The Experts below are selected from a list of 303 Experts worldwide ranked by ideXlab platform
Seung Woo Ra - One of the best experts on this subject based on the ideXlab platform.
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Development of Annular Optics for the Inspection of Surface Defects on Screw Threads Using Ray Tracing Simulation
Journal of the Korean Society for Precision Engineering, 2016Co-Authors: Keun Park, Seung Woo RaAbstract:This study aims to develop a vision inspection system for Screw Threads. To inspect external defects in Screw Threads, the vision inspection system was developed using front light illumination from which bright images can be obtained. The front light system, however, requires multiple side images for inspection of the entire thread surface, which can be performed by omnidirectional optics. In this study, an omnidirectional optical system was designed to obtain annular images of Screw Threads using an image sensor and two reflection mirrors; one large concave mirror and one small convex mirror. Optical simulations using backward and forward ray tracing were performed to determine the dimensional parameters of the proposed optical system, so that an annular image of the Screw Threads could be obtained with high quality and resolution. Microscale surface defects on the Screw Threads could be successfully detected using the developed annular inspection system.
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optical simulation of omnidirectional inspection system for Screw Threads
Key Engineering Materials, 2014Co-Authors: Keun Park, Seung Woo RaAbstract:Machine vision systems have been used in the automatic inspection of Screw Threads using backlight illumination for the inspection of the Screw thread profiles. In this study, an alternative inspection system based on front light illumination is developed to directly obtain thread images so that surface defects can be measured. To realize such an inspection system, an omnidirectional optical measurement device is proposed to obtain 360o images of Screws for inspection of whole thread regions. Optical simulation based on ray tracing is then performed to analyze optical paths and to optimize the image quality of the designed optical system.
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design and analysis of illumination optics for image uniformity in omnidirectional vision inspection system for Screw Threads
Journal of the Korean Society for Precision Engineering, 2014Co-Authors: Keun Park, Seung Woo RaAbstract:Precision Screws have a wide range of industrial applications such as electrical and automotive products. To produce Screw Threads with high precision, not only high precision manufacturing technology but also reliable measurement technology is required. Machine vision systems have been used in the automatic inspection of Screw Threads based on backlight illumination, which cannot detect defects on the thread surface. Recently, an omnidirectional inspection system for Screw Threads was developed to obtain images of Screws, based on front light illumination. In this study, the illumination design for the omnidirectional inspection system was modified by adding a light shield to improve the image uniformity. Optical simulation for various shield designs was performed to analyze image uniformity of the obtained images. The simulation results were analyzed statistically using response surface method, from which optical performance of the omnidirectional inspection system could be optimized in terms of image quality and uniformity.
Jill T. Callaghan - One of the best experts on this subject based on the ideXlab platform.
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Polymer-hydroxyapatite composite versus polymer interference Screws in anterior cruciate ligament reconstruction in a large animal model
Knee Surgery Sports Traumatology Arthroscopy, 2008Co-Authors: John A. Hunt, Jill T. CallaghanAbstract:The aim of the study was to assess the hard tissue response of a composite hydroxyapatite/poly l -lactic acid (HA/PLLA) interference Screw for anterior cruciate ligament (ACL) reconstruction compared to a standard PLLA Screw. Twelve skeletally mature rams underwent unilateral ACL reconstruction using an autologous bone-patellar tendon graft. Each animal received either two test HA/PLLA interference Screws or two control PLLA interference Screws. Animals were sacrificed at 6 and 12 months post-implantation and the operated knees excised. Undecalcified sections of the Screw and surrounding tissues were cut from resin embedded samples and stained; sections were approximately parallel to the longitudinal axis of the Screws. A quantitative assessment of bone formation between each Screw type (PLLA vs. HA/PLLA) and adjacent tissue in both the tibia and femur was undertaken using automated image analysis (KS400, Zeiss, UK). The inflammatory response of each Screw type was assessed by histological evaluation. New bone formation along the perimeter of the Screw Threads was statistically significantly higher with the HA/PLLA than the PLLA alone. The inflammatory response as assessed semi-quantitatively by histologically determining the number of inflammatory cells present in the tissue adjacent to the implant, was higher for PLLA than HA/PLLA. Significantly increased new bone formation and decreased inflammatory cells were observed in vivo with the composite Screw in comparison with the standard polymer. A novel HA/PLLA composite biomaterial in the form of an interference Screw demonstrated an improved hard-tissue response compared to PLLA in a large animal ACL reconstruction. This study determined the differences in the tissue response between PLLA and a composite material of HA/PLLA. The improved tissue related outcomes observed in vivo, may be of benefit clinically in ACL reconstruction.
