• 한국철도학회논문집
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• 제9권4호
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• pp.419-424
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• 2006

In this paper we study on a method to predict and to demonstrate the reliability of the Korea high speed train control system in quantitative point of view. For the prediction of the reliability in train control system which is composed of electronic parts, Relax Software 7.7 automation tool is employed and MIL-HDBK-217 Handbook that is a standard for the prediction of the failure rate in electronic components is used. Mean Time Between Failure (MTBF) is predicted based on the failure rate of the subsystems, State Modeling and Markov Modeling method is used to express a reliability function of the train control system composed by hardware redundancy as a function of time. We propose a Reliability Test which is performed on the level of the subsystems and Failure Report, Analysing, Correction action system which use the test operation data to prove the predicted reliability.

• International Journal of Reliability and Applications
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• 제16권1호
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• pp.15-26
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• 2015

Present study investigates the fuzzy reliability of some systems using intuitionistic fuzzy Weibull lifetime distribution, in which the lifetime parameters are assumed to be fuzzy parameter due to uncertainty and inaccuracy of data. Expressions for fuzzy reliability, fuzzy mean time to failure, fuzzy hazard function and their ${\alpha}$-cut have been discussed when systems follow intuitionistic fuzzy Weibull lifetime distribution. A numerical example is also taken to illustrate the methodology to calculate the fuzzy reliability characteristics of systems.

• Journal of the Korean Data and Information Science Society
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• 제20권5호
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• pp.955-960
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• 2009

As we shall dene an exponentiated complementary power function distribution, we shall consider moments, hazard rate, and inference for parameter in the distribution. And we shall consider an inference of the reliability and distributions for the quotient and the ratio in two independent exponentiated complementary power function random variables.

• 재활치료과학
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• 제11권1호
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• pp.69-85
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• 2022

목적 : 본 연구는 연하장애 환자를 대상으로 구강안면기능을 평가할 수 있는 포괄적 구강안면기능척도(Comprehensive Oro-Facial Function Scale; COFFS)를 개발하고자 실시되었다. 연구방법 : COFFS의 문항 구성과 신뢰도를 검증하는 연구로 4개의 선행 연구를 선택 분석하여 예비문항을 수집하였고, 전문가를 대상으로 2차의 설문조사를 통해 내용타당도(Content Validity Ratio; CVR)를 도출하였다. 평가 항목의 내적 타당도를 위해 Cronbach's 𝛼값을 산출하였으며, 급간 내 상관계수(Internal Classification Coefficients; ICC)를 이용하여 검사-재검사 신뢰도 및 검사자간 신뢰도를 구하였다. 결과 : 전체 문항의 내용타당도는 0.67로 나타났으며, 영역별 Cronbach's 𝛼값의 경우 의사소통 영역 0.849, 구강안면 구조 및 형태 -0.224, 구강안면 움직임 수행능력 0.831, 저작 및 삼킴 기능은 0.946으로 도출되었으며, 검사-재검사 신뢰도는 0.974, 검사자간 신뢰도는 0.937로 높은 신뢰도를 보였다. 결론 : 본 연구에서 COFFS의 평가도구는 4개의 영역에서 34개의 문항을 최종적으로 선정하였고, 평가항목에 따라 3~5점 척도로 개발되었다. 추후 연구에서는 구강안면기능을 측정하는 다른 평가도구와의 상관관계를 통해 타당도를 입증할 추가연구가 필요할 것으로 사료된다.

• Structural Engineering and Mechanics
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• 제49권1호
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• pp.111-128
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• 2014

The stochastic response surface method (SRSM) and the response surface method (RSM) are often used for structural reliability analysis, especially for reliability problems with implicit performance functions. This paper aims to compare these two methods in terms of fitting the performance function, accuracy and efficiency in estimating probability of failure as well as statistical moments of system output response. The computational procedures of two response surface methods are briefly introduced first. Then their capabilities are demonstrated and compared in detail through two examples. The results indicate that the probability of failure mainly reflects the accuracy of the response surface function (RSF) fitting the performance function in the vicinity of the design point, while the statistical moments of system output response reflect the accuracy of the RSF fitting the performance function in the entire space. In addition, the performance function can be well fitted by the SRSM with an optimal order polynomial chaos expansion both in the entire physical and in the independent standard normal spaces. However, it can be only well fitted by the RSM in the vicinity of the design point. For reliability problems involving random variables with approximate normal distributions, such as normal, lognormal, and Gumbel Max distributions, both the probability of failure and statistical moments of system output response can be accurately estimated by the SRSM, whereas the RSM can only produce the probability of failure with a reasonable accuracy.

