• 품질경영학회지
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• 제34권2호
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• pp.122-128
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• 2006

One feature of a computer simulation experiment, different from a physical experiment, is that the output is often deterministic. Moreover the codes are computationally very expensive to run. This paper deals with the design and analysis of computer experiments(DACE) which is a relatively new statistical research area. We model the response of computer experiments as the realization of a stochastic process. This approach is basically the same as using a spatial linear model. Applications to the optimal mechanical designing and model calibration problems are illustrated. Algorithms for selecting the best spatial linear model are also proposed.

• 품질경영학회지
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• 제17권1호
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• pp.89-106
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• 1989

For Weibull distributed lifetimes, this paper presents asymptotically optimal accelerated life test plans for practical applications under intermittent inspection and type-I censoring. Computational results show that the asymptotic variance of a low quantile at the design stress as optimal criterion is insensitive to the number of inspections at overstress levels. Sensitivity analyses indicate that optimal plans are robust enough to moderate departures of estimated failure probabilities at the design and high stresses as input parameters to plan accelerated life tests from their true values. Monte Carlo simulation for small sample study on optimal accelerated life test plans developed by the asymptotic maximum likelihood theory is conducted. Simulation results suggest that optimal plans are satisfactory for sample size in practice.

• 한국철도학회논문집
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• 제6권4호
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• pp.279-285
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• 2003

In an electric traction system in which power is supplied from a catenary via a pantograph, the mechanical design of the catenary and pantograph is clearly of importance in relation to the problem of current collection at high speed. A computer-simulation technique is used to study the effects of changing parameters of pantograph and catenary on the quality of current collection at high speed. The current collection system is evaluated on the basis of the contact-force variations and displacement responses of the pantograph and contact wire. This study shows that current-collection quality is determined primarily by the overhead line parameters rather than by the pantograph. The results can be applied to optimize the design of current-collection systems.

• 한국습지학회지
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• 제14권4호
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• pp.645-656
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• 2012

지난 반세기 동안 무분별한 산업 활동으로 인하여 유역환경은 심각하게 훼손되었다. 이를 관리하기 위한 요구는 증대되고 있으나 정량적으로 유역환경을 예측하여 판단하기 위한 시스템은 부족한 실정이다. 따라서 본 연구에서는 우리나라 유역 환경을 모의하기에 가장 적합한 HSPF(Hydrological Simulation Program-Fortran) 모델을 GIS기반 시스템에 적용하여 영산강 유역에 활용가능한 수질모의 시스템 개발에 관한 연구를 수행하였다. 이를 지원하기 위하여 HSPF 모델 모의에 필요한 입력 및 결과자료와 공간분석을 위한 GIS 공간자료를 수집하였다. 또한 GIS와 수질모델의 연계방안을 비교 분석 후, Loose coupling 연계방안을 적용하여 수질모의 시스템의 주요기능을 모듈단위별로 설계하였다. 최종적으로 설계단계에서 정의된 모듈단위 기능들을 Microsoft사의 VB.NET을 개발언어로 선정하고 ESRI사의 ArcObjects 컴포넌트를 이용하여 시스템을 개발하였다. 본 연구를 통해 개발된 GIS기반 영산강 유역 수질모의 시스템은 영산강 유역환경을 정량적으로 예측할 수 있으며, 문서형식의 모의 결과를 GIS 환경에 표출함으로써 사용자의 공간적 이해도를 높였다. 향후에는 HSPF 모의 결과를 통한 시나리오 수립이 진행되어야하며, 이는 의사결정지원시스템과 연계하여 의사결정자들로 하여금 미래 영산강유역 환경에 대한 진단 및 정책 수립에 지원할 수 있을 것으로 기대된다.

• International journal of advanced smart convergence
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• 제10권1호
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• pp.159-165
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• 2021

Electronic devices used in the mobile environments fabricated under the plasma conditions in high vacuum system. Especially for the development of advanced electronic devices, high quality plasma as the process conditions are required. For this purpose, the variable conductance throttle valves for controllable plasma employed to the high vacuum system. In this study, we analyzed the effects of throttle valve applications on vacuum characteristics simulated to obtain the optimum design modelling for plasma conditions of high vacuum system. We used commercial simulator of vacuum system, VacSim(multi) on this study. Reliability of simulator verified by simulation of the commercially available models of high vacuum system. Simulated vacuum characteristics of the proposed modelling agreed with the observed experimental behaviour of real systems. Pressure limit valve and normally on-off control valve schematized as the modelling of throttle valve for the constant process-pressure of below 10-3 torr. Simulation results plotted as pump down curve of chamber, variable valve conductance and conductance logic of throttle valve. Simulated behaviors showed the applications of throttle valve sustained the process-pressure constantly, stably, and reliably in plasma process.

