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최성대(Seong-Dae Choi),이미나(Mi-Na Lee) 한국기계가공학회 2014 한국기계가공학회지 Vol.13 No.3
The purpose of this study is to develop a manpower training program of technological development. The types of developed manpower training models are education about the technological development process, literacy education about technological development, and field experience. The education about the technological development process is accomplished through industry-university cooperation based on shared technical concerns. Literacy education about technological development includes information about essential methods for manpower education. Field experience involves the development of effective teaching plans.
최성대(Seong-Dae Choi),정선환(Seon-Hwan Cheong),권현규(Hyun-Kyu Kwon),정영관(Young-Kwan Jeong),홍영배(Yong-Bae Hong) 한국산업융합학회 2007 한국산업융합학회 논문집 Vol.10 No.4
Glass-to-metal contact should be prevented in the design of any structural glass component. Because glass is extremely brittle and will fracture readily if even a small point load is applied. If the assembly includes a glass component supported by metallic structure, designers should provide a pliable interface of some kind between the two parts. But there happens high demand of glass-to metal contact in semiconductor industries due to adoption of dry cleaning process as one of the good solution to reduce running cost - carry out equipments cleaning with high corrosive and etching gas such as CF4 with keeping process temperature as the same as high service temperature. Therefore the quartz glass have to be received compression by direct contact with metal as the form of weight itself and vacuum pressure and fatigue by vibrations caused by process during the process. In this paper investigation will be carried out on fracture behavior of quartz glass contacted with metal directly under local load and fatigue given by process vibration with apparatus which can give lox\cal load and vibration through PZT ceramics to give guideline to prevent unintended fracture of quartz glass.
최성대(Seong-Dae Choi),정선환(Seon-Hwan Cheong),김기만(Gi-Man Kim),변용근(Yong-Kun Byun),김잠규(Jam-Gyu Kim),양승철(Seung-Cheol Yang) 한국생산제조학회 2007 한국공작기계학회 춘계학술대회논문집 Vol.2007 No.-
Industrial technology has been used to surface hardening method to improve the surface. Shot peening is the one of the surface hardening method and it is used for removing the defect from the surface of steel and improving the fatigue strength on surface. The object of this research work is to investigate the influence of mechanical property by shot peening of hinge spring throughout the experimental method on roughness, hardness, creep, fatigue test and photography. From the result of the this paper, shot peening is improved the surface hardness, heating resistance, fatigue strength of hinge spring and has examined that shot peening is essential requirement to design the hinge spring.
최성대(Seong-Dae Choi),정선환(Seon-Hwan Cheong),김기만(Gi-Man Kim),양승철(Seung-Cheol Yang),김잠규(Jam-Gyu Kim) 한국기계가공학회 2007 한국기계가공학회지 Vol.6 No.3
An experimental investigation with diode laser system was carried out to study the effect of surface heat treatment on the die materials(SM45C, SKD11, SK3). The surface heat treatment characteristics of the laser beam are evaluated using hardness tests, optical microscopy, X-ray diffraction and energy dispersive X-ray spectroscopy(EDS). Results indicated that the beam size, focal length, feed rates are changed surface hardened characteristics. SM45C is higher hardness than other materials and composed to martensite grain at hardened zone, whereas other materials(SKD11, SK3)are low hardness than expected and composed to austenite and allayed martensite at hardened zone. The intensive X-ray diffraction patterns of (110)-(200)-(211) is detected hardened surface and the hardened surface distributed plenty of carbon density than metal zone.
