• Physical Therapy Rehabilitation Science
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• 제11권4호
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• pp.454-463
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• 2022

Objective: The purpose of this study was to compare concurrent validity and test-retest reliability based on Craniovertebral angle of 'Angles video goniometer', a smart phone application for convenient range of motion measurement, and 'Image J', an analysis software with high reliability and validity. This was conducted to find out whether 'Angle video goniometer' can be used clinically. Design: Cross-sectional study Methods: Fifty subjects were imaged laterally, and the angle of the head and spine was measured using Image J and the Angles video goniometer, respectively, in a resting posture and a chin in posture. The level of concurrent validity between the two measurement methods and the level of inter-rater reliability and intra-rater reliability were analyzed. Results: For forty participants, the concurrent validity between Image J and Angles video goniometer showed very high validity with ICC of 0.997(0.995~0.999) and 0.994(0.994~0.998), CVME% 0.71~0.72%, SEM% 0.31~0.34, MDC% 0.86~0.94. The test-retest intra-rater reliability showed very high reliability ICC 0.994(0.991~0.996), CVME% 0.71%, SEM% 0.31~0.43, MDC% 0.86~1.19%. The test-retest inter-rater showed very high reliability ICC 0.995(0.992~0.997), CVME% 0.71%, SEM% 0.43~0.59%, MDC% 1.20~1.62% Conclusions: Angles video goniometer', a smartphone application, is a device with very high reliability and validity for craniovertebral angle measurement in healthy adults, and it is a device that can be easily used in clinical practice.

• Steel and Composite Structures
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• 제19권4호
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• pp.811-827
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• 2015

This paper presents a probabilistic investigation of American and European specifications (i.e., AISC and Eurocode 4) for square concrete-filled steel tubular (CFT) stub columns. The study is based on experimental results of 100 axially loaded square CFT stub columns from the literature. By comparing experimental results for ultimate loads with code-predicted column resistances, the uncertainty of resistance models is analyzed and it is found that the modeling uncertainty parameter can be described using random variables of lognormal distribution. Reliability analyses were then performed with/without considering the modeling uncertainty parameter and the safety level of the specifications is evaluated in terms of sufficient and uniform reliability criteria. Results show that: (1) The AISC design code provided slightly conservative results of square CFT stub columns with reliability indices larger than 3.25 and the uniformness of reliability indices is no better because of the quality of the resistance model; (2) The uniformness of reliability indices for the Eurocode 4 was better than that of AISC, but the reliability indices of columns designed following the Eurocode 4 were found to be quite below the target reliability level of Eurocode 4.

• Nuclear Engineering and Technology
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• 제39권2호
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• pp.129-132
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• 2007

It is generally known that software reliability growth models such as the Jelinski-Moranda model and the Goel-Okumoto's non-homogeneous Poisson process (NHPP) model cannot be applied to safety-critical software due to a lack of software failure data. In this paper, by applying two of the most widely known software reliability growth models to sample software failure data, we demonstrate the possibility of using the software reliability growth models to prove the high reliability of safety-critical software. The high sensitivity of a piece of software's reliability to software failure data, as well as a lack of sufficient software failure data, is also identified as a possible limitation when applying the software reliability growth models to safety-critical software.

• 가족자원경영과 정책
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• 제9권2호
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• pp.77-92
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• 2005

This study examined the differences on the amount of purchase of and willingness-to-pay more for organic products by socio-economic variables, knowledge and reliability of organic products, and concern for food. In addition the effects of the reliability and the price of organic products on the amount of purchase and willingness-to-pay more for organic products in the Path analysis. The results were below. First, consumers who had high education, were the age of 40's, high income, high level of knowledge and reliability for organic products were more likely to purchase organic products. Second, the level of willingness-to-pay more for organic Products were high when consumers with more than three children, not lowest level of health, and higher reliability. Third, the reliability of organic products impact the amount of purchase of organic products, but not the perception of organic products' price. Forth, both the reliability and the perception of those price impact the level of willingness-to-pay more for organic products.

