• Geomechanics and Engineering
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• v.15 no.6
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• pp.1183-1191
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• 2018

Reliability analysis is generally regarded as the most appropriate method when uncertainties are taken into account in slope designs. With the help of limit analysis, probability evaluation for three-dimensional rock slope stability was conducted based upon the Mote Carlo method. The nonlinear Hoek-Brown failure criterion was employed to reflect the practical strength characteristics of rock mass. A form of stability factor is used to perform reliability analysis for rock slopes. Results show that the variation of strength uncertainties has significant influence on probability of failure for rock slopes, as well as strength constants. It is found that the relationship between probability of failure and mean safety factor is independent of the magnitudes of input parameters but relative to the variability of variables. Due to the phenomenon, curves displaying this relationship can provide guidance for designers to obtain factor of safety according to required failure probability.

• Computational Structural Engineering : An International Journal
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• v.1 no.2
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• pp.137-137
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• 2001

The reliability/redundancy of structural system has become a serious concern among engineers and researchers after structural failures in Northridge and Kobe earthquakes. The reliability/redundancy factor, ρ, in current codes considers only member force and floor area and has received much criticism from dissatisfied engineers. Within a reliability framework. the redundancy is investigated for dual systems of primary shear walls and secondary moment frames and steel moment frame systems. Probabilistic performance analyses are carried out baled on nonlinear responses under SAC ground motion. The effects of structural configuration, ductilily capacity, 3-D motion, and uncertainty of demand verses capacity are investigated. Important redundancy-contributing factors are identified and a uniform-risk redundancy factor is developed for design. The result are compared with the p factor and its inconsistency is pointed out.

• Proceedings of the Korean Reliability Society Conference
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• 2002.06a
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• pp.199-204
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• 2002

본 연구에서는 저압 증기 터빈블레이드의 안전성 확보를 위하여 작용응력 및 강도의 변동성을 고려한 확률론적 해석을 수행하였다. 정상상태에서 작용응력은 이론 및 유한요소해석에 의해서 얻을 수 있으며, 최대 von-Mises 응력은 215.4MPa이다. 회전굽힘 하중하에서의 피로한도는 응력비 R= -1에서 계단식 시험법을 이용하여 구하였으며, 이의 확률론적 특성에 가장 적합한 분포는 3 모수 와이블 분포이다. 그리고 신뢰성에 미치는 다양한 인자들의 영향은 영향계수(sensitivity factor)를 이용하여 정량적으로 평가하였다.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.779-783
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• 2008

LRFD Resistance factors for static bearing capacity of driven steel pipe piles were calibrated in the freamework of reliability theory. Reliability analysis was performed by the First Order Reliability Method (FORM) using resistance bias factor statistics.The target reliability indices are selected as 2.0 and 2.33 for group pile case and 2.5 for single pile case, based on the reliability level of the current design practice and considering redundancy of pile group, acceptable risk level, construction quality control, and significance of individual structure.

• Journal of Applied Reliability
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• v.6 no.1
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• pp.37-50
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• 2006

The accelerated life tests of the catalytic gas sensor were performed at three different gas concentration conditions. From the test data, the power-Weibull model was estimated and the acceleration factor between test condition 25%LEL(Lowe Explosive Limit) and use condition 5%LEL was about 3 according to this acceleration model. Using this acceleration factor, life test specification for qualifying that B10 lifetime of the catalytic gas sensor meets the goal lifetime (5 years) was designed.

• Geomechanics and Engineering
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• v.15 no.3
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• pp.879-888
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• 2018

Probability-based design codes have been developed to sufficiently confirm the safety level of structures. One of the most acceptable probability-based approaches is Load Resistance Factor Design (LRFD), which measures the safety level of the structures in terms of the reliability index. The main contribution of this paper is to calibrate the load and resistance factors of the design code for tunnels. The load and resistance factors are calculated using the available statistical models and probability-based procedures. The major steps include selection of representative structures, consideration of the limit state functions, calculation of reliability for the selected structures, selection of the target reliability index and calculation of load factors and resistance factors. The load and resistance models are reviewed. Statistical models of resistance (load carrying capacity) are summarized for strength limit state in bending, shear and compression. The reliability indices are calculated for several segments of a selected circular tunnel designed according to the tunnel manual report (Tunnel Manual). The novelty of this paper is the selection of the target reliability. In doing so, the uniform spectrum of reliability indices is proposed based on the probability paper. The final recommendation is proposed based on the closeness to the target reliability index.

