• Geomechanics and Engineering
• /
• v.6 no.2
• /
• pp.99-115
• /
• 2014

Uncertainties in design variables and design equations have a significant impact on the safety of geotechnical structures like retaining walls and slopes. This paper presents a possible framework for obtaining the partial safety factors based on reliability approach for different random variables affecting the stability of a reinforced concrete cantilever retaining wall and a slope under static loading conditions. Reliability analysis is carried out by Mean First Order Second Moment Method, Point Estimate Method, Monte Carlo Simulation and Response Surface Methodology. A target reliability index ${\beta}$ = 3 is set and partial safety factors for each random variable are calculated based on different coefficient of variations of the random variables. The study shows that although deterministic analysis reveals a safety factor greater than 1.5 which is considered to be safe in conventional approach, reliability analysis indicates quite high failure probability due to variation of soil properties. The results also reveal that a higher factor of safety is required for internal friction angle ${\varphi}$, while almost negligible values of safety factors are required for soil unit weight ${\gamma}$ in case of cantilever retaining wall and soil unit weight ${\gamma}$ and cohesion c in case of slope. Importance of partial safety factors is shown by analyzing two simple geotechnical structures. However, it can be applied for any complex system to achieve economization.

• Journal of Fisheries and Marine Sciences Education
• /
• v.27 no.5
• /
• pp.1436-1446
• /
• 2015

This study aims to understand how scuba diving instructors' expertise, instructor reliability and instruction efficiency are related to each other. In order to achieve the research goal, the study used a multi-stage stratified cluster sampling method and collected valid samples from 400 individuals at age of 20 and older who were scuba diving in scuba diving clubs in Busan, Gyeongnam, Gyeongbuk, Jeonnam and Jeonbuk. The 400 valid samples were applied to the data analysis. The study used SPSS 21.0 for processing the gathered data via a frequency analysis, a reliability analysis and a correlation analysis and in order to verify the hypotheses, the study applied AMOS 21.0 and conducted a confirmatory factor analysis and a structure equation model analysis. Findings that the study had extracted are summarized as follows. First, the study confirmed that the scuba diving instructors' expertise has a positive effect on the instructor reliability. Second, the scuba diving instructors' expertise was reported to positively influence the instruction efficiency. Third, the results revealed that the scuba diving club members' reliability in the instructors has a positive influence on the instruction efficiency.

• International Journal of Advanced Culture Technology
• /
• v.11 no.4
• /
• pp.244-254
• /
• 2023

The purpose of the study is to determine the relationship between leisure sports activities among the elderly, wellness awareness, perceived freedom, and subjective well-being. In order to achieve the purpose of this study, the study subjects were selected as the population aged 65 or older who lived in the Gwangju Metropolitan City area in 2022 and engaged in leisure sports activities. As for the sampling method, samples were extracted using cluster random sampling. A total of 300 people, 150 male and 150 female, were sampled. The survey tool was modified and supplemented according to this study based on the questionnaire that had been verified for reliability and validity in previous studies, and all questionnaire items were composed of a 5-point scale. The statistical analysis used for data analysis was frequency analysis, exploratory factor analysis, reliability analysis, and multiple regression analysis using SPSS Windows 21.0 Version. First, it was found that the wellness perception of the elderly partially affects the perceived sense of freedom. Second, it was found that the wellness perception of the elderly partially affects psychological happiness. Third, the elderly's perceived sense of freedom was found to affect their subjective well-being. Considering these research results, in order to effectively improve the quality of life in old age, it is important to promote physical, mental, emotional, and social relationships through nature-friendly sports activities to improve subjective life motivation, satisfaction, and happiness. It can be said that it increases the sense of well-being.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2004.05a
• /
• pp.35-38
• /
• 2004

In general, tube drawing process is composed of two steps, so called first drawing and second drawing. Drawing cracks are mainly occurred during the 2nd drawing process due to the improper drawing process. In order to analyze the reduction distribution in successive two-step drawing process, tube drawing process was simulated by finite element method. From the finite element analysis, the balance between first and second reduction is proved to be important factor to prevent drawing cracks. Hence the numerical expression was developed for tube drawing process to distribute even strain and criteria curves that can predict the safe drawing region were also proposed using this numerical formula.

• Wind and Structures
• /
• v.1 no.4
• /
• pp.287-302
• /
• 1998

This paper formulates a probabilistic model which is able to represent the maximum instantaneous wind velocity. Unlike the classical methods, where the randomness is circumscribed within the mean maximum component, this model relies also on the randomness of the maximum value of the turbulent fluctuation. The application of the FOSM method furnishes the first and second statistical moments in closed form. The comparison between the results herein obtained and those supplied by classical methods points out the central role of the turbulence intensity. Its importance is exalted when extending the analysis from the wind velocity to the wind pressure.

