• 한국수자원학회논문집
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• 제42권3호
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• pp.227-234
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• 2009

본 연구에서는 지점 간 확률가중모멘트의 교차상관관계를 구하기 위해 Monte Carlo 모의를 이용하여 이를 지점간 표본자료의 교차상관성에 대한 관계식으로 확장하여 근사값을 구하고자 하였다. 모의실험 결과 각각의 확률가중 모멘트간 교차상관계수는 지점 간 표본자료의 교차상관계수와 자료크기가 동일하고 동시간 자료일 경우 기울기 1인 선형관계를 보이며, 자료크기에 따른 동시간 자료의 비율이 작아질수록 선형적인 관계는 점점 약해지게 된다. 따라서 자료크기에 따른 영향을 고려하기 위하여 보정항을 추가한 제곱함수식을 제시하였으며, 이 식에 발생된 자료를 적합시켜 각각의 경우에 따른 매개변수를 추정하였다. 이 결과를 이용하여 지역빈도해석의 지점 간 교차 상관성을 고려한 수문추정량의 분산 추정 등의 연구에 이용될 수 있을 것으로 기대된다.

• 터널과지하공간
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• 제12권3호
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• pp.189-197
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• 2002

최근 들어 확률론적 해석 방법이 암반사면공학에서 많이 사용되고 있으며 이는 불연속면과 암반의 지질학적 및 지반공학적 특성에 불확실성이 포함되며 이러한 불확실성에 의해 해석결과에 영향을 미치고 있기 때문이다. 암반사면의 안정성 해석에서 주로 사용되고 있는 전통적인 결정론적인 해석에서는 이러한 불확실성을 해석에 고려하기 어려운 반면 확률론적 해석에서는 불확실성을 수량화하여 해석에 고려할 수 있다는 장점을 가지고 있다. 이러한 확률론적 해석방법으로는 몬테카를로 방법이 주로 사용되고 있으나 방법은 파괴확률을 획득하기 위하여 많은 반복된 계산이 요구되며 따라서 많은 시간과 노력이 필요하다는 단점을 가지고 이다. 반면 본 연구에서 제안된 점추정법은 확률변수의 통계적 파라미터, 즉, 평균과 표준편차만을 이용하여 단순한 계산을 통해 파괴확률을 구할 수 있는 장점을 가지고 있다. 따라서 본 연구에서는 점추정법을 이용하여 평면파괴의 파괴확률을 산정하였으며 이를 몬테카를로 방법과 비교해 보았다.

• 한국수자원학회논문집
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• 제35권4호
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• pp.385-395
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• 2002

하천에서의 수질변동을 예측하기 위해 FOEA(First-Order Error-Analysis)와 Monte Carlo 모의를 적용한 추계학적 모형을 개발하였다. 영향메트릭스(Influential matrix)를 이용한 민감도 분석을 실시하여 주요 반응계수를 결정하였고, BFGS(Broyden-Fletcher-Goldfarb-Shanno) 최적화 기법을 사용하여 주요 반응계수 값을 산정하였다. 본 모형을 확정론적 수질해석과 동일한 실제 하도구간에 적용하여 추계학적 수질해석을 실시하였고, 그 결과는 확정론적 해석결과와 잘 일치하였다. 유량과 수질, 반응계수 등에 포함된 불확실도가 하류단의 불확실도에 끼치는 영향을 산정하기 위해 상류단과 지류의 유량 및 수질에 대한 불확실도, 그리고 반응계수의 불확실도에 대한 분석과정이 모형에 포함되었다. 모의수행 결과로부터 각 변수들이 가지고 있는 불확실도가 총 불확실도에 끼치는 영향에 대한 기여도를 산정 할 수 있었다.

• 대한기계학회논문집
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• 제5권3호
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• pp.244-250
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• 1981

The rediant heat tranfer and temperature distribution between infinite parallel gray plates at different temperatures separated by an absorbing and emitting gray gas with or without a sinusoidal heat source in the gas are analyzed by Monte Carlo method. The Monte Carlo result were compared with the numerical solution by Usiskin and Sparrow and the exact solution by Hottel in the case of similar problem limited black walls and gas optical thickness is less than two. For gray walls and large optical thichness the results were compared with modified diffusion approximate solution by Deissler.