• 항공우주기술
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• 제1권2호
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• pp.173-178
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• 2002

전자부품 높은 신뢰성이 요구되며 극한의 운용 환경을 견디어야 하는 우주 프로그램에는 High-Reliability Part로 분류되는 Class S 이상의 Microcircuit, JANS 급 이상의 Discrete Semiconductor, 그리고 ER(Established Reliability) 등급 R 수준 이상의 Passive 소자들이 주로 사용된다. 그러나 일부 부품에 대해서는 High-Reliability Part로서 검증되지 않은 이른바 비표준 부품을 사용해할 경우가 빈번하게 생기고 있다. 이 경우 위성의 제작자는 자체적으로 부품을 검증하여 잠재적인 결함이 있는 부품들을 Screening할 수 있어야 한다. 본 기술 논문에서는 아리랑위성 1호기 및 2호기 개발을 통해서 이루어진 부품 검증과정을 간략히 소개하고자한다.

• 한국신뢰성학회:학술대회논문집
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• 한국신뢰성학회 2006년도 학술발표대회 논문집
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• pp.116-125
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• 2006

Piston assemblies, which are key components of hydraulic high pressure pumps & motors, are major failure products operating at high pressure and high speed, and the main failure mode is wearout of the shoe surface. To predict the actual life of piston assemblies. we require to find out the most sensitive parameters and establish related empirical formula. In this study, we analyzed the life of piston and shoe assemblies in accordance with variation of speed, pressure, and temperature to reduce the life test time, then analyzed the result of combined accelerated life test which is applied by high speed, speed pressure, and high temperature simultaneously, and finally developed combined accelerated life test model.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 추계학술대회 논문집
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• pp.1463-1472
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• 2008

The present paper to relate with the maintenance of the high-speed vehicle, KTX and is to treat a reliability evaluation. The reliability of the high-speed vehicle while operating between-failure average mileage (MKBSF) and parts between-failure average mileage (MKBF), 1,000,000 per km service failure number of items and availability and per km evaluated a maintenance expense. The reliability evaluation results and 2007 year reliability management indexes compared in 2006 years and they improved, per km the maintenance expense compared at 2006 and 36.6% was decreased. Reliability management activity leads and availability of the high-speed vehicle, safety improves and with the fact that will be able to decrease the maintenance expense which is an economic scale of railroad service is expected.

• International Journal of Aeronautical and Space Sciences
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• 제16권4호
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• pp.510-519
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• 2015

Concerning the issue of high-dimensions, hybrid uncertainties of randomness and intervals including implicit and highly nonlinear limit state function, reliability analysis based on the hybrid uncertainty reliability mode combining with back propagation neural network (HU-BP neural network) is proposed in this paper. Random variables and interval variables are as input layer of the neural network, after the training and approximation of the neural network, the response variables are obtained through the output layer. Reliability index is calculated by solving the optimization model of the most probable point (MPP) searching in the limit state band. Two numerical cases are used to demonstrate the method proposed in this paper, and finally the method is employed to solving an engineering problem of the aerospace friction plate. For this high nonlinear, small failure probability problem with interval variables, this method could achieve a good analysis result.

• 한국신뢰성학회:학술대회논문집
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• 한국신뢰성학회 2004년도 정기학술대회
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• pp.233-237
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• 2004

In this paper, to assess and enhance the reliability of Korea High Speed Train, electric traction system is selected and reliability analysis is carried out. The electric traction system is classified into subsystems and the functional block diagram and the reliability block diagram are drawn. Expressions to calculate the reliability are deduced and Mean Kilometer Between Service Failure is calculated using the trial test results on the track. Calculated results show reliability growth of the electric traction system.

• 대한안전경영과학회:학술대회논문집
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• 대한안전경영과학회 2011년도 춘계학술대회
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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.