeasible for machining. For a given cutter size, the algorithms automatically identify the regions that are unfeasible for machining and dichotomize the surface into the critical region and the machinable region. A rolling-ball method is used to find the starting points of the critical region boundary. A contour marching method is then used to construct the actual boundary of the critical regions by using the starting points found in the rolling-ball method. Different sets of tool paths can be generated for both the machinable region and the critical region. The proposed method allows manufacturing engineers to use different sizes of cutters to machine complex surface parts. Computer implementation and illustrative examples are presented in this paper.}, number={2}, journal={COMPUTERS IN INDUSTRY}, author={Lee, YS and Ma, YW and Jegadesh, G}, year={2000}, month={Mar}, pages={163–180} }
 @article{koc_ma_lee_2000, title={Smoothing STL files by Max-Fit biarc curves for rapid prototyping}, volume={6}, ISSN={["1355-2546"]}, DOI={10.1108/13552540010337065}, abstractNote={Presents a method of Max‐Fit biarc curve fitting technique to improve the accuracy of STL files and to reduce the file size for rapid prototyping. STL file has been widely accepted as a de facto standard file format for the rapid prototyping industry. However, STL format is an approximated representation of a true solid/surface model, and a huge amount of STL data is needed to provide sufficient accuracy for rapid prototyping. Presents a Max‐Fit biarc curve fitting technique to reconstruct STL slicing data for rapid prototyping. The Max‐Fit algorithm progresses through the STL slicing intersection points to find the most efficient biarc curve fitting, while improving the accuracy. Our results show that the proposed biarc curve‐fitting technique can significantly improve the accuracy of poorly generated STL files by smoothing the intersection points for rapid prototyping. Therefore, less strict requirements (i.e. loose triangle tolerances) can be used while generating the STL files.}, number={3}, journal={RAPID PROTOTYPING JOURNAL}, author={Koc, Bahattin and Ma, Yawei and Lee, Yuan-Shin}, year={2000}, pages={186–203} }
 @article{chiou_lee_1999, title={A shape-generating approach for multi-axis machining G-buffer models}, volume={31}, ISSN={["0010-4485"]}, DOI={10.1016/S0010-4485(99)00069-X}, abstractNote={In this paper, a new approach is presented to find the 3D shape-generating profiles of different types of cutters for constructing the G-buffer models for 5-axis machining. The G-buffer for 3-axis machining is natural because the tool has only three degrees of freedom (x,y,z) for the configuration space. Five-axis machining has five degrees of freedom, and two of them are non-Euclidean. The traditional G-buffer method cannot be directly used for 5-axis machining due to the complex tool motions. In this paper, the analytic 3D shape-generating profiles are formulated to construct the swept envelope in 5-axis tool motion. The enhanced G-buffer models are updated by the constructed 5-axis swept envelope. A generalized cutter geometry, which represents different types of endmills, is used in this study. The techniques presented in this paper can be used for 5-axis tool path generation and the machined surface error analysis. Computer implementation and illustrative examples are presented in this paper.}, number={12}, journal={COMPUTER-AIDED DESIGN}, author={Chiou, CJ and Lee, YS}, year={1999}, month={Oct}, pages={761–776} }
 @inproceedings{lee_1999, title={Adaptive tool path planning for 5-axis sculptured surface machining by machining strip evaluation}, booktitle={Machining impossible shapes: IFIP TC5 WG5.3 International Conference on Sculptured Surfaces (SSM98), November 5-11, 1998, Chrysler Technology Center, Michigan}, publisher={Boston: Kluwer Academic}, author={Lee, Y. S.}, editor={G. J. Olling, B. K. Choi and Jerard, R. B.Editors}, year={1999}, pages={351–360} }
 @article{lee_daftari_krishnaswami_1999, title={Application of virtual convex polytope in transforming protrusions for automated process planning}, volume={36}, ISSN={["0360-8352"]}, DOI={10.1016/S0360-8352(99)00002-9}, abstractNote={In this paper, a two-tier methodology for the transformation of protrusion design features to manufacturing features is presented. In the first stage of the proposed algorithm, a method is proposed to encapsulate the protrusions with virtual convex polytope and transform them into a set of negative machining volumes. The design feature model is transformed into the intermediate feature model that consists of machining volumes using the concept of generic virtual pocket. In the second stage, called the feature refinement stage, relevant manufacturing information is appended to the negative machining volumes to transform the intermediate feature model into the manufacturing feature model. The proposed methodology can be used in the feature-based design and manufacturing systems to support automated process planning and machining functions. Practical examples and computer implementation in an object-oriented environment are also presented in this paper.}, number={1}, journal={COMPUTERS & INDUSTRIAL ENGINEERING}, author={Lee, YS and Daftari, DM and Krishnaswami, P}, year={1999}, month={Jan}, pages={67–96} }
 @inbook{chow_lee_trussell_1999, title={Motor incipient fault detection using artificial neural}, DOI={10.1007/978-1-4615-5305-2_12}, booktitle={Computer-aided maintenance: methodologies and practices (Manufacturing systems engineering series ; 5).}, publisher={Dordrecht: Kluwer Academic}, author={Chow, M.-Y. and Lee, Yuan-Shin and Trussell, H. J.}, editor={Lee, J. and Wang, B.Editors}, year={1999}, pages={263–280} }
