• 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.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.127_128
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• 2009

A new technique using a search method which is based on fuzzy multi-criteria function is proposed for GMS(generator maintenance scheduling) in order to consider multi-objective function. Not only minimization of probabilistic production cost but also maximization of system reliability level are considered for fuzzy multi-criteria function. To obtain an optimal solution for generator maintenance scheduling under fuzzy environment, fuzzy multi-criteria relaxation method(fuzzy search method) is used. The practicality and effectiveness of the proposed approach are demonstrated by simulation studies for a real size power system model in Korea in 2010.

• 대한의생명과학회지
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• 제24권3호
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• pp.150-156
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• 2018

Tankyrases are multifunctional poly (ADP-ribose) polymerases that regulate a variety of cellular processes including WNT signaling, telomere maintenance, regulation of mitosis, and many others. Tankyrases interact with target proteins and regulate their interactions and stability through poly (ADP-ribosyl) ation. In addition to their roles in telomere maintenance and regulation of mitosis, tankyrase proteins regulate tumor suppressors such as AXIN, PTEN, and AMOT. Therefore, tankyrases can be effective targets for cancer treatment. Tankyrase inhibitors could affect a variety of pathways that are carcinogenic (essential for the unlimited proliferation of human cancer cells), including WNT, AKT, YAP, telomere maintenance, and regulation of mitosis. Recently, new aspects of the function and mechanism of tankyrases have been reported and several tankyrase inhibitors have been identified. Also, it has been proposed that the combination of conventional chemotherapy agents with tankyrase inhibitors may have synergistic anti-cancer effects. Based on this, it is expected that more advanced and improved tankyrase inhibitors will be developed, enabling new therapeutic strategies against cancer and other tankyrase linked diseases. This review discusses tankyrase function and the role of tankyrase inhibitors in the treatment of cancer.

• 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.

• 한국안전학회지
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• 제30권3호
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• pp.13-19
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• 2015

Railway vehicle equipment goes back again to the state just before when failure by the repair. In repairable system, we are interested in the failure interval. As such, a statistical model of the point process, NHPP power law is often used for the reliability analysis of a repairable system. In order to derive a quantitative reliability value of repairable system, we analyze the failure data of the air brake system of the train line 7. The quantitative value is the failure intensity function that was modified, converted into a cost-rate function. Finally we studied the optimal number and optimal interval in which the costs to a minimum consumption point as cost-rate function. The minimum cost point was 194,613 (won/day) during the total life cycle of the braking system, then the optimal interval were 2,251days and the number of optimal preventive maintenance were 7 times. Additionally, we were compared to the cost of a currently fixed interval(4Y) and the optimum interval then the optimal interval is 3,853(won/day) consuming smaller. In addition, judging from the total life, "fixed interval" is smaller than 1,157 days as "optimal interval".

• 산업경영시스템학회지
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• 제41권1호
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• pp.110-117
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• 2018

Machines and facilities are physically or chemically degenerated by continuous usage. One of the results of this degeneration is the process mean shift. By the result of degeneration, non-conforming products and malfunction of machine occur. Therefore a periodic preventive resetting the process is necessary. This type of preventive action is called 'preventive maintenance policy.' Preventive maintenance presupposes that the preventive (resetting the process) cost is smaller than the cost of failure caused by the malfunction of machine. The process mean shift problem is a field of preventive maintenance. This field deals the interrelationship between the quality cost and the process resetting cost before machine breaks down. Quality cost is the sum of the non-conforming item cost and quality loss cost. Quality loss cost is due to the deviation between the quality characteristics from the target value. Under the process mean shift, the quality cost is increasing continuously whereas the process resetting cost is constant value. The objective function is total costs per unit wear, the decision variables are the wear limit (resetting period) and the initial process mean. Comparing the previous studies, we set the process variance as an increasing concave function and set the quality loss function as Cpm+ simultaneously. In the Cpm+, loss function has different cost coefficients according to the direction of the quality characteristics from target value. A numerical example is presented.

• 기술경영경제학회:학술대회논문집
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• 기술경영경제학회 1996년도 제10회 동계학술발표회 논문집
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• pp.241-264
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• 1996

This article introduces the five functions of the national innovation system (NIS). As the national innovation system is a kind of social systems in the national level, the five generic functions of open system-production boundary spanning, maintenance, adaptation management functions-are applied to the NIS. The production function is the primary process, which produces innovative products and services of the NIS. The boundary spanning function is the function of procuring the input and disposing the innovation output or aiding in these process. Experienced R&D human resources, R&D funds, technology etc. belong to the input of the NIS. The maintenance function is responsible for the smooth operation and upkeep of the system in terms of various conditions. The adaptive function is to help the system change and adapt, scan the environment for problems, opportunities, and technological developments. It faces outward for the survival of the system from the long-term view. The management function carries out planning and controlling the overall activities for the other four functions in order to run the system. Finally it discuses implications for the diagnosis and the decision making process of S&T policy.

• 한국강구조학회 논문집
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• 제14권5호통권60호
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• pp.627-639
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• 2002

교량의 건설은 여러 국가에서 거의 완료되었으며, 정부나 고속도로 관계기관은 유지관리쪽에 초점을 맞추고 있다. 교량을 효과적으로 유지관리하기 위해, 시스템 신뢰성을 이용한 교량의 잔존수명을 예측하는 것은 매우 시급하다. 그리고 시스템 신뢰성을 이용한 교량의 유지관리 모델을 개발하는 것은 필수적이다. 이 논문에서는 시스템 신뢰성과 생애함수를 이용하여 예방 (Preventive) 유지관리 와 사후 (Essential) 유지관리 모델을 개발하였다. 이 논문에서 개발된 유지관리 모델을 이용해서 현존하는 교량에 대해 최적의 유지관리 계획을 구하였다.

• 산업경영시스템학회지
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• 제30권1호
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• pp.1-7
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• 2007

This paper addresses a the maintenance system based on the concept of RAMS (Reliability, Availability, Maintenance, Safety) for the effective maintenance of the urban transit. A systematic approach for developing a cost-effective maintenance strategy based on the component reliability of the system in question is performed according to the following steps : definition of function, functional failures of the systems, construction of RBD (Reliability Block Diagram), and the calculation of reliability indices. The developed preventive maintenance system generates maintenance plan and repair request based on the analysed RAMS data of components and maintenance experience.

• 한국철도학회논문집
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• 제8권6호
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• pp.544-549
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• 2005

Nowadays, most of bridge networks are complete or close to completion. The biggest challenge railroad./highway agencies and departments of transportation face is the maintenance of these networks, keeping them safe and serviceable, with limited funds. To maintain the bridges effectively, there is an urgent need to predict their remaining life from a system reliability viewpoint. And, it is necessary to develop the maintenance models based on system reliability concept. In this paper, maintenance models are developed for preventive maintenance and essential maintenance by using system reliability and lifetime distributions. The proposed model is applied to an existing railroad bridge. The optimal maintenance strategy of this bridge is obtained in terms of services life extension and cumulative maintenance cost.