• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.7
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• pp.4469-4474
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• 2014

This paper proposes a novel analysis method on the driving performance of LIM (linear induction motor) by FEM (finite element method). First, a linear model was converted with a rotation model to perform the dynamic analysis for a long time. Through the FEM model, the slip parameter for the control algorithm could be induced effectively. The LIM for the traction system was performed at a constant V/f in the region of constant torque, and a constant V and variable f in the region of constant power. Several slip characteristic curves according to the voltage and frequency were calculated by FEM in advance. The driving performance was then induced by interpolating the slip characteristic curves according to the load of the vehicle.

• Tunnel and Underground Space
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• v.23 no.1
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• pp.54-65
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• 2013

The LCM (Linear Cutting Machine) test is one of the most powerful and reliable methods for designing the disc cutter and for predicting the TBM (Tunnel Boring Machine) performance. It has an advantage to predict the actual load on disc cutter from the laboratory test on the real-size large rock samples, however, it also has a disadvantage to transport and/or prepare the large rock samples and to need an extra cost for experiment. In order to overcome this problem, lots of numerical studies have been performed. In this study, the PFC3D (Particle Flow Code in 3 Dimension) has been adopted for numerical analysis on optimum cutter spacing and failure aspects of Busan Tuff. The optimum cutting condition with s/p ratio of 16 and minimum specific energy of $14MJ/m^3$ was derived from numerical analyses. The cutter spacing for Busan Tuff had the good agreements with those of LCM test and numerical analysis by finite element method.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.23 no.1
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• pp.37-43
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• 2010

In this paper, a reliability-based design optimization is developed for the topology design of linear structures using a performance measure approach. Spatial domain is discretized using three dimensional Reissner-Mindlin plate elements and design variable is taken as the material property of each element. A continuum based adjoint variable method is employed for the efficient computation of sensitivity with respect to the design and random variables. The performance measure approach of RBDO is employed to evaluate the probabilistic constraints. The topology optimizationproblem is formulated to have probabilistic displacement constraints. The uncertainties such as material property and external loads are considered. Numerical examples show that the developed topology optimization method could effectively yield a reliable design, comparing with the other methods such as deterministic, safety factor, and worst case approaches.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.490-490
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• 2021

상수도 관망은 대표적인 사회기반시설로 수원으로부터 수용가에게 수질적으로 안전한 물을 안정하게 공급하는 것을 목표로 한다. 초기의 상수도 관망의 최적 설계는 비용만을 고려함으로써 미래의 불확실한 상황에 대한 대처가 매우 취약하고, 사용자의 다양한 요구를 충족시키지 못하였다. 또한, 유량과 안정적인 수질 공급을 고려하는 설계는 몇몇 비선형적 요소를 포함하고 있으며, 특히 사용자의 수요 패턴에 따른 잔류 염소 농도가 설계 기준에 부합하지 못하는 문제가 되는 경우 사용자의 심미적, 심리적 불편을 초래할 수 있다. 이는, 수질의 안전성과 직결되는 문제이다. 따라서 본 연구에서는 상수도 관망의 설계에 대하여 수질과 수리학적 특성을 고려한 상수도 관망 다목적 최적 설계를 수행하였다. 상수도 관망은 수질적인 측면을 고려하기 위해 수원에서 수용가까지 용수를 공급하는 과정에서 병원성 미생물을 소독하기 위하여 염소를 주입한다. 또한, 유리 잔류 염소의 평상시 기준을 (1.0-4.0mg/L) 유지하도록 규정하였다 (수도법 시행규칙 제22조의2). 하지만 사용자의 사용패턴, 체류 시간에 따라 잔류염소량이 달라진다. 따라서, 본 연구에서는 상수도 관망의 설계 비용과 염소 주입량을 동시에 설계 인자로서 고려하기 위해 Multi-objective Harmony Search를 적용하고, 그 결과를 분석하였다. 이러한 상수도 관망의 수질 인자와 설계 비용을 고려한 최적 설계안은 경제적 측면 뿐만 아니라 사용자의 수질 측면의 안전성을 충족하는 방안을 제시할 수 있다.

