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헬리콘 플라즈마로부터 중성입자 흐름의 생성 및 이를 이용한 실리콘의 건식식각
정석재(S. J. Jeong),양호식(H. S. Yang),조성민(S. M. Cho) 한국진공학회(ASCT) 1998 Applied Science and Convergence Technology Vol.7 No.4
헬리콘(Helicon) 플라즈마로부터 중성입자 흐름을 생성하여 높은 에너지의 이온에 의한 기판의 물리적, 전기적 손상을 방지할 수 있는 실리콘 식각공정이 연구되었다. 기판의 하부에 영구자석을 설치하여 cusp 모양의 자계를 형성하므로써 이온 및 전자를 기판으로부터 제거되도록 하였고 이러한 방법으로 완전히 제거되지 않는 이온의 제거를 위해서 기판 하부에 양의 전압을 가하여 자계나 전계에 영향을 받지 않는 중성입자 흐름을 얻을 수 있도록 하였다. 발생시킨 자계 및 전계에 의해 기판 상부에서의 전자밀도는 자계나 전계가 가해지지 않은 경우에 비해 약 1/1,000 정도로 낮아졌으며, 이온밀도 또한 약 1/10 정도로 감소하였다. 이러한 공정을 통해 얻어진 실리콘의 식각속도는 Cl₂와 10%의 SF_6를 혼합하여 사용할 때 8.5×10^(-4) Torr의 압력에서 약 100 Å/min 이하로 매우 낮았으며 실리콘의 식각이 비등방성을 가지며 진행될 수 있음이 보여졌다. Neutral stream was generated from Helicon plasma source and was applied to etch silicon for the purpose of preventing physical and electrical damages from the bombardment of charged particles with high translation energy. By installing a permanent magnet and applying positive bias beneath the substrate, the cusp-magnetic and electric fields were generated in order to remove the charged particles from the downstream plasma. As a result, the electron density and ion density in the vicinity of the substrate were reduced by 1/1000 and 1/10, respectively. The directional etching of silicon was observed and the etch rate was found to be very low to below 100 Å/min at a pressure of 8.5×10^(-4) Torr, when Cl₂and 10% SF_6 etchant gases were used.
발전기세트 공진 회피를 위한 베이스프레임 최적설계에 관한 연구
정석현(S H Jeong),곽용석(Y S Kwak),김원현(W H Kim) 한국소음진동공학회 2012 한국소음진동공학회 학술대회논문집 Vol.2012 No.4
A structural modification of baseframe is an effective method to avoid resonance in marine diesel generator (D/G) set which consists of diesel engine, generator and baseframe. However the reinforcement with thick plates or additional parts to increase the natural frequency can be less effective because of increased weight. Especially fine control of target mode based on the experience is difficult because the weight and interference of system have to be considered In this paper, the design optimization of baseframe was performed to reduce the resonant vibration using a gradient descent method. The design parameters such as thickness, shape and location of baseframe parts are optimized to increase the torsional natural frequency of D/G set. From the actual test, the new designed baseframe reduced the vibration level in resonance by 55% without any increase of weight and interference.
정석후 ( Seok Hu Jeong ),오경용 ( Kyong Yong Oh ),신동수 ( Dong Su Shin ),최성한 ( Shung Han Choi ),정을식 ( Eul Sik Jung ),박진선 ( Jin Sun Park ),나선영 ( Sun Young Na ),성지윤 ( Ji Yoon Sung ),정지용 ( Ji Yong Jung ),김세중 ( S 대한신장학회 2010 Kidney Research and Clinical Practice Vol.29 No.4
Kaposi`s sarcoma (KS) is an unusual multifocal neoplasm of vascular endothelial cell origin. The trunk, arms, head, and neck are the most common sites. It is common in men and has four distinct variants: classic, Africa-endemic, immunosuppressive drug-associated, and acquired immunodeficiency syndromeassociated KS. KS appears to develop immunosuppressed patients, but is uncommon in patients on dialysis. A 79-year-old man on hemodialysis for 2 months presented with pruritus over the entire body and multiple, discrete, variable-sized, dark blue papulonodules (papuloplaques, maculopapules) on the left arm and shoulder. A biopsy specimen form the left arm showed spindle cells with slit-like spaces and extravasated red blood cells. The specimen was positive for CD 34 antigen, and human herpesvirus 8 was detected. We report a case of KS that occurred in a 79-year-old patient on hemodialysis.