 @article{chiu_fang_lee_1999, title={Sequencing parallel machining operations by genetic algorithms}, volume={36}, ISSN={["0360-8352"]}, DOI={10.1016/S0360-8352(99)00132-1}, abstractNote={Parallel machines (mill/turn machining centers) provide a powerful and efficient machining alternative to the traditional sequential machining process. The underutilization of parallel machines due to their operating complexity has increased interest in developing an efficient methodology for sequencing the parallel machining operations. This paper presents a mixed integer programming model for sequencing parallel machining operations. A genetic-based algorithm for finding an optimal parallel operation sequence on parallel machines is proposed. Two new genetic operators for solving order-based genetic algorithms and computational experiments are also included.}, number={2}, journal={COMPUTERS & INDUSTRIAL ENGINEERING}, author={Chiu, NC and Fang, SC and Lee, YS}, year={1999}, month={Apr}, pages={259–280} }
 @article{lee_chiou_1999, title={Unfolded projection approach to machining non-coaxial parts on mill-turn machines}, volume={39}, ISSN={["0166-3615"]}, DOI={10.1016/S0166-3615(98)00140-7}, abstractNote={This paper presents a new method to analyze the effective cutting shapes and machined surface errors for mill-turn machining of non-coaxial parts. While the traditional projection methods fail in the mill-turn machining case, the Unfolded Projection Method maps the part surface and the cutter into an unfolded domain (Xu–Yu–Zu) to calculate the critical distance between the part surface and the cutter. The techniques presented in this paper can be used to analyze the machined surface errors and to improve the accuracy of the mill-turn machining processes. Computer implementation and illustrative examples are also presented in this paper.}, number={2}, journal={COMPUTERS IN INDUSTRY}, author={Lee, YS and Chiou, CJ}, year={1999}, month={Jul}, pages={147–173} }
 @article{ma_lees_1998, title={Detection of loops and singularities of surface intersections}, volume={30}, ISSN={["1879-2685"]}, DOI={10.1016/S0010-4485(98)00056-6}, abstractNote={Two surface patches intersecting each other generally at a set of points (singularities), form open curves or closed loops. While open curves are easily located by following the boundary curves of the two patches, closed loops and singularities pose a robustness challenge since such points or loops can easily be missed by any subdivision or marching-based intersection algorithms, especially when the intersecting patches are flat and ill-positioned. This paper presents a topological method to detect the existence of closed loops or singularities when two flat surface patches intersect each other. The algorithm is based on an oriented distance function defined between two intersecting surfaces. The distance function is evaluated in a vector field to identify the existence of singular points of the distance function since these singular points indicate possible existence of closed intersection loops. The algorithm detects the existence rather than the absence of closed loops and singularities. This algorithm requires general C2 parametric surfaces.}, number={14}, journal={COMPUTER-AIDED DESIGN}, author={Ma, YW and Lees, YS}, year={1998}, month={Dec}, pages={1059–1067} }
 @article{lee_koc_1998, title={Ellipse-offset approach and inclined zig-zag method for multi-axis roughing of ruled surface pockets}, volume={30}, ISSN={["0010-4485"]}, DOI={10.1016/S0010-4485(98)00051-7}, abstractNote={This paper presents a new method for 5-axis rough cutting of ruled surface pockets. An inclined zig-zag method is proposed for rough cutting the core material region, and an ellipse-offset method is developed for semi-roughing the residual material regions of ruled surface pockets. The ellipse-offset method is developed to calculate the non-constant offset curves for 5-axis tool path planning of rough cutting. Different from the traditional 21/2D machining method, the developed ellipse-offset method allows the cutter to change its tool orientation and to get as close to the part surface as possible in roughing. The proposed method allows the manufacturing engineers to use 5-axis machining to rough cut the parts to near-finish shape for finishing. Computer implementation and illustrative examples are presented in this paper.}, number={12}, journal={COMPUTER-AIDED DESIGN}, author={Lee, YS and Koc, B}, year={1998}, month={Oct}, pages={957–971} }
 @article{lee_1998, title={Mathematical modelling using different endmills and tool placement problems for 4- and 5-axis NC complex surface machining}, volume={36}, ISSN={["0020-7543"]}, DOI={10.1080/002075498193697}, abstractNote={This paper presents the mathematical methods and algorithms to compute milling cutter placement and machined surface error analysis problems for 4- and 5-axis finished-surface machining. Different types of endmill cutters, such as the torusshaped (filleted) endmill, flat-endmill and sphere-endmill, are used for multi-axis NC machining. A generalized tool description with tool orientation variables for variant types of cutters is developed for 5-axis machining. Methods of finding an instantaneous cutting profile and the local surface geometry to analyse machined surface errors are discussed for cutter location generation. A method of deciding tool orientation to avoid rear tool collision using global geometry information is also presented. The techniques presented in this paper can be used to eliminate errors of milling tool path generation in the area of simultaneous multi-axis NC complex surface machining.}, number={3}, journal={INTERNATIONAL JOURNAL OF PRODUCTION RESEARCH}, author={Lee, YS}, year={1998}, month={Mar}, pages={785–814} }
