• 터널과지하공간
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• 제24권4호
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• pp.275-281
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• 2014

국내 국도에 분포하는 160개 비탈면에서의 발생한 낙석에너지의 특성을 고려하여 신뢰도지수를 산정하고 낙석방지울타리의 요구성능을 고찰하였다. 몬테카를로 시뮬레이션을 통해 낙석에너지를 결정하는 변수의 통계적 특성을 고찰한 결과 비탈면 경사는 정규분포형태이며, 낙석중량과 발생높이는 대수정규분포형태인 것으로 나타났다. 낙석에너지는 대수정규분포형태인 것으로 나타났으며 이는 낙석중량에 영향을 받은 결과로 판단된다. 낙석방지울타리의 신뢰성지수는 0.678이며 파괴확률은 24.9%로 매우 높은 것으로 나타났다. 국내의 낙석에너지 규모를 고려하여 제시된 낙석방지울타리의 요구성능은 최대 500kJ 수준이며 신뢰성지수의 범위는 1.028~1.956으로 분석되었다. 제시된 신뢰도지수를 통해 비탈면의 낙석에너지가 고려된 요구성능을 적용할 경우 낙석방지울타리의 파괴확률은 14.8~2.5% 수준인 것으로 분석되었다.

• 한국생산제조학회지
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• 제19권4호
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• pp.469-475
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• 2010

The objective of this study is to integrate reliability analysis into shape optimization problem using the evolutionary structural optimization (ESO) in the application example. Reliability-based shape optimization is formulated as volume minimization problem with probabilistic stress constraint under minimization max. von Mises stress and allow stress. Young's modulus, external load and thickness are considered as uncertain variables. In order to compute reliability index, four methods, i.e., reliability index approach (RIA), performance measure approach (PMA), single-loop singlevector (SLSV) and adaptive-loop (ADL), are used. Reliability-based shape optimization design process is conducted to obtain optimal shape satisfying max. von Mises stress and reliability index constraints with the above four methods, and then each result is compared with respect to numerical stability and computing time.

• 한국터널지하공간학회 논문집
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• 제22권3호
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• pp.249-259
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• 2020

지중 구조물의 한계상태설계를 위한 설계 기준이 해외에서는 이미 발표된 바 있고 국내에서도 설계법 개정을 위한 연구가 수행되고 있다. 지진 시 파괴확률을 추정하기 위해서는 신뢰성 분석에서 확률변수를 고려해야 한다. 본 연구에서는 국내 지반 확률 특성치를 고려한 토압에 대한 변동계수와 지진하중 효과에 대한 변동계수를 적용하여 기존 쉴드 터널 설계 단면에 대한 지진 시 파괴확률을 계산하였다. 산정된 파괴확률로부터 신뢰도지수(β)를 산정하고 하중 계수의 변화에 따른 신뢰도지수를 분석한 결과와 국내외 연구결과를 토대로 쉴드 터널 세그먼트 라이닝의 지진 시 목표 신뢰도지수(β_T)는 2.3이 합리적인 것으로 분석되어, 지진 시 한계상태설계를 위한 목표 신뢰도 지수로 제안하였다.

• 한국전문물리치료학회지
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• 제14권3호
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• pp.97-106
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• 2007

The purpose of this study was to determine reliability and validity of the Neck Disability Index (NDI) now in use for the first time in neck pain patients of Korea. Fifty subjects (26 males and24 female) with neck pain enrolled in the study. They completed a standardized self-administered questionnaire that include pain intensity, personal care, lifting, reading, headaches, concentration, work, driving, sleeping and recreation. Reliability was determined by intra-class correlation coefficient (ICC) and Cronbach's alpha by internal consistency. Validity was examined by correlating the NDI scores to the Visual Analog Scale (VAS) score. The Test-retest reliability of the translated versions of the NDI was good ICC (2,1) = .90 (95%CI .85 .95). Cronbach's alpha value for NDI was found to be .95 and this was statistically significant (p<.05). The criterion-related validity coefficients was .72 (p<.01). We conclude that the Korean version of NDI has shown to be a reliable and valid instrument for the assessment of neck pain.

• 한국신뢰성학회지:신뢰성응용연구
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• 제13권3호
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• pp.191-206
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• 2013

Application areas for Lifetime Performance Index(LPI), a kind of process capability index to be frequently used as a means of measuring process performance are illustrated with examples. Statistical properties for maximum likelihood and unbiased estimators of LPI are evaluated and discussed under Weibull distribution with known shape parameter. Furthermore, guidelines for selecting an estimator of LPI are also presented.

