• 한국신뢰성학회지:신뢰성응용연구
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• 제11권1호
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• pp.43-57
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• 2011

In the paper, we consider two-dimensional warranty policy with failure times and repair times. The failure times are considered within the warranty period and the repair times are considered within the repair time limit. Under the renewable warranty policy and non-renewable warranty policy, we consider the number of warranty services in the censored area by warranty period and repair time limit to conduct warranty cost analysis. We investigate the field data to check their dependency and implement our proposed approaches to conduct warranty cost analysis using the parametric methods. Numerical examples are discussed to demonstrate the applicability of the methodologies and results based on the proposed approach in the paper.

• 정보처리학회논문지D
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• 제8D권6호
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• pp.835-842
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• 2001

본 논문에서는 소프트웨어 시험 단계중에 발생되는 시험노력 소요량을 고려한 소프트웨어 신뢰도 성장 모델을 제시하여 시간종속적인 시험 노력소요량 동태를 웨이블 곡선으로 설명한다. 시험 단계중에 소요되는 시험노력의 양에 대한 결함 검출비를 현재의 결함 내용에 비례하는 것으로 가정하여 소프트웨어 신뢰도 성장 모델을 비동차 포아송 프로세스(NHPP)로 공식화하되, 이 모델을 이용하여 소프트웨어 신뢰도 척도에 대한 데이터 분석기법을 개발한다. 시험 시간의 경과와 신뢰도와의 관계, 시험비용과 신뢰도와의 관계를 연구한다. 소프트웨어의 비용을 고찰함에 있어서 조건별로 검토하여 비용이 최소로 되는 발행시각을 결정하되, 목표신뢰도를 만족시키는 최적발행시각을 정한다. 비용의 입장에서 발행 시각을 결정하는 문제와 신뢰도의 입장에서 발행 시각을 결정하는 문제를 동시에 고려하여 최적 발행시각을 결정하도록 한다.

• 한국구조물진단유지관리공학회 논문집
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• 제5권4호
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• pp.177-184
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• 2001

In this study, three most distinct types of general rigid connections are included in the modelling, with is implemented into a computer code. The cost, functions of connections are constructed by using the estimated unit cost of bolting, welding and connection-steel elements incorporating all the effect of materials, labor, and fabrication work. Bused on the recent developments of the reliability-based structural analysis and design as well as the extending knowledge on the probabilistic characteristics of load and resistances, the probability based design criteria have been successfully developed for many standards. Since the probabilistic characteristics depend highly on the local load and resistances, it is recognized to develop the design criterion compatible with domestic requirements. The existing optimum design methods, which are generally based on the structural theory and certain engineering experience, do not realistically consider the uncertainties of load and resistances and the basic reliability concepts.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 추계 학술발표회
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• pp.508-518
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• 2008

Reliability and sensitivity analysis of the design parameters for a section of caisson type quaywall which is the most applicable in Korea were performed. It was tried to estimate probabilities of failure for the system of the multiple failure modes and to analyze LCC in the quaywall structure. The reliability analysis was performed by FORM. Also, sensitivity indices were estimated using the reliability indices, which may be used inferring effects of each design parameter on the reliability indices. As a result, the coefficient of friction between caisson and rubble, the moment by self weight and the moment of resistance mostly affected on the reliability indices in the sliding, overturning and foundation failure, respectively. System reliability theorem was applied in order to estimate the probabilities of failure for the system of the multiple failure modes. As the results of estimation of the probabilities of failure for the system, all cases were more conservative than those for the elements, according to both failure mode and load combination applied to series system. It entirely exceeded the target reliability index, but it was consistent with the theorem. According to the optimum LCC with the width of the caisson, the probability of failure exceeded the target probability of failure at then time. Therefore, it was judged to be insufficient to the practical application.

• 한국항공운항학회지
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• 제23권1호
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• pp.103-112
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• 2015

In this study, a study was carried out to see what influence low-cost carrier's e-service quality has on low-cost carrier customers' perceived value and customer satisfaction and what impact the results have on customer loyalty based on the results of previous studies related to e-SERVQUAL, an e-SERVQUAL measurement model for general e-commerce. In addition, a survey of consumers who have experienced using low-cost carrier experience through web sites was conducted. For the analysis of the data collected, SPSS 18.0 was used to conduct frequency analysis, factor analysis, reliability analysis, correlation analysis, and regression analysis and thus to test a hypothesis. Research findings showed that perceived value and customer satisfaction are closely related to customer loyalty, and it was also observed that the reliability factor on the service provided on the web site acts as an important influencing factor for customer loyalty in the perceived value and security factors such as payment by credit cards and protection of personal information serve as important one in terms of customer satisfaction. This study has its limitation in that samples of users who have experienced low-cost carrier are concentrated on specific ages and professions. In the future, it is required to conduct further studies on whether difference is made on the importance of measurement factors related to e-service quality by gender, age group, occupation, and e-service quality.

