• Journal of Korean Society of Industrial and Systems Engineering
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• v.37 no.4
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• pp.24-34
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• 2014

In order to manage essential parts that are required for the repairable parts services performed at the military maintenance depots, the United States Air Force developed the Repairability Forecasting Model (RFM). In the RFM, if the requirements of the parts are assumed to follow the normal probability distribution after applying means from the past data to the replacement rate and lead times, the chance of the AWP (Awaiting Parts) occurring is 50%. In this study, to counter the uncertainties of requirements and lead times from the RFM, the safety level concept is considered. To obtain the safety level for requirements, the binomial probability distribution is applied, while the safety level for lead time is obtained by applying the normal probability distribution. After adding this concept, the improved RFM is renamed as the ARFM (Advanced RFM), and by conducting the numerical stimulation, the effectiveness of the ARFM, minimizing the occurrence of the AWP, is shown by increasing the efficiency of the maintenance process and the operating rate of the weapon system.

• Korean Journal of Construction Engineering and Management
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• v.16 no.3
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• pp.24-35
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• 2015

Aging educational facility shall be managed and maintained through integrated service perspectives, in consideration of functions of each facility to provide safe and comfortable environment, rather than temporarily fixing/repairing problems. For doing this, it is a must to firstly understand the limitation of highly biased performance-based maintenance practice, which is a most common type applied at present, and therefore to establish maintenance system that reflects the functions and characteristics of maintenance service that a facility was designed with. Therefore, the objective of this study is to find items that have an influence on service level recognition in order to fairly evaluate service functions of educational facilities, and subsequently to use these factors as ingredients of establishing a consistent and efficient maintenance system. Therefore this study proposed explanatory variables to measure influential factors for each major maintenance category. Then appropriate statistical verification was carried out on questionnaires that collected from a number of industry experts to test its fe asibility.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.12
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• pp.789-796
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• 2019

If the development of Integrated Logistics Support (ILS) for maintenance of the end step is conducted systematically and efficiently, the weapon system lifecycle can be postponed and the availability can be improved. DEFense CONdition (DEFCON) is maintained as perfect. Nevertheless, like its importance, the guide for maintaining the depot performance is applied differently for each weapon system. The errors that can result cause additional cost, etc. ILS development at depot level maintenance is different from full scale development. Therefore, this study distinguishes the management and deployment section for the development concept. An additional way to perform an efficient development of depot maintenance element when determining the depot maintenance period were presented. This study examined how the Reliability, Availability, Maintainability (RAM), Logistics Support Analysis (LSA), and ILS 11 elements intersect at the depot maintenance sources. An analytical study of concrete adoptable plans was performed. The systematic adoption of a development procedure can make it possible to calculate the adoptable development cost. In addition, it can be helpful for improving the quality level and practical use of work products.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.6
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• pp.121-130
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• 2021

Recently, the need for new approaches and recognition of safety and maintenance has been raised for small vulnerable facilities in Korea due to the acceleration of aging facilities, various safety accidents, and increased frequency of use. In particular, small vulnerable facilities(SVF), including most social welfare facilities, are facilities used by many of the vulnerable groups, and safety management is very important. Therefore, this study investigated various statuses based on safety inspection results (31,114 cases) conducted over the past 13 years (2008-2020) for small vulnerable facilities in Korea, and evaluated the characteristics of each field and safety and maintenance performance level. This aims to present policy directions for strengthening safety management of facilities for the vulnerable by using basic data such as improvement of safety standards and maintenance strategies for small vulnerable facilities in Korea in the future.

• Journal of the Korean Society for Railway
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• v.14 no.3
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• pp.216-221
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• 2011

An important problem in reliability analysis for repairable systems is to model the maintenance effect. The most of researches have assumed two extreme cases; one is perfect maintenance and the other is minimal maintenance. However, many of maintenances performed by domestic subway operators are imperfect maintenances which have the effect between both of two extreme cases. This article deals with the problem determining the imperfect preventive maintenance intervals based on failure data in units of the PDS(passenger door system) in Metro EMU. This paper deals with a case study on determining imperfect maintenance interval by using the level of maintenance effect through reliability analysis of PDS.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.784-791
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• 2007

Most operational organization and railway authority which conduct scheduled maintenance(SM) have carried out the preventive maintenance(PM) based on the information provided from supplier and manufacturer of railway system. However these activities are far away from reality and low the efficiency, it is because an appropriate methods for system selection didn't take into account for improving maintenance efficiency. Therefore, the current SM tasks and maintenance activities lead to lots of spend on the cost and time. To solve the above problem, this thesis presents new approach methodology. This proposes the criteria for reliability centered maintenance(RCM) system selection through level of quantification of each parameter, i.e, frequency, severity and maintenance cost, etc. To do this, the field operation data and information of maintenance cost are essential. As applying this methodology, we can look forward to improving efficiency of PM/SM, and reducing cost.

