• 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.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.21 no.11
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• pp.1051-1058
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• 2011

The military communication equipment is required the high reliability for operating adequate functions under severe conditions. This reliability is the essential element for the quality of the product, for the uncontrolled factors, such as the clearance, damage of the material, the reduction of stiffness, which are the designer is unable to handle. In this paper, the uncertainty for the dimension was supposed to the probability model for the military communication equipment, and the average of the objective function was minimized for reducing design uncertainty. The reliability-based design optimization which was implemented the limit state function was formulated into the mathematical model, so the reliable optimized structure was implemented than the base-line design.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.10a
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• pp.504-509
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• 2011

The military communication equipment is required the high reliability for operating adequate functions under severe conditions. This reliability is the essential element for the quality of the product, for the uncontrolled factors, such as the clearance, damage of the material, the reduction of stiffness, which are the designer is unable to handle. In this paper, the uncertainty for the design was supposed to the probability model for the military communication equipment, and the average of the objective function was minimized for reducing design uncertainty. The reliability-based design optimization which was implemented the limit state function was formulated into the mathematical model, so the reliable optimized structure was implemented than the base-line design.

• Journal of Korean Society for Quality Management
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• v.19 no.1
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• pp.43-50
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• 1991

Very little work has been done in the design of process with purchased equipment; therefore it is the intent of this project to expand the current application of reliability considerations to purchased equipment. The procurement of equipment in a manufacturing system which has both qualitative and quantitative aspects.

• Journal of the Korean Society for Railway
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• v.9 no.6 s.37
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• pp.732-738
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• 2006

This research provides a scheme for Highly Accelerated Stress Test that is necessary to demonstrate reliability prediction of Korean Rapid Transit Railway Train Control System sub-equipment, which is calculated by a relevant standard for failure rate prediction of electronic products. Although determining failure information generated in the process of trial running by statistic analysis is widely accepted as a measure of confirmation for reliability prediction, this research suggests the modeling for System Life Test determined by accelerating stress factors as a measure of confirmation for reliability prediction of sub-equipment unit that is generated ahead of a trial running in System Life Cycle. Consequently, the research demonstrates sub-equipment unit reliability test, which is based on the model derived from Accelerated Stress Test, according to accuracy level and the number of samples, and conducts an official experiment by making out a reliability test procedure sheet based on test time as well.

• Journal of Electrical Engineering and Technology
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• v.4 no.1
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• pp.43-48
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• 2009

The purpose of the this paper is to make decision of the maintenance priority of power distribution system using Time-Varying Failure Rate(TVFR) with interruption cost. This paper emphasizes the practical use of the reliability indices and interruption cost. To make a decision of maintenance priority on power distribution system equipment, the quantification of the reliability level should be represented as a cost. In this paper, the TVFR of power distribution system equipment applied in this paper utilizes analytic method to use the historical data of KEPCO. From this result, the sensitivity analysis on TVFR of equipment was done for the priority, which represents that high priority of the equipment has more effect on system reliability, such as SAIDI or SAIFI, than other equipment. By this priority, the investment plan is established. In this result, customer interruption cost(CIC) could be extracted, and CIC is used as weighting factor to consider a importance of customer. After that, the result calculated the proposal method in this paper is compared with other priority method, such as lifetime, failure rate or only sensitivity.

• Journal of the Korean Institute of Gas
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• v.10 no.1 s.30
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• pp.13-18
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• 2006

Chemical plants should perform Quantitative Risk Assessment that evaluates types of accident, frequency and damage which can happen through using the hazardous equipment and the hazardous materials for preventing and preparing industrial disasters. It is necessary that Chemical plants should include the reliability database which efficiently evaluate the Quantitative Risk Assessment. So in this study, we suggest a which methodology applies Quantitative Risk Assessment on the basis of the constructed data to imply the reliability of industrial facilities and equipment, collection of reliability data, system analysis and development of software.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.65 no.3
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• pp.199-203
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• 2016

The cost needed to managing equipment is constantly increasing because of increase of power equipment. The regulations such as PAS 55 and ISO 55000 were enacted to manage equipment assets. The advanced management methods such as real-time monitoring, condition evaluation, and health indices are avalable in generation system, transmission system, and substation transformers. However, These methods can not be applied to distribution equipment because of a lot of equipment. Therefore reliability assessment is very important in case of distribution equipment. In this paper, failure rates are extracted considering characteristics of regions, and which are the essential factors to reliability evaluation.

• Proceedings of the KSR Conference
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• 2005.05a
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• pp.806-812
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• 2005

This paper proposes a new reliability evaluation for traction power system. The electric railway consists of traction power systems, various vehicles, operating equipment, track, overhead line and electric equipment. It is a fundamental function of traction power systems that supply customers with reasonable price, acceptable reliability and high quality power. In a general way, the power system reliability deals with the ability to satisfy load demands in supply capability or rating of every factor. On the other hand, the reliability of traction power systems has been focused on train time delay caused by power outage. In this paper, we make a selection optimum reliability indices for the reliability evaluation of electric traction power systems. The reliability study not only applies a plan for traction supply system after detecting the vulnerable point of existing traction supply systems but also makes a role in stable operating railway.

• Journal of the Korean Society for Railway
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• v.12 no.6
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• pp.852-858
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• 2009

This paper is a study on the reliability management of onboard signaling equipment for the Koran Tilting Train (TTX) to run the existing railway to express railway. For safe running of tilting train which operates at Automatic Train Protection (ATP) and Automatic Train Stop (ATS), a reliability management plan for TTX onboard is proposed for preventing train safety from driver oversight and malfunction by establishing braking curves based on movement authority and speed limit, according to preceding train location and rail conditions. Also, reliability of TTX onboard equipment on the basis of proposed plan was estimated, and actual case studies based on the international requirements IEC 62278 (EN 50126) were provided to verify its reliability.