 @article{lee_1998, title={Non-isoparametric tool path planning by machining strip evaluation for 5-axis sculptured surface machining}, volume={30}, ISSN={["0010-4485"]}, DOI={10.1016/S0010-4485(98)00822-7}, abstractNote={Presented in this paper is a new approach to 5-axis NC tool path generation for sculptured surface machining. Techniques of feasible machining strip evaluation are used for non-isoparametric 5-axis tool path generation. A searching algorithm is proposed to find the parameter increments of adjacent cutter locations along orthogonal path intervals for optimal non-isoparametric path generation. Compared to the use of the smallest path interval by the traditional constant parametric path planning, the proposed methodology can generate efficient tool paths for sculptured surface machining by reducing the redundant overlapping between adjacent tool paths. The proposed methodology includes three steps: (1) evaluating feasible machining strip, (2) solving parameter increments (Δu, Δv) along orthogonal path intervals, and (3) searching for adjacent non-isoparametric cutter locations. The techniques presented in this paper can be used to improve 5-axis machined surface quality and to automate the non-isoparametric cutter path generation for CAD/CAM systems.}, number={7}, journal={COMPUTER-AIDED DESIGN}, author={Lee, YS}, year={1998}, month={Jun}, pages={559–570} }
 @inproceedings{fang_chiu_lee_1998, title={Operation scheduling of mill/turn machining centers with genetic algorithms}, volume={2}, number={1998}, booktitle={Proceedings of the Fourth Joint Conference of Information Sciences. 1998}, author={Fang, S.-C. and Chiu, N. C. and Lee, Y. S.}, year={1998}, pages={437–440} }
 @article{chen_lee_fang_1998, title={Optimal cutter selection and machining plane determination for process planning and NC machining of complex surfaces}, volume={17}, ISSN={["0278-6125"]}, DOI={10.1016/S0278-6125(98)80004-6}, abstractNote={This paper deals with the optimal cutter selection and machining plane determination problems for NC machining and process planning. Two optimization methods, an integer programming (IP) method and a dynamic programming (DP) method, are presented. While the IP method provides an upper bound for such a problem, the DP method provides an optimal solution at the cost of longer computational time. Both methods can be used to automate the traditional, experience-based cutter selection tasks and to reduce the total machining time in NC machining operations. Numerical examples are included to illustrate both methods.}, number={5}, journal={JOURNAL OF MANUFACTURING SYSTEMS}, author={Chen, YH and Lee, YS and Fang, SC}, year={1998}, pages={371–388} }
 @article{lee_1997, title={Admissible tool orientation control of gouging avoidance for 5 axis complex surface machining}, volume={29}, ISSN={["0010-4485"]}, DOI={10.1016/S0010-4485(97)00002-X}, abstractNote={This paper presents a methodology and algorithms of admissible tool orientation control for gouging avoidance in 5-axis machining. A method is proposed to find the admissible tool orientation by considering both local and global surface shapes. A filleted endmill is used in this study for 5-axis machining. Based on the evaluation of local surface shape, a geometry analysis method is developed to first find a feasible tool orientation for gouging avoidance along two orthogonal cutting places. Adjacent geometry is then taken into consideration for detecting possible rear gouging. A localization algorithm is developed for filleted endmills to identify potential rear gouging area. Both the circular approximation, and the detailed gouging checking methods are proposed for rear gouging correction. The techniques presented in this paper can be used to eliminate errors of tool paths as they are generated. Unlike the traditional graphical verification and user-interactive correction of tool path generation, the proposed methodology can be used to automate the planning and programming of cutter path generation for 5-axis machining.}, number={7}, journal={COMPUTER-AIDED DESIGN}, author={Lee, YS}, year={1997}, month={Jul}, pages={507–521} }
 @article{lee_ji_1997, title={Surface interrogation and machining strip evaluation for 5-axis CNC die and mold machining}, volume={35}, ISSN={["0020-7543"]}, DOI={10.1080/002075497196064}, abstractNote={This research is focused on the investigation of robust surface interrogation tools which can support the planning and programming of 5-axis die/mold surface machining. Surface curvature information is evaluated to determine optimal tool orientation for 5-axis machining. A method for calculating machining strip width is proposed for 5-axis cutter path generation. This paper is focused on the development of computational geometry techniques and their application to design, analysis, and manufacturing automation. The proposed planning and programming methodology consists of three phases: (1) surface interrogation; (2) machining strip width evaluation; and (3) optimum tool orientation for 5-axis machining. This proposed research can be used to improve the quality of 5-axis die/mold machining.}, number={1}, journal={INTERNATIONAL JOURNAL OF PRODUCTION RESEARCH}, author={Lee, YS and Ji, H}, year={1997}, month={Jan}, pages={225–252} }
 @article{full professor }