• Journal of Korean Society of Transportation
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• v.26 no.5
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• pp.217-226
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• 2008

The term, travel-time reliability, refers to variations in journey time that travelers cannot predict. The purpose of this paper is to suggest a standard way to measure travel time reliability. A modified buffer time indicator is proposed. The index is represented by the difference between planned and actual travel times based on lognormal type travel time distribution. Using this framework, a constant function for railways and a negative parabola function for roads are discussed. The model developed is applied to the real data of Korean road and rail usages to empirically verify the methodology proposed. In this process, the unit value of travel time reliability for each group is estimated. The result of this research is expected to be helpful of conducting more cautious economic feasibility studies of transport.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.969-973
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• 2005

This paper presents a survey of software reliability modeling and it's application to pre-built software system combined with hardware such as numerical controller based on personal computer systems. Many a systems in these days are much more becoming software intensive and many software intensive systems are safety critical. For this reason, the technique well developed to measure of software reliability is very important for whom to assess such a system. This paper provides a brief idea of method to evaluate such a system's reliability based on hardware performance.

• Journal of Korean Society for Quality Management
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• v.30 no.1
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• pp.162-171
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• 2002

A practical algorithm of generating most probable states in decreasing order of probability, given the probability of each unit\`s state, is suggested for approximating reliability(performability) evaluation of a network with multistate(multimode) units. Method of approximating network reliability for a given measure with most probable states is illustrated with a numerical example. The proposed method in this paper is compared with the previous method regarding memory requirement. Our method has some advantages for computation and achieves improvement with regard to memory requirement for a certain condition judging from the computation experiment.

• Journal of the military operations research society of Korea
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• v.3 no.1
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• pp.137-150
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• 1977

The effectiveness of an actual combat tank system is analyzed. A measure of effectiveness which includes performance and reliability called pseudo-reliability is introduced. A model is introduced to optimize the design of the system in which the system pseudo-reliability is maximized subject to cost constraint. This model is a nonlinear programming problem and is solved by the sequential unconstrained minimization technique (SUMT). A numerical exampl with actual data from the test evaluation of five combat tanks is used to illustrate the model.

• Communications for Statistical Applications and Methods
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• v.20 no.6
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• pp.467-474
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• 2013

It is common to measure multiple coverage metrics during software testing. Software reliability growth models and coverage growth functions have been applied to each coverage metric to evaluate software reliability; however, analysis results for the individual coverage metrics may conflict with each other. This paper proposes the virtual coverage metric of a normalized first principal component in order to avoid conflicting cases. The use of the virtual coverage metric causes a negligible loss of information.

• Proceedings of the KIEE Conference
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• 2003.07b
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• pp.741-743
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• 2003

A reliability-based topology optimization (RBTO) for electromagnetic systems using the finite element method is presented. Permeability and applied current density are considered as uncertain variable. In order to compute reliability constraints, performance measure approach is used. To find the reliability index, the limit state function is linearly approximated at each iteration. Numerical examples show the effectiveness of the proposed method.

• Journal of Korean Academy of Nursing
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• v.46 no.1
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• pp.109-117
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• 2016

Purpose: The aim of this study was to develop a Korean version of Night Eating Questionnaire (KNEQ) and test its psychometric properties and evaluate items according to item response theory. Methods: The 14-item NEQ as a measure of severity of the night eating syndrome was translated into Korean, and then this KNEQ was evaluated. A total of 1171 participants aged 20 to 50 completed the KNEQ on the Internet. To test reliability and validity, Cronbach's alpha, correlation, simple regression, and factor analysis were used. Each item was analyzed according to Rasch-Andrich rating scale model and item difficulty, discrimination, infit/outfit, and point measure correlation were evaluated. Results: Construct validity was evident. Cronbach's alpha was .78. The items of evening hyperphagia and nocturnal ingestion showed high ability in discriminating people with night eating syndrome, while items of morning anorexia and mood/sleep provided relatively little information. The results of item analysis showed that item2 and item7 needed to be revised to improve the reliability of KNEQ. Conclusion: KNEQ is an appropriate instrument to measure severity of night eating syndrome with good validity and reliability. However, further studies are needed to find cut-off scores to screen persons with night eating syndrome.

• Proceedings of the KIEE Conference
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• 2006.04b
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• pp.130-132
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• 2006

For the reliability assessment of solenoid actuator, firstly, we analyzed the cause of major failures and the effect of each failure modes through FMEA and FTA, and decided the main test items through 2-stage QFD. And then, as a measure of life of solenoid actuator, TypeII censored five data were collected from and operation test which was performed as the life test of solenoid actuator. In this paper, we present the reliability parameters of solenoid actuator like shape parameter, scale parameter, etc., which they are produced by MINITAB analysis and marking of Weibull probability paper using the measure of life, and also present the 6 kinds of detailed failure mode analysis.

• Physical Therapy Korea
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• v.11 no.2
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• pp.9-16
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• 2004

The purpose of this study was to validate the Korean version of the Gross Motor Function Measure (GMFM) using Rasch analysis. The data was obtained from the assessments of 59 children with cerebral palsy in Korea and were applied to Rasch's rating scale model to estimate the difficulty and goodness-of-fit of each item. Rasch modeling helped us to identify 76 items from the original 88-item GMFM that form an unidimensional hierarchical scale to rearrange 76 items in order of difficulty. Reliability coefficients of the 88-item and 76-item GMFM were .99 and .99, respectively. In this preliminary report, the Korean version of GMFM seems to have significant validity and reliability. These results may be useful in assessment of gross motor functions in children with cerebral palsy.

• Journal of Korea Multimedia Society
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• v.20 no.7
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• pp.1046-1053
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• 2017

We propose a design method of high accuracy power measuring device and the method of securing the reliability of the measured data. As a design method for the development of the high accuracy power measuring device, the circuit was made by reflecting the high accuracy power measuring ICs and the CT (Current Transformer). To ensure the reliability of the power meter, we requested to the watt-hour meter certified testing organization to measure the error rate, and the error rate of active power based on the "Wattmeter Technical Standard(Revision notify 2014-283)" was measure, and the error rate was confirmed to be less than 0.1%.