• Journal of the Korean Society for Precision Engineering
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• v.34 no.2
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• pp.95-99
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• 2017

The recent development of core techniques in the IT industry can be summarized as a technical advancement for safety and convenience, and mechanical technology for being "eco-friendly" and lightweight. Under these circumstances, research of lightweight material has become attractive. In this study, CFRP (Carbon Fiber Reinforced Plastic) laminate specimens are subjected to a tensile test using the UTM(Universal Testing Machine, AG-IS 100 kN) to estimate their mechanical properties in terms of the Hole machining impact evaluation. The FEM (Finite Elements Method) analysis method is applied and the material properties obtained from basic experiments such as the Tensile test, the compressive test, and the shear test. CFRP materials properties from a previous study, as well as a finite element analysis program for Hole machining CFRP was compared with the experiments.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.2
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• pp.137-144
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• 2010

In general, spinal fusion surgery takes pressure off the pain induced nerves, by restoring the alignment of the spine. Therefore spinal fixation system is used to maintain the alignment of spine. In this study, a biomechanical study was performed comparing the SROM(Spinal Range Of Motion) of three types of system such as Rigid, Dynesys, and Fused system to analyze the behavior of spinal fixation system inserted in vertebra. Dynesys system, a flexible posterior stabilization system that provides an alternative to fusion, is designed to preserve inter-segmental kinematics and alleviate loading at the facet joints. In this study, SROM of inter-vertebra with spinal fixation system installed in the virtual vertebra from L4 to S1 is estimated. To compare with spinal fixation system, a simulation was performed by BRG. LifeMOD 2005.5.0 was used to create the human virtual model of spinal fixation system. Through this, each SROM of flexion, extension, lateral bending, and axial rotation of human virtual model was measured. The result demonstrates that the movement of Dynesys system was similar to normal condition through allowing the movement of lumbar.

• Journal of the Korean Society for Precision Engineering
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• v.32 no.6
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• pp.517-521
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• 2015

Recent development of core techniques the IT electronics industry can condense into lightweight and slimmer. In this circumstance, researches for the lightweight materials and subminiature screw have been attracted. In this study, the CFRP was produced by stacking angle to obtain the tensile properties. And Comparing the coated screws and non-coated screws on the specimen, and evaluating the adequacy for the application of CFRP using the result. So The clamping force measured by comparison evaluation. Low screw reverse and Superior torque value at each stacking angle were found the optimum conditions, when Subminiature Screw is applied on smart devices. Both tensile strength and stiffness of $[{\pm}0^{\circ}]_{10}$ is the highest. Followed by $[90^{\circ}/0^{\circ}]_{10}$ is the highest. The largest clamping torque is $[90^{\circ}/0^{\circ}]_{10}$ When Subminiature Screw is applied coating and non-coating to prevent loosening. Based on the above, Subminiature Screw should be applied in smart devices, because $[90^{\circ}/0^{\circ}]_{10}$ meet both tensile properties and clamping force.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.9
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• pp.86-94
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• 2007

The design process must be planned carefully and executed systematically in order to support designers who are faced with many engineering design problems. In particular, conceptual design stage is very important than other stages such as detailed design or manufacturing stage on designing engineering systems. When designers are faced contradictory situation in task, conceptual design usually requires inventive thinking which depends on their creativity. And in order to develop good concepts, it is necessary to resolve contradictory situations during conceptual design. This paper presents a structure of systematic conceptual design process for designing engineering systems. And we developed the automatic feeding screw device using the proposed design process structure.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1993.10a
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• pp.37-41
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• 1993

ball screw is a critical machine component which dictates the precison of a given machine tool. The conventional manufacturing method requires the heat treated ball screw to be ground to its final dimensions. This study looks into the the feasibility of replacing the grinding process with a simpler process, namely threading on NC lathe. The purpose is to reduce the capital investment as well as production time in the manufacture of ball screws. Ceramics and CBN cutting tools are compared with respect to their ability to machine hardened steel. It is shown that CBN tools can be successfully utilized to machine precision ball screws with superior suface qualities.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.6 s.183
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• pp.180-186
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• 2006

To investigate the bone remodeling phenomenon around implant device, 3-D mathematical simulation model was developed. Strain energy density from the finite element method was chosen for the indicator for remodeling process. Recursive calculations continued until converged results between FEM and mathematical model. For a osteo-integration example, bone-remodeling process in a implanted tibia of beagle was adapted. Calculated results indicated that the bone densities around screw pitch were increased which indicates firm fixations between the bone and implant. Screw design parameters have an influence on initial stability of the implant rather than remodeling process.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.4 s.97
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• pp.122-128
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• 1999

Bolted joint assembly for nuclear power plants consists of various components : cover plate, retainer plate, manway flange, gasket and stud bolts/nuts. To guarantee the soundness of the joint, it is important to prevent leakage through the gasket and reduce the stress concentration factor at the thread root. In this paper, Submodeling technique for the finite element method is proposed to accurately compute three dimensional contact stresses which govern the sealing performance and the maximum contact stresses at the threads root. For verification of global solutions used as boundary conditions of submodel solution, the stresses on the cover plate and the manway flange are measured by strain gages when internal pressure is applied to the bolted joint assembly. The numerical results are compared with the experimental results.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.05a
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• pp.271-271
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• 2004

다양한 목적으로 개발이 요구되는 로봇의 작업환경과 운동능력에 맞게 로봇을 개발하기 위해서는 다음의 설계 과정을 필요로 한다. 하나, 로봇의 전체 설계 중 개념설계/기초설계로 로봇링크의 길이나, 작업영역에 대한 설계 변수를 결정하는 로봇 기구설계. 둘, 로봇 상세설계로 작업을 실행하는데 필요한 운동능력에 대한 설계 변수를 결정하는 로봇 동역학 설계. 셋, 로봇 기구, 동역학 설계를 기초로 하여 로봇이 최적의 성능을 발휘할 수 있는 로봇 부품들에 대한 요소품 설계가 있다.(중략)

• Journal of Dental Rehabilitation and Applied Science
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• v.26 no.4
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• pp.419-432
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• 2010

Various torque generating devices have been developed and employed to apply a proper torque. These devices are usually calibrated by the manufacturer to apply appropriate torque levels for their specific implants and attachments. The purpose of this investigation was to determine and compare the accuracy of the torque controllers. In this study, 4 types of torque controllers were used; torque limiting device(TLD), torque indicating device(TID) and contra angle torque driver(CA), electronic torque controller(ETC). Digital torque gauge was employed to measure the de-torque value. Thirty cycles of tightening and loosening were repeated with each torque controller. All implant torque controllers have shown slight errors and deviations. The contra angle torque driver exhibited the most accurate data. In the limitation of this study, it would be recommended that the implant torque controllers should be checked whether uniformed and precise torque can be generated and a measuring error should be corrected.

• Journal of the Korean Society for Precision Engineering
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• v.33 no.6
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• pp.491-497
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• 2016

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.