• 산업경영시스템학회지
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• 제22권50호
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• pp.23-32
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• 1999

Reliability and maintainability allocation in the analysis of the system's design, with the objective of planning and installing the individual components in such a way that the system performance is achieved. This paper has been made to solve an important task in reliability management of manufacturing systems within the general objective being to increase productivity while maintaining costs low. Thus, the purpose of this paper is to provide an analytical approach to determine an optimal reliability and maintainability allocation, trading off among system performance and parts investment costs. Two important considerations will be addressed in this regard : (ⅰ) determine the reliability and maintainability allocation of parts which maximizes a given production index, having fixed the total cost of investments ; and (ⅱ) determine the reliability and maintainability allocation which minimizes the total cost of investments, having fixed a minimum acceptable level of productivity. The procedure proposed in this paper is able to provide to managers and designers useful indications on the reliability and maintainability characteristics of parts in series -parallel systems. And this heuristic model is a decision support tool for contractors who are involved in large scale design projects such as ship and aircraft design. Numerical examples prove that an approximate expression of the average throughput rate is sufficiently accurate to be used in a numerical optimization method.

• Structural Engineering and Mechanics
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• 제52권6호
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• pp.1099-1120
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• 2014

In this paper, reliability-based design optimization (RBDO) of structures is addressed. For this purpose, the global search and optimization capabilities of genetic algorithm (GA) are combined with the efficiency and reasonable accuracy of an advanced moment-based finite element reliability method. For performing RBDO, three variants of GA including a real-coded, a binary-coded and an improved binary-coded GA are developed. In these methods, GA performs (finite element) reliability analyses to evaluate reliability constraints. For truss structures which include finite element modeling, reliability constraints are evaluated using finite element reliability analysis. Response sensitivity required for finite element reliability analysis is obtained by direct differentiation method (DDM) rather than finite difference method (FDM). The proposed methods are examined within four standard test examples and real-world design problems. The results illustrate the superiority and efficiency of the improved binary-coded GA. Results also illustrate that DDM significantly reduces the computational cost and improves the efficiency of the optimization procedure.

• 전산구조공학
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• 제5권4호
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• pp.113-124
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• 1992

토목구조물 설계에 있어서 가장 보편적으로 사용되고 있는 도로교에 대한 하중계수에 기초한 최적신뢰성해석모델을 제안하고, 또 총기대비용 최소화원칙에 기인한 최적하중-저항계수 및 최적 공칭안전율에 대한 이론적 근거를 제시하는 것이 본 연구의 주요내용이다. MFOSM과 AFOSM을 포함하는 주요 2차 모멘트신뢰성 이론을 비교분석함으로써 AFOSM의 근사식과 대수정규포근사식을 본 연구에서 제안하는 최적신뢰성 및 설계규준의 유도에 사용함이 적절하다는 것을 알 수 있었다.

• 한국안전학회지
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• 제21권3호
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• pp.94-100
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• 2006

The goal of this study is to show the way to increase the safety of deteriorated PSC beam bridges by the to-box reinforcing method. This method is to change the open girder section into the closed box section by connecting bottom flanges of neighboring PSC girders with the precast panels embedding PS tendons at the anchor block. The box section is composed of three concrete members with different casting ages, RC slab, PSC beam, precast panel. This different aging requires a time-dependent analysis considering construction sequences. Reliability index and failure probability are produced by the AFOSM reliability analysis. Transversely five schemes and longitudinally two schemes are considered. The full reinforcing scheme, transversely and longitudinally, shows the highest reliability index, but it requires more cost for retrofit. The partial reinforcing scheme 4, 4-1 are recommended in this study as the economically best scheme.

• International Journal of Reliability and Applications
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• 제8권1호
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• pp.67-82
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• 2007

This paper deals with the effectiveness analysis of an engineering system, which has two units of different strengths in parallel and one unit as a cold standby unit. Failure times for all the units have negative exponential distribution whereas their repair times have general distribution. Single server caters the need for the system. The effectiveness analysis of the system is done by using regenerative point technique. The different measures of effectiveness such as mean sojourn time, mean time to system failure, availability, busy period, etc, are derived. Cost factors also taken into consideration.