• Title, Summary, Keyword: Reliability analysis

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A Study for Reliability Target Setting Considering Warranty Cost and Reliability Analysis Result of Process Controller in Nuclear Power Plant (원자력 발전소용 공정 제어기의 보증 비용을 고려한 신뢰도 목표치 설정과 신뢰도 분석 결과에 대한 연구)

  • Kim, Gun Myung
    • Journal of Applied Reliability
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    • v.15 no.3
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    • pp.145-148
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    • 2015
  • The products to meet the requirement of are installed in nuclear power plant and the reliability target should be provided in the requirement. However, it is not easy to set a reliability target using quantitative analysis. The objective of this paper is to propose a method of reliability target setting considered warranty cost for process controller and then compare a reliability target with reliability analysis result.

Reliability Analysis of Degradation Data for LEDs (LED 열화데이터의 신뢰성 분석)

  • Park, Chang-Kyu
    • Journal of Applied Reliability
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    • v.9 no.1
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    • pp.59-69
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    • 2009
  • LEDs have rapidly replaced old light devices such as incandescent or fluorescent lamps, and have been widely applied in general lighting, signals, automobile, signs and others. Since LEDs are for both indoor and outdoor use, temperature and humidity inevitably affect its reliability. We explain the result of the degradation life test on LEDs, and guide to reliability analysis procedure. Analysis on reliability measures are performed by Weibull++6 program, and a common shape parameter of Weibull distribution on the LED is suggested. Also, we make a description of reliability analysis procedures for the degradation data using collected test data from degradation tests. Reliability analysis procedures are consisted of estimating degradation models and failure time, verifying of distribution and parameters of the distribution, and estimating of reliability measures. Finally, this paper suggests reliability analysis method for light characteristics on LEDs.

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FORM-based Structural Reliability Analysis of Dynamical Active Control System (동적능동제어시스템의 FORM기반 구조신뢰성해석)

  • Ok, Seung-Yong
    • Journal of the Korean Society of Safety
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    • v.28 no.1
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    • pp.74-80
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    • 2013
  • This study describes structural reliability analysis of actively-controlled structure for which random vibration analysis is incorporated into the first-order reliability method (FORM) framework. The existing approaches perform the reliability analysis based on the RMS response, whereas the proposed study uses the peak response for the reliability analysis. Therefore, the proposed approach provides us a meaningful performance measure of the active control system, i.e., realistic failure probability. In addition, it can deal with the uncertainties in the system parameters as well as the excitations in single-loop reliability analysis, whereas the conventional random vibration analysis requires double-loop reliability analysis; one is for the system parameters and the other is for stochastic excitations. The effectiveness of the proposed approach is demonstrated through a numerical example where the proposed approach shows fast and accurate reliability (or inversely failure probability) assessment results of the dynamical active control system against random seismic excitations in the presence of parametric uncertainties of the dynamical structural system.

Human Reliability Analysis of Soft Control Operations in Nuclear Power Plants: Issues and Perspectives

  • Lee, Seung Jun;Jung, Wondea
    • Journal of the Ergonomics Society of Korea
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    • v.32 no.1
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    • pp.87-96
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    • 2013
  • Objective: The aim of this study is to describe several issues which should be considered in the human reliability analysis of soft control operations in nuclear power plants. Background: The operational environment of advanced main control rooms is totally different from that of conventional control rooms. The soft control is one of the major distinguishable features of the advanced main control rooms. The soft control operations should be analyzed to estimate the effects on human reliability. Method: The literatures, about task analysis, simulation data analysis, and a human reliability analysis method for the soft control, were reviewed. From the review, important issues for the human reliability analysis of the soft control were raised. Results: The results of task and simulation data analysis showed that the soft control characteristics could have large effect on human reliability and they should be considered in the human reliability analysis of the soft control operations. Conclusion: The soft control may affect human error and performance of operators. The issues described in this paper should be considered in the human reliability method for the advanced main control rooms. Application: The results of the soft control operation analysis might help to design more efficient interface and education/training program for preventing human errors. The described issues might help to develop a human reliability analysis method for soft control operations.

Parallel Reservoir Analysis of Drought Period by Water Supply Allocation Method (공급량 배분기법을 이용한 갈수기 병렬저수지 해석)

  • Park Ki-Bum;Lee Soon-Tak
    • Journal of Environmental Science International
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    • v.15 no.3
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    • pp.261-269
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    • 2006
  • In this study, an optimization technique was developed from the application of allocation rule. The results obtained from the water supply analysis and reliability indices analysis of Andong dam and Imha dam which are consist of parallel reservoir system are summarized as the followings; Allocation rule(C) is effective technique at the parallel reservoir system because results of the water supply analysis, storage analysis and reliability indices analysis is calculated reasonable results. Also, reliability indices analysis results are not sufficient occurrence based reliability or quantity based reliability. Thus reliability indices analysis are need as occurrence based reliability, quantity based reliability vulnerability, resilience, average water supply deficits and average storage. And water supply condition is better varying water supply condition than constant water supply condition.

