냉각판을 이용한 반응고 A356합금의 미세조직

임수근,윤병은,장동훈,엄정필,김득규 慶尙大學校生産技術硏究所 1997 生産技術硏究所論文集 Vol.13 No.-

In this study, microstructure, size of primary α, solid fraction and hardness of A356 Al alloy were investigated. Semi-solid A356 alloys were obtained by semi-solid continuous casting apparatus consists of melting furnace, formation apparatus of granular primary α and continuous casting apparatus. Size of primary α and solid fraction were decreased with decreasing temperature, and with increasing volume of cooling water. At the cooling water temperature of 15℃ and cooling water volume of 18.2ℓ/min, the sizes of primary α phases were decreased up to 40㎛, and fraction solid was 0.68.

동종 골수이식 후 만성 이식편대숙주질환과 동반되어 신증후군으로 발현된 IgA 신병증 1예

정철권,김현수,박준성,정성현,조도연,최진혁,남동기,임호영,김명성,신규태,임현이,김효철 대한조혈모세포이식학회 1999 대한조혈모세포이식학회지 Vol.4 No.2

동종 골수이식 후 발생하는 신기능부전은 원인이 다양하여 감별에 어려움이 있다. 만성 GVHD는 흉선의 기능저하에 따른 면역관용의 실패로 발생되는 자가면역현상에 의해 발생되는 것으로 알려져 있으며 드물게 신장을 침범하여 신증후군을 일으키기도 한다. CaA의 용량을 줄이거나 투약중지 후 발생한 만성 GVHD에 동반된 신증후군의 경우 조기에 신조직검사를 시행하여 감별진단하고 CsA의 용량을 증량하거나 재투약하여 좋은 치료 결과를 보일 것으로 기대된다. 저자들은 문헌고찰을 통해 동종 골수이식 후 발생된 신증후군이 유사한 임상양상을 보이며 발생기전에 만성 GVHD와 자가면역현상이 연관되어 있음을 확인하였으며 동종 골수이식 후 신증후군의 임상양상을 보이는 환자에서 병리조직학적으로 lgA 신병증을 진단하고 이러한 lgA 신병증이 발생기전에 만성 GVHD와 자가 면역현상이 연관되어 있을 가능성을 최초로 확인하였으며 CsA를 이용하여 성공적으로 치료한 경험을 하였기에 보고하는 바이다. Renal insufficiency is occasionally encountered in allogeneic bone marrow transplantation and its cause is difficult to ascertain. Chronic graft-versus-host disease (GVHD) related to thymic dysfunction is immune-mediated and involves autoreactivity of T-lymphocytes derived from donor marrow to recipient's major histocompatibility complex(MHC) minor antigens. The clinical mainifestations of chronic GVHD are similar to those of autoimmune disease but kidney involvement is rare. Few cases of nephrotic syndrome with membranous nephropathy or minimal change nephrotic syndrome have been reported to be associated with chronic GVHD in allogeneic bone marrow transplant recipient especially after cyclosporine A(CsA) withdrawal, and these cases have responded well to CsA. Therefore, it is prudent to differentiate the cause of post-transplant renal insufficiency using renal biopsy and to start CsA in a case of nephrotic syndrome associated with chronic GVHD as early as possible. We report a case who had a massive proteinuria during the post-allogeneic marrow transplantation period. The cause of nephrotic syndrome was diagnosed as IgA nephropathy by renal biopsy. The patient was successfully treated with reintroduction of CsA.

균일가열법으로 제조한 반용융 A390합금의 미세조직 및 성형성

임수근,윤병은,장동훈,엄정필,김득규 慶尙大學校生産技術硏究所 1997 生産技術硏究所論文集 Vol.13 No.-

Microstructure of hypereutectic Al-17wt.% Si alloy, fabricated by mechanical stirring and by reheating at semi-solid state, was investigated by optical microscope. Flow behavior semi-solid metal also was investigated at diffentent mould temperatures 280℃, 290℃ and 300℃ . Size of silicon particles were increased over 100㎛ durig solidification as a result of stirring. It is considered as microstructural coarsening by bonding between neighbouring primary silicon particles during stirring of slurry. In case of reheating at semi-state, however, primary silicon particle was not increased at size of 40㎛ and nearly spherical aluminum solde particle also was improved when solid fraction was 0.7 at mould temperature of 300℃ than other conditions.

