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LIGA 금형몰드를 이용한 Fe-Ni계 나노분말의 초미세 가스베어링 제조
손수정,조영상,김대종,김종현,장석상,최철진,Son, Soo-Jung,Cho, Young-Sang,Kim, Dae-Jung,Kim, Jong-Hyun,Chang, Suk-Sang,Choi, Chul-Jin 한국분말야금학회 2012 한국분말재료학회지 (KPMI) Vol.19 No.2
This paper describes the manufacturing process of tilting pad gas bearing with a diameter of 5 mm and a length of 0.5-1 mm for power MEMS (Micro Electomechanical Systems) applications. The bearing compacts with nanopowder feedstock were prepared by Ni-metal mold with 2-mold system using LIGA process. The effect of the manufacturing conditions on sintering properties of nanopowder gas bearing was investigated. In this work, Fe-45 wt%Ni nanopowder with an average diameter of 30-50 nm size was used as starting material. After mixing the nanopowder and the wax-based binders, the amount of powder was controlled to obtain the certain mixing ratio. The nanopowder bearing compacts were sintered with 1-2 hr holding time under hydrogen atmospheres and under temperatures of $600^{\circ}C$ to $1,000^{\circ}C$. Finally, the critical batch of mixed powder system was found to be 70% particle fraction in total volume. The maximum density of the sintered bearing specimen was about 94% of theoretical density.
김종현(Jong-Hyun Kim),장석상(Suk-Sang Chang) 한국기계가공학회 2007 한국기계가공학회 춘추계학술대회 논문집 Vol.2007 No.-
At the micro scale, there are many machining technologies for fabrication of precise devices and structures. However, as industries' demands for precision and accuracy are getting higher, the conventional machining method is no more available and a novel methode to satisfy these needs strictly is necessary. We propose next generation micro-machining technology using synchrotron radiation x-ray. Compared to the existing other method, it has excellent features such as high accuracy, low side-wall roughness, variety of material and subminiature feature size. We developed x-ray machining tools and equipment to be able to apply actually in industry. For this study, we have investigated optimum x-ray machining facility and process condition. In addition, we fabricated several precision device like vacuum electron device, micro-mold and other micro structures.
마이크로 밀링과 X-선 리소그래피 공정을 이용한 다층 마이크로 구조물 제작 공정 개발
김종현(Jong Hyun Kim),장석상(Suk Sang Chang),임근배(Geunbae Lim) Korean Society for Precision Engineering 2014 한국정밀공학회지 Vol.31 No.3
Conventional machining technologies such as a milling process have limitations in accuracy to fabricate microstructures. Deep X-ray lithography using the synchrotron radiation is a promising micromachining process with an excellent accuracy, whereas there are difficulties in the fabrication of multi-layered structures. Therefore, it is mainly used for fabricating simple monolayered microstructures with a high aspect ratio. In this study, a novel technology for fabricating multi-layered microstructures is proposed by combining two processes. In advance, an X-ray resist material is cut and machined into various shapes and heights by the micro milling process. Subsequent X-ray irradiation process facilitates the fabrication of multi-layered microstructures. The proposed technology can overcome the limitation of the pattern accuracy in conventional milling process and the difficulty of the multi-layered machining in x-ray process. The usefulness of the proposed technology is demonstrated in this study by applying the technique in the realization of various multi-layered microstructures.
Time-Average Holographic Interferometry에 依한 悲調和振動의 解析
李起白,張錫相 부산대학교 공과대학 1983 硏究報告 Vol.26 No.-
An equation describing the reconstruction holographic images of object in state of non-sinsoidal vibration is obtained from consideration of characteristic functions for time-average holography. Applications to the measurement of motion for the special case of vibration are presented together with several experimental results.