• Journal of Power System Engineering
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• v.16 no.3
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• pp.44-50
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• 2012

The reliability qualification test is essential in order to ensure the life time of the product under the normal operation conditions when a new product is developed. The reliability qualification test period has an important impact on the development time of new product. Therefore, some researches to reduce the test time of reliability qualification test have been actively studied. Generally, accelerated life test is well known as one method that can save the test time of the reliability qualification test. This test is conducted under the higher stress condition than normal condition. So we need to investigate what factor affects to the higher stress condition. This paper shows the relationship between the acceleration factor and reliability qualification test period. Especially, we focused on the method to obtain effective acceleration factors under the high temperature condition. Through some experiments for a refrigerator's compressor, we were able to confirm how to increase acceleration factors and how to reduce the reliability qualification test period with minimum samples.

• Journal of Oriental Neuropsychiatry
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• v.28 no.3
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• pp.207-216
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• 2017

Objectives: To simplify the mindfulness scale and to ensure reliability and validity of the scale. Methods: To develop scale items using the original scale and to identify factor structure of the scale, exploratory factor analysis was conducted based on results of factor analysis, the short-form 5-factor mindfulness scale item was selected. Internal consistency coefficient was calculated and confirmatory factor analysis was conducted to verify reliability of the short-form scale. Finally, to verify validity of the abbreviated scale, we conducted correlation analysis with the abbreviated scale and the mindfulness scale (FFMQ). Results: As with the original scales, scaled scales were composed of 5 factors and consisted of 15 items in total. Factor analysis revealed factor loadings were adequate and reliability and validity were secured. Conclusions: It provided that mindfulness shortening scale validation can be used more simply to measure mindfulness in the clinical scene.

• Journal of Korean Academy of Nursing
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• v.32 no.3
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• pp.395-405
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• 2002

The purpose of this study was to develop the instrument to measure family functioning for Korean family with a chronic ill child, and to test the validity and reliability of the instrument. Method: The items of instrument were consisted based on researchers' previous study of concept analysis of the Korean family functioning. Twenty six item scale was developed with six domains. In order to test reliability and validity of the scale, data were collected from the 231 families, who have a child with a chronic illness. Data was collected between August and September in 2001 in a General Hospital in Seoul, Korea. Result: The results were as follows: As a result of the item analysis, 24 items were selected from the total of 26 items, excluding items with low correlation with total scale. Six factors were evolved by factor analysis. Six factors explained 61.4% of the total variance. The first factor 'Affective bonding' explained 15.4%, 2nd factor 'External relationship' 11.8%, 3rd factor 'Family norm' 10.5%, 4th factor 'Role and responsibilities' 8.3%, 5th factor ' Communication' 7.9%, and the 6th factor 'Financial resource' explained 7.3%. Cronbach's $\alpha$ coefficient of this scale was .87 and Guttman spilt- half coefficient was .84. Conclusion: The study support the reliability and validity of the scale. There were distinct differences in dimensions of family functioning scales developed in the U. S.

• Women's Health Nursing
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• v.10 no.4
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• pp.360-367
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• 2004

Purpose: The purpose of this study was to develop an instrument to measure breastfeeding empowerment for the Korean mother, and to test the validity and reliability of the instrument. Method: The items of instruments used was based on literature review. Nineteen item scales were developed with five domains. In order to test reliability and validity of the scale, data was collected from 99 mothers who were within 4weeks, postpatum and 88 mothers who had had children within 1 year. Data was collected between September 2nd and 24th by a self-reported questionnaire. Result: The results were as follows: As a result of factor analysis three times, 19 items were selected from the total of 24 items. Five factors evolved by factor analysis, which explained 65.7% of the total variance. The first factor 'breastfeeding skill' explained 34.1%, the 2nd factor 'group empowerment' 10.6%, the 3rd factor 'breastfeeding will' explained 7.8%, the 4th factor 'social policy empowerment' 7.0%, and the 5th factor 'adherence to exclusive breastfeeding' 6.2%. Cronbach's alpha coefficient of this scale was .8781. Conclusion: The study supports the reliability and validity of the scale. Because the main concept of breastfeeding empowerment was breastfeeding skill, there were distinct differences in the dimensions of breastfeeding empowerment scales.