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Study on Effect of Left-Truncated Data Rate on ML Estimation for Power Law Process
Alfonsus Julanto Endharta,김종운,최성수 한국철도학회 2019 한국철도학회논문집 Vol.22 No.9
This paper used parameter estimation to analyze left-truncated and right-censored failure time data frommultiple repairable systems. The systems were identical; the failure occurrence followed a Non-Homogeneous PoissonProcess (NHPP) and the intensity rate function followed a power law function. Maximum Likelihood (ML) method wasused to estimate the function parameters. Two scenarios were considered. In the first scenario, it was assumed that therewere no failures between the operation starting time and the observation starting time points. In the second one, lefttruncationwas considered and thus the possibility of failure occurrence existed between the operation starting time andthe observation starting time points. The parameters estimated from these scenarios were compared to the real inputparameters in the data generation to show the importance of the truncation information.
Condition-based maintenance policy for linear consecutive-<i>k</i>-out-of-<i>n</i>: <i>F</i> system
Endharta, Alfonsus Julanto,Yun, Won Young Informa UK (TaylorFrancis) 2017 Communications in statistics Simulation and comput Vol.46 No.4
<P>In the article, a condition-based maintenance policy is proposed for a linear consecutive-k-out-of-n: F system. The failure times of components are assumed to be independent and identically distributed. It is assumed that the component states in the system can be known at any time and the system failure can be detected immediately. The preventive maintenance action is based on the number of working components in minimal cut sets of the system. If there is at least one minimal cut set consisting of only one working component, the system is maintained preventively after a certain time interval. The proposed policy is compared with corrective maintenance and age-based maintenance policies. As an extended case, it is assumed that the component states can only be known by inspection, but the system failure can be detected immediately. In this case, the system is inspected periodically and is also maintained preventively based on the system state at inspection. Numerical examples are studied to evaluate the performance of the proposed policy and investigate the effects of cost parameters on the expected cost rate.</P>
Endharta, Alfonsus Julanto,Yun, Won Young,Ko, Young Myoung Elsevier 2018 Reliability engineering & system safety Vol.180 No.-
<P><B>Abstract</B></P> <P>This paper studies a circular <I>k</I>-out-of-<I>n</I>: G balanced systems with identical and independent spatially distributed units. The system consists of an even number of units <I>n</I> which have constant survival probability <I>r</I> and failure probability 1 – <I>r</I>. The system is operating if at least <I>k</I> units are operating and it is balanced. A new balance definition is proposed for this system and the system reliability is calculated when the existing and the proposed system balance conditions are considered. The minimal path sets of the system are considered in the evaluation of the system reliability. The difference between the system reliability values reinforces the need to carefully select the system balance definition, depending on the system.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Reliability of circular <I>k</I>-out-of-<I>n</I>: G balanced system is evaluated. </LI> <LI> New balance condition is defined. </LI> <LI> New method to evaluate the system balance is proposed. </LI> <LI> Procedure to enumerate the minimal path sets is built. </LI> <LI> System reliability increases for certain cases. </LI> </UL> </P>
RAM-C 분석을 통해 무기체계에 CBM+ 적용 효과도에 관한 연구
엔드하르타 알폰수스 주란토(Alfonsus Julanto Endharta),김영선(Young-Seon Kim),김종운(Jongwoon Kim),조일훈(Il-Hoon Cho),박연경(Yun-Kyung Park) 한국산학기술학회 2023 한국산학기술학회논문지 Vol.24 No.9
본 논문은 RAM-C(신뢰성 기반 비용 관리) 분석을 통해 무기체계에서 상태기반정비(Condition-Based Maintenance, CBM+) 적용의 효과에 대한 연구를 제시한다. 연구의 목적은 RAM-C 지표에 대한 CBM+ 적용 효과를 평가하고 CBM+적용에 의한 잠재적인 장점을 식별하는 것이다. 고려하는 주요 지표는 운용 가용도와 같은 핵심성능지표(Key Performance Parameter, KPA)와 O&S(운용 및 지원) 비용과 같은 핵심시스템속성(Key System Attribute, KSA)이다. 무기체계의 성능, 신뢰성, 가용성, 유지보수 비용을 평가하기 위해 모델링 및 시뮬레이션(Modelling and Simulation, M&S) 접근 방식을 사용한다. 레이더 시스템이 사례 연구로 사용한다. 본 연구에서 제시된 결과는 CBM+ 적용을 통해 무기체계의 유지보수 프로세스를 최적화하는 데 관련된 방위 산업 전문가, 시스템 설계자 및 의사 결정자에게 실질적인 시사점을 제공할 수 있다. This paper presents a study on the effectiveness of condition-based maintenance plus (CBM+) implementation in weapon systems through RAM-C (reliability, availability, maintainability, and cost) analysis. The aim of this study was to assess the effect of CBM+ application on RAM-C parameters and identify the potential benefits and challenges associated with its adoption. The key parameters considered in the study are key performance parameters, such as operational availability, and key system attributes, such as operating and support cost. The study employed modeling and simulation to assess the performance, reliability, availability, and maintenance cost of weapon systems. A radar system was used as a case study. The results presented in this study have practical implications for defense industry professionals, system designers, and decision-makers involved in optimizing the maintenance processes of weapon systems through CBM+ adoption.