• Wind and Structures
• /
• 제24권3호
• /
• pp.249-265
• /
• 2017

An efficient and accurate algorithm is proposed to estimate flutter safety factor of suspension bridges satisfying prescribed reliability levels. Uncertainties which arise from the basic wind speed at the bridge deck location, critical flutter velocity, the wind conversion factor from a scaled model to the prototype structure and the gust speed factor are incorporated. The proposed algorithm integrates the concepts of the inverse reliability method and the calculation method of the critical flutter velocity of suspension bridges. The unique feature of the proposed method is that it offers a tool for flutter safety assessment of suspension bridges, when the reliability level is specified as a target to be satisfied by the designer. Accuracy and efficiency of this method with reference to three example suspension bridges is studied and numerical results validate its superiority over conventional deterministic method. Finally, the effects of various parameters on the flutter safety factor of suspension bridges are also investigated.

• 대한간호학회지
• /
• 제43권4호
• /
• pp.568-578
• /
• 2013

Purpose: The purpose of this study was to evaluate the reliability and validity of the Korean version of the Successful Aging Inventory (SAI-K) to determine its suitability for use with older Korean adults. Methods: Exploratory and confirmatory factor analyses were utilized to assess the factor structure and the construct validity of the SAI-K. First- and second-order Confirmatory Factor Analysis (CFA) were conducted to identify the most adequate model. Cronbach's alpha was used to test the reliability. Results: Using a second-order CFA, a four-factor structure was validated (${\chi}^2$=122.82, p<.001, GFI=.92, AGFI=.88, SRMR=.06 RMSEA=.07, 90% CI=.05-.09, CFI=.93). The four-factor SAI-K showed reliable internal consistency with a Cronbach's alpha for the total scale of .86. Conclusion: The four-factor, 13-item SAI-K showed satisfactory reliability and validity and, thus, has the potential to be an appropriate instrument for measuring successful aging in older Korean adults.

• Earthquakes and Structures
• /
• 제8권5호
• /
• pp.995-1016
• /
• 2015

The reliability or the safety index is a measure of how far a structure is from the state of collapse. Also it defined as the probability that a structure will not fail in its lifetime. Having any increase in the reliability index is typically interpreted as increasing in the safety of structures. On the other hand most of researchers acknowledged that one of the most effective means of increasing both the reliability and the safety of structures is to increase the structural redundancy. They also acknowledged that increasing the number of vertical seismic framing will make structural system more reliable and safer against stochastic events such as earthquakes. In this paper the reliability index and the behavior factor of a numbers of three dimensional RC moment resisting frames with the same story area, equal lateral resistant as well as different redundancy has been evaluated numerically using both deterministic and probabilistic approaches. Study on the reliability index and the behavior factor in the case study models of this research illustrated that the changes of these two factors do not have always the same manner due to the increasing of the structural redundancy. In some cases, structures with larger reliability index have smaller behavior factor. Also assuming the same ultimate lateral resistance of structures which causes an increase to a certain level of redundancy can enhance behavior factor of structures. However any further increase in the redundancy of that certain level might decrease the behavior factor. Furthermore, the results of this study illustrate that concerning any increase in the structural redundancy will make the reliability index of structure to be larger.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2006년도 춘계 학술발표회 논문집
• /
• pp.466-475
• /
• 2006

Reliability analysis between safety factor and reliability index for driven and bored pile load capacity was analyzed in this study. 0.1B, Chin, De Beer, and Davisson's methods were used for determining pile load capacity by using load-settlement curve from pile load test. Each method define ultimate, yield and allowable pile load capacities. LCPC method using CPT results was performed for comparing with results of pile load test. Based on FOSM analysis using load factors, it is obtained that reliability indices for ultimate pile load capacity were higher than those of yield and allowable condition. Present safety factor 2 for yield and allowable load capacities are not enough to satisfy target reliability index $2.0\sim2.5$. However, it is sufficient for ultimate pile load capacity using safety factor 3.

• Structural Engineering and Mechanics
• /
• 제23권2호
• /
• pp.195-207
• /
• 2006

An efficient and accurate algorithm is proposed to estimate cable safety factor of suspension bridges satisfying prescribed reliability levels. Uncertainties in the structure and load parameters are incorporated. The proposed algorithm integrates the concepts of the inverse reliability method and deterministic method for assessing cable safety factors of suspension bridges. The unique feature of the proposed method is that it offers a tool for cable safety assessment of suspension bridges, when the reliability level is specified as a target to be satisfied by the designer. After the accuracy and efficiency of the method are demonstrated through two numerical examples, the method is used to estimate cable safety factors of suspension bridges with span length ranging from 2000 to 5000 m. The results show that the deterministic method overestimates cable safety factor of suspension bridges because of neglecting the parameter uncertainty effects. The actual cable safety factor of suspension bridges should be estimated based on the proposed method.

