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이인우,박현호,김명호 ( In Woo Lee,Hyun Ho Park,Myung Ho Kim ) 한국주조공학회 1995 한국주조공학회지 Vol.15 No.5
N/A For high performance aerospace structures, the properties of highest priority are low density, high strength, and high stiffness(modulus of elasticity). Addition of beryllium decrease the density of the aluminum alloy and increase the strength and the stiffness of the alloy. However it is very difficult to produce the Al-Be alloy having useful engineering properties by conventional ingot casting, because of the extremely limited solid solubility of beryllium in aluminum. So, rapid solidification processing is necessary to obtain extended solid solubility. In this study, rapidly solidified Al-6 at% Be alloy were prepared by twin roll melt spinning process and single roll melt spinning process. Twin roll melt spun ribbons were extruded at 450℃ with reduction in area of 25 : 1 after vacuum hot pressing at 550℃ and 375℃. The microstructure of melt spun ribbon exhibited a refined cellular microstructure with dispersed Be particles. As advance velocity of liquid/solid interface increase, the morphology of Be particle vary from rod-like type to spherical type and the crystal structure of Be particle from HCP to BCC. These microstructural characteristics of rapidly solidified Al-6at.%Be alloy were described on the basis of metastable phase diagram proposed by Perepezko and Boettinger. The extruded ribbon consisted of recrystallized grains dispersed with Be particles and exhibited improved tensile property compared with that of extruded ingot.
급속응고한 Al-Mg-Be 합금의 미세조직 및 인장특성
이인우,박현호,김명호 ( In Woo Lee,Hyun Ho Park,Myung Ho Kim ) 한국주조공학회 1996 한국주조공학회지 Vol.16 No.4
N/A Twin roll quenched Al-Be ribbons were vacuum hot-pressed at 450℃ under 100㎫ and hot-extruded with reduction in area of 25:1 at 450℃. The extruded Al-Be ribbons consisted of refined Al grains and homogeneously dispersed fine Be particles, and exhibited improved tensile properties with increasing of solidification rate and Be contents. Also in order to develop a light weight-high strength Al alloy, rapidly solidified Al-Mg-Be alloy system was studied. Rapidly solidified Al-Mg-Be alloy by twin roll quenching process was vacuum hot -pressed and subsequently hot-extruded. Compared with extruded Al-Mg ribbons, extruded Al-Mg-Be ribbons exhibited finer recrystallized grains and improved tensile properties, as subgrain boundaries of extruded Al-Mg-Be ribbons were pinned by fine Be particles. With increasing of solidification rate and Mg contents, extruded Al-Mg-Be ribbons exhibited very fine recrystallized grains and improved tensile properties. These tendencies could be due to promoted recrystallization by refined Be particles. T4 treatment for the extruded Al-13Mg-1Be ribbons was found to improve the elongation, possibly by the resolution of Al₃Mg₂at grain boundaries.
이인우,남옥현,김문일 ( In Woo Lee,O . H . Nam,Moon Il Kim ) 한국열처리공학회 1993 熱處理工學會誌 Vol.6 No.4
Extensive reseach has been performed on the process condition-micro structure-stress relations of TiN film. The various proposed models are mainly base on physical vapor deposition processes. Especially the study on the micro-structure and deposition condition has not been sufficient in TiN deposited by PECVD. In this study, therefore, we discussed the morphological changes of TiN films by PECVD with different temperature and pressure, and compared it with the structure zone model. We could find out chat the oxygen and chlorine contents and the texture coefficient increased with deposition temperature, and the morphology of TiN transformed from Zone 1 to Zone T, but deposition pressure didn`t remarkly affected.
이인우,김명호 ( In Woo Lee,Myung Ho Kim ) 한국주조공학회 1995 한국주조공학회지 Vol.15 No.3
N/A Highly alloyed high speed tool steels(ASP steels) were rapidly solidified by melt spinning process, and the microstructures of melt spun tool steel ribbons were examined by optical microscopy and transmission electron microscopy with energy dispersive x-ray spectroscope. The microstructure of melt spun tool steel ribbon was found to be consisted of δ-ferrite cells surrounded by austenite and V-rich MC carbides. The size of δ-ferrite cells and intercellular MC carbides were about 0.4㎛ or less and 30㎚ or less, respectively. From the melt spun tool steel ribbons, only the MC type carbide phase was observed, instead of M₂C, M_(23)C_6 and M_6C carbides which were generally observed in other rapidly solidified high speed steels. Such a change in type of carbide phase formed could be attributed to the increase in alloying content of vanadium and carbon. However, changes in microsturcture of melt spun tool steels with alloying content of cobalt, vanadium and carbon were not observed.
직병렬 보상형 모정전 전원장치의 단일 스위치 직렬 요소
이인우(In-woo Lee),박진형(Jin-hyung Park),전성즙(Seong-jeub Jean) 전력전자학회 1999 전력전자학술대회 논문집 Vol.1999 No.7
A single-switched series element for series?parallel compensated UPS is proposed, The proposed series element can handle only unidirectional power and the input voltage must be higher than the output voltage, But it IS very useful when DC-link voltage is low and isolation transformer IS need for output stage since only one active switch is used