• Proceedings of the KIEE Conference
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• 2004.11b
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• pp.143-146
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• 2004

This paper presents a method to improve reliability by dispersed generation (DG) installation considering load types and interruption cost. The objective functions such as power losses cost, operation cost of DGS, power buy cost and interruption cost are minimized for reliability improvement and efficient operation. The several indices for reliability evaluation are improved by dispersed generation system installation.

• IE interfaces
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• v.23 no.2
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• pp.147-155
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• 2010

Reliability allocation is defined as a problem of determination of the reliability for subsystems and components to achieve target system reliability. The determination of both optimal component reliability and the number of component redundancy allowing mixed components to maximize the system reliability under resource constraints is called reliability-redundancy allocation problem(RAP). The main objective of this study is to suggest a mathematical programming model and a hybrid parallel genetic algorithm(HPGA) for reliability-redundancy allocation problem that decides both optimal component reliability and the number of component redundancy to maximize the system reliability under cost and weight constraints. The global optimal solutions of each example are obtained by using CPLEX 11.1. The component structure, reliability, cost, and weight were computed by using HPGA and compared the results of existing metaheuristic such as Genetic Algoritm(GA), Tabu Search(TS), Ant Colony Optimization(ACO), Immune Algorithm(IA) and also evaluated performance of HPGA. The result of suggested algorithm gives the same or better solutions when compared with existing algorithms, because the suggested algorithm could paratactically evolved by operating several sub-populations and improve solution through swap, 2-opt, and interchange processes. In order to calculate the improvement of reliability for existing studies and suggested algorithm, a maximum possible improvement(MPI) was applied in this study.

• Proceedings of the Korean Reliability Society Conference
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• 2001.06a
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• pp.289-289
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• 2001

Experimental design has become one of the primary tools for achieving quality of manufactured products. Because of a devision in the diciplines of quality and reliability, this important tool has not been used to extensively to achieve reliability. In this talk, we describe how experimental design can be used to achieve reliability.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.64 no.4
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• pp.251-255
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• 2015

Chiller system plays an important role of maintaining room temperature constantly by supplying chilled water to Heating, Ventilating and Air Conditioning(HVAC)or area room cooler equipment during plant normal operation or accident condition. Chiller failures are one of the most frequently occurring equipment failures. If the types of chiller failures are analyzed and grouped thoroughly, it would be helpful to make chiller maintenance strategy at the plants. That would enhance equipment reliability of chiller in the end. In this paper, chiller failure data during three years were analyzed and categorized by specific failure code. In addition, the various proposals to improve equipment reliability of chiller were suggested such as Preventive Maintenance Optimization(PMO) strategy and performance monitoring reinforcement and so on.

• Journal of Power System Engineering
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• v.16 no.6
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• pp.59-65
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• 2012

Torque Generator is a product which has function to transform hydraulic energy to mechanical energy of torque and rotating speed, and be used for direction change device of agricultural machines. This study proposes failure analysis and test analysis on torque generator and introduces a process that reliability of a product is enhanced by design improvement. And also it presents improvements of maximum output torque by modifying design and surface treatment. Lastly it verifies reliability improvement by analyzing test results of before and after life test.

• Proceedings of the Korean Society for Quality Management Conference
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• 2004.04a
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• pp.272-277
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• 2004

Recently reliability Improvement and certification are considered as important issues by world-wide leading and highly qualified companies in advanced countries. In Korea, from a few years ago, the policy for reliability certification newly has been driven to improve product competitiveness in part and material industry. As yet the reliability certification is local and domestic, it is necessary to develop local certification system to global certification system. Reliability certification system is composed of accreditation body, testing laboratory and reliability assurance. In this paper, we review the reliability certification system and its application in Korea and the current research trends in advanced countries. Finally we propose some suggestions for the eliability certification system to be an international standard.

• Journal of Applied Reliability
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• v.4 no.1
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• pp.27-37
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• 2004

In this paper, we propose a framework of reliability education program for industry people taking charge of reliability improvement or reliability evaluation. To this end, we investigate the situation of how reliability theories or reliability technologies are applied to industry and how industry people have reliability educations. And we also identify reliability theories or technologies which industry people need to ensure. Based on the result of such studies, we design a reliability education program which is appropriate for industry people.

• Proceedings of the Korean Reliability Society Conference
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• 2004.07a
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• pp.269-280
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• 2004

In this paper, we propose a framework of reliability education program for industry people taking charge of reliability improvement or reliability evaluation. To this end, we investigate the situation of how reliability theories or reliability technologies are applied to industry and how industry people have reliability educations. And we also identify reliability theory or technology which industry people need to ensure. Based on the result of such studies, we design a reliability education program which is appropriate for industry people.

• KIPS Transactions on Software and Data Engineering
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• v.3 no.10
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• pp.389-396
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• 2014

There are many defects when we're working on a project. Especially, if we don't have experience in similar field, defects have a strong influence on the system entirely. Therefore, management of risk such like defects is important the factor for success of project. Finally, efficient management of risk can guarantee handling problems such like fault tolerancy, unexpected quality and delay of schedule. In this paper, we propose checkpoint for improvement of reliability and are willing to improve the reliability of an entire system using it.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1712-1717
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• 2007

This paper presents a derating design approach for reliability improvement of an aluminum electrolytic capacitor. The capacitor, usually mounted in a printed circuit board, is used to stabilize the circuit. The main failure mechanism of interest is dry-up of the electrolyte that is mainly caused by two stresses-temperature and voltage. The lifetime under these stresses is modeled as a function of these stresses and time using accelerated life testing. Quantitative variation in the lifetime, according to variations in these stresses, is investigated to perform the derating design of the capacitor so that the stress levels are selected to achieve required reliability measures for reliability improvement. Moreover, sensitivity analysis shows which stress would be a more important factor determining the lifetime.