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강성가변 스프링연결 블록 모델을 이용한 평면 링크기구 자동 합성
남상준(S. J. Nam),현진섭(J. S. Hyun),장강원(G. W. Jang),김윤영(Y. Y Kim) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.6
A linkage mechanism in a machine or a robot is a device to convert an input motion into a desired motion. Machines and robots having improper mechanisms can be unstable, unnecessarily complicated or energy-inefficient. However, tradition linkage mechanism design practice based on trial-and-error approaches or mere size/shape changes of already-available mechanisms often results in improper designs. This observation has motivated us to develop a so-called “automatic” design methodology that can yield optimal at least sub-optimal mechanisms automatically by computer simulation and optimization algorithms. The specific target in this work is to design planar linkages consisting of links and revolute joints. One of the key ingredients to realize the automatic design is to find a computational efficient planar mo del that can simulate any possible planar linkage combinations; otherwise the automatic design process would require impractical computation time. The model proposed by our group is a so-called spring-connected rigid block model consisting of a group of rigid blocks connected by zero-length elastic springs. This work shows how this new idea works. We also pose several challenge problems to be solved in the future.
표면 조도와 곡률 반경에 대한 U-자관 압력 손실의 상관관계
박정후(J.H. Park),장세명(S.M. Chang),이신영(S.Y. Lee),장강원(G.W. Jang) 한국전산유체공학회 2015 한국전산유체공학회지 Vol.20 No.1
In this research, we studied the pressure drop affecting on the internal surface roughness and the curvature radius of a U-tube, which is used for the cooling system in PWR(Pressurized Water Reactor). Using ANSYS-FLUENT, a commercial code based on CFD(Computational Fluid Dynamics) technique, we compared a Moody chart with the Darcy friction factor changed by a range of various surface roughness and Reynolds numbers of a straight pipe model. We studied the effect giving variation about a range of various surface roughness and the curvature radius of the full scale U-tube model. The material of the heat transfer tube is Inconel 690 used in the steam generator. We compared the velocity distribution of selected 4 locations, and derived the correlation between the surface roughness and the pressure drop for the U-tube of each representative curvature radius using the linear regression method.
보조동력장치 연료 공급용 서보밸브 토크모터의 기초 수치모사 연구
장세명(S. M. Chang),정헌술(H. S. Jeong),장강원(G. W. Jang),양인영(I. Y. Yang),이원중(W. Lee) 유공압건설기계학회 2009 드라이브·컨트롤 Vol.6 No.2
The APU(Auxiliary Power Unit) needs a set of complex pipeline for the fuel supply system where some of the main valves controlling the flow rate consist of the servo valve worked with a torque motor. The input electric current produces an induced magnetic field almost perpendicular to the background magnetic filed generated by fixed permanent magnets. The induced torque deforms the tubular bushing, and directly rotates an armature, which can open and close the valve. In this study, we start from a basic analytic model using a simple electro-magneto-statics, and expand our model to the three-dimensional one computationally applying a commercial code named COMSOL. The result is compared with each other, and reasonable numerical data are obtained for the dynamic behavior and multi-physics system.