• Structural Engineering and Mechanics
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• 제42권2호
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• pp.175-189
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• 2012

This paper presents an algorithm for structural reliability with the response surface method. For this aim, an approach with three stages is proposed named as improved response surface method. In the algorithm, firstly, a quadratic approximate function is formed and design point is determined with First Order Reliability Method. Secondly, a point close to the exact limit state function is searched using the design point. Lastly, vector projected method is used to generate the sample points and Second Order Reliability Method is performed to obtain reliability index and probability of failure. Five numerical examples are selected to illustrate the proposed algorithm. The limit state functions of three examples (cantilever beam, highly nonlinear limit state function and dynamic response of an oscillator) are defined explicitly and the others (frame and truss structures) are defined implicitly. ANSYS finite element program is utilized to obtain the response of the structures which are needed in the reliability analysis of implicit limit state functions. The results (reliability index, probability of failure and limit state function evaluations) obtained from the improved response surface are compared with those of Monte Carlo Simulation, First Order Reliability Method, Second Order Reliability Method and Classical Response Surface Method. According to the results, proposed algorithm gives better results for both reliability index and limit state function evaluations.

• 한국전산구조공학회논문집
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• 제14권3호
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• pp.339-348
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• 2001

상용 구조해석 프로그램을 이용한 구조물의 최적설계에서는 최적화 프로그램과 구조해석 프로그램의 연결 및 두 프로그램 사이의 데이터 교환이 용이하지 못하다. 최근 많은 구조물 설계자들은 근사 최적화 기법을 이용하여 이와 같은 문제들을 해결하고 있다. 일반적으로 최적실계 문제의 설계변수에 대한 설계영역은 아주 작은 값에서 아주 큰 값으로 범위가 정해진다. 이렇게 넓은 설계영역에서 생성된 시스템 응답 근사식의 정확도는 떨어지게 되며, 이는 근사 최적해에 지배적인 영향을 미친다. 따라서, 본 연구의 목적은 넓은 설계영역에서 정확도가 높은 근사식 생성을 위한 순차 설계영역법 개발에 있다. 순차 설계영역에서의 근사식은 반응표면법을 이용하여 구성하고, 반응표면법에 필요한 실험방법으로는 직교 배열표를 사용한다. 본 연구에서는 순차 설계영역법의 신뢰도 검증을 위하여 3부재 및 10부재 트러스 구조물을 수치예제로 선정한다.

• 한국해안해양공학회지
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• 제19권5호
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• pp.399-407
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• 2007

수리학적 파괴모드인 소단의 후퇴거리와 구조적 파괴모드인 사석재의 파손에 대한 발생 가능성을 확률적으로 해석할 수 있는 신뢰성 해석 모형이 개발되었다. 본 연구에서 수립된 신뢰함수를 이용하여 관련 변수들의 불확실성을 고려할 수 있는 AFDA(Approximate Full Distribution Approach)법과 Monte-Carlo 모의법이 개발되었다. 다른 연구 결과들과 상호 비교하여 신뢰성 해석 모형이 올바르게 수립되었음을 확인할 수 있었다. 또한 기존의 연구자들이 수행하지 못한 각 파괴모드와 관련된 확률변수들의 영향이 해석되었다. 마지막으로 동일한 입사파랑 조건에서 발생되는 두 파괴모드의 의존성을 산정하기 위해 다중파괴모드에 대한 해석도 수행하였다. 다중파괴모드 해석 결과에 의하면 허용 후퇴거리 일정 이상의 범위에서는 구조적 파괴모드가 소단형 방파제의 주 파괴모드가 됨을 확인할 수 있었다.

• Journal of information and communication convergence engineering
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• 제20권2호
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• pp.79-89
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• 2022

To compute the mean and variance of component-based reliability software, we focused on path-based reliability analysis. System reliability depends on the transition probabilities of components within a system and reliability of the individual components as basic input parameters. The uncertainty in these parameters is estimated from the test data of the corresponding components and arises from the software architecture, failure behaviors, software growth models etc. Typically, researchers perform Monte Carlo simulations to study uncertainty. Thus, we considered a Markov chain Monte Carlo (MCMC) simulation to calculate uncertainty, as it generates random samples through sequential methods. The MCMC approach determines the input parameters from the probability distribution, and then calculates the average approximate expectations for a reliability estimation. The comparison of different techniques for uncertainty analysis helps in selecting the most suitable technique based on data requirements and reliability measures related to the number of components.