국균세포벽을 모델로 한 새로운 고정화담체의 개발

유은정,김종덕,송상호,임현수,최명락,정규화 여수대학교 1997 論文集 Vol.11 No.2

The purpose of this investigation was to develop a new carrier using chitin and glucan as the model for Aspergillus oryzae cell wall. In case of the ratio of chitin and glucan(3/1), the activity of the immobilized protease had higher than that of model(chitin/glucan=1/3) and carriers were formed gel. In case of soluble chitin and glucan treated with calcium carbonate, there were a 1.8-fold increase in activity of immobilized protease compared with untreated chitin. The scanning electron microscope image showed that a pore size of this carrier had a homogenized pore size and a smooth surface.

토양 표면의 전기화학적 특성과 응용

옥용식,임수길,김정규 고려대학교 생명자원연구소 2002 생명자원연구 Vol.10 No.-

양친매성 유기점토를 이용한 중금속과 유기 오염물질 동시제거 기술

옥용식,임수길,김정규 한국환경농학회 2003 한국환경농학회지 Vol.22 No.3

Although clay can sorb significant amounts of inorganic contaminants from soils and waste-water, the hydration of exchangeable cations in clay minerals makes it hydrophilic at the clay mineral surfaces and interlayers. Thus, natural clays are often ineffective in complexing and stabilizing toxic organic contaminants in soils and groundwater environment. But, substituting these hydrated cations with cationic surfactant such as QAC(Quaternary ammonium Compound) can change the natural clay from hydrophilic to hydropobic. Furthermore functionalized organoclay can act as a powerful dual function sorbent for both toxic metals and organic compounds. It also can be used as landfill clay liners, slurry walls, nano-composite materials, petroleum tank farms, waste treatment, and fflter systems. To use this modified clay minerals effectively, it is required to understand the fundamental chemistry of organoclay, synthetic procedures, its engineering application, bioavailability of sorbed ion-clay complex, and potential risk of organoclay. In this review, we investigate the use, application and historical background of the organoclay in remediation technology. The state-of-the-art of organoclay research is also discussed. Finally, we suggest some future implications of organoclay in environmental research.

Digital Control of Phase-Shifted Full-Bridge PWM Converter

Jeong-Gyu Lim,Se-Kyo Chung 전력전자학회 2008 JOURNAL OF POWER ELECTRONICS Vol.8 No.3

This paper presents the modeling and design of a digital controller for a phase-shifted full-bridge converter (PSFBC) in a discrete-time domain. The discretized PSFBC model is first derived and then analyzed considering the sampling effect and the system parameters. Based on this model, the digital controller is directly designed in a discrete-time domain. The simulation and experimental results are provided to show the validity of the proposed modeling and controller design.

Digital Control of Phase-Shifted Full Bridge PWM Converter

Jeong-Gyu Lim,Soo-Hyun Lim,Se-Kyo Chung 전력전자학회 2007 ICPE(ISPE)논문집 Vol.- No.-

This paper presents the modeling and design of the digital controller for a phase-shifted full-bridge converter (PSFBC) in the discrete-time domain. The discretized PSFBC model is first derived and then analyzed considering the sampling effect and the system parameters. Based on this model, the digital controller was directly designed in discrete-time domain. The simulation and experimental results are provided to verify the proposed modeling and controller design.

Digital Control of Phase-Shifted Full-Bridge PWM Converter

Lim, Jeong-Gyu,Chung, Se-Kyo The Korean Institute of Power Electronics 2008 JOURNAL OF POWER ELECTRONICS Vol.8 No.3

This paper presents the modeling and design of a digital controller for a phase-shifted full-bridge converter (PSFBC) in a discrete-time domain. The discretized PSFBC model is first derived and then analyzed considering the sampling effect and the system parameters. Based on this model, the digital controller is directly designed in a discrete-time domain. The simulation and experimental results are provided to show the validity of the proposed modeling and controller design.

Implementation of a Fuel Cell Dynamic Simulator

Jeong-Gyu Lim,정세교 전력전자학회 2007 JOURNAL OF POWER ELECTRONICS Vol.7 No.4

This paper presents the development of a fuel cell dynamic simulator using a programmable DC power supply and LabVIEW graphical user interface. The developed simulator closely describes the static and dynamic characteristics of an actual proton exchange membrance fuel cell (PEMFC). The experimental results are provided to verify the operation of the simulator. The developed simulator can be used as a convenient and economic alternative to an actual fuel cell for developing and testing a fuel cell power conditioning system.