최성대(Seong-Dae Choi),정선환(Seon-Hwan Cheong),권현규(Hyun-Gyu Kwon),전재목(Jae-Mock Jun),최명수(Myeong-Soo Choi),양승철(Seung-Cheol Yang) 한국생산제조학회 2007 한국공작기계학회 춘계학술대회논문집 Vol.2007 No.-
Glass cutting is a fundamental step in sizing the substrate needed for FPD and should produce a cut with good edge quality. Recently, laser cutting and scribe wheel cutting method has used to cut glass substrate However, both of methods have occurred some problems. For example laser cutting occurred thermal shock, thermal defeat edge of section in cutting process the wheel cutting method occurred cracks and sharp edges of sections in cutting process. This study provided the required flexibility to implement the laser and scribe wheel cutting process on the glass substrates. Data acquisition, data management, instrument control and motion control performed on a single platform(the PC)allowed the relatively easier implementation of test to determine the appropriate sets of condition to cut glass substrates successfully. Union cutting system(laser+scribe wheel)was performed on glass substrates and it can be cutting successfully on soda-lime glass.
최성대(Seong-Dae Choi),정선환(Seon-Hwan Cheong),김잠규(Jam-Kyu Kim),최명수(Myoung-Su Choi),공병채(Byeong-Chae Gong) 한국기계가공학회 2009 한국기계가공학회 춘추계학술대회 논문집 Vol.2009 No.6
The complicated stress modes which are common in most machine structures and parts make the analysis of fracture mechanism The fracture mechanism which are common in most machine structures and parts shows mixed-mode stress. It is very difficult to analyze its behavior using numerical method. In this study, the experiment of fatigue crack growth as varying of stress ratio was carried out and its effects was analyzed. And existence of fatigue fracture closure was observed through fractured surface.
최성대(Seong-Dae Choi),정선환(Seon-Hwan Cheong),김기만(Gi-Man Kim),양승철(Seung-Cheol Yang),김잠규(Jam-Gyu Kim) 한국기계가공학회 2007 한국기계가공학회 춘추계학술대회 논문집 Vol.2007 No.-
An experimental investigation with diode laser system was carried out to study on the improvement of thin sheet structure characteristics. The surface heat treatment characteristics of the laser beam on the thin sheet are evaluated using hardness tests, tensile test. The mechanical properties of hardening area indicated such as 877Hv hardness, 345㎬ elastic modulus and 774㎫ tensile strength compare to the low material. We were carried out structure characteristics of thin sheet by laser bean using ANSYS 11.0. Results indicated that the structure characteristics were improving value such as stress and displacement according to the increasing of irradiated laser beam times on the thin sheet. The direction of cross section on the thin sheet was improving structure characteristics more than axial direction and longitudinal direction.
최성대 ( Seong-dae Choi ),정선환 ( Seon-hwan Cheong ),정영관 ( Young-kwan Jeong ),김기만 ( Gi-man Kim ),홍영배 ( Yong-bae Hong ) 한국산업융합학회 2007 한국산업융합학회 논문집 Vol.10 No.3
Quartz glass are used in semiconductor industries as the reaction furnace, wafer carrier and accessaries. During the process the quartz glass received compression by direct contact with other quartz glass ware and metal as the form of weight itself and vacuum pressure and fatigue by vibrations caused by process. Even as the other ceramic materials quartz glass have high compressive strength but often there happened crack and breakage of quartz glass resulted in a great damage in the process. In this paper investigation will be carried out on fracture behavior of quartz glass under local load to give guideline to prevent unintended fracture of quartz glass.
최성대(Seong-Dae Choi),정선환(Seon-Hwan Cheong),권현규(Hyun-Kyu Kweon),김기만(Gi-Man Kim),김잠규(Jam-Kyu Kim) 한국기계가공학회 2007 한국기계가공학회지 Vol.6 No.3
The overlay welding the automobile where the durability is demanded, it is used in the vessel engine valve, plant valve and pump parts. Cause of damage public opinion one what is thought is the fatigue load due to the opening and shutting operation right time repetition of the engine valve. The damage cause of the engine valve or explanation of destruction mechanism is very difficult. The research which it sees to make clear a overlay welding of Co-alloy by Plasma Transferred Arc Weld Surfacing Process reconsideration fatigue crack initiation and fatigue crack growth mechanism at high temperature.