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멀티 영벡터를 갖는 2상 랜덤 중앙 분포 변조기법의 파워 스펙트럼
오승열(S.Y.Oh),김정근(J.G.Kim),임영철(Y.C.Lim),양형렬(H.Y.Yang),정영국(Y.G.Jung) 전력전자학회 2003 전력전자학술대회 논문집 Vol.2003 No.11
본 연구에서는 변조지수 M이 큰 영역에서는 고조파 스펙트럼의 광대역화 효과가 저하되는 2상 랜덤 중앙 정렬 변조기법(Random Centered Distribution PWM.RCD)기법의 문제점을 해결하고자 멀티 영벡터 2상 RCD(Multi Zero Vector RCD.MZRCD)변조기법을 제안하였다. 제안된 2상 MZRCD기법은 변조지수 M=07을 기준으로 하여 M이 07다 큰 영역에서는 영벡터를 V(111)로 선택하고, 07보다 작은 영역에서는 V(000)을 선택한다. 제안된 방법을 유도모터 구동시스템에 적용해 본 결과, M이 07이상인 영역에서도 모터의 전압/전류 및 소음 스펙트럼의 광대역화 특성이 종전의 방법에 비하여 우수함을 확인할 수 있었다.
유전알고리즘을 이용한 비균일 하중을 받는 구조물의 지지 위치 최적화 연구
김근홍(G.H. Kim),이영신(Y.S. Lee),김학근(H.K. Kim),허남일(N.I. Her),사정우(J.W. Sa),양형렬(H.L. Yang),김병철(B.C. Kim),박주식(J.S. Bak) 대한기계학회 2003 대한기계학회 춘추학술대회 Vol.2003 No.11
It is important to determine supporting locations for structural stability of a structure under non-uniform<br/> load in space interfered by other parts. In this case, There are many local optima with discontinuous design<br/> space. Therefore, The traditional optimization methods based on derivative are not suitable. Whereas, Genetic<br/> algorithm(GA) based on stochastic search technique is a very robust and general method. This paper has been<br/> presented to determine supporting locations of the vertical supports for reducing stress of the KSTAR(Korea<br/> super Superconducting Tokamak Advanced Research) IVCC(In-vessel control coil) under non-uniform<br/> electromagnetic load and space interfered by other parts using genetic algorithm. For this study, we develop a<br/> program combining finite element analysis with a genetic algorithm to perform structural analysis of IVCC. In<br/> addition, this paper presents a technique to perform optimization with FEM when design variables are trapped<br/> in an incongruent design space.
박동성(D.-S. Park),주재준(J.-J. Joo),문경모(K.-M. Moon),장용복(Y.-B. Chang),박영민(Y.-M. Park),김남원(N.-W. Kim),이현정(H.-J. Lee),곽상우(S.-W. Kwag),송낙형(N.-H. Song),우인식(I.-S. Woo),양형렬(H.-L. Yang) 대한기계학회 2012 대한기계학회 춘추학술대회 Vol.2012 No.11
Korea Superconducting Tokamak Advanced Research (KSTAR) was constructed for Korean fusion research and has been operated successfully since 2008. Different from other tokamak devices, KSTAR is fully superconducting (SC) magnet tokamak which consists of 30 magnets and is made of Nb₃Sn and NbTi superconductor. To reach appropriate operating condition of the KSTAR SC magnets, the magnets temperature should be cooled down to liquid helium temperature. A Helium Refrigeration System(HRS) with an exegetic equivalent cooling power of 9㎾ at 4.5K is dedicated to cool down and keep the KSTAR SC magnets in cryogenic temperature. Since the commissioning period and the first campaign of KSTAR, the HRS has showed sufficient performance for the KSTAR SC magnets operation. The estimated time of cool-down for KSTAR cold components was 30 days, but the KSTAR SC magnets were reached to cryogenic temperature in 23 days at the first cool-down operation. Due to the long period of the KSTAR campaign, the reliable operation of the HRS is as important as its performance. During the past 4 years of campaign, the abnormal events were occurred several times and they were influenced to the reliability of the KSTAR HRS and the system availability was decreased. This paper will present the operation result of the KSTAR HRS since the first campaign and the record of the abnormal events and reliability will be discussed.