• 대한기계학회논문집A
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• 제36권2호
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• pp.157-164
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• 2012

많은 기능 또는 임무를 수행하는 다수의 부품들로 구성되어 있는 다기능 시스템 개발에 있어 시스템과 부품의 신뢰도(reliability), 가용도(availability) 그리고 정비도(maintainability)를 결정하는 것은 설계 단계에서의 중요한 일이다. 본 논문에서는 시스템을 구성하고 있는 최하위 부품을 대상으로 개발기준의 시스템 목표가용도(target availability)를 만족하는 각 구성품의 MTBF 와 MTTR 을 결정하고자 한다. 대안 생성을 위해 휴리스틱 기법(heuristic method)을 개발하였으며, 각 대안의 시스템 가용도와 수명주기비용을 계산하기 위해 시뮬레이션을 이용한다. 그리고 수치예제를 통해 모형매개변수의 영향을 알아 본다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2009년도 춘계학술대회 논문집
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• pp.1989-1992
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• 2009

Maintenance is classified preventive maintenance before performing equipment failure and corrective maintenance after performing equipment failure. In preventive maintenance, we may analyze the failure data to end from beginning of equipment and allocate maintenance method and calculate maintenance cycle quantitatively by the failure data analysis. So, it has a merit to reduce system maintenance cost and to operate effectively but, it require high cost in system introducing and continuous operation to end of system. In corrective maintenance, we may calculate MTTR(mean time to repair) quantitatively based on function failure time. it can be based on establishing maintenance system for operation efficiency. In this paper, we may reflect the MTTR for the onboard equipped in Tilting train to establish maintenance system for Tilting train operation efficiency.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2004년도 추계학술대회 논문집
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• pp.539-544
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• 2004

In this paper, we present reliability modeling and analysis method of the Automated Guideway Transit(AGT) vehicle system using analytical models, based on Markov Chains. The Markov model can express state transition of the AGT vehicle sys. that is considered to be in one of four states, such as basic operating (0), minor delay(1), major delay(2) and non-operating(3) state. The proposed Markov model is illustrated with a numerical example and cases to find a steady state availability, MTBF(mean time between failures), and MTTR(mean time to repair) under specified failure and repair rate arc demonstrated.

• 한국콘텐츠학회논문지
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• 제8권8호
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• pp.47-56
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• 2008

임무컴퓨터는 항공전자시스템에서 임무 수행에 필요한 각종 전술데이터 처리, 영상처리, 항법정보의 관리 및 융합 등의 매우 중요한 기능을 수행한다. 이러한 중요 시스템이 단일시스템으로 구성되면, 여러 가지 SPOF(Single Point Of Failure) 요소의 고장으로 인해 전체 시스템의 고장으로 이어질 수 있다. 이는 서비스 중단으로 인한 임무의 실패뿐만 아니라 조종사의 생명까지도 위협할 수 있다. 본 논문에서는 단일 시스템의 이중화를 통해 SPOF 요소를 제거하고, 이를 운영하기 위한 방안으로 리눅스 기반의 Heartbeat, Fake, DRBD(Distributed Replicated Block Device), Bonding 등의 기법을 이용하여 고가용 시스템을 구현하였다. 또한, 구현한 고가용 시스템에서 빠른 고장 탐지를 위한 FDT(Fault Detection Time)와 고장 발생 시 임무 연속성을 위해 중요한 요소일 MTTR(Mean Time To Repair)의 평균값을 측정하고, 그에 따른 성능분석 결과를 제시한다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 춘계학술대회 논문집
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• pp.993-999
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• 2007

With the introduction of the RAMS(Reliability, Availability, Maintainability, Safety), the interest of the system assurance has been increased. First of all, fast-growing electronic circuit requires analyzing the failure rates, by dividing the signalling system more specifically. Since 2005, the K.N.R (Korean National Railway) has incorporated ERP(Enterprise Resource Planning) in order to establish the complete status as the top international comprise, therefore while ordering the project, it has established the classification system and then has been applying to ERP system in 2007. Due to the complex of the classification system, the reliability analysis of the signalling system was assessed with the limit of IXL ATP with On-board and wayside equipment. This paper assumed MTBF(Mean Time Between Failure), MTTR((Mean Time Between Repair) of total signalling system, by using the classification of ERP program.

• 한국군사과학기술학회지
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• 제13권1호
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• pp.41-49
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• 2010

In this paper, we propose a hierarchical RAM simulation model framework which are used to analyze the RAM specifications on the concept refinement phase. The hierarchical RAM simulation model framework consists of RAM simulation models, class library and each model's input and output data lists. The hierarchical RAM simulation models are co-operated with 3 kinds of model - type I, II, III. Type I, II models are used to analyze the target operational availability and Type III is used to establish the initial RAM specifications. Each model's input and output data lists are defined by considering each model's purpose of RAM analysis. The class library is arranged with each model's classes for implementing the hierarchical simulation models. The proposed framework may be applied for executing the RAM activities effectively.

• 한국국방경영분석학회지
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• 제27권1호
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• pp.58-72
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• 2001

This research deals with the weapon system RAM which is the reliability, availability and maintainability for weapon systems. This weapon system RAM is one of very important factors because it is related to the life cycle cost and combat readiness of weapon systems. Therefore, in this research we introduce the weapon system RAM and analyze the problems of weapon system RAM management during system life cycle including acquisition period. Finally we suggest an alternative to improve the weapon system RAM in various agencies which are the department of defense and army headquarter level, etc., in the process of defense acquisition.

• 한국군사과학기술학회지
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• 제22권6호
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• pp.824-831
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• 2019

For effective development in consideration of the maintainability of the weapon system, it is necessary to understand whether the maintainability design requirements are satisfied at the early phase of development. This requires the application of an early design phase maintainability prediction process to provide opportunities for improvement. By defining the ambiguity group definition, fault isolation level, fault isolation probability, and countermeasures for faults, it was possible to predict early phase development. The MTTR of the initial design phase applying Procedure V to the artillery system was 3.46H, which is about 16 % higher than 2.98H, the MTTR using Procedure II. This is a result of system design ambiguity that has not been specified in the early phase of development.

• 한국CDE학회논문집
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• 제20권1호
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• pp.36-43
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• 2015

Recently, a number of evaluation studies on availability of plant were carried out. This study was conducted to verify of the reliability of a simulation with some variable such as configuration of process, failure probability density function and the number of iteration times for the natural gas liquefaction plant. The error rate of the KICT-RAM solution was evaluated as 0.03~1.79% compared with the result of the MAROS(commercial solution). And the error-rate change was observed in the range of 0.03~1.75 on the condition of the iteration times as 30, 100, 250. As a result the plant availability evaluation approach of KICT-RAM solution was verified as reasonable. However, the careful approach was required to use the solution because the error-rate increased according to iteration times change.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 추계학술대회 논문집
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• pp.109-114
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• 1997

As CNC machine tool is one of core elements of manufacturing system, it is much important that it remains without troubleshoots. As a virtual machine is a recent alternative using IT for optimal utilization of CNC machine tool, it is a computer model that represents a CNC machine tool. But a virtual machine is still conceptual. So, in this paper, it is proposed that a virtual machine be a realistic model in the fault diagnosis module. For this purpose, the fault diagnosis system of machine tool using CORBA and fault diagnosis expert system has been implemented. Using this system, we have expections to diagnose exactly and prompty without the restriction of time or location, to reduce MTTR(Mean Time To Repair) and finally to increase the availability of manufacturing system.