• Proceedings of the Korea Water Resources Association Conference
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• 한국수자원학회 2008년도 학술발표회 논문집
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• pp.850-853
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• 2008

송수관이나 배수관은 계획된 필요유량을 특정 지점까지 안전하게 전달할 수 있도록 설계되지만 여러 가지원인으로 인하여 갑작스런 파열이나 균열이 일어난다. 파이프 파괴의 원인으로는 수격현상, 관의노화, 파이프 외부로부터의 충격, 흙의 상태, 그리고 파이프 설치시의 공사여건 등이 있다. 본 연구에서 여러 가지 요인들을 불확실성 인자로 가정하여 파이프의 파괴확률을 산정할 수 있는 신뢰성 해석 모형이 개발되었다. 상수관망의 설계 시 파이프의 두께를 산정하는 주 장력 공식을 이용하여 신뢰함수를 만들고 파이프의 파괴확률을 계산하였다. 신뢰함수를 구성하는 확률변수들 중 파이프의 내압에 대한 분포함수는 정규분포가 아닌 극치분포(Gumbel distribution)를 따른다는 것을 부정류 수치해석 결과로서 알 수 있었고 AFDA(Approximate Full Distribution Approach) 기법을 사용하여 파괴확률을 산정하였다. 신뢰성 모형을 이용하여 파이프의 두께, 직경, 허용응력, 그리고 파이프 내압에 따른 파괴확률을 정량적으로 산정할 수 있었다. 본 연구에서 개발된 신뢰성 해석모형을 이용하여 보다 안전하고 경제적인 송배수관의 설계기법을 구축할 수 있을 것이다.

• Journal of Korean Society of Coastal and Ocean Engineers
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• 제22권6호
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• pp.415-422
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• 2010

Development of the reliability-based design program in the GUI environment is inadequate for engineers familiar with the deterministic design to deal with the international design criterion based on the probabilistic design. In this study, the design program based on the GUI environment is developed in order to more efficiently input the design factor and more easily carry out the design works. The GUI environment is the GUIDE (Graphic User Interface Development Environment) tool supported by the latest MATALB version 7.1. In order to test the model reliability, the probabilities of failure (POF) on the breakwater armor block (AB) and gravity quay-wall (QW) in the sliding mode are computed using the model in the Level II and Level III. The POF are 55.4~55.7% for breakwater AB and 0.0006~0.0007% for gravity QW. A non-GUI environment program results of the POF are 55.6% for breakwater AB and 0.0018% for gravity QW. In comparison, the POF difference is negligible for breakwater AB because the exact input design parameters are available, whereas the large POF difference, but within the same order, for gravity QW can be explained by the difference of the input design factors because of the poor input data information.

• Journal of Korean Society of Industrial and Systems Engineering
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• 제19권40호
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• pp.69-79
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• 1996

하드웨어 설계 과정에서 신뢰성 담당자들에게 당면한 문제는 요구된 임무에 필요한 기능적 요구사항의 달성 가능성과 요구된 임무를 달성할 확률의 예측여부 및 이의 적합성을 판단하는 것이다. 첫번째의 문제는 기존의 신뢰성 공학의 방법을 사용하여 해결되지만 두번째의 문제는 잦은 사후 설계 변경을 필요로 하기 때문에 항상 시스템 전체에서의 최적을 고려하여 이루어지지 못하고 있다. 본 논문에서는 그러한 잦은 사후 설계 변경등으로 인한 취약한 점을 극복하기 위한 방법론으로 하드웨어 설계 신뢰성 공학을 다루며 그 분석 도구로서 목표달성 나무(Goal-tree)의 사용과 그 응용을 제시하고자 한다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• 제34권7호
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• pp.18-27
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• 2006

The conventional reliability based design optimization(RBDO) methods require high computational cost compared with the deterministic design optimization(DO) methods, therefore it is hard to apply directly to large-scaled problems such as an aerodynamic shape design optimization. In this study, to overcome this computational limitation the efficient RBDO procedure with the two-point approximation(TPA) and adjoint sensitivity analysis is proposed, that the computational requirement is nearly the same as DO and the reliability accuracy is good compared with that of RBDO. Using this, the 3-D aerodynamic shape design optimization is performed very efficiently.

