점검-정비 모형에서 열화부품의 발견확률을 고려한 시스템의 최적 점검주기

김대경,박병노,송미옥,임재학 한국신뢰성학회 2022 신뢰성응용연구 Vol.22 No.4

Purpose: The determination of the optimal inspection interval of a system is a critical factor that can influence its maintenance. Frequent inspections yield shorter inspection intervals and higher inspection costs compared with infrequent inspections, which lead to an increase in the total maintenance cost due to the frequent occurrence of failures. The objective of this study is to determine the optimal inspection interval, which minimizes the total expected cost until the system is overhauled. Methods: We developed an inspection - maintenance cost model by considering the unit inspection cost, the cost for preventive maintenance, and the cost for corrective maintenance as well as the cost and quantity of a component, the distribution of the lifetime of components, and the probability of finding fault or failure during inspections. Results: We propose a novel method for determining the optimal inspection interval, which minimizes the total expected cost. The proposed method can be applied to systems consisting of one or more types of components. The data, which is derived from the case study that is documented in the previous research [13], are utilized to illustrate that the proposed method is effective for determining the optimal inspection interval and for conducting sensitivity analysis. Finally, we apply the proposed method to determine the optimal inspection interval pertaining to a component of auxiliary power that is built into railway trains. Consequently, we observed that a relationship exists between the reduction in the cost of operating the system and the current inspection interval. Conclusions: The proposed method can be effective for other repairable systems, which undergo inspection, preventive maintenance, and corrective maintenance.

항공기 캐노피 고정 장치 검사 주기 연장을 위한 내구성 시험

이관호,은성진,최재원,손진일 대한기계학회 2023 大韓機械學會論文集A Vol.47 No.11

캐노피 고정 장치는 항공기 중요 부품으로 정기적인 검사 및 교환 주기를 설정하여 파손을 방지하고 조종사의 안전 확보가 중요하다. 본 논문에서는 항공기 캐노피 고정 장치 부속의 적정 검사 주기 설정을 위하여 실험적 방법으로 검사 주기 연장을 위한 기초 데이터 확보에 대하여 연구하였다. 실제 전투기가 기동하는 상황에서 발생하는 스펙트럼 하중을 인가한 피로 시험으로 수명을 평가하였으며 획득한 수명 데이터를 기존 해석적인 방법으로 수립한 기존 검사 주기와 비교하였다. 캐노피 고정 장치의 내구성 시험을 실시한 결과 기존 검사 주기 대비 약 80배 이상의 피로 수명 검증 데이터를 확보하였으며, 표면 관찰과 변형률 데이터를 이용하여 시편을 검사한 결과 표면에 코팅층 박리가 생성되었지만, 특별한 변형이 발견되지 않음을 확인하였다. The canopy fixing device is an important part of the aircraft, and it is important to prevent damage and ensure pilot safety by assigning a periodic inspection and replacement interval. In this work, to set up an appropriate inspection interval for the parts of an aircraft canopy fixing device, an experimental method was studied to obtain basic data for extending the inspection interval. The lifespan was evaluated through a fatigue test in which a spectral load generated in the actual fighter maneuvering situation was applied, and the acquired lifespan data was compared with the existing inspection interval established by an existing analytical method. According to the results of a durability test of the canopy fixing device, fatigue life verification data of approximately 80 times more than the existing inspection interval was obtained. Specimen inspection using surface observation and strain data confirmed that peeling of the coating layer occurred on the surface, but no special deformation was observed.

Genetic Algorithm-based Optimum Inspection Interval Determination for Plant Maintenance

(Kwang Kyu Seo) 상명대학교 공학기술연구소 2004 공학기술연구 Vol.2004 No.1

The operation and management of a plant require proper accounting for the constraints coming from reliability requirements as well as from budget and resource considerations. Most of the mathematical methods to decide the inspection time interval for plant maintenance by reliability theory are too complicated to be solved. Moreover, the mathematical and theoretical models are not usually cases in the practical applications. In order to overcome these problems, we propose a new the method for a genetic algorithm based optimal inspection interval determination to minimize the maintenance cost with reliability theory. The most merit of the proposed method is to decide the inspection interval for a plant machine of which failure rate λ(t) conforms to any probability distribution. Therefore, this method is more practical. The efficiency of the proposed method is verified by comparing the results obtained by GA-based method with the inspection model having regular time interval.