• Journal of the Regional Association of Architectural Institute of Korea
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• v.20 no.6
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• pp.105-112
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• 2018

The purpose of this study is to develop an application that supports a user in the maintenance of small photovoltaic device. To this end, this study analyzed the maintenance status, related regulations and existing application contents in Korea. According to the analysis results, most users did not maintain device for themselves. In addition, the maintenance market has not been activated due to its low profitability. Regulations on the maintenance of photovoltaic device prescribed by the KESCO and Japanese counterpart were analyzed to establish the standards for photovoltaic device inspection, and an application was developed based on the existing applications and research results. In order to evaluate the completeness and satisfaction of the developed application, it surveyed 52 users and 22 experts. The survey results showed that the completeness was calculated to be 90 points, and the level of satisfaction was 93 points on a 100-point scale. Therefore, it is expected that the maintenance application developed in this study will be useful for users to maintain the photovoltaic device.

• Journal of Information Technology Applications and Management
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• v.29 no.6
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• pp.63-80
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• 2022

In this paper, we study structural changes and performance gains in condition-based maintenance process redesign when mobile IoT technology is embedded into urban railway rolling stock. We first develop condition-based maintenance To-Be process model in accordance with the IoT deployment scheme. Secondly, we draw upon theoretical framework of redesign process analysis to develop performance evaluation method suitable to predictive maintenance shift from As-Is ordinary maintenance practice. Subsequently, To-Be process performance evaluations are conducted adopting both the quantitative and qualitative method for time, cost, and dependability dimensions. The results ascertain the considerable benefits captured through detection abnormality prior to actual rolling stock failure occurrence, and details of performance improvements and enhancement of standardization level is revealed. The procedures and results presented in this paper offers useful insights in the fields of IoT economic analysis, condition based maintenance, and business process redesign.

• Journal of Energy Engineering
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• v.20 no.2
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• pp.154-162
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• 2011

PMT(Preventive Maintenance Template) is a standardized maintenance program that describes maintenance items & period as operation condition to increase component reliability at the component level. The existing maintenance programs are focused on time based maintenance to inspect and repair component depend on fixed period. But recently, we have developed advanced maintenance program(named PMT) to increase reliability and optimize maintenance program of the plant significant component. This paper presents how to develop the PMT for nuclear power plant's static exciter.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.58 no.4
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• pp.410-415
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• 2009

With the implementation of electric power industry reform, the utilities are looking for effective ways to improve the economic efficiency. One area in particular, the equipment maintenance, is being scrutinized for reducing costs while keeping a reasonable level of the reliability in the overall system. Here the conventional RCM requires the tradeoff between the upfront maintenance costs and the potential costs of losing loads. In this paper we describe the issues related to applying so-called the "Reliability-centered Maintenance" (RCM) method in managing electric power distribution equipment. The RCM method is especially useful as it explicitly incorporates the cost-tradeoff of interest, i.e. the upfront maintenance costs and the potential interruption costs, in determining which equipment to be maintained and how often. In comparison, the "Time-based Maintenance" (TBM) method, the traditional method widely used, only takes the lifetime of equipment into consideration. In this paper, the modified Markov model for maintenance is developed. First, the existing Markov model for maintenance is explained and analyzed about transformer and circuit breaker, so on. Second, developed model is introduced and described. This model has two different points compared with existing model: TVFR and nonlinear customer interruption cost (CIC). That is, normal stage at the middle of bathtub curve has not CFR but the gradual increasing failure rate and the unit cost of CIC is increasing as the interruption time is increasing. The results of case studies represent the optimal maintenance interval to maintain the equipment with minimum costs. A numerical example is presented for illustration purposes.