• 한국공작기계학회논문집
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• 제15권5호
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• pp.21-28
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• 2006

Vibration of a non-linear system with multiple degrees of freedom under random parametric excitations was evaluated by probabilistic method. The non-linear characteristic terms of system structure were quasi-linearized and excitation terms were remained as they were. An analytical method where the expectation values of square mean of error was minimized was used. The numerical results were compared with those obtained by Monte Carlo simulation. A linear congruential generator and Box-Muller method were used in Monte Carlo simulation. The comparison showed the results by probabilistic method agreed well with those by Monte Carlo simulation.

• 한국안전학회지
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• 제32권3호
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• pp.54-59
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• 2017

This paper presents an efficient finite analysis model and a simulation-based reliability analysis method for stowage device system failure of a container crane with respect to lateral load. A quasi-static analysis model is introduced to simulate the nonlinear resistance characteristics and failure of tie-down and stowage pin, which are the main structural stowage devices of a crane. As a reliability analysis method, a subset simulation method is applied considering the uncertainties of later load and mechanical characteristic parameters of stowage devices. An efficient Markov chain Monte Carlo (MCMC) method is applied to sample random variables. Analysis result shows that the proposed model is able to estimate the probability of failure of crane system effectively which cannot be calculated practically by crude Monte Carlo simulation method.

• Journal of Welding and Joining
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• 제18권3호
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• pp.122-130
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• 2000

Due to the inherent dimensional uncertainty, the tolerances accumulate in the assembly of plasma cutting torch. Tolerance accumulation has serious effect on the performance of the plasma torch. This study proposes a statistical tolerance propagation model, which is based on matrix transform. This model can predict the final tolerance distributions of the completed plasma torch assembly with the prescribed statistical tolerance distribution of each part to be assembled. Verification of the proposed model was performed by making use of Monte Carlo simulation. Monte Carlo simulation generates a large number of discrete plasma torch assembly instances and randomly selects a point within the tolerance region with the prescribed statistical distribution. Monte Carlo simulation results show good agreement with that of the proposed model. This results are promising in that we can predict the final tolerance distributions in advance before assembly process of plasma torch thus provide great benefit at the assembly design stage of plasma torch.

• 반도체디스플레이기술학회지
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• 제8권4호
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• pp.37-42
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• 2009

The performance of an OLED(organic luminescent emitting device) fabrication system strongly depends on the design of the evaporation cell-source. Trends in display sizes have hauled the enlargement of mother glass substrates. The enlargement of substrates requires the improvement and the enlargement of the effusion cell-source for OLED evaporation process. The deposited layers should be as uniform as possible, and therefore it is important to know the effusion profile of the molecules emitted from the cell-source. Conventional 2D DSMC algorithm cannot be used for simulating the new concept cell-source design, such as a linear source. This work concerns the development of 3D DSMC (direct simulation Monte Carlo) analysis for simulating the behavior of the evaporation cell-sources. In this paper, the 3D DSMC algorithm was developed and the film thickness profiles were obtained by the numerical analysis.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1987년도 정기총회 및 창립40주년기념 학술대회 학회본부
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• pp.193-196
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• 1987

We reported that hot electron phenomena in submicron nMOSFET by Monte Carlo method. In order to predict the influence of the hot electron effects on the device reliability, either simple analytical model or a complete two dimensional numerical simulation has been adopted. Results of numerical simulation, based on the static mobility model, may be inaccurate when gate length of MOSFET is scaled down to less than 1um. Most of device simulation packages utilize the static nobility model. Monte Carlo method based on stochastic analysis of carrier movement may be a powerful tool to characterize hot electrons. In this work, energy and velocity distribution of carriers were obtained to predict the relative degree of short channel effects for different device parameters. Our analysis shows a few interesting results when $V_{ds}$ is 5 volt, average electron energy does not increase with gate bias as evidenced by substrate current.

• 한국자동차공학회논문집
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• 제12권6호
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• pp.135-142
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• 2004

The severe frontal crash tests are NCAP with belted occupant at 35mph and FMVSS 208 with unbelted occupant at 25mph, This paper describes the design process of occupant protection systems, airbag and seat belt, under the two tests. In this study, NCAP simulations are performed by Monte Carlo search method and cluster analysis. The Monte Carlo search method is a global optimization technique and requires execution of a series of deterministic analyses, The procedure is as follows. 1) Define the region of interest 2) Perform Monte Carlo simulation with uniform distribution 3) Transform output to obtain points grouped around the local minima 4) Perform cluster analysis to obtain groups that are close to each other 5) Define the several feasible design ranges. The several feasible designs are acquired and checked under FMVSS 208 simulation with unbelted occupant at 25mph.