• 산업경영시스템학회지
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• 제40권4호
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• pp.96-104
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• 2017

A one-shot system (device) refers to a system that is stored for a long period of time and is then disposed of after a single mission because it is accompanied by a chemical reaction or physical destruction when it operates, such as shells, munitions in a defense weapon system and automobile airbags. Because these systems are primarily related with safety and life, it is required to maintain a high level of storage reliability. Storage reliability is the probability that the system will operate at a particular point in time after storage. Since the stored one-shot system can be confirmed only through inspection, periodic inspection and maintenance should be performed to maintain a high level of storage reliability. Since the one-shot system is characterized by a large loss in the event of a failure, it is necessary to determine an appropriate inspection period to maintain the storage reliability above the reliability goal. In this study, we propose an optimal inspection policy that minimizes the total cost while exceeding the reliability goal that the storage reliability is set in advance for the one-shot system in which periodic inspections are performed. We assume that the failure time is the Weibull distribution. And the cost model is presented considering the existing storage reliability model by Martinez and Kim et al. The cost components to be included in the cost model are the cost of inspection $c_1$, the cost of loss per unit time between failure and detection $c_2$, the cost of minimum repair of the detected breakdown of units $c_3$, and the overhaul cost $c_4$ of $R_s{\leq}R_g$. And in this paper, we will determine the optimal inspection policy to find the inspection period and number of tests that minimize the expected cost per unit time from the finite lifetime to the overhaul. Compare them through numerical examples.

• 산업경영시스템학회지
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• 제20권44호
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• pp.263-271
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• 1997

This paper presents a preventive maintenance model for determining the preventive replacement period of a system in which a failure rate is affected by the cumulative damage of fault and inspection. Especially, the failure rate function is considered to be a function of the cumulative damage of the fault and inspection time. Types of replacement considered are preventive replacement and failure replacement. Failure rate and expected cost function between replacement are derived. An optimal policy is obtained that minimizes the average cost per unit time for preventive replacement, failure replacement, inspection and repair.

• 한국시뮬레이션학회논문지
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• 제18권4호
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• pp.95-105
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• 2009

본 연구에서는 M&S(Modeling and Simulation) 기법을 통하여 보증 유도탄의 주기적 검사방법을 제시하였다. 유도탄 운용 개념과 예측된 저장신뢰도로부터 시나리오를 작성, 이를 기반으로 모의시험을 위한 모델링을 수행하고 시뮬레이션 프로그램으로 구현하였다. 그리고, 시뮬레이션 결과와 이론적인 추정치를 비교 검토하고, 목표로 하는 정상작동확률을 달성할 수 있는 최적의 주기점검 방안을 제시한다.

• 제어로봇시스템학회논문지
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• 제5권8호
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• pp.898-906
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• 1999

A control structure is introduced for the purpose of rejecting periodic (or repetitive) disturbances on a tracking system. The objective of the proposed structure is to drive the output of the system to the reference input that will result in perfect following without any changing the inner configuration of the system. The structure includes an adaptation block which learns the dynamics of the periodic disturbance and forces the interferences, caused by disturbances, on the output of the system to be reduced. Since the control structure acquires the dynamics of the disturbance by on-line adaptation, it is possible to generate control signals that reject any slowly varying time-periodic disturbance provided that its amplitude is bounded. The artificial neural network is adopted as the adaptation block. The adaptation is done at an on-line process. For this , the real-time recurrent learning (RTRL) algoritnm is applied to the training of the artificial neural network.

• 한국경영과학회:학술대회논문집
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• 대한산업공학회/한국경영과학회 1994년도 춘계공동학술대회논문집; 창원대학교; 08월 09일 Apr. 1994
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• pp.372-372
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• 1994

• 한국압력기기공학회 논문집
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• 제9권1호
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• pp.25-30
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• 2013

The periodic inspection of piping and pressure vessels welds in nuclear power plant has to provide reliable result related to weld flaws, such as location, maximum amplitude response, ultrasonic length, height and finally the nature or flaw pattern. The founded flaw in ultrasonic inspection is accepted or rejected based on these data. Specially, the amplitude of flaw response is used as basic parameter for flaw sizing and it may cause some deviation in length sizing result. Currently the ultrasonic inspections in nuclear power plant components are performed by specific inspection procedure which describing inspection technique include inspection system, calibration methodology and flaw characterizing. To perform ultrasonic inspection during in-service inspection, reference gain should be established before starting ultrasonic inspection by the requirement of ASME code. This reference gain used as basic criteria to evaluate flaw sizing. Sometimes, a little difference in establishing reference gain between calibration and field condition can lead to deviation in flaw sizing. Due to this difference, the inspection result may cause flaw sizing error. Therefore, the objective of this study is to compare and evaluate the ultrasonic amplitude difference between air filled and water filled pipe in nuclear power plant. Additionally, the accuracy of flaw sizing is estimated by comparing both conditions.

