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최병기,이동길,최병희,Choi, Byung-Ky,Lee, Dong-Gil,Choi, Byung-Hui 한국생산제조학회 2010 한국생산제조학회지 Vol.25 No.3
Metal Injection Molding (MIM) is attractive because it produces consistent, complex-geometry components for high-volume, high-strength, and high-performance applications. Also MIM using in optical communication field, display field, and semi-conductor field is a cost-effective alternative to metal machining or investment casting parts. It offers tremendous single-step parts consolidation potential and design flexibility. The objective of this paper is to study the suitability of design, flow analysis, debinding and sinterin processes, and capability analysis. The suitable injection conditions were 0.5~1.5 second filling time, 11.0~12.5 MPa injection pressure derived from flow analysis. The gravity of the product is measured after debinding an sintering. The maximum and minimum gravity levels are 7.5939 and 7.5097. the average and standard deviation are 7.5579 and 0.0122; when converted into density, the figure stands at 98.154%. According to an analysis of overall capacity, PPM total, which refers to defect per million opportunities(DPMO), stands at 166,066.3 Z.Bench-the sum of defect rates exceeding the actual lowest and highest limits-is 0.97, which translates into the good quality rate of around 88.4% and the sigma level of 2.47.
Ni-Co 합금강의 기계적 특성에 대한 탄소함량의 영향
최병기(Byung-Ky Choi),장경천(Kyeung-Cheun Jang),최병희(Byung-Hui Choi),이기안(Kee-Ahn Lee) 한국생산제조학회 2006 한국생산제조학회지 Vol.15 No.5
This study was to evaluate the effect of carbon content on metallic change and fatigue characteristics with Fe-29%Ni-17%Co, low heat expansion alloy, widely using electronic components, precision machines, and sealing with glass and metal etc. The steels were fabricated with variation of carbon content, 0, 0.03, 0.06, 0.1, and 0.20% with VIM and tensile test and fatigue test were performed to achieve the above purpose. The more carbon content, the higher hardness value and yield strength. But elongation of 0.03%C, 0.06%C, and 0.10%C specimen decreased about 2.2%, 1.5% and 0.8% respectively more than that of the base metal. Especially the strength and elongation of 0.20%C specimen increased simultaneously about 14.4% and 7.5%. Fatigue life of 0.03%C specimen decreased but the more carbon content, the higher fatigue life over 0.06% carbon content more than that of base metal.
Multi-Color Chip-LED용 어레이 렌즈 개발에 관한 연구
최병기(Byung-Ky Choi),장경천(Kyeung-cheun Jang),이동길(Dong-Gil Lee) 한국생산제조학회 2007 한국생산제조학회지 Vol.16 No.3
The purpose of this research is to enhance the luminance of the LED and to improve the implementation of color by mounting an array lens on the LED without special technology in process. The workmanship of key components considering the economical efficiency and the injection molding technology for high quality of the product are essential to achieve it. In this paper, the mold was computer-aided was designed and manufactured by CAM software(NX4) and high speed machining center. the applied final machining conditions were 3,000-5,000㎜/min feed speed, 15,000-25,000rpm and Φ0.3㎜ ball end-mill. And the Flow analysis was performed using the mold flow software(MPI) in order to get uniformity of resin. Injection conditions acquired by the flow analysis and the injection experiment are as follows. The cylinder temperature is 220-260℃, the mold temperature is 70-80℃, the injection time is about 1.2sec, the injection pressure and velocity is each 7.8-14.7㎫, and the injection velocity is 0.8-1.2m/sec.
최병기(Byung-ky Choi),이동길(Dong-gil Lee),최병희(Byung-hui Choi) 한국생산제조학회 2010 한국생산제조학회지 Vol.19 No.1
Metal Injection Molding (MIM) is attractive because it produces consistent, complex-geometry components for high-volume, high-strength, and high-performance applications. Also MIM using in optical communication field, display field, and semi-conductor field is a cost-effective alternative to metal machining or investment casting parts. It offers tremendous single-step parts consolidation potential and design flexibility. The objective of this paper is to study the suitability of design, flow analysis, debinding and sinterin processes, and capability analysis. The suitable injection conditions were 0.5~1.5 second filling time, 11.0~12.5 MPa injection pressure derived from flow analysis. The gravity of the product is measured after debinding an sintering. The maximum and minimum gravity levels are 7.5939 and 7.5097. the average and standard deviation are 7.5579 and 0.0122; when converted into density, the figure stands at 98.154%. According to an analysis of overall capacity, PPM total, which refers to defect per million opportunities(DPMO), stands at 166,066.3 Z.Bench-the sum of defect rates exceeding the actual lowest and highest limits-is 0.97, which translates into the good quality rate of around 88.4% and the sigma level of 2.47.
