• Proceedings of the Korean Society of Precision Engineering Conference
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• 1993.10a
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• pp.475-481
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• 1993

The objective of this study is to develope the reliability prediction model for Float Rated Integrating Gyroscope( :FRIG) at maximum loading. The equation of motion for FRIG is firstly derived to set up the reliability prediction model. To analysis reliability or all parts of the gyro is not easy due to their complicated structure. Therefore the failure parts are chosen by Failure Mode Effective Analysis (:FMEA). F.E.M is utilized to calculate loads for the selseced rotating assembly and pivot / jewel. The technical reliability is calculated by applying reliability design theory with these results and the performance reliability is sought through distribution estimation with error test data. The bulk reliability of gyroscope is sought by applying the two results. The present prediction results are compared with the accumulation time in good agreement.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.1
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• pp.101-106
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• 2011

The failure of cooling system in Superconducting Fault Current Limiter(SFCL) increases the impedance of superconducting device, and due to malfunction of inner switches the SFCL opens the distribution system inadvertently when required to do so. In this paper, the ground fault and short circuit fault were classified as active failure and the open circuit fault was passive failure. A reliability model of SFCL considers the passive failure as well as active failure, and in the case study the reliability indices of distribution system are evaluated. It is possible that the reliability evaluation excluded passive failure makes the customers reliability seem so worse than it really was. Therefore, the reliability models of SFCL must include the active failure and passive failure together to evaluate the reliability of distribution system connected SFCL.

• Journal of Applied Reliability
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• v.16 no.4
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• pp.263-271
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• 2016

Purpose: A slurry pump for flue gas desulfurization system performs a role that discharges the slurry of a plaster shape in a thermal power plant. Since a slurry pump transfers the slurry by the centrifugal force, it has the friction wear in the impeller and liner because of the slurry. Methods: In this study, failure analysis and test evaluation on the slurry pump have been proposed and the process that reliability of the product improves through design improvement has been presented. And failure cause of typical failure case has been investigated and improvement design has been presented. Results: Reliability improvement is established by analysis of the test results of before and after acceleration test. Conclusion: This study can be provided to improve the product reliability through failure analysis of a slurry pump.

• Physical Therapy Korea
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• v.2 no.1
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• pp.1-13
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• 1995

The purpose of this study was to examine the inter-rater reliability of the Korean translation of the GMFM(Gross Motor Function Measure). Three licensed physical therapists with varying amounts(2 - 6 years) of clinical experience served as raters. Thirty patients with cerebral palsy were subjects for this study. Subjects were 22 boys and 8 girls, aged 1 to 8 years. Reliability of each dimension and each total score of the GMGM were analyzed using ICCs(intraclass correlation coefficients). The reliability of each dimension score ranged from .76 to .98, with the walking, running, and jumping dimension having higher reliability values. The reliability of the total dimension score was .94. We conclude that the GMFM has inter-rater reliability for assessing gross motor function in patients with cerebral palsy.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.1014-1017
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• 2000

Reliability engineering is regarded as the major and important roll for all industry. And advanced manufacturing systems with high speed and intelligent have been developed for the betterment of machining ability. In this study, we have systemized evaluation of reliability for machinery system. We proposed the reliability assessment and design review method using analyzing critical units of high speed and intelligent machine system. In addition, we have not only designed and developed test bed system for acquiring reliability data, but also have constructing WEB system for suppling reliability which is provided in design phase. From this study, we will expect to guide and introduce the reliability engineering in developing and processing phase of high quality product.

• Proceedings of the Safety Management and Science Conference
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• 2011.04a
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• pp.663-674
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• 2011

Continuing and Developing the growth, the company should focus on 'time to market of high quality production' and 'cost down'. Due to the complexity of the production, reliability is being one of the important factor. In this study, in particular, focus on parts reliability test improvement about printer product and proceeded. Need test improvement for time to market that is developed, and reduce expense with test period that is required at Reliability Test time of new parts and should high quality level of product. Finally huge Failure Cost (F-COST) occurs because quality level of product drops if parts that accomplish product does not ensure reliability and this is associated by malfunction in marketplace.

• Journal of the Korea Safety Management & Science
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• v.12 no.3
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• pp.153-162
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• 2010

Continuing and Developing the growth, the company should focus on 'time to market of high quality production' and 'cost down'. Due to the complexity of the production, reliability is being one of the important factor. In this study, in particular, focus on parts reliability test improvement about printer product and proceeded. Need test improvement for time to market that is developed, and reduce expense with test period that is required at Reliability Test time of new parts and should high quality level of product. Finally huge Failure Cost (F-COST) occurs because quality level of product drops if parts that accomplish product does not ensure reliability and this is associated by malfunction in marketplace.

• Journal of Applied Reliability
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• v.17 no.2
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• pp.83-91
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• 2017

Purpose: The purpose of this study is to develop a quality assurance model and to determine appropriate warranty period for a guided missile using its field data. Methods: 10 years of actual firing data is collected from the defense industry company and military. Parametric maximum likelihood estimation for a reliability function is determined with the data. Results: The reliability function estimates average lifetime of the missile. That function shows a user requirement, 80% reliability (lifetime) is come up when 8 years have passed, which is longer than the estimates in the missile's development phase. Conclusion: Quality assurance warranty for a guided missile must be established with actual test data. It is necessary to update and modify the reliability prediction and the warranty period with actual field test data.

• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.3
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• pp.63-71
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• 2007

During the design phase of a product, reliability and design engineers are called upon to evaluate the reliability of the system, The question of how to meet target reliability for the system arises when estimated reliability or cost is inadequate. This then becomes a problem of reliability allocation and system structure design. This study proposes the optimization methodology to achieve target reliability with minimum cost through construction of the cost function of system. In cost function, total cost means the sum of initial cost, repair cost and maintenance cost. This study constructs optimization problem about system structure design and reliability allocation using cost function. This problem constructed is solved by Multi-island Genetic Algorithm(MIGA), and applies to urban transit brake system. Current brake system of the urban transit is series system. Series system is the simplest and perhaps one of the most common system, but it demands high reliability and maintenance cost because all components must be operating to ensure system operation. Thus this study makes a comparative study by applying k-out-of-n system to brake system. This methodology presented can be a great tool for aiding reliability and design engineers in their decision-makings.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.13 no.22
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• pp.59-64
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• 1990

This paper is aimed to study the standby redundant system with the relay of parallel structure, by making use of the character of standby system, which reliability is higher than parallel system's if the relay has higher reliability than a certain level. By assigning the low-priced relay to the subsystem, this method increases the relay reliability, optimizes the standby redundant system reliability without violating the restrictions, and consequently reduces the cost.