• 산업경영시스템학회지
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• 제40권1호
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• pp.35-40
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• 2017

A most important progress in civilization was the introduction of mass production. One of main methods for mass production is die-casting molds. Due to the high velocity of the liquid metal, aluminum die-casting is so complex where flow momentum is critical matter in the mold filling process. Actually in complex parts, it is almost impossible to calculate the exact mold filling performance with using experimental knowledge. To manufacture the lightweight automobile bodies, aluminum die-castings play a definitive role in the automotive part industry. Due to this condition in the design procedure, the simulation is becoming more important. Simulation can make a casting system optimal and also elevate the casting quality with less experiment. The most advantage of using simulation programs is the time and cost saving of the casting layout design. For a die casting mold, generally, the casting layout design should be considered based on the relation among injection system, casting condition, gate system, and cooling system. Also, the extent or the location of product defects was differentiated according to the various relations of the above conditions. In this research, in order to optimize the casting layout design of an automotive Oil Pan_BR2E, Computer Aided Engineering (CAE) simulation was performed with three layout designs by using the simulation software (AnyCasting). The simulation results were analyzed and compared carefully in order to apply them into the production die-casting mold. During the filling process with three models, internal porosities caused by air entrapments were predicted and also compared with the modification of the gate system and overflows. With the solidification analysis, internal porosities occurring during the solidification process were predicted and also compared with the modified gate system.

• 한국시뮬레이션학회논문지
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• 제22권3호
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• pp.15-23
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• 2013

공학설계분야에서 시뮬레이션 모델을 이용한 실험은 매우 중요한 역할을 한다. 그러나 최적의 설계 파라미터를 구하기 위한 시뮬레이션 실험은 많은 실행시간과 자원의 소요를 필요로 한다. 이를 극복하는 방안으로 입력 변수와 성능척도 간의 관계를 표현한 메타모형이 효과적으로 이용된다. 메타모형을 수립하기 위해서는 샘플 시나리오들을 입력으로 하는 시뮬레이션 실행이 요구된다. 이때 샘플 시나리의 수와 질이 메타 모형을 수립하는데 걸리는 시간과 메타모형의 정확성을 결정한다. 공간채움 특성은 샘플 시나리오들의 질을 결정하는 중요한 조건이 된다. 이 논문은 maxmin, Audze-Eglais, centered L2-discrepancy의 3가지 공간채움 척도에 기초한 샘플 시나리오 생성 방법을 제안하고, 실험을 통해 이들 생성방법에 대한 성능을 분석한 결과를 논의한다.

• 소성∙가공
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• 제26권1호
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• pp.28-34
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• 2017

Multi-pass shape rolling is performed to produce long products of arbitrary cross-sectional shapes. In the past, the multi-pass shape rolling process has been designed by the trial and error method or the experience of experts based on the empirical approach. Particularly, the design of roll caliber in shape rolling is important to improve product quality and dimensional accuracy. In this paper, the caliber design and pass schedule of multi-pass shape rolling were proposed for manufacturing piston ring wire. In order to design roll caliber, major shape parameter and dimension was determined by analysis of various caliber design. FE-simulation was conducted to verify effectiveness of proposed process design. At first, forming simulation was performed to predict shape of the product. Then, fracture of the wire was evaluated by critical damage value using normalized Cockcroft-Latham criteria. The experiment was carried out and the results are within the allowable tolerance.

• 반도체디스플레이기술학회지
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• 제15권1호
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• pp.56-64
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• 2016

It is generally accepted that the surface quality of wafer edge is mostly damaged by the vibrations of the edge grinding machine. The surface quality of wafer edge is supposed to be the most dominant factor of the cracks, scratches, burrs and chips on the edge surfaces, which are the main defects of the wafers. In this study, the structure of a wafer edge grinder has been investigated through the frequency response experiment and the computer simulation to find ways to suppress the vibrations from the structure. The main reasons of the structural vibrations were analyzed. And further the design alterations were deduced from the results of the experiment and the simulation, and applied to the machine to check the effects of those alterations and to eventually improve the structural stability. The result shows that the machine can have much improved stability with relatively simple design changes.

• 대한산업공학회지
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• 제39권6호
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• pp.461-472
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• 2013

In this paper, we deal with a simulation-based reliability and maintainability design problem of a warship and want to determine the optimal values of MTBF and MTTR of all units and ALDT of the warship. The system availability and life cycle cost are used as optimization criteria and estimated by simulation. A hybrid genetic algorithm with a heuristic method is proposed to find near-optimal solutions and numerical examples are also studied to investigate the effect of model parameters to the optimal solutions and compare with a general genetic algorithm.