ATOS 80 고장력강의 보호가스량에 따른 용접부 방사선검사에 관한 연구
백정환(Jung-Hwan Baek),최병기(Byung-Ky Choi) 한국생산제조학회 2012 한국생산제조학회지 Vol.21 No.6
In constructing all kinds of equipment and steel structures, discontinuous areas such as weld defects formed in a welded structure tend to generate cracks that will result in damage. In this study, ATOS high-strength steel welding becomes important in butt welding where the tensile strength of the steel is over 80kg/mm2. Structural discontinuities such as joints are more susceptible cracks in part due to their repeated loading and fatigue crack growth. The quality of parts produced depend or the shielded amounts of steel and on the skill of the welders in making strong welds. It is true that there are many factors that can be used to generate a lot of research in this area. However geometry and load conditions due to the combined effects with many issues could be solved through this study. Butt welding material at a plate thickness of 12t in ATOS 80 high-strength steel with a 4 pass, 20l/min, 24V/200A welder is good at making specimens with the quality shown in radiographic testing.
ATOS 80 고장력강의 용접 패스에 따른 용접부 방사선검사에 관한 연구
백정환(Jung-Hwan Baek),최병기(Byung-Ky Choi) 한국생산제조학회 2012 한국생산제조학회지 Vol.21 No.6
In constructing all kinds of equipment and steel structure, parts with discontinuities such as weld defects formed in the welded structure can generate fatigue cracks that results in damage or accidents. In this study, weld zones are investigated with X-rays and the latent images are put on film. Weld zone defects can be verified by developing the film. As weld defects are investigated by radiographic testing and correlated with the welding condition, more appropriate welding conditions can be found. According to the result of X-ray radiographic inspection of butt welding ATOS 80 high-strength steel with a thickness of 12 ㎜, the best conditions for welding without creating weld defects are 4 weld-passes, a protective gas of 20% CO₂ and 80% Ar, a protective gas flow of 20L/min, a welding current of 200A, an arc voltage of 24V, a welding speed of 14.4 ㎝/min, a welding rod angle of 50°, a welding gap of 5 ㎜ with a ceramic base, and sand pre-heating to 160° Celsius prior to welding.
LPI엔진의 인젝터 클리닝이 배기가스에 미치는 영향 연구
김만재 ( Man-jae Kim ),홍성인 ( Sung-in Hong ),최병기 ( Byung-ky Choi ) 조선대학교 공학기술연구원 2016 공학기술논문지 Vol.9 No.3
Domestic vehicles using LPG as a fuel are decreased. In Europe and the advanced country, support from governments has been made because vehicles using LPG are classified as alternative fuel vehicles. Fuel supply system of vehicles using LPG uses the same method as in gasoline engines. This experiments were carried out the vehicle exhaust gas inspection method enforced by the Korea Transportation Safety Authority. Exhaust gas(HC, CO, NOx) of LPI vehicles was analyzed the generated component of the before and after of injector cleaning. Exhaust gas of LPI vehicles using LPG was analyzed the impact on the environment.
김만재 ( Man-jea Kim ),김태중 ( Tae-jung Kim ),최병기 ( Byung-ky Choi ) 조선대학교 공학기술연구원 2018 공학기술논문지 Vol.11 No.4
Exhaust gas from the combustion of automobiles adversely affects the human body and even pollutes the atmosphere. This study investigated the influence of exhaust gas change on intake manifold using the nozzle. First, the flow analysis was performed using the 3D flow analysis program. When the nozzle inlet air velocity increased, the average air velocity in the nozzle diameters of Φ2.5 and Φ5 increased 37.3% and 31.9% respectively at the intake manifold outlet. As the nozzle inlet air velocity increased, the maximum flow rate of air increased to 42.2% and 32.6%, respectively at nozzle diameters of Φ2.5 and Φ5. In order to verify the analysis results, experiments on the exhaust gas were performed in the engine simulation system. As the nozzle inlet velocity increased, HC values decreased by 42.4% and 31.4% at nozzle diameters of Φ2.5 and Φ5, respectively. And CO values decreased by 40.7% and 31.1% at nozzle diameters of Φ2.5 and Φ5.