• Journal of the Computational Structural Engineering Institute of Korea
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• 제34권5호
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• pp.263-270
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• 2021

In this study, a reliability-based design optimization of a 130-m class fixed-type offshore platform, to be installed in the North Sea, was carried out, while considering environmental, material, and manufacturing uncertainties to enhance its structural safety and economic aspects. For the reliability analysis, and reliability-based design optimization of the structural integrity, unity check values (defined as the ratio between working and allowable stress, for axial, bending, and shear stresses), of the members of the offshore platform were considered as constraints. Weight of the supporting jacket structure was minimized to reduce the manufacturing cost of the offshore platform. Statistical characteristics of uncertainties were defined based on observed and measured data references. Reliability analysis and reliability-based design optimization of a jacket-type offshore structure were computationally burdensome due to the large number of members; therefore, we suggested a method for variable screening, based on the importance of their output responses, to reduce the dimension of the problem. Furthermore, a deterministic design optimization was carried out prior to the reliability-based design optimization, to improve overall computational efficiency. Finally, the optimal design obtained was compared with the conventional rule-based offshore platform design in terms of safety and cost.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• 제33권11호
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• pp.33-40
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• 2005

The reliability of flight control system(FCS) for Unmanned Air Vehicle(UAV) is underestimated because of the design restrictions such as small size, low cost and light weight. However because the failure of FCS may cause the loss of aircraft, the reliability of FCS must be analysed and validated whether it meet the reliability requirements in design phase.In this paper the failure rate of subsystems was divided with its function based on the design experience of FCS. The redundancy models which satisfy the system reliability requirements were suggested. These results may be utilized in the hardware design of FCS.

• Journal of the Korean Magnetics Society
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• 제23권2호
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• pp.62-67
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• 2013

This paper introduces an effective methodology for reliability-based design optimization of electromagnetic products, where a performance measure approach is adopted to accurately assess probabilistic constrains. Two design problems consisting of a loudspeaker and a superconducting magnetic energy storage system are considered. The efficiency of the proposed method in evaluating the failure probability of performances during the optimization process are compared with the existing method based on the reliability index approach. Moreover, in term of the accuracy of probability failure values, optimized design results are examined with reference values obtained from the Monte Carlo simulation.

• Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
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• 한국해안해양공학회 2002년도 한국해안해양공학발표논문집 Proceedings of Coastal and Ocean Engineering in Korea
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• pp.82-91
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• 2002

방파제에 대한 신뢰성 설계 방법은 유럽과 일본을 중심으로1980년대 중반 이후로 발전되어 왔다. 유럽에서는 van der Meer(1988a)가 방파제 피복재의 설계에 확률론적인 방법을 도입하였고, Burcharth(1991)는 사석방파제에 대하여 부분안전계수(partial safety factor)를 이용한 신뢰성 설계 방법을 제시하였다 최근 Burcharth and Sørensen(1999)은 PIANC (Permanent International Association of Navigation Congress) Working Groups의 결과를 요약하여 사석방파제와 직립방파제에 대한 부분안전계수들을 확립하였다. (중략)

• Proceedings of the Korean Information Science Society Conference
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• 한국정보과학회 2002년도 가을 학술발표논문집 Vol.29 No.2 (3)
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• pp.319-321
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• 2002

인터넷 기반 네트워크 통신의 형태가 단순한 텍스트 위주의 데이터로부터 실시간 환경을 요구하는 멀티미디어 데이터 형태로 변하고 있으며, 실시간 분산처리 시스템에 대한 수요가 증가하고 있다. 이러한 실시간 시스템은 분산 실시간 처리 시스템에 대한 전반적인 분야의 발전이 필요하며, 특히 그 중에서도 신뢰성이 높은 그룹 통신 시스템의 개발은 매우 중요하다. 따라서 본 논문에서는 고장탐지 기능이 있는 실시간 그룹 통신 시스템을 설계하였다. 설계된 실시간 그룹통신 시스템은 이미 TMO 모델을 통하여 메시지 신뢰성과 고장탐지에 관한 시뮬레이션을 하였고, 그 결과를 분석하여 실시간 그룹통신 시스템 설계에 반영하였다.

• Journal of the Korea Academia-Industrial cooperation Society
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• 제19권8호
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• pp.239-245
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• 2018

The importance of reliability in the development of weapons systems and reliability tests has been emphasized recently. Therefore, this study evaluated a reliability test design method of a bladder type accumulator and proposed a process for reliability test design. To design the reliability test of the accumulator, the main failure modes and failure mechanisms were investigated, and the main stress factors were analyzed to select the appropriate acceleration model. A steady - state reliability test was designed according to the number of samples, and the reliability level and accelerated life test time were calculated according to the acceleration factor computed using the selected acceleration model.