• 한국해안·해양공학회논문집
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• 제21권3호
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• pp.224-229
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• 2009

케이슨식 안벽의 Level I 신뢰성설계를 위한 부분안전계수를 산정하였다. 일계신뢰도법에 의한 부분안전계수는 한계상태함수의 확률변수에 대한 민감도, 목표신뢰도지수, 확률특성치 및 설계특성치 등의 함수로써 표현하였으며 전면조위와 잔류수위에 대해서는 현행설계법과의 연계성을 유지하기 위하여 수정부분안전계수를 새롭게 정의하였다. 수치해석을 통하여 목표신뢰도지수에 대한 부분안전계수를 산정하였으며 지진계수의 확률분포는 극치분포를 사용하였다. 지진계수의 설계치를 적용함에 있어서 재현주기가 길수록 부분안전계수가 작게 산정됨을 확인하였다.

• 대한물리치료과학회지
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• 제18권3호
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• pp.53-61
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• 2011

Purpose : his study was to analyze the reliability and validity on Oswestry Low Back Pain Disability Index (OLBPDI) in patients with low back pain. Methods : The sample consisted of 211 patients who had received treatments at the physical therapy units of 3 medical institutions from February to December 2008 in Andong city. Questionnaires on the OLBPDI were recruited by 6 physical therapists. The internal structure and reliability of the scales were evaluated by means of item-internal consistency(Cronbach's alpha coefficient:${\alpha}$), item-discriminant validity, Pearson's relation coefficient. Results : An average of patients's age was 41.1 years. The range of OLBPDI subscales were .93~.94 in Cronbach's ${\alpha}$. The internal consistency reliability of total item-each item were also internally consistent with Cronbach's ${\alpha}$ range of .94~.95(Pearson's correlation coefficient range: .62~.89). However, high correlation were obtained among 10 items(.67~.83), therefore the item-discriminant validity was a little low. Conclusion: In conclusion, the results reported here confirm the reliability of the OLBPDI scales in patients with low back pain. The collection of information on the level of disability due to low back pain using this instrument was acceptable to patients. A further prospective multi-center study will be necessary to prove the reliability and validity.

• 대한전기학회논문지:전력기술부문A
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• 제54권4호
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• pp.177-184
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• 2005

This paper proposes a improved investment priority decision method of the facilities considering the reliability of distribution networks. The proposed method decides a investment order of the facilities combining, by fuzzy rules, the investment priority decision of KEPCO and the priority decision considering reliability evaluation indices. Where reliability evaluation indices are SAIFI(System Average Interruption Frequency Index) and SAIDI(System Average Interruption Duration Index), as referred to evaluation index for sustained interruption. The reliability analysis method of distribution networks applied in this paper utilizes analytic method, where the used reliability data is historical data of KEPCO. Particularly, we assumed that the failure rate increased as the equipment ages. To verify the performance of the proposed method, we applied it with the planned projects to reinforce the weak facility electrical facilities in KEPCO in 2004. The evaluation result showed that, under a limited budget, the reliability of the KEPCO in the Busan region using the proposed method can be enhanced than using the conventional KEPCO's method. Therefore, the results verify the proposed method can be efficiently used in the actual priorities method for investing the electrical facilities.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 추계 학술발표회
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• pp.427-435
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• 2008

A reliability based slope stability assessment method is proposed and examined considering the variation of matric suction which is measured by a real time slope monitoring system. Mean value first order reliability method and advanced first order reliability method are used to calculate reliability indices of a slope. The applicability of methods is compared by applying them to the range of matric suctions measured by the real-time monitoring system. Sensitivity analysis is also performed to examine the contribution of random variables to the reliability index of slope. Finally, the proposed method is applied to a model slope. The results show that the reliability index of slope can be used for efficient slope management by quantifying the risk of slope in real time.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2000년도 가을 학술발표회논문집
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• pp.101-108
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• 2000

An optimum design algorithm using efficient reanalysis is proposed for reliability-based optimization problems formulated as the minimization of initial cost and expected failure cost with reliability constraints. The reliability-based optimization is high cost to evaluate objective function and constraints needed reliability analysis. Therefore the sensitivity analysis of reliability index for approximated reanalysis is necessary. In this paper, three solution approaches are suggested and tested. The approaches include : (1) sensitivity analysis using finite difference; (2) sensitivity analysis using automatic differentiation (AD); and (3) sensitivity analysis with respect to intermediate variables using AD. Numerical example is optimized to show the reliability and effectiveness of the new algorithm.