• 제목/요약/키워드: reliability analysis

검색결과 12,037건 처리시간 0.039초

L.E.O. Satellite Power Subsystem Reliability Analysis

  • Zahran M.;Tawfik S.;Dyakov Gennady
    • Journal of Power Electronics
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    • 제6권2호
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    • pp.104-113
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    • 2006
  • Satellites have provided the impetus for the orderly development of reliability engineering research and analysis because they tend to have complex systems and hence acute problems. They were instrumental in developing mathematical models for reliability, as well as design techniques to permit quantitative specification, prediction and measurement of reliability. Reliability engineering is based on implementing measures which insure an item will perform its mission successfully. The discipline of reliability engineering consists of two fundamental aspects; $(1^{st})$ paying attention to details, and $(2^{nd})$ handling uncertainties. This paper uses some of the basic concepts, formulas and examples of reliability theory in application. This paper emphasizes the practical reliability analysis of a Low Earth Orbit (LEO) Micro-satellite power subsystem. Approaches for specifying and allocating the reliability of each element of the power system so as to meet the overall power system reliability requirements, as well as to give detailed modeling and predicting of equipment/system reliability are introduced. The results are handled and analyzed to form the final reliability results for the satellite power system. The results show that the Electric Power Subsystem (EPS) reliability meets the requirements with quad microcontrollers (MC), two boards working as main and cold redundant while each board contains two MCs in a hot redundant.

종속을 고려한 Network동적 신뢰도 분석 시스템 (Reliability Analysis system For Network with Dependent Components)

  • 윤원영;하영주
    • 산업공학
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    • 제10권2호
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    • pp.41-50
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    • 1997
  • This paper considers the reliability computation of the network with dependent components and a software system is developed for supporting the reliability analysis and improvement of the system reliability. At first, We propose the common cause failure and load sharing models as the typical models considering the dynamic behaviors of networks with dependent components. Secondly, the algorithm is proposed to obtain the network reliability and reliability importance of component. The software, Delphi, is used to develop the our reliability analysis system.

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우울증 변증도구의 신뢰도, 타당도 평가 (Reliability and Validity Analysis of the Instrument on Pattern Identifications for Depression)

  • 이헌수;강위창;정인철
    • 동의신경정신과학회지
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    • 제26권4호
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    • pp.407-416
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    • 2015
  • Objectives: This study was performed to evaluate the reliability and validity of the instrument on pattern identifications for depression. Methods: Two assessors carried out an evaluation about the instrument on pattern identifications for depression, targeting 201 participants, who after taking the HAM-D score over 12 or under 7 twice. Results: Inter-assessor reliability was higher than intra-assessor reliability in a reliability analysis about classification of pattern identification evaluated by the instrument on pattern identifications for depression. Reliability of intra-assessor and inter-assessor showed a moderate to strong agreement when reliability analysis about classification score of the pattern identification had been performed. Reliability analysis to evaluate the validity of the instrument on pattern identifications for depression showed moderate agreement. Conclusions: The results reveal that reliability analysis of the instrument on pattern identifications for depression showed an over moderate agreement and validity analysis represented a positive correlation.

철도차량 접촉기의 신뢰성 분석 및 교환주기 결정에 대한 연구 (A Study on Reliability Analysis & Determination of Replacement Cycle of the Railway Vehicle Contactor)

  • 박민흥;이세헌
    • 한국신뢰성학회지:신뢰성응용연구
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    • 제17권4호
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    • pp.316-324
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    • 2017
  • Purpose: The purpose of this study is to determine the replacement cycle applied age replacement policy by reliability analysis based on railway vehicle contactor's failure history data. Method: We performed reliability analysis based on railway vehicle contactor's failure history data. We found a suitable distribution by goodness of fit test and predicted the reliability through estimation of scale & shape parameter. Considering cost information we determined the replacement cycle that minimize the opportunity cost. Result: Suitable distribution was the Weibull and scale parameter & shape parameter are estimated by reliability analysis. The replacement cycle was predicted and MTTF, $B_6$ percentile life were suggested additionally. Conclusion: We confirmed that failure rate type of railway vehicle contactor is degradation model having a time dependent characteristic and examined the replacement cycle in our country's operating environment. We expect that this study result contribute to railway operation agency for maintenance policy decision.

