• Nuclear Engineering and Technology
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• v.54 no.5
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• pp.1804-1812
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• 2022

The aim of this paper is to assess the reliability and accuracy of the PSI standard method, used in many previous works, for the quantification of ND uncertainties in the SPERT-III RIA transient, by quantifying the discrepancy between the actual inserted reactivity and the original static reactivity worth and their associated uncertainties. The assessment has shown that the inherent S3K neutron source renormalization scheme, introduced before starting the transient, alters the original static reactivity worth of the transient CR and reduces the associated uncertainty due to the ND perturbation. In order to overcome these limitations, two additional methods have been developed based on CR adjustment. The comparative study performed between the three methods has showed clearly the high sensitivity of the obtained results to the selected approach and pointed out the importance of using the right procedure in order to simulate correctly the effect of ND uncertainties on the overall parameters in a RIA transient. This study has proven that the approach that allows matching the original static reactivity worth and starting the transient from criticality is the most reliable method since it conservatively preserves the effect of the ND uncertainties on the inserted reactivity during a RIA transient.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.17 no.4
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• pp.81-86
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• 2003

Using DG for peak-shaving unit could reduce the overall system operating cost, and using DG for standby power unit could improve the reliability of the distribution system The models of peak-shaving unit and standby power unit are different from each other. The Monte-Carlo simulation is suitable for the purpose of the analysis of two DG models. In this paper, the reliability indices are calculated from the time-sequential method, and the merit and defect of the peak-shaving unit and standby power unit are investigated.

• International Journal of Reliability and Applications
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• v.3 no.1
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• pp.1-16
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• 2002

In reliability engineering, the bathtub-shaped hazard rates play an important role in survival analysis and many other applications as well. For the bathtub-shaped, initially the hazard rate decreases from a relatively high value due to manufacturing defects or infant mortality to a relatively stable middle useful life value and then slowly increases with the onset of old age or wear out. In this paper, we present a new two-parameter lifetime distribution function, called the Loglog distribution, with Vtub-shaped hazard rate function. We illustrate the usefulness of the new Vtub-shaped hazard rate function by evaluating the reliability of several helicopter parts based on the data obtained in the maintenance malfunction information reporting system database collected from October 1995 to September 1999. We develop the S-Plus add-in software tool, called Reliability and Safety Assessment (RSA), to calculate reliability measures include mean time to failure, mean residual function, and confidence Intervals of the two helicopter critical parts. We use the mean squared error to compare relative goodness of fit test of the distribution models include normal, lognormal, and Weibull within the two data sets. This research indicates that the result of the new Vtub-shaped hazard rate function is worth the extra function-complexity for a better relative fit. More application in broader validation of this conclusion is needed using other data sets for reliability modeling in a general industrial setting.

• KIEE International Transactions on Power Engineering
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• v.4A no.1
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• pp.6-10
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• 2004

This paper presents an assessment of the customer interruption costs using a macro economic methodology of Korean customers by cities and provinces. The customer interruption cost is considered a very useful index in quantifying reliability worth from a customer point of view. This paper reviews the methodology to evaluate the customer interruption costs and ratio to the average revenues per electric energy sold for public, service agriculture, fishery, mining, manufacturing and residential sectors by cities and provinces in Korea.

• Journal of Korean Academy of Nursing
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• v.37 no.5
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• pp.736-743
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• 2007

Purpose: The purpose of this study was to develop a scale of free nursing home adjustment for the elderly in Korea. Method: The developmental processes were construction of a conceptual framework, development of preliminary items, verification of content validity, twice data gathering, verification of construct validity, and reliability of final items. The first 53 preliminary items were obtained through review of literatures about nursing home adjustment and in depth interviews with 5 staffs of nursing home. These items were reviewed by five specialists for content validity and 39 items were chosen. The first data was collected from 107 elderly residing in 3 nursing homes and the second survey was from 147 residents who were living in five nursing homes. Finally this data was analyzed for construct validity and reliability. Result: There were 23 final items which were sorted into 5 factors. The factors were identified as 'Relocation distress symptom'(8items), 'Making friends'(4items), 'Acceptance of new residence'(6items), 'Difficulty in group life'(3items), and 'Having self-worth'(2items). The cumulative percent of variance was 53.466%. The reliability of the scale, Cronbach's alpha was .837. Conclusion: The result of this study could be used for measuring nursing home adjustment of the elderly. However, for further validity and reliability, repeated researches are needed.

