• Aerospace Engineering and Technology
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• v.3 no.2
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• pp.91-97
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• 2004

In this paper, we conducted basic study on the reliability management that is a key factor to develop highly-reliable launch vehicles, and proposed the strategy for reliability management that can be applied to the KSLV program. Based on the analysis of international launch vehicles data, this paper also presented the reliability target that is essential for Korea's entering into the international commercial market.

• Journal of the Korean Society of Food Culture
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• v.26 no.2
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• pp.159-169
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• 2011

We suggested specific and practical marketing strategies to coffee shop managers and customers to create a symbiotic relationship. The coffee shop's relationship to reliability, commitment, and shop loyalty was analyzed thoroughly. The samples for this study were 393 coffee shop customers in Seoul. The results showed that customer reliability about coffee shops improved as reputation, customer orientation, specialty, and tie increased, but reliability was reduced as the size of the coffee shop became larger. Communication did not significantly affect reliability. Second, customer reliability positively affected commitment, so commitment increased as customer reliability increased. Third, customer reliability positively affected shop loyalty, so shop loyalty increased as customer reliability increased. Fourth, customer commitment positively affected shop loyalty, so shop loyalty increased as customer commitment increased.

• Journal of Applied Reliability
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• v.14 no.4
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• pp.262-266
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• 2014

In this paper, we consider the problem of determining the confidence level in zero-failure reliability sampling plans when the life distribution is Weibull distribution with a shape parameter m and a scale parameter ${\eta}$. We introduce zero-failure reliability sampling plans for Weibull distribution and investigate some characteristics of zero-failure reliability sampling plans. Finally, We propose new guideline for determining the confidence level in zero-failure reliability sampling plans for assuring $B_x-life$.

• Journal of Applied Reliability
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• v.11 no.4
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• pp.371-385
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• 2011

Because consumer mostly utilizes company test standard, supplier spends burden of expenses on building test equipments and managing expert manpower to fulfill consumer's various tests. Therefore, it is urgent to standardize test assessment which has a bond of sympathy between consumer and supplier and evaluates reliability of their products. This study develops reliability assessment standard which is composed of 12 test items considering international and domestic test standards, company internal test standards of consumer companies and field conditions. Also this study introduces overall technical procedure on accelerated test with no failure which is used for the main technology of reliability assessment. To verify effectiveness of reliability assessment, the test results are herein analyzed through building the test equipments and performing the test items.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.35 no.1
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• pp.124-131
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• 2012

This paper presents a spreadsheet-based reliability prediction simulation framework for the conceptual product design stage to acquire system reliability information in timely manner. During early stage, reliability performance deals with both known and unknown failure rates and component-level and subsystem-level failure estimate to predict system reliability. A technique for performing life testing simulation using Excel spreadsheet has been developed under the such circumstances. This paper also discuss the results obtainable from this method such as reliability estimate, mean and variance of failures and confidence intervals. The resultant of this reliability prediction system is mainly benefitting small and medium-sized enterprise's field engineers.

• Journal of Applied Reliability
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• v.9 no.2
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• pp.107-119
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• 2009

Reliability tests should be designed to verify whether reliability requirements are satisfied or not effectively and efficiently. The portion of reliability requirements that a reliability test scheme composed of different types of tests can cover is defined as test coverage in software engineering. For the cases of hardwares, to be effective, a reliability test scheme should enhance the test coverage. This study is to develop an evaluation method of test coverage for a reliability test scheme proposed for new products. Case studies are also given.

• Transactions of the Korean Society of Automotive Engineers
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• v.19 no.4
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• pp.1-7
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• 2011

Various convenient systems which are telecommunication and navigation system and safety system which include Antilock Braking System, Electronic Stability Control, Adaptive Cruise Control have been developed and applied to meet customer needs and each standards since vehicles are used. The complexity of new electronics become significant reason of breakdown especially embedded software failures. Hardware reliability is almost stabilized with long history but software reliability needs more improvements through reliability researches. This new challenge will improve software reliability to clear its overall failures in vehicles. This paper introduces some software reliability models and evaluates embedded software reliability using failure data which occurred during operating.

• Journal of the Korean Society for Precision Engineering
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• v.31 no.1
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• pp.67-73
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• 2014

A reliability evaluation or prediction can be defined as MTBF which stands for mean time between failures (Exclusively for repairable failures). Spindle system has huge effect on performance of machine tools and working quality as well as is required of high reliability. Especially, it takes great importance in producing automobiles which includes a large number of working processes. However, it is unusually difficult to predict reliability because there are lack of data and research about reliability of spindle system. Standards and methods of examinations for reliability evaluation of machine tools are scarce at local and abroad as well. Therefore, this research is meant to improve the reliability of spindle system before mass produced with developing standards of reliability and methods of examinations through FMEA to assess reliability of spindle system in prototype stages of developing high speed spindle system of machining center.

• Journal of Applied Reliability
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• v.9 no.3
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• pp.219-231
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• 2009

Power light emitting diodes(LED) for lighting fittings are so much environment-friendly, highly reliable and consume less energy that they are widely used at home and in industries such as electronics, telecommunications and industrial machineries. However, they are exposed to a very diverse environment and consists of complex components and, therefore needs careful approach to the enhancement and assessment of reliability of the item. In this article reliability assessment criteria for LED are established in terms of performance assessment test, reliability assessment test and accelerated test.

• Structural Engineering and Mechanics
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• v.22 no.6
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• pp.665-683
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• 2006

The strength behaviors of Fiber Reinforced Plastics (FRP) Composites can be greatly influenced by the properties of constitutive materials, the laminate structures, and load conditions etc, accompanied by many uncertainty factors. So the reliability study on FRP is an important subject of research. Many achievements have been made in reliability studies based on the probability theory, but little has been done on the roles played by fuzzy variables. In this paper, a fuzzy reliability model for FRP laminates is established first, in which the loads are considered as random variables and the strengths as fuzzy variables. Then a numerical model is developed to assess the fuzzy reliability. The Monte Carlo simulation method is utilized to compute the reliability of laminas under the maximum stress criterion. In the second part of this paper, a generalized fuzzy reliability model (GFRM) is proposed. By virtue of the fact that there may exist a series of states between the failure state and the function state, a fuzzy assumption for the structure state together with the probabilistic assumption for strength parameters is adopted to construct the GFRM of composite materials. By defining a generalized limit state function, the problem is converted to the conventional reliability formula that enables the first-order reliability method (FORM) applicable in calculating the reliability index. Several examples are worked out to show the validity of the models and the efficiency of the methods proposed in this paper. The parameter sensitivity analysis shows that some of the mean values of the strength parameters have great influence on the laminated composites' reliability. The differences resulting from the application of different failure criteria and different fuzzy assumptions are also discussed. It is concluded that the GFRM is feasible to use, and can provide an effective and synthetic method to evaluate the reliability of a system with different types of uncertainty factors.