• 대한간호학회지
• /
• 제50권4호
• /
• pp.611-620
• /
• 2020

Purpose: The aim of this study was to evaluate the reliability and validity of the Korean version of the Wong and Law Emotional Intelligence Scale (K-WLEIS). Methods: Data were collected from 360 nursing students using a self reported questionnaire. Exploratory and confirmatory factor analysis were used to test construct validity. Convergence validity was identified by correlation with communication competency. Item convergent and discriminant validity were also analyzed. Reliability was evaluated internal consistency and test-retest reliability. Results: The results of exploratory factor analysis showed that the eigen values ranged from 1.34 to 5.86 and 73.2% of the total explained variance. Confirmatory factor analysis showed adequate model fit indices (χ²/df 1.89, RMSEA .07, GFI .89, CFI .95, and TLI .93) and standardized factor loadings (.48 to .87). The average extracted variances (.71 to .79) and composite reliability (.80 to .87) validated convergence and discriminant validity of the items. Test-retest reliability of intra-class correlation coefficient was .90 and the Cronbach's alpha coefficient was .88. Conclusion: The K-WLEIS is an appropriate scale for measuring the emotional intelligence of Korean nursing students. Therefore, it is expected that the K-WLEIS will be used for nursing education programs to improve nursing students' emotional intelligence.

• Earthquakes and Structures
• /
• 제14권6호
• /
• pp.537-549
• /
• 2018

Using vertical links in eccentric braced frames is one of the best passive structural control approaches due to its effectiveness and practicality advantages. However, in spite of the subject importance there are limited studies which evaluate the seismic reliability and response reduction factor (R-factor) in this system. Therefore, the present study has been conducted to improve the current understanding about failure mechanism in the structural systems equipped with vertical links. For this purpose, following definition of demand and capacity response reduction factors, these parameters are computed for three different buildings (4, 8 and 12 stories) equipped with this system. In this regards, pushover and incremental dynamic analysis have been employed, and seismic reliability as well as multi-level response reduction factor according to the seismic demand and capacity of the frames have been derived. Based on the results, this system demonstrates high ductility and seismic energy dissipation capacity, and using the response reduction factor as high as 8 also provides acceptable reliability for the frame in the moderate and high earthquake intensities. This system can be used in original buildings as lateral load resisting system in addition to seismic rehabilitation of the existing buildings.

• Geomechanics and Engineering
• /
• 재33권6호
• /
• pp.543-552
• /
• 2023

The design of foundations based on a deterministic approach may not be safe and reliable occasionally, since soils sometimes show considerable spatial variability, and thus, significant uncertainties in turn affect the estimation of footing bearing capacity. The design of footing on cohesionless stratums on the basis of reliability analysis has not received much attention. This paper performs two-dimensional random finite difference analyses of shallow strip footings on a spatially variable frictional soil considering correlation structure. Friction angle (ϕ) is considered as a log-normally distributed random variable and Monte Carlo Simulation is then performed to determine the statistical response based on the random fields. A new approach reliability-based safety factor is defined based on various reliability levels by considering the coefficient of variation of ϕ and correlation length in both the horizontal and vertical directions. The comparison of the probabilistic safety factor and the conventional one illustrates the limitations of the deterministic safety factor and provides insight into how the heterogeneity of soils properties affects the required safety factor. Results show that the conventional safety factor of 3 can be conservative in some cases, especially for soil with low values of mean ϕ and COV_ϕ.

• International Journal of Reliability and Applications
• /
• 제10권1호
• /
• pp.43-57
• /
• 2009

In this article, we study the reliability equivalence factor of a series system. The failure rates of the system components are functions of time t. we study two cases of non-constat failure rates (i) weibull distribution (ii) linear increasing failure rate distribution. There are two methods are used to improve the given system. Two types of reliability equivalence factors are discussed. Numerical examples are presented to interpret how one can utilize the obtained results.

• 대한간호학회지
• /
• 제32권2호
• /
• pp.243-253
• /
• 2002

The purpose of this study was to develop Nurse's Suffering Experience Scale and to test the reliability and validity of the instrument. Method: The subjects used to verify the scale's reliability and validity were 220 nurses who were taking care of the end stage cancer patients, while working at university and general hospitals in Daegu and Kyungbuk province from April 20. to July 10, 2001. The data was analyzed by the SPSS/WIN 8.0 program. Results: A factor analysis was conducted, and items that had a factor loading more than .40, and an eigen value more than 1.0. were selected. The factor analysis classified a total of seven factors statistically, and it's communality was 44%. The explanation of factors based on the conceptual framework and item content are as follows: The first factor was expanding self consciousness, the second factor was forming empathy with family, the third factor was professional challenge, the fourth factor was change of values, the fifth factor was spiritual sublimation, the sixth factor was helplessness, and finally the seventh factor was rejection to death. Cronbach's coefficient to test reliability of the scale was .8665 for total of 44 items. The Scale for Nurse's Suffering Experience developed in the study was identified as a tool with a high degree of reliability and validity. Therefore this scale can be effectively utilized for the evaluation of the degree of nurse's suffering experience in clinical settings.