• Aerospace Engineering and Technology
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• v.5 no.2
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• pp.227-239
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• 2006

Reliability prediction provides a rational basis for design decisions such as the choice between alternative concepts, choice of part quality levels, derating factors to be applied, use of proven versus state-of-the-art techniques, and other factors. For this reasons, reliability prediction is essential functions in developing space systems. The worth of the quantitative expression lies in the information conveyed with the numerical value and the use which is made of that information and reliability prediction should be initiated early in the configuration definition stage to aid in the evaluation of the design and to provide a basis for item reliability allocation (apportionment) and establishing corrective action priorities. Reliability models and predictions are updated when there is a significant change in the item design availability of design details, environmental requirements, stress data, failure rate data, or service use profile. In this paper, the procedure, selection of reliability data and methods for space system reliability prediction is presented.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.10
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• pp.1703-1711
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• 2010

Electric power utilities are facing increasing uncertainties regarding the economic, political, societal, environmental constraints under they operate and plan their future systems. The utilities have to integrate consumers' interruption cost representing reliability worth of electricity into the process of determining the optimum investment level. In order to do so, the estimated outage cost must be included into quantitative index corresponding to system capital and operation investment cost to establish an optimal expansion plan. This paper is a study on the outage cost assessment by using macro approach for calculating IEAR(Interrupted Energy Assessment Rates) and the TRELSS(Transmission Reliability Evaluation for Large-Scale Systems) program was used to calculate EENS(Expected Energy Not Served).

• Proceedings of the KIEE Conference
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• 2003.07a
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• pp.139-141
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• 2003

The outage cost has very important position for determination of the optimal level or optimal range of reliability in power system expansion planning. Establishing the worth of service reliability is a very difficult and subjective task. This paper addresses the role, need and assessment algorithm and methodology of the outage cost on power system expansion planning. Furthermore outage cost has been assessed using macro approach for our country 15years(1986-2001) in the case study.

• Proceedings of the KIEE Conference
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• 2003.11a
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• pp.479-483
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• 2003

The outage cost has very important position for determination of the optimal level or optimal range of reliability in power system expansion planning. Establishing the worth of service reliability is a very difficult and subjective task. This paper suggests strategies for the role, need and assessment algorithm and methodology of the outage cost in power system expansion planning. Organization, data collections and method about D/B for outage cost assessment is proposed in the this study.

• Journal of Korean Academy of Nursing
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• v.21 no.3
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• pp.339-348
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• 1991

The study problem was to determine the reliability of the Stewart pain circle measurement tool with Korean subjects. The purpose was to assess the tool for potential use in research in Korea. The subjects were 95 primary school students and 103 university students in Seoul. The study was conducted from May to June 1990, using Stewart's pain color circle tool. To determine the difference in the rated intensity of the order of the pain color circles, statistical mean and standard deviation were employed. Item reliability and test - retest reliability were used to test for reliability. ANOVA and t-test were used to explore for differences in the rated intensity of the order of the pain color circles according to the subjects' general characteristics. The findings were as follows ; 1. Higher level pain intensity was assigned to color circle numbers 2, 4, and 6 (These contain large amounts of color). Lower level pain intensity was assigned to numbers 1, 3, and 5(These contain small amounts of color). Higher and lower levels of pain intensity selection patterns were the same as Stewart's but the highest rating of pain was different. The highest pain intensity rating was given to the color red in this study instead of black as in Stewart's test. 2. University students and primary school students' ratings were not very difteferent. 3. Pain color circle reliability was $\alpha$＝0.3468, Test - retest reliability was supported (t＝0.02~0.97, p＝0.337~0.988) 4. Differences in the rating of the pain intensity order were related to the subjects' age and sex, but not to religion. It was concluded that the pain color circle measurement tool is worth for further study as a research instrument with both Korean adult and child clients for validity and reliability.