• Journal of Applied Reliability
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• v.3 no.1
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• pp.83-92
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• 2003

We studied the trend change of failure rate function and uncertainty of residual life function in terms of location of their trend change points. It is shown that the trend change of uncertainty of residual life takes place before the failure rate changes its trend. Like DIFR(IDFR) does not necessary implies IDMRL(DIMRL), we find the fact that DIFR(IDFR) does not always imply IDURL(DIURL) under certain conditions, through the exponentiated-weibull distribution.

• International Journal of Reliability and Applications
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• v.8 no.2
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• pp.175-182
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• 2007

In this note, some comments concerning the testing procedures for the problems of stochastic comparison, testing IFR and testing NBU ageing properties are presented showing that the tests proposed in Belzunce, Candel and Ruiz(1998) are cumbersome to calculate and do not have as good asymptotic Pittman efficacies as simpler others already in the literature. This is done via new presentations of the measures on which Belzunce et al. base their tests.

• Journal of The Korean Society of Integrative Medicine
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• v.4 no.2
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• pp.89-96
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• 2016

Purpose : The purpose of this study was to evaluate inter-tester reliability and Intra-tester reliability about range of motion(ROM) measurement of hip joint with smartphone inclinometer. Method : Six observers performed goniometric and smartphone inclinometer measurements of various hip movements, including both active ROM for flexion, extension, external rotation, internal rotation. Measurements were performed in the right hip of fifty normal subjects. All measures were performed three times for evaluating reliability of observer. Inter- and intra-observer reliabilities were evaluated using the intraclass correlation coefficient(ICC). Result : The results were as follows, inter-observer reliability ICC value showed .948-.974 in smartphone inclinometer. And showed .781-.827 in goniometer. Intra-observer reliability ICC value showed .653-.992 in smartphone inclinometer. And showed .613-.854 in goniometer. Conclusion : Smartphone inclinometer are portable and widely available tools that are mostly reliable and valid for assessing active hip range of motion, with potential use when a goniometer is not available.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.33 no.2
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• pp.48-55
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• 2010

Reliability has been considered as a one of the major design measures in various industrial and military systems. The main objective is to suggest a mathematical programming model and a hybrid parallel genetic algorithm(HPGA) for the problem that determines the optimal component reliability to maximize the system reliability under cost constraint in this study. Reliability optimization problem has been known as a NP-hard problem and normally formulated as a mixed binary integer programming model. Component structure, reliability, and cost were computed by using HPGA and compared with the results of existing meta-heuristic such as Ant Colony Optimization(ACO), Simulated Annealing(SA), Tabu Search(TS) and Reoptimization Procedure. The global optimal solutions of each problem are obtained by using CPLEX 11.1. The results of suggested algorithm give the same or better solutions than existing algorithms, because the suggested algorithm could paratactically evolved by operating several sub-populations and improving solution through swap and 2-opt processes.

• Magazine of the Korea Concrete Institute
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• v.7 no.3
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• pp.164-174
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• 1995

Reliability of RC beanls designed for flexure under the provisions of ACI Building Code is analyzed. The results are compared with those obtained previously. It is shown that in some cases the reliability is inadequate and changes substantiallv with reinforcernent ratio. The probability of brittle failure appears to be rather high. The reasons for these phenomena are revealed and some measures to remedy the situation are recommentied. hluch attention is given to the conditions askthey stand at present in Korea.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1712-1717
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• 2007

This paper presents a derating design approach for reliability improvement of an aluminum electrolytic capacitor. The capacitor, usually mounted in a printed circuit board, is used to stabilize the circuit. The main failure mechanism of interest is dry-up of the electrolyte that is mainly caused by two stresses-temperature and voltage. The lifetime under these stresses is modeled as a function of these stresses and time using accelerated life testing. Quantitative variation in the lifetime, according to variations in these stresses, is investigated to perform the derating design of the capacitor so that the stress levels are selected to achieve required reliability measures for reliability improvement. Moreover, sensitivity analysis shows which stress would be a more important factor determining the lifetime.

• Journal of Applied Reliability
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• v.15 no.1
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• pp.67-75
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• 2015

Differential pressure sensor for DPF (Diesel Particulate Filter) is the important part of a automobile exhaust system. This device measures the pressure of before DOC and after DPF to determine whether the DPF regenerate. In this paper reliability assessment criteria for DPF differential pressure sensor are established on terms of quality calcification test and lifetime test. The former quality certification test comprises general performance test and environmental test. Items which pass the test undergo lifetime test which guarantees the extent of mean lifetime with certain confidence.

• Proceedings of the KIEE Conference
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• 1997.07c
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• pp.1112-1114
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• 1997

When reliability is estimated to be insufficient, a planner must take action to improve them. So, the measures for improving reliability are mainly considered in the planning process. In order to provide quantitative information concerning reliability evaluation, this paper-describes an algorithm to find reserve margin in power system planning. The IEEE Reliability Test System(RTS) is used to demonstrate the effectiveness of the proposed algorithm.

• Journal of Industrial Technology
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• v.27 no.B
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• pp.245-253
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• 2007

Failure rate serves as a pivotal role in reliability study. Of all, the constant failure rate is the most popularly used in field exercises. In reality, however, the electrical and electronic parts' life is represented by not only the constant failure rate but the decreasing and/or increasing failure rates. Explicit consideration and incorporation of them into the model development may yield more desirable results. In this study, we built a reliability model for failure rates varying over time intervals and derived well known measures such as probability density function, reliability function, mean life, moments, and mission time. We then evaluated mean life with consideration of the first-year multiplier and compared the results those with constant failure rate. The results given in the study may provide a reference applying for practical decision making.

• Physical Therapy Korea
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• v.4 no.3
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• pp.45-60
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• 1997

This study was performed to determine the inter-rater reliability of the Chedoke-McMaster Stroke Assessment translated in Korean. This measures the physical impairments and disabilities that impact on the lives of individuals with stroke. The purposes of this measure were 1) to stage motor recovery to classify individuals in terms of clinical characteristics, 2) to predict rehabilitation outcomes, and 3) to measure clinically important change in physical function. Twenty-two subjects from physical therapy unit were assessed by two physical therapists. The ratings were compared by Spearman's rank correlation The correlation between two raters ranged from 0.85 to 0.98. Inter-rater reliability coefficient for total scores ranged from 0.95 to 0.97. This study confirms that the Chedoke-McMaster Stroke Assessment yields reliable results.