H S Gill - One of the best experts on this subject based on the ideXlab platform.
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3d printed locking osteosynthesis Screw Threads have comparable strength to machined or hand tapped Screw Threads
Journal of Orthopaedic Research, 2020Co-Authors: Alisdair Macleod, Michael Patterson, Kate Mactear, H S GillAbstract:Additive manufacturing, aka three dimensional (3D) printing, is increasingly being used for personalized orthopedic implants. Additively manufactured components normally undergo further processing, in particular 3D printed locking osteosynthesis plates require post-printing Screw thread creation. The aim of this study was to compare 3D printed Threads with machined and hand-tapped Threads for a locking plate application. Pushout tests were performed on 115 additively manufactured specimens with tapered Screw holes; additive manufacture was performed at 0°, 20°, 45°, or 90° build orientations. The Screw holes were either machined, hand-tapped or 3D printed. The 3D printed Screw holes were left as printed, or run through with a tap lubricated with water or with thread cutting oil. Printed Threads run through using oil, with a build orientation of 90°, had comparable pushout force (median: 6377 N 95% confidence interval [CI]: 5616-7739 N) to machined (median: 6757 N; 95% CI: 6682-7303 N) and hand-tapped (median: 7805 N; 95% CI: 7154-7850 N) Threads. As printed Threads and those run through using water had significantly lower pushout forces. This study shows for the first time that 3D printed Screw Threads for a locking osteosynthesis plate application have comparable strength to traditionally produced Screw Threads.
H Fujita - One of the best experts on this subject based on the ideXlab platform.
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A threaded wobble motor with a 6-pole stator-a micro motor generating large linear displacement
MHS'96 Proceedings of the Seventh International Symposium on Micro Machine and Human Science, 1996Co-Authors: T Iizuka, H FujitaAbstract:This paper deals with the driving principle and the experimental demonstration of a micro motor which can convert rotation into linear motion and generate large displacement. The motor is a wobble type one; its rotor and stators have Screw Threads. When the rotor turns, it moves linearly in the axial direction like a Screw. The range of linear motion is limited only by the length of the rotor. We have fabricated a threaded wobble motor by the electromagnetic actuation and operated it successfully.
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A Threaded Wobble Motor A Micro Motor Generating Large Linear Displacement
Proceedings of the International Solid-State Sensors and Actuators Conference - TRANSDUCERS '95, 1995Co-Authors: H Fujita, T IizukaAbstract:SUMMARY This paper deals with the driving principle and the experimental demonstration of, a micro motor which can convert rotation into linear motion and generate large displacement. The motor is a wobble type one; its rotor and stators have Screw Threads. When the rotor turns, it moves linearly in the axial direction like a Screw. The range of linear motion is limited only by the length of the rotor. The threaded wobble motor can be driven either magnetically or electrostatically. We have fabricated a magnetic version having a rotor of lmm in diameter and operated it successfully.
T Iizuka - One of the best experts on this subject based on the ideXlab platform.
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A threaded wobble motor with a 6-pole stator-a micro motor generating large linear displacement
MHS'96 Proceedings of the Seventh International Symposium on Micro Machine and Human Science, 1996Co-Authors: T Iizuka, H FujitaAbstract:This paper deals with the driving principle and the experimental demonstration of a micro motor which can convert rotation into linear motion and generate large displacement. The motor is a wobble type one; its rotor and stators have Screw Threads. When the rotor turns, it moves linearly in the axial direction like a Screw. The range of linear motion is limited only by the length of the rotor. We have fabricated a threaded wobble motor by the electromagnetic actuation and operated it successfully.
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A Threaded Wobble Motor A Micro Motor Generating Large Linear Displacement
Proceedings of the International Solid-State Sensors and Actuators Conference - TRANSDUCERS '95, 1995Co-Authors: H Fujita, T IizukaAbstract:SUMMARY This paper deals with the driving principle and the experimental demonstration of, a micro motor which can convert rotation into linear motion and generate large displacement. The motor is a wobble type one; its rotor and stators have Screw Threads. When the rotor turns, it moves linearly in the axial direction like a Screw. The range of linear motion is limited only by the length of the rotor. The threaded wobble motor can be driven either magnetically or electrostatically. We have fabricated a magnetic version having a rotor of lmm in diameter and operated it successfully.