Human Reliability Analysis for Risk Assessment of Nuclear Power Plants (원자력발전소 위험도 평가를 위한 인간신뢰도분석)

  • Jung, Won-Dea;Kim, Jae-Whan
    • Journal of the Ergonomics Society of Korea
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    • v.30 no.1
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    • pp.55-64
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    • 2011
  • Objective: The aim of this paper is to introduce the activities and research trends of human reliability analysis including brief summary about contents and methods of the analysis. Background: Various approaches and methods have been suggested and used to assess human reliability in field of risk assessment of nuclear power plants. However, it has noticed that there is high uncertainty in human reliability analysis which results in a major bottleneck for risk-informed activities of nuclear power plants. Method: First and second generation methods of human reliability analysis are reviewed and a few representative methods are discussed from the risk assessment perspective. The strength and weakness of each method is also examined from the viewpoint of reliability analyst as a user. In addition, new research trends in this field are briefly summarized. Results: Human reliability analysis has become an important tool to support not only risk assessment but also system design of a centralized complex system. Conclusion: Human reliability analysis should be improved by active cooperation with researchers in field of human factors. Application: The trends of human reliability analysis explained in this paper will help researchers to find interest topics to which they could contribute.

A Study on the reliability method development for the LCC analysis (LCC분석에 있어서 신뢰성기법 활용에 관한 연구)

  • Lee, J.B.;Cho, S.H.;Min, B.C.;Hong, D.Y.;Lee, W.J.
    • Proceedings of the Korean Reliability Society Conference
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    • pp.319-328
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    • 2011
  • The failure of LCC analysis is recognized as a serious risk for companies in fast-paced business environment. LCC analysis has been mentioned and analyzed only in accounting perspectives, but recently engineering perspectives of LCC analysis based on the execution of appropriate procedures become more important than the accounting perspectives. Especially, the practical use of reliability engineering related methodologies is recognized as a key factor for the LCC analysis. For the practical use of reliability methods, LCC analysis for unexposed problems is a key issue, and utilizing FMEA and FTA techniques is needed to solve the unexposed problems. Reliability, maintainability, availability, and safety should be evaluated by the LCC analysis with the reliability methods, so we study methodologies for the LCC analysis. Present Worth can be calculated by multiplication of Annual Equivalent Cost and PWAF. Reliability engineering related methods are needed for the process of dividing Present Worth into PWAF, and the practical use of reliability methods can improve accuracy of LCC analysis.

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Reliability-based design optimization using reliability mapping functions

  • Zhao, Weitao;Shi, Xueyan;Tang, Kai
    • Structural Engineering and Mechanics
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    • v.62 no.2
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    • pp.125-138
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    • 2017
  • Reliability-based design optimization (RBDO) is a powerful tool for design optimization when considering probabilistic characteristics of design variables. However, it is often computationally intensive because of the coupling of reliability analysis and cost minimization. In this study, the concept of reliability mapping function is defined based on the relationship between the reliability index obtained by using the mean value first order reliability method and the failure probability obtained by using an improved response surface method. Double-loop involved in the classical RBDO can be converted into single-loop by using the reliability mapping function. Since the computational effort of the mean value first order reliability method is minimal, RBDO by using reliability mapping functions should be highly efficient. Engineering examples are given to demonstrate the efficiency and accuracy of the proposed method. Numerical results indicated that the proposed method has the similar accuracy as Monte Carlo simulation, and it can obviously reduce the computational effort.

Reliability Analysis of Auxiliary Power System on Korea High Speed Train (한국형 고속열차 보조전원 시스템의 신뢰성 해석)

  • 서승일;박춘수;한영재;이태형;김기환
    • Journal of the Korean Society for Railway
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    • v.7 no.4
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    • pp.356-359
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    • 2004
  • In this paper, as the first step to assess and enhance the reliability of Korea High Speed Train, auxiliary power system is selected and reliability analysis is carried out. The auxiliary power system is classified into subsystems and functional analysis is conducted. Reliability block diagrams are drawn and reliability parametric analysis is performed. Analysis results show that the reliability of auxiliary power system depends on critical items. To grow the system reliability, activities should be concentrated on improvement of critical items.

Reliability analysis of shallow tunnel with surface settlement

  • Yang, X.L.;Li, W.T.
    • Geomechanics and Engineering
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    • v.12 no.2
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    • pp.313-326
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    • 2017
  • Based on the reliability theory and limit analysis method, the roof stability of a shallow tunnel is investigated under the condition of surface settlement. Nonlinear Hoek-Brown failure criterion is adopted in the present analysis. With the consideration of surface settlement, the internal energy and external work are calculated. Equating the rate of energy dissipation to the external rate of work, the expression of support pressure is derived. With the help of variational approach, a performance function is proposed to reliability analysis. Improved response surface method is used to calculate the Hasofer-Lind reliability index and the failure probability. In order to assess the validity of the present results, Monte-Carlo simulation is performed to examine the correctness. Sensitivity analysis is used to estimate the influence of different variables on reliability index. Among random variables, the unit weight significantly affects the reliability index. It is found that the greater coefficient of variation of variables lead to the higher failure probability. On the basis of the discussions, the reliability-based design is achieved to calculate the required tunnel support pressure under different situations when the target reliability index is obtained.