위험도에 따른 설비의 재검사 주기산정 연구

한상인(Sang-In Han),최송천(Song-Chun Choi),김영섭(Young-Sup Kim) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.5

In recent years, a domestic refineries and petrochemical plants being encouraged to adopt risk management programs such as risk-based inspection (RBI) because they can enhance safety management and maintenance cost saving in Korea. The construction of RBI is purpose to manage the effective inspection, but each equipment are not avoid an inspection by regulatory body's law The recommended inspection interval from RBI always would not correspond with related law's interval. In this study, the re-inspection interval establishment for the pressure equipment would be showing the focused on the Damage Subfactor from the Technical Module.

An Optimal Inspection Policy for Protection Devices of Electronic Equipment Using Delay Time Model

Jiang Xin-liang,Zhao Jian-min,Li Zhi-wei 보안공학연구지원센터 2015 International Journal of u- and e- Service, Scienc Vol.8 No.8

In order to reduce or eliminate the consequences of the electronic equipment malfunction, some important electronic equipment were installed protection devices. Failures of protection devices are of hidden feature, and can only be found by inspections. Protection device failing to system malfunctioning has a delay characteristic. According to this delay characteristic, an inspection policy was proposed based on delay time model. An inspection model was developed to minimize the average cost per unit time with constraint of availability. Based on the model, optimal inspection interval can be determined to meet the objective of the opti

위험도평가 기반의 항공기 구조물 RCM 적용 방안 연구

김근원 ( Keun Won Kim ),신기수 ( Ki Su Shin ) 한국항공경영학회 2013 한국항공경영학회지 Vol.11 No.1

신뢰도중심정비는 최소의 비용으로 장비의 요구 신뢰도를 유지하기 위한 최적의 정비 방법을 찾는데 사용되는 기법이다. 항공기 구조물에 대한 건전성을 보장하고 총 수명주기 비용을 최소화하기 위하여 신뢰도중심정비 기반의 정비정책 수립이 중요하다. 신뢰도중심정비 분석에 있어서 항공기 구조물의 건전성을 보장하기 위해서는 확률론적 파괴역학 기반의 위험도평가를 수행하고, 이를 신뢰도중심정비 분석에 반영하는 노력이 필요하다. 특히 항공기 구조물의 경우 운영단계에서의 실제 운용 정비자료를 이용하여 위험도평가를 수행함으로써 신뢰도중심정비 능력을 극대화 시킬 수 있다. 본 연구에서는 신뢰도중심정비와 위험도평가 개념을 알아보고, 신뢰도중심정비 적용을 위한 위험도 평가 활동을 분석하였다. 그리고 항공기 구조물의 신뢰도중심정비 적용을 위한 위험도평가 프로세스를 제시하고, 수치예제로 cockpit upper longeron에 대한 위험도평가를 수행하였다. 연구수행 결과 실제운용 정비자료를 이용하여 위험도평가를 수행함으로써 개선된 정비계획 및 점검주기 산정이 가능함을 확인할 수 있었다. RCM(Reliability Centered Maintenance) is an analytical process to determine the appropriate maintenance strategies. RCM is recommended to ensure the integrity of aircraft structural and reduce total life cycle cost. Processing RCM analytical, it is one of essential factor to regard the risk assessment based on probabilistic fracture mechanics. Especially, the probabilistic risk assessment, which was conducted by utilizing operational maintenance data during sustainment phase, could enhance the ability of RCM. In this paper, the concept of RCM and risk assessment was described. Furthermore, the activity of risk assessment for applying RCM has been analysis. In addition, we suggest the risk assessment process for applying RCM of aircraft structural. As a numerical example, the cockpit upper longeron was selected to evaluate probabilistic risk assessment process. In conclusion, it was revealed that the proposed process could improve for maintenance plan and inspection interval.

