• Journal of the Korea Safety Management & Science
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• v.10 no.3
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• pp.81-87
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• 2008

The reliability prediction and evaluation for general electronic components are required to guarantee in quality and in efficiency. Although many methodologies for predicting the reliability of electronic components have been developed, their reliability might be subjective according to a particular set of circumstances, and therefore it is not easy to quantify their reliability. In this study reliability prediction of electronic components, that is the interface card, which is used in the CNC(Computerized Numerical Controller) of machine tools, was carried out using PRISM reliability prediction specification. Reliability performances such as MTBF(Mean Time Between Failure), failure rate and reliability were obtained, and the variation of failure rate for electronic components according to temperature change was predicted. The results obtained from this study are useful information to consider a counter plan for weak components before they are used.

• Journal of Applied Reliability
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• v.9 no.1
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• pp.59-69
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• 2009

LEDs have rapidly replaced old light devices such as incandescent or fluorescent lamps, and have been widely applied in general lighting, signals, automobile, signs and others. Since LEDs are for both indoor and outdoor use, temperature and humidity inevitably affect its reliability. We explain the result of the degradation life test on LEDs, and guide to reliability analysis procedure. Analysis on reliability measures are performed by Weibull++6 program, and a common shape parameter of Weibull distribution on the LED is suggested. Also, we make a description of reliability analysis procedures for the degradation data using collected test data from degradation tests. Reliability analysis procedures are consisted of estimating degradation models and failure time, verifying of distribution and parameters of the distribution, and estimating of reliability measures. Finally, this paper suggests reliability analysis method for light characteristics on LEDs.

• Journal of Power Electronics
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• v.6 no.2
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• pp.104-113
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• 2006

Satellites have provided the impetus for the orderly development of reliability engineering research and analysis because they tend to have complex systems and hence acute problems. They were instrumental in developing mathematical models for reliability, as well as design techniques to permit quantitative specification, prediction and measurement of reliability. Reliability engineering is based on implementing measures which insure an item will perform its mission successfully. The discipline of reliability engineering consists of two fundamental aspects; $(1^{st})$ paying attention to details, and $(2^{nd})$ handling uncertainties. This paper uses some of the basic concepts, formulas and examples of reliability theory in application. This paper emphasizes the practical reliability analysis of a Low Earth Orbit (LEO) Micro-satellite power subsystem. Approaches for specifying and allocating the reliability of each element of the power system so as to meet the overall power system reliability requirements, as well as to give detailed modeling and predicting of equipment/system reliability are introduced. The results are handled and analyzed to form the final reliability results for the satellite power system. The results show that the Electric Power Subsystem (EPS) reliability meets the requirements with quad microcontrollers (MC), two boards working as main and cold redundant while each board contains two MCs in a hot redundant.

• Journal of Applied Reliability
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• v.14 no.1
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• pp.29-35
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• 2014

To improve the reliability of a weapon system, we perform the activities: setting the target reliability, reliability allocation, and reliability management, etc. Before starting weapon system development, the target reliability of system is set through advanced research and is allocated to its subsystems at the beginning of development. Then we manage the reliability of system and subsystems to meet the target reliability until completion of system development. In this paper, we research representative reliability allocation methods and introduce the suitable reliability allocation method followed by its application to the underwater guided weapon system. The purpose of this research is to review the proposed reliability allocation techniques and find an appropriate method for underwater weapon systems followed by the validation of its application.

• 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 Society of Precision Engineering Conference
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• 1997.10a
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• pp.43-46
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• 1997

Reliability engineering is regarded as the major and important roll for all industry. And advanced manufacturing systems with high sped and intelligent have been developing for betterment of machining ability. In this study, we have systemized evaluation of reliability for machinery system. We proposed the reliability assessment and designed and manufactured reliability test-bed to evaluate reliability. In addition we acquired reliability data using test-bed system and made database to handle reliability data. And also we not only use reliability data by analyzing reliability, but also apply design review method using analyzing critical units of machinery system. Form this study, we will expect to guide and increase the reliability engineering in developing and processing phase of high quality product.

• Journal of Korean Society for Quality Management
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• v.44 no.1
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• pp.29-42
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• 2016

Purpose: This paper reviews the papers on reliability issues which are published in the Journal of the Korean Society for Quality Management (KSQM) since 1965. The literature review is purposed to survey a variety of reliability issues for several categories Methods: We divide all of reliability issues into 9 categories: acceleration test, reliability estimation, system reliability, software reliability, reliability data collection and analysis method, lifetime distribution, maintenance and warranty strategy, reliability applications, and reliability applications to military area Results: Dividing all of papers on reliability published in KSQM for 50 years into 9 categories, we provide a chronological roadmap for individual categories, and summarize the contents and contributions of surveyed papers Conclusion: The review paper is expected to provide future direction to improve reliaiblity theories and applications in manufacturing and service industries

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.51 no.7
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• pp.357-363
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• 2002

The target reliability values are defined for the train, signaling, rail track and electric power supply system of the LRT under development. The allocation of the reliability value is based on the failure rate and the failure type in the Korean subways. The reliability allocation in the train system is the made ore detail than others. The purpose of the allocation is to verify the reliability value of the results from each of the development stage, which could be the designing, manufacturing and purchasing work. The reliability of braking system, traction system, door system and other control system could be verified by establishing reliability models of these system. It could also enable us to estimate and analyse the reliability value and redo the work if necessary to achieve the shooting reliability value. A guide to the LRT reliability criteria is to be prepared after running test on the test track.

• International Journal of Precision Engineering and Manufacturing
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• v.8 no.3
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• pp.50-53
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• 2007

Improving the reliability or long-term dependability of a system requires a different approach from the previous emphasis on short-term concerns. The purpose of this paper is to present a reliability evaluation method for an oil cooler intended for high-precision machining centers. The oil cooler system in question is a cooling device that minimizes the deformation caused from the heat generated by driving devices. This system is used for machine tools and semiconductor equipment. We predicted the reliability of the system based on the failure rate database and conducted the reliability test using a test-bed to evaluate the life of the oil cooler. The results provided an indication of the reliability of the system in terms of the failure rate and the MTBF of the oil cooler system and its components, as well as a distribution of the failure mode. These results will help increase the reliability of oil cooler systems. The evaluation method can also be used to determine the reliability of other machinery products.

• Journal of Korean Society for Quality Management
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• v.40 no.3
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• pp.259-269
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• 2012

Purpose: The purpose of this study was to find out that the statistical method of stockpile reliability of ammunition by items can be applied to the reliability assessment of stockpile ammunition. Methods: We reviewed the statistical method of stockpile reliability of ammunition by items and verified the possibility of its application by case study. Results: We found that the statistical method of stockpile reliability of ammunition by items is very useful and effective to present the reliability of ammunition based on each item and to predict the change of the reliability in the future. The reliability of proximity fuse was about 94.5% and was influenced by manufacture's year and the difference between lot and lot more than storage period. Conclusion: The statistical method of stockpile reliability of ammunition by items can be applied to the reliability assessment of various stockpile ammunitions such as ammunition for mortar and canon.