다분야 통합해석 시스템의 효율적인 신뢰성 해석기법 연구 (An Efficient Approach on Reliability Analysis under Multidisciplinary Analysis Systems)

  • 안중기;권장혁
    • 한국항공우주학회지
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    • 제33권3호
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    • pp.18-25
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    • 2005
  • 다분야 통합해석 시스템의 신뢰성 해석에 대한 기존의 연구들은 대부분 비선형 최적화 기법을 기반으로 하고 있다. 이들은 다분야 통합최적설계 프레임워크를 이용하여 신뢰성을 직접 해석하기 때문에 효율적인 AFORM기법을 적용하는 것이 불가능하다. 본 논문은 AFORM기법을 적용한 다분야 통합시스템의 순차적 신뢰성 해석기법(SARAM)을 제안한다. 이를 위해 신뢰성 해석과 다분야 통합시스템의 해석(MDA)을 분리하고, 순차적으로 배열하여, 되풀이구조를 가지는 해석구조를 구성하였다. 제안된 방법의 효율성은 계산량, 정확도, 그리고 동시 수행기능의 관점에서 평가하였다. 3개의 다분야 통합시스템 예제를 계산한 결과, 제안된 기법은 정확도를 보장하면서 기존의 방법에 비해 우수한 계산효율을 보였다.

철도시스템 RCM 적용을 위한 신뢰성 및 안전성 분석 활동에 관한 연구 (A Study on the Analysis of the Reliability and the Safety to apply RCM to Railway System)

  • 김수명;이덕규;이경학;이기서;신석균
    • 한국철도학회논문집
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    • 제9권6호
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    • pp.739-745
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    • 2006
  • The role of maintenance in railway is going to be extended to improve the reliability of railway system in the aspect of Asset management gradually. In this paper, the meaning of reliability and safety in RCM which has been applied in order to improve the efficiency of maintenance is deduced. And the analysis task of reliability and safely which has been recommended in railway standards such as EN50126 and IEC62278 is reviewed in the aspect of RCM. Finally, the several ways are proposed to apply RCM to railway system through the comparison between the RCM procedure and the analysis procedure for the reliability and safety in railway standards. Hereafter, if the analysis of reliability and safety is performed with the concept of RCM in the beginning of railway business, it will be more efficient to improve the reliability and manage the railway asset.

Reliability-based design optimization using reliability mapping functions

  • Zhao, Weitao;Shi, Xueyan;Tang, Kai
    • Structural Engineering and Mechanics
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    • 제62권2호
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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.

DEVS 환경에서 LNG FPSO 액화 공정의 신뢰도 해석 (Reliability Analysis of LNG FPSO Liquefaction Cycle in DEVS Environment)

  • 하솔;구남국;노명일
    • 한국CDE학회논문집
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    • 제18권2호
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    • pp.138-147
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    • 2013
  • The liquefaction process system is regarded as primary among all topside systems in LNG FPSO. This liquefaction process system is composed of many types of equipment. LNG equipment on offshore plants has quite different demands on the equipment compared to traditional onshore LNG plants, so the reliability analysis of this process system needs to be performed. This study investigates how DEVS formalism for discrete event simulation can be used to reliability analysis of the liquefaction cycle for LNG FPSO. The reliability analysis method based on DEVS formalism could be better model for reflecting the system configuration than the conventional reliability analysis methods, such as fault tree analysis and event tree analysis.

Reliability Analysis of the 300 W GaInP/GaAs/Ge Solar Cell Array Using PCM

  • Shin, Goo-Hwan;Kwon, Se-Jin;Lee, Hu-Seung
    • Journal of Astronomy and Space Sciences
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    • 제36권2호
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    • pp.69-74
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    • 2019
  • Spacecraft requires sufficient power in orbit to perform its mission. So as to comply with system requirements, the sufficient power should be made by a solar cell array by photovoltaic power conversion. A life time of space program depends on its mission considering parts reliability and parts grade. Based on the mission life time, power equipment might be designed to meet specifications. In outer space, solar cell array might generate the dc power by photovoltaic conversion effects and GaInP/GaAs/Ge solar cells are used in this study. Space programs that require more than five years should select parts for high reliability applications. Therefore, reliability analysis for high reliability applications should be performed to check its fulfilment of the requirements. This program should also require more five years for its mission and we performed its analysis using parts count method (PCM) for its reliability. Finally, we performed reliability analysis and obtained quantitative figures found out 99.9%. In this study, we presented the reliability analysis of the 300 W GaInP/GaAs/Ge solar cell array.

NHPP 기반의 신뢰성 성장 예측 모델에 대한 민감도 분석 (Sensitivity Analysis for Reliability Growth Projection Model based on NHPP)

  • 조강훈;이홍철;장중순;박상철
    • 한국신뢰성학회지:신뢰성응용연구
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    • 제16권4호
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    • pp.305-312
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    • 2016
  • Purpose: The purpose of this study is to provide a sensitivity analysis of system reliability for recognizing effectiveness of changing of BD mode failures using reliability growth projection model based on NHPP. Methods: Crow extended reliability projection model (CERPM) is used to analyze the changing of two factors 1) the number of BD mode failures, 2) fix effectiveness factor (FEF) values. Results: The system reliability has increased in accordance with the number of BD mode failures and FEF values have increased. Conclusion: It is necessary to design failure modes and FEF values to supervise the reliability.