TMSF를 이용한 NCC플랜트의 RBI 구축에 따른 검사주기 산정

한상인(Sang-In Han),이창헌(Chan-Hun Lee),최송천(Song-Chun Choi),박교식(Kyo-Sik Park),김대중(Dae-Jung Kim),김지윤(Ji-Yoon Kim) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.6

A RBI is defined by the consequence of failure and the likelihood of failure which ranks the equipments using a method based on the risk for the management of inspection program and the effectiveness. The considerable details for the management of safety on the petroleum equipments such as the refinery and the petrochemical plants are to not only improve the inspection quality but also save the inspection cost. In order to satisfy these purposes, the RBI applies to the evaluation of risk assessment in the world wide and it may be improve the inspection effectiveness and the reduction of inspection cost. In this paper, pressure vessels such as reactors, towers, heat exchangers, piping on the NCC(Naphtha Cracking Center) plants were applied by the Risk Based Inspection method and these equipment are quantified by TMSF(Technical Module Sub factor) used to the damage sub factor in the RBI assessment. TMSF is classified by 8items which are thinning, stress corrosion cracking (SCC), brittle fracture, piping fatigue and should be assessed according to the prior damage mechanisms for the each equipment. This paper describes the results which are evaluated about the likelihood of failure, risk, and an inspection interval with the related factors.

Life Cycle Cost Analysis on Pavement Inspection Intervals Considering Maintenance Work Delay

한대석,도명식 대한토목학회 2015 KSCE JOURNAL OF CIVIL ENGINEERING Vol.19 No.6

Inspection strategy has a significant effect on the entire working process of pavement management. Most countries or road agencies casually define their inspection intervals without careful consideration. Moreover, most conventional pavement management analysis models do not treat inspection strategy as an important issue. Thus, with an economic analysis of inspection intervals, this paper aims to give a wider publicity to the importance of inspection strategy. An improved LCCA (Life Cycle Cost Analysis) model has been developed as an analytical tool. This model can take delays into consideration, as well as estimate various LCC contents and decision indicators. Both the hypothesis and the developed LCCA model have been empirically tested with pavement data from Korean National Highways. As a result, we can confirm that 1) the inspection interval affects overall management activities and LCCA results, 2) the suggested method shows an improvement in estimation results which consider the effects of delay in maintenance, and 3) either a 2 year or 3 year interval is the most beneficial interval, from both engineering and economical perspectives. In conclusion, the inspection interval needs to be carefully determined by analysis works. It is potentially a critical index that will improve current management strategy by in-house efforts.

Interval Scan Inspection Technique for Contact Failure of Advanced DRAM Process using Electron Beam-Inspection System

J. H. Oh,G. Kwon,D. Y. Mun,D. J. Kim,I. K. Han,H. W. Yoo,J. C. Jo,Y. Ominami,T. Ninomiya,M. Nozoe 대한전자공학회 2012 Journal of semiconductor technology and science Vol.12 No.1

We have developed a highly sensitive inspection technique based on an electron beam inspection for detecting the contact failure of a poly-Si plugged layer. It was difficult to distinguish the contact failure from normal landing plugs with high impedance. Normally, the thermal annealing method has been used to decrease the impedance of poly-Si plugs and this method increases the difference of charged characteristics and voltage contrast. However, the additional process made the loss of time and broke down the device characteristics. Here, the interval scanning method without thermal annealing was effectively applied to enhance the difference of surface voltage between well-contacted poly-Si plugs and incomplete contact plugs. It is extremely useful to detect the contact failures of non-annealed plug contacts with high impedance.

Interval Scan Inspection Technique for Contact Failure of Advanced DRAM Process using Electron Beam-Inspection System

Oh, J.H.,Kwon, G.,Mun, D.Y.,Kim, D.J.,Han, I.K.,Yoo, H.W.,Jo, J.C.,Ominami, Y.,Ninomiya, T.,Nozoe, M. The Institute of Electronics and Information Engin 2012 Journal of semiconductor technology and science Vol.12 No.1

We have developed a highly sensitive inspection technique based on an electron beam inspection for detecting the contact failure of a poly-Si plugged layer. It was difficult to distinguish the contact failure from normal landing plugs with high impedance. Normally, the thermal annealing method has been used to decrease the impedance of poly-Si plugs and this method increases the difference of charged characteristics and voltage contrast. However, the additional process made the loss of time and broke down the device characteristics. Here, the interval scanning method without thermal annealing was effectively applied to enhance the difference of surface voltage between well-contacted poly-Si plugs and incomplete contact plugs. It is extremely useful to detect the contact failures of non-annealed plug contacts with high impedance.