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하이퍼써멀 에너지 영역에서 높은 플럭스 입자빔 생성을 위한 플라즈마 발생원
유석재,김성봉,Yoo, S.J.,Kim, S.B. 한국진공학회 2009 Applied Science and Convergence Technology Vol.18 No.3
하이퍼써멀 영역의 에너지 ($1{\sim}100\;eV$), 특히, 50 eV 이하의 에너지를 갖는 높은($10^{16}$ particles/$cm^2\;s$ 이상) 플럭스의 이온빔을 직접 인출하기는 어렵지만, 이온을 중성화한 중성입자빔 경우에는 가능하다. 높은 플럭스의 하이퍼써멀 중성입자빔을 생성하고 효율적으로 수송하기 위해서는 낮은 플라즈마 운전압력(0.3 mTorr 이하)에서도 높은 이온밀도($10^{11}\;cm^{-3}$ 이상)를 유지할 수 있는 대면적 플라즈마 발생원이 요구된다. 이러한 하이퍼써멀 중성입자빔의 생성을 위해 요구되는 플라즈마 발생원을 구현하기 위해서는 자기장에 의한 전자가둠 방식이 도입되어야 하는데, 영구자석을 이용한 다양한 자기장 구조를 갖는 Electron Cyclotron Resonance (ECR) 플라즈마 발생 방식이 하나의 해결 방법이 될 수 있음을 제안하였다. 여기에는 마그네트론 구조를 갖는 자기장을 채택한 평면형 ECR 플라즈마 발생 방식과 원통형 플라즈마 용기 외벽 둘레에 영구자석 어레이를 설치하여 축방향 자기장을 형성하고 용기 중심부에 전자를 가두는 원통형 방식이 있다. 두 경우 모두 기본적으로 mirror field 구조에 의한 전자 가둠을 기반으로 하고 전자의 drift에 의해 더욱 효율적으로 전자를 플라즈마 공간에 가두는 방식을 도입하고 있어서 낮은 운전압력에서도 높은 밀도의 플라즈마를 발생시키고 유지할 수 있다.
김성봉(S. B. Kim),김인철(I. C. Kim),한승우(S. W. Han),전채홍(C. H. Jun) 한국동력기계공학회 2007 동력시스템공학회지 Vol.11 No.1
In the recently released accident-investigation report on blade failure, almost 70% of blade failures was found at low pressure turbine blades, and it is well known that main cause is due to the vibration modes. This paper describes the systematic approach on the root cause of the blade failure at L-0 stage, 30MW single flow industrial steam turbine which had tripped by high vibration after ten-month commercial operation. A fracture was found at the only one damping wire hole of 59 blades, and crack was detected at three damping wire holes by NDT. According to the analysis result for the crack fracture surface and the chain of the sequential operational events, we come to the conclusion that a typical high cycle fatigue is the most dominant factor caused to the blade failure, the resonance frequency margin was narrowed by the cut damping wire and the high cycle vibration was amplified, and then the blade was broken at once by the centrifugal force when the crack reached the critical size.
스퍼터링압력 및 온도 효과에 의한 Co(2Å) / Pd(13Å) 다층박막의 자화반전 거동
김성봉(S. B. Kim),정순영(S. Y. Jeong) 한국자기학회 1996 한국자기학회지 Vol.6 No.4
To study the magnetization reversal behavior of Co/Pd multilayers, we first demagnetized the samples by the field-demagnetized method and then measured initial curves and minor loops. The coercivity and the perpendicular magnetic anisotropy were obtained from the perpendicular and parallel magnetization curves measured at different temperatures. We interpret our experimental results by applying several qualitative and semiquantative approaches. From these study, we found that the magnetization reversal behavior is dominated by the domain wall pinning for all samples and the coercivity incremental tendency can be explained by Kronmuller's formula Hc(T) ∝ r。ㆍKu.
실시간 ABS 시뮬레이션을 위한 차륜속도 시뮬레이터의 개발
김석민(S.M.Kim),배봉국(B.K.Bae),정재현(J.H.Chung),서명원(M.W.Suh),석창성(C.S.Seok),김영진(Y.J.Kim),이재천(J.C.Lee),김성봉(S.B.Kim),이선일(S.I.Lee),김장성(J.S.Kim) 한국자동차공학회 1997 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1997 No.6_2
In order to perform a vehicle driving simulation test in laboratory for the electronic control unit(ECU) analysis of anti-lock brake system(ABS), it is necessary to simulate the wheel speed signal which is to be controlled for the various road and driving conditions. The speed signal from the real wheel speed sensor is not only for the speed calculation but also for the diagnosis of the ABS system. In this research, wheel speed simulator is developed which can generate the equivalent signal as that of a real wheel speed sensor. The applicability of the wheel speed simulator is validated by the simulation tests using commercial ECU of ABS. The wheel speed simulator is based on the personal computer so that it can be applied to other vehicle tests involving vehicle speed and/or wheel speed.<br/>
김석민(S.M.Kim),배봉국(B.K.Bae),정재현(J.H.Chung),서명원(M.W.Suh),석창성(C.S.Seok),김영진(Y.J.Kim),이재천(J.C.Lee),김성봉(S.B.Kim),이선일(S.I.Lee),김장성(J.S.kim) 한국자동차공학회 1997 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1997 No.6_2
The prevalence of microprocessor-based controllers in automotive systems has greatly increased the need for tools which can be used to validate and test control systems over their full time range of operation. The objective of this paper is to develope the real time simulator of anti-lock braking system using hardware-in-the-loop simulationbased on a personal computer. By use of this simulator, the analyses of commercial electronic control unit as well as the validation of the developed control logics for ABS were performed successfully. The simulator of this research can be applied to development of more advanced control system, such as traction control cystem,vehicle dynamic control system and etc.<br/>