• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1842-1847
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• 2007

In this study, we are to analyze the life and the main failure mode of flexible tubes fitting for pneumatic that are usually applied in the factory automation line. Flexible tubes fitting for pneumatic have complicated failure cause because they are organized as a complex of various elements. Therefore, in this paper, we analyzed the main failure mode of flexible tubes fitting for pneumatic, and then performed life test and performance test according to the international standards. On the basis of these processes, we estimate shape parameter that is the main factor for the calculation of test time for the reliability of flexible tubes fitting for pneumatic and their data analysis of life distribution.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.24 no.4
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• pp.26-34
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• 2016

In this study, reliability prediction of the ignition system of hybrid rocket is performed. The FMECA is preceded to the reliability prediction. To this end, the ignition system is divided into 5 components and 19 potential failure modes. The failure cause and effects are identified and criticality analysis is carried out for each failure mode, in which the criticality number is estimated using the failure rate databases. Among the numbers, the failure modes and components with higher criticality and severity are chosen and allocated with higher weighting factor. The reliability predictions are performed using the failure rate databases, from which the current ignition system is found to satisfy the target reliability.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.14 no.3
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• pp.59-67
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• 2000

This paper describes the unified reliability evaluation with partial loss of continuity for Inchon international airport distribution system which is complex and difficult system to implement. To evaluate reliability considering line limitation and voltage drop of the system, PLOC technique which is based on deterministic evaluation technique and failure mode & effective analysis method is employed. And reliability indices calculation method is used. Finally, to evaluate the system performance and to improve the reliability of the system, Analytic network process method is employed. As a result, calculating accurate reliability, finding weak points, and expansion scheduling of the system is possible.

• Journal of Applied Reliability
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• v.5 no.2
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• pp.221-239
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• 2005

General chip SMD parts(chip resistance, chip capacitor, chip varistor etc.) are very wide used electronics parts for IT units. But, failure modes are indistinct for these chip parts. In factory and field the failure modes are recognized to accidental failure mode caused by potential defect. In this paper used chip varistor ALT(Accelerate Life Test) test for verify general failure modes in chip SMD parts. Also the results are useful for general chip SMD ALT tests.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.563-564
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• 2015

Recently, distributed generation using renewable energy resources have increased due to the limitation of conventional energy. To utilize these energy source effectively, a method of applying the energy storage system(ESS) in distribution system has been considered. In this paper, we simulated the one line-to-ground fault in power system with ESS. Based on these simulations, we analyzed the effect on Over Current Relay(OCR) operation. As a result, ESS operation modes result fault current fluctuation. Thus, OCR need to reset the pick up current. This paper analyze effect of ESS in distribution system according to OCR setting by using ElectroMagnetic Transient Program(EMTP).

• Journal of Korean Society of Industrial and Systems Engineering
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• v.35 no.3
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• pp.180-186
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• 2012

신제품 개발에 있어서 제품의 잠재적 고장모드를 줄이기 위한 설계 노력은 매우 중요하며 이를 위해서는 체계적이고 혁신적인 신뢰성프로그램을 적용하는 것이 반드시 필요하다. 기업에서 동시공학을 기초로 한 건전한 신뢰성프로그램에 포함된 주요활동으로는 DFR(Design for Reliability), 신뢰성검증 및 물리적 해석활동 등이 있으며, 이 중 DFR은 제품 개발을 지원하는 첫 번째 과학적 신뢰성활동이다. 본 연구는 브레이크패드의 신뢰성을 향상시키기 위하여 회사조직전체에서 여러 부서의 팀 구성원이 유기적으로 참여하는 DFR 프로세스를 조직하고 실행하는 전략과 기술에 대한 연구이다. 본 사례연구의 동기는 해당기업에서 DFR에 적용된 모든 도구와 기술을 통해 제품의 신뢰성을 향상시키고 동시에 글로벌시장의 잠재고객에 대하여 품질과 신뢰성에 대한 확신을 주는데 유용하게 활용하기 위함이다. 본 논문에서는 제품개발주기의 개념설계단계 부터 제품의 폐기까지의 DFR 개념 전개에 대하여 설명하고, 기술적 도구를 적용한 설계초기 단계에서의 분석사례를 제시하였다.

• Proceedings of the KSR Conference
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• 2009.05a
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• pp.162-168
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• 2009

FMEA(Failure Mode and Effect Analysis) is a failure analysis method for the system to identify the potential failure modes, and their effects and causes to reduce or mitigate the critical effects of the system. FMEA for railway was introduced with reliability of railway system, and this was used for identifying and analysing the possible hazards qualitatively to meet the requirements in early stage of business. In general, the overall failure data of system could be managed from design stage by FMEA, and also the countermeasures to prevent many predicted failures could be established by identification of failure modes and assement of failure effects by FMEA. Using these advantages of FMEA, the effectiveness of reliability improvement could be expected if FMEA is applied continuously in operation stage. It is essential that railway vehicles are maintained with high level of safety and reliability not to happen any failures in operation. This paper is proposed the proper FMEA for maintenance of railway vehicles compared with existing FMEA.

• Journal of Applied Reliability
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• v.10 no.2
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• pp.123-135
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• 2010

Failure mode and effects analysis (FMEA) is a widely used technique to assess or to improve reliability of products or processes at early stage of development. Traditionally, the prioritization of failures for corrective actions is performed by evaluating risk priority numbers (RPN). In practice, due to insufficient evaluation criteria specific to related products and processes, RPN is not always evaluated properly. This paper reestablishes an effective methodology for prioritization of failure modes in FMEA procedure. Revised evaluation criteria of RPN are devised and a refined FMEA sheet is introduced. To verify the proposed methodology, it is applied to inspection processes of PCB products.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.7
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• pp.1186-1192
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• 2016

This paper proposes techniques to diagnose short-circuit faults of both the diodes and power FET in switching mode power supply (SMPS) by using a simple analog tester. The diodes in full-bridge rectifier, power FET, switching transformer, and some sensors are modelled with resistor. The total resistance value measured at the input terminal of a SMPS is analyzed when the short-circuit faults of diodes in a full bridge rectifier or power FET are occurred. The short-circuit faults of one or two diodes in a full bridge rectifier, power FET, and both the diodes in a full bridge rectifier and power FET can be detected by a range of total resistance, which is measured by the analog tester. Through experiments, the theoretical analysis for total resistance under short-circuit faults can be verified.

• Journal of the Korean Society for Precision Engineering
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• v.26 no.9
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• pp.96-102
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• 2009

In this study, performs analysis of the life of parallel opening type pneumatic chucks that are usually applied in the factory automation line. Pneumatic chucks have complicated failure cause because they are organized as a complex of various elements. Therefore, we analyzed the main failure mode of pneumatic chuck, and then performed life test and performance test according to the international standards. On the basis of these processes, shape parameter of pneumatic chuk is proposed that is the main factor for the calculation of zero failure test time for the reliability of pneumatic chuck and their data analysis of life distribution.