• 대한산업공학회지
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• 제11권1호
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• pp.3-10
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• 1985

Periodic replacement policies are proposed for a system whose repair cost, when it fails, can be estimated by inspection. The system is replaced when it reaches age T (Policy A), or when it fails for the first time after age T (Policy B). If it fails before reaching age T, the repair cost is estimated and minimal repair is then undertaken if the estimated cost is less than a predetermined limit L; otherwise, the system is replaced. The expected cost rate functions are obtained, their behaviors are examined, and ways of obtaining optimal T and L are explored.

• 한국국방경영분석학회지
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• 제18권1호
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• pp.110-127
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• 1992

In the preventive replacement policies of system that the failure can be detected through only periodic inspection, there is a penalty cost associated with the lapsed time between system failure and its detection. The system under study is replaced if the system fails before $n^{th}$ inspection, otherwise, preventive replacement is performed at the $n^{th}$ inspection. The decision variables are the inspection interval and the period of preventive replacement. This study presents the optimal preventive replacement policy that minimizes the long-run expected cost per unit time.

• Journal of Platform Technology
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• 제9권4호
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• pp.51-59
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• 2021

본 논문은 사전에 위치가 알려져 있는 시설물에 설치된 Wi-Fi AP에 접속한 기록을 이용하여 결정한 사용자의 위치 정보를 이용하여 서비스를 제공하는 방법을 제안한다. 본 논문에서 제안하는 위치 기반 서비스는 작업자의 위치 및 시간 정보를 이용하여 승강기 등 주기적 점검 및 유지보수가 필요한 시설물을 대상으로 현장 작업자의 작업 진행 상황을 관리하는 것이다. 본 논문에서 제안하는 작업 스케줄 관리 방법은 작업을 위해 작업자가 시설물에 도착해야 하는 사전 스케줄된 시간과 실제 그 시설물에 도착한 시간을 기반으로 한다. 또, Wi-Fi AP 접속 정보를 기반으로 한 위치 결정 및 시간 정보를 기반으로 한 작업스케줄 관리의 가능성을 보이기 위해 본 논문에서는 주기적 점검 및 유지보수가 필요한 승강기 유지보수 분야에서 적용할 수 있는 실험적 구현을 일부 하였다. 실험적으로 구현한 결과는 본 논문에서 제안한 방법이 시설물의 점검 및 유지보수 관련 분야에 활용될 수 있음을 보인다.

• Journal of Platform Technology
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• 제10권1호
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• pp.11-19
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• 2022

본 논문은 사전에 위치가 알려져 있는 시설물에 설치된 Wi-Fi AP에 접속한 기록을 이용하여 결정한 사용자의 위치 정보를 이용하여 서비스를 제공하는 방법을 제안한다. 본 논문에서 제안하는 위치 기반 서비스는 작업자의 위치 및 시간 정보를 이용하여 승강기 등 주기적 점검 및 유지보수가 필요한 시설물을 대상으로 현장 작업자의 작업 진행 상황을 관리하는 것이다. 본 논문에서 제안하는 작업 스케줄 관리 방법은 작업을 위해 작업자가 시설물에 도착해야 하는 사전 스케줄 된 시간과 실제 그 시설물에 도착한 시간을 기반으로 한다. 또, Wi-Fi AP 접속 정보를 기반으로 한 위치 결정 및 시간 정보를 기반으로 한 작업 스케줄 관리의 가능성을 보이기 위해 본 논문에서는 주기적 점검 및 유지보수가 필요한 승강기 유지보수 분야에서 적용할 수 있는 실험적 구현을 일부 하였다. 실험적으로 구현한 결과는 본 논문에서 제안한 방법이 시설물의 점검 및 유지보수 관련 분야에 활용될 수 있음을 보인다.