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김규식(K. S. Kim),이영재(Y. J. Lee),성시영(S. Y. Sung),한범석(B. S. Han),박중철(J. C. Park),이기안(K. A. Lee) 한국소성가공학회 2011 한국소성가공학회 학술대회 논문집 Vol.2011 No.5
Fatigue deformation behavior of new heat resistant A1 alloy was studied at elevated temperature. The results of phase analysis showed that this alloy has basic A1 matrix, small amount of eutectic Si and Mg2Si phase, particulates with of (Co, Ni)3Al4 strengthening phase. High temperature tensile tests were conducted to identify the mechanical properties. From room temperature to 250℃, yield and tensile strengths of new heat resistant aluminum alloy didn"t show significant decrease and elongations increased slightly. High cycle fatigue tests were performed with R= 0,30 Hz at 130℃ and low cycle fatigue tests with strain rate of 2×10<SUP>-3</SUP> s<SUP>-1</SUP> at 250℃ respectively. Fatigue limit of high cycle fatigue of this alloy was 120 MPa at the 10<SUP>7</SUP> cycles. At plastic strain amplitude of 0.12%, a fatigue limit was got at 10<SUP>3</SUP> cycles with low cycle fatigue regime. These values were superior than those of conventional heat resistant aluminum alloy such as A319. Results of fractographical observation showed that second phases, especially (Co, Ni)3Al4 particles, affected to fatigue behavior. It is also attempted to clarify the mechanism of fatigue deformation of new resistant aluminum alloy related with its microstructure.
Al - Mg - Si - (Co, Ni) 알루미늄 합금의 고온 저주기 피로 변형 거동
김규식(K. S. Kim),성시영(S. Y. Sung),한범석(B. S. Han),박중철(J. C. Park),이기안(K. A. Lee) 한국소성가공학회 2011 한국소성가공학회 학술대회 논문집 Vol.2011 No.10
High temperature low cycle fatigue tests of new heat resistant aluminum alloy were conducted in this study. Al-Mg-Si-(Co, Ni) aluminum alloy consists of Al matrix, small amount of Mg2Si and (Co, Ni)3Al4 strengthening particles. Low cycle fatigue tests controlled by total strain were performed with strain ratio (R)=-1, strain rate=2x10<SUP>-3</SUP>s<SUP>-1</SUP> at 250℃. Fatigue limit of low cycle fatigue of this alloy showed plastic strain amplitue(Δεps) of 0.22% at the 10<SUP>3</SUP> cycles. This value was superior that that of conventional aluminum alloy such as A319. Results of fractographical observation showed that second phases, especially (Co, Ni)3Al4 particles, could act a strengthening role for low cycle fatigue behavior. It is also attempted to clarify the mechanism of high temperature low cycle fatigue behavior of Al-Mg-Si-(Co, Ni) alloy related with its micorstructure and energy dissipation anaysis.
스폿용접기의 용접품질 향상을 위한 동저항 데이터 베이스 구축
조승진(S.J.CHO),김재문(J.M.KIM),원충연(C.Y.WON),최규하(K.H.CHOI),김규식(K.S.KIM),목형수(H.S.MOK) 전력전자학회 1998 전력전자학술대회 논문집 Vol.- No.-
A dynamic electrical parameter monitoring device was designed to simultaneously record the instantaneous value of voltage, current, power. and resistance during spot welding. The data obtained using this technique have been analyzed in tern of the relationship of theses parameters to the phenomena occuring during the formation(surface break-down, nugget formation and mechanical collapse) of spot weld. Finally ,a database implementation is undertaken to develop techniques for improving weld quality of the resistance spot welder.<br/> <br/>
퍼지제어기를 이용한 엘리베이터 구동용 영구자석형 동기전동기의 속도제어
황선모(S.M Hwang),유재성(J.S Yu),원충연(C.Y Won),김규식(K.S Kim),최세완(S.W Choi) 전력전자학회 2004 전력전자학술대회 논문집 Vol.- No.-
This paper proposes a fuzzy logic based vector control for the gearless traction machine drive systems using a permanent-magnet synchronous motor (PMSM). The performance of the proposed Fuzzy Logic Control(FLC)-based PMSM drive are investigated and compared to those obtained from the conventional PI controll-based drive system. We have confirmed theoretically and experimentally at different dynamic operating conditions such as step change in command speed, step change in load, etc. The comparative experimental results show that the FLC is more robust and, hence, found to be a suitable replacement of the conventional PI controller for the high-performance elevator drive system.
아크 재생 검출에 의한 CO₂인버터 아크 용접기의 용접성능향상에 관한 연구
김길남(K.N Kim),이정락(J.R Lee),고재석(J.S Gho),목형수(H.S Mok),최규하(G.H Choe),김규식(K.S Kim),원충연(C.Y Won) 전력전자학회 2000 전력전자학술대회 논문집 Vol.2000 No.11
Gas metal arc welding(GMAW) uses a continuously fed electrode as a filler metal. The arc is shielded from atmospheric contamination by an inert gas. active gas or inert/active gas mixture delivered through the welding gun and cable assembly. The recent research topics on CO₂ arc welding machines are focused mainly on the reduction method of generated spatter by using new type consumable electrode metal or inverter control method. The various current waveform control methods have been researched for welding performance improvement<br/> Until now current waveform control methods reduce to spatter occurred by instantaneous short circuiting<br/> but. these methods is drawback that no reduce spatter occurred by arc reignition. In this paper the previous arc reignition current control method for welding performance improvement of inverter arc welding machine is studied and compared the various current control methods With the previous arc reignition current control method.