• Journal of Magnetics
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• 제17권4호
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• pp.291-297
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• 2012

This paper presents an efficient methodology for accurate reliability assessment of electromagnetic devices. To achieve the goal, elaborate surrogated models to approximate constraint functions of interest are generated based on the dynamic Kriging method and a hypercube local window. Then, the Monte Carlo simulation scheme is applied to the surrogate models. This leads to reducing computational cost dramatically without degrading accuracy of the reliability analysis. The validity of the proposed method is tested and examined with a mathematical example and a loudspeaker design.

• Journal of information and communication convergence engineering
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• 제16권1호
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• pp.38-42
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• 2018

In this paper, we consider measurement allocation problem in a spatially correlated sensor field. Our goal is to determine the probability of each sensor's being measured based on its contribution to the estimation reliability; it is desirable that a sensor improving the estimation reliability is measured more frequently. We consider a spatial correlation model of a sensor field reflecting transmission power limit, noise in measurement and transmission channel, and channel attenuation. Then the estimation reliability is defined distortion error between event source and its estimation at sink. Motivated by the correlation nature, we model the measurement allocation problem into a cooperative game, and then quantify each sensor's contribution using Shapley value. Against the intractability in the computation of exact Shapley value, we deploy a randomized method that enables to compute the approximate Shapley value within a reasonable time. Besides, we envisage a measurement scheduling achieving the balance between network lifetime and estimation reliability.

• Geomechanics and Engineering
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• 제15권4호
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• pp.937-945
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• 2018

A probabilistic study of a reinforced earth wall in a frictional soil using the surface response methodology (RSM) is presented. A deterministic model based on numerical simulations is used (Abdelouhab et al. 2011, 2012b) and the serviceability limit state (SLS) is considered in the analysis. The model computes the maximum horizontal displacement of the wall. The response surface methodology is utilized for the assessment of the Hasofer-Lind reliability index and is optimized by the use of a genetic algorithm. The soil friction angle and the unit weight are considered as random variables while studying the SLS. The assumption of non-normal distribution for the random variables has an important effect on the reliability index for the practical range of values of the wall horizontal displacement.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.468-473
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• 2004

New reliability-based topology optimization method is proposed by utilizing single-loop single vector approach, which approximate searching the most probable point in the probabilistic design domain analytically, to reduce the time cost and dealing with several constraints to handle practical design requirements. To examine uncertainties in the topology design of a structure, the modulus of elasticity of the material and applied loadings are considered as probabilistic design variables. The results of design examples show that the proposed method provides efficiency curtailing the time for the optimization process and accuracy satisfying the specified reliability.

• 한국신뢰성학회지:신뢰성응용연구
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• 제8권1호
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• pp.15-27
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• 2008

본 논문에서는 무선 CORBA에서 MS구조의 근사 신뢰도계정을 제안하였다. 기존의 정확한 계정 방법은 마코프모델을 적용하여 복잡도가 높은 반면, 제안하는 방법은 단말의 이동에 따른 핸드오프 이전의 정상상태와 핸드오프상태 중에서 시스템의 성능향상과 부품의 고장률이 향상된 것을 고려하여 핸드오프상태를 계정에서 제외하여 복잡도를 줄였다. 제안하는 근사 신뢰도계정이 정확한 신뢰도 계정과 비교한 결과 편차는 1/1000정도 이었다. 그러나 이 편차는 시스템의 동작시간이 길어질수록 점점 줄어드는 것으로 확인되었다.

• Structural Engineering and Mechanics
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• 제47권1호
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• pp.45-58
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• 2013

In structural reliability analysis, the response surface method is a powerful method to evaluate the probability of failure. However, the location of experimental points used to form a response surface function must be selected in a judicious way. It is necessary for the highly nonlinear limit state functions to consider the design point and the nonlinear trend of the limit state, because both of them influence the probability of failure. In this paper, in order to approximate the actual limit state more accurately, experimental points are selected close to the design point and the actual limit state, and consider the nonlinear trend of the limit state. Linear, quadratic and cubic polynomials without mixed terms are utilized to approximate the actual limit state. The direct Monte Carlo simulation on the approximated limit state is carried out to determine the probability of failure. Four examples are given to demonstrate the efficiency and the accuracy of the proposed method for both numerical and implicit limit states.