• Journal of the Korean Magnetics Society
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• v.5 no.5
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• pp.892-899
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• 1995

A numerical simulation program based on the finite elerrent method is developed for calculating electromagnetic field of the cylindrical electromagnetic pump. The calculated results by the developed program show that Lorentz forces show maximum peak at an optimum length ($L_c$) of the induction coil. The value of $L_c$ depends on the radius of the molten metal when the skin depth is large. On the other hand, the value of $L_c$ depends on the skin depth when it is small.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.1
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• pp.184-190
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• 2006

Using COMS which provides multi-beam switching function, the optimal transmission channel environments which provides the high data rate communication are proposed in this paper. Also the link budget for communication transponder of COMSAT is designed. Bsaed on the channel modeling for group delay, non-linear and gain flatness characteristics, the system performances which provide high data rate (HDR) service were analyzed in Ka-band satellite channel. As the transmission data rate is increased, the degradation due to these channel characteristics is severely affect the system performance. To efficiently provide the various service via the same transmission system it is necessary to equlize the primary impairment factors. The optimum operating points of HDR satellite transmission system are implemeted and operated by considering the analyzed results on channel characteristics.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.1
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• pp.1113-1116
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• 2005

Using COMSAT which provides multi-beam switching function, the optimal transmission channel environment which provides the high data rate communication are proposed in this paper. Also the link budget for communication transponder of COMSAT is designed. Based on the channel modeling for group delay, non-linear and gain flatness characteristics, the system performances which provide various data rate services were analyzed in Ka-band satellite channel. As the transmission data rate is increased, the degradation due to these channel characteristics is severely increased. The linear component of group delay and the AM-AM component of non-linear characteristics severely affect the system performance. To efficiently provide the various service via the same transmission system it is necessary to equalize the primary impairment factors. The optimum operating points of HDR satellite transmission system are implemented and operated by considering the analyzed results on channel characteristics.

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.2
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• pp.74-81
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• 2014

In this study, it was conducted to improve the performance of stud of Steel Plate Concrete(SC) walls subjected to bending moment. Non-linearity of contact interface, connection, and material properties were considered in finite element modeling of SC wall. In order to validate the analytical model, furthermore, a foregoing laboratory experiment was simulated by FEM, so that comparison between the measured result and the analysis result have be done. The size of the analytical model was determined by reflecting various references and the analyses were performed according to various shapes and arrangements of stud. Additionally, the validity of the model considering the related provisions in the KEPIC SNG standard was also considered. As a result, the optimal shape and spacing of studs was proposed through this numerical analysis and standard verification.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.16 no.4
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• pp.345-351
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• 2003

Due to increasing legal and market demands for safety in the automotive design process, the design of integrated seat is important more and mote because it should satisfy the conflict between stronger and lower weight for safety and environmental demands. In this study for crash simulations, the numerical simulations have been carried out using the explicit finite element program LS-Dyna according to the FMVSS 210 standard for safety test of seat. Since crash simulations are very time-consuming and a series of simulations that does not lead to a better result is very costly, the optimization method must be both efficient and reliable. As a result of that, statistical approaches such as design of experiments and response surface model have been successfully implemented to reduce time-consuming LS-Dyna simulations and optimize the safety and environmental demands together with nonlinear optimization algorithm. Design of experiments is used lot exploring the design space of maximum displacement and total weight and for building response surface models in order to minimize the maximum displacement and total weight of integrated seat.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 1997.11a
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• pp.29-29
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• 1997

각광 받는 구조재료인 섬유강화 복합적층재에 대한 기계적 체결 거동은 본질적인 재료의 이방성에 의해서 파단강도가 파단 모우드와 매우 밀접한 관련을 갖는 것으로 알려져 있다. 따라서, 복합적층판 체결부의 정밀 구조 설계에서는 단순화에 따른 오차를 줄이고 정밀해에 의한 설계 및 해석이 요청된다. 특히, 층간응력 성분을 무시할 수 없는 두께를 갖는 복합적층 판의 기계적 체결부 해석이나 실제 구조물의 체결부에서 발생하는 굽힘이나 비틀림과 같은 하중 상태를 묘사하기 위해서도 정밀한 3차원 응력 해석은 필요하다. 하지만, 지금까지 기계적 체결부의 거동에 관한 연구는 층간응력 성분들을 어느정도 무시할 수 있는 얇은 평판에 대한 2차원 응력해석에 주로 국한되어 왔으며, 일부 수행된 체결부에 대한 3차원 응력 해석의 경우 여러 단점을 갖는 3차원 연속체 요소에 의한 유한요소 해석이 수행되었을 뿐이다.본 연구는 층간응력 성분들을 무시할 수 없는 두께를 갖는 복합적층판의 기계적 체결부 해석에 지금까지 사용되어온 3차원 연속체 요소에 의한 유한요소 방법이 갖는 단점들을 개선한 Layerwise 유한요소법을 이용하여 3차원 응력해석을 수행하였다. 특히, 선형상보성원리에 근거한 최적설계 기법을 응용하여, 기계적 체결시 핀과 적층판의 홀 사이에 발생하는 하중 전달 과정을 모사하고, 접촉력에 의한 홀 주위의 복잡하고 국부적인 응력 집중현상을 규명하여본다.