• PNF and Movement
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• 제10권1호
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• pp.1-7
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• 2012

Purpose : To verify the interrater reliability of upper extremity function assessment among three tools(Wolf motor function test, Motor assessment scale, Fugl-meyer assessment scale). Methods : The subjects of this study 40 (20 was physical therapists and 20 was physical therapy students). For the test one patients with chronic hemiparesis after stroke participated in the study. The Wolf Motor Function Test consists of 16 functional tasks. The motor assessment scale consists of 3 functional tasks. The fugl-meyer assessment scale consists of 8 functional tasks. All test sessions were videotaped and scored by 40 subjects. Analysis : The data was analysis by SPSS PC 14.0 with Cronbach alpha Coefficients, intraclass Correlation Coefficients Kendall tau-b value. Results : WMFT was highly scored in Cronbach's value, Cronbach's ${\alpha}=0.819$ that means high interrater reliability among assessment. WMFT was highly scored all items in p-value except one item, that means high p-value between therapists and students. WMFT was highly scored in Intrarater correlation coefficient (ICC) = 0.79, that means high interrater reliability of each examination item. WMFT was low index of coincidence from all items, MAS was low index of coincidence from a tim and FMA was low index of coincidence from 4 items. Conclusion : The interrater reliability of WMFT were compared with MAS, FMA and highly verified. WMFT can be more useful tool among upper extremity function assessment.

• 한국산업정보학회논문지
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• 제28권6호
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• pp.1-10
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• 2023

원전 계측제어계통은 정상운전 시 자가 진단기능의 유지보수를 위해 일정 주기로 건전성을 확인하고 있으며, 계획예방정비 기간 동안 기능 및 성능점검을 실시하여 필요한 경우 유지보수를 하고 있다. 하지만 원전의 정보를 계측하고 제어하는 계측제어계통에서도 선제적으로 고장을 진단하고 대처하여 사고전파를 방지할 수 있는 기술개발이 필요하다. 이에 본 논문에서는 계측제어 장비의 환경조건과 자가 진단 데이터를 활용한 신뢰도 함수 추정 방안을 연구하였으며, 고장데이터의 획득을 위해 계측제어 장비의 부품에 대한 Feature 별 확률분포를 가정하여 가상 고장데이터를 생산하였다. 이러한 고장데이터를 바탕으로 생존분석에서 활용되는 대표적인 인공지능 모델(DeepSurve, DeepHit)을 이용하여 신뢰도 함수를 추정하였고, 그와 동시에 전통적인 준모수적 방법론인 Cox 회귀모델을 통해 신뢰도 함수를 추정하여 환경조건과 진단 데이터를 바탕으로 한 잔여 수명 계산을 통해 적용 가능성을 확인하였다.

• Structural Engineering and Mechanics
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• 제63권6호
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• pp.789-797
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• 2017

Recently, some integrated structural identification/damage detection and reliability evaluation of structures with uncertainties have been proposed. However, these techniques are applicable for off-line synthesis of structural identification and reliability evaluation. In this paper, based on the recursive formulation of the extended Kalman filter, an on-line integration of structural identification/damage detection and reliability evaluation of stochastic building structures is investigated. Structural limit state is expanded by the Taylor series in terms of uncertain variables to obtain the probability density function (PDF). Both structural component reliability with only one limit state function and system reliability with multi-limit state functions are studied. Then, it is extended to adopt the recent extended Kalman filter with unknown input (EKF-UI) proposed by the authors for on-line integration of structural identification/damage detection and structural reliability evaluation of stochastic building structures subject to unknown excitations. Numerical examples are used to demonstrate the proposed method. The evaluated results of structural component reliability and structural system reliability are compared with those by the Monte Carlo simulation to validate the performances of the proposed method.

• Earthquakes and Structures
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• 제2권3호
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• pp.279-295
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• 2011

This paper develops a probabilistic methodology for the seismic reliability analysis of structures with random properties. The earthquake loading is assumed to be described in terms of response spectra. The proposed methodology takes advantage of the response spectra and thus does not require explicit dynamic analysis of the actual structure. Uncertainties in the structural properties (e.g. member cross-sections, modulus of elasticity, member strengths, mass and damping) as well as in the seismic load (due to uncertainty associated with the earthquake load specification) are considered. The structural reliability is estimated by determining the failure probability or the reliability index associated with a performance function that defines safe and unsafe domains. The structural failure is estimated using a performance function that evaluates whether the maximum displacement has been exceeded. Numerical illustrations of reliability analysis of elastic and elastic-plastic single-story frame structures are presented first. The extension of the proposed method to elastic multi-degree-of-freedom uncertain structures is also studied and a solved example is provided.

• International Journal of Reliability and Applications
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• 제12권1호
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• pp.49-60
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• 2011

The geometric process (GP) has been widely used for modeling failure and repair time sequences of repairable systems. The GP is mathematically tractable but restrictive in reliability applications since it actually assumes that the mean function of inter-failure times sequence asymptotically decreases to zero; and the mean function of successive repair times sequence asymptotically increases to infinity. This is generally unrealistic from an engineering perspective. This paper presents three extended GP models for modeling reliability deterioration and improvement (or growth) process. The extensions maintain the advantage of mathematical tractability of GP model. Their usefulness and appropriateness are illustrated with three real-world examples.