• Journal of Korean Neurosurgical Society
• /
• v.64 no.1
• /
• pp.125-135
• /
• 2021

Objective : This study aimed to validate the Korean version of the Repeatable Battery for the Assessment of Neuropsychological Status Update (K-RBANS). Methods : We performed a retrospective analysis of 283 psychiatric and neurosurgery patients. To investigate the convergent validity of the K-RBANS, correlation analyses were performed for other intelligence and neuropsychological test results. Confirmatory factor analysis was used to test a series of alternative plausible models of the K-RBANS. To analyze the various capabilities of the K-RBANS, we compared the area under the receiver operating characteristic (ROC) curves (AUC). Results : Significant correlations were observed, confirming the convergent validity of the K-RBANS among the Total Scale Index (TSI) and indices of the K-RBANS and indices of intelligence (r=0.47-0.81; p<0.001) and other neuropsychological tests at moderate and above significance (r=0.41-0.63; p<0.001). Additionally, the results testing the construct validity of the K-RBANS showed that the second-order factor structure model (model 2, similar to an original factor structure of RBANS), which includes a first-order factor comprising five index scores (immediate memory, visuospatial capacity, language, attention, delayed memory) and one higher-order factor (TSI), was statistically acceptable. The comparative fit index (CFI) (CFI, 0.949) values and the goodness of fit index (GFI) (GFI, 0.942) values higher than 0.90 indicated an excellent fit. The root mean squared error of approximation (RMSEA) (RMSEA, 0.082) was considered an acceptable fit. Additionally, the factor structure of model 2 was found to be better and more valid than the other model in χ2 values (Δχ2=7.69, p<0.05). In the ROC analysis, the AUCs of the TSI and five indices were 0.716-0.837, and the AUC of TSI (AUC, 0.837; 95% confidence interval, 0.760-0.896) was higher than the AUCs of the other indices. The sensitivity and specificity of TSI were 77.66% and 78.12%, respectively. Conclusion : The overall results of this study suggest that the K-RBANS may be used as a valid tool for the brief screening of neuropsychological patients in Korea.

• Journal of the Korea Society of Computer and Information
• /
• v.24 no.4
• /
• pp.83-90
• /
• 2019

Is this paper, We propose to examined the relationship between advertising attributes and brand preference, consumer psychological repulsion, and consumer happiness. Due to the infinite competition between the companies, they are experiencing significant difficulties in operation. In this situation, effective advertising is obviously a very important means to overcome the difficulties of operation. Therefore, in order to maximize the advertising effect, sufficient awareness of the advertisement property and the production and exposure of the advertisement based on it can be very important. As such, the purpose of this study is to verify the effect of indirect advertising appearing on entertainment programs on consumers' preference for brands and their psychological resistance, and to verify the effect of consumers' preference for brands and psychological backlash on consumer happiness. In addition, the exposure pattern of indirect advertisement is intended to verify whether there is a control effect between the nature of the advertisement and the brand preference and psychological backlash. A total of 209 questionnaires were distributed to consumers who viewed program in order to achieve the purpose of this study. For empirical analysis, exploratory factor analysis, confirmatory factor analysis, frequency analysis, reliability analysis, structural equation model, and multimodal simultaneous comparison analysis were performed using SPSS V. 22.0 and AMOS V. 22.0. The results of the empirical analysis of this study are as follows. First, advertising attributes have a significant effect on brand preference. Second, the hypothesis that advertising attributes have a significant effect on psychological repulsiveness of consumers is partially adopted. Third, brand preference and psychological repulsion have a significant effect on consumer happiness. Fourth, we confirmed the moderating effect of PPL expression form in ad property, brand preference, and psychological repulsion. Based on these findings, we presented the implications, limitations and future research directions of the study.

• International Journal of Human Ecology
• /
• v.4 no.2
• /
• pp.77-87
• /
• 2003

This paper tried to construct statistical and econometric models on the basis of economic theory in order to discuss the issue of statistical efficiency and unbiasedness including the sample selection bias correcting problem. Comparative analytical tool were one stage Tobit of Maximum Likelihood estimation and Heckman's two-step Tobit of Ordinary Least Squares. The results showed that the adequacy of model for the analysis on demand and choice, we believe that there is no big difference in explanatory variables between the first selection model and the second linear probability model. Since the Lambda, the self- selectivity correction factor, in the Type II Tobit is not statistically significant, there is no self-selectivity in the Type II Tobit model, indicating that Type I Tobit model would give us better explanation in the demand for and choice which is less complicated statistical method rather than type II model.

• Proceedings of the Korean Geotechical Society Conference
• /
• 1999.10a
• /
• pp.147-152
• /
• 1999

Distribution of fracture system is an important factor to analyse instability of jointed rock slope. In the most case of rock slopes, joint distribution properties are related to potential, shape, size and locality of slope failure. The purpose of this paper is to present an application of fracture characterization related to rock slope failure. Fracture data used in this study are collected by scanline survey. Two aspects of fracture characterization for rock slope are handled in this study First, In order to determine the potential and shape of slope failure, trace length of joints is considered as the weighting factor about collected orientation data. Second, Relationship between trace length and spacing is analysed to estimate failure location and size. The distribution of fracture system is directly influenced on wedge failure. It is effective to analyse the orientation of fractures by using weighting factors associated with the trace length of fractures rather than to analyse only that of fractures. It gives a conclusion that the wedge failure occurred along the peak of fracture density(or intensity) cycles.

• Journal of The Korean Association of Information Education
• /
• v.12 no.1
• /
• pp.109-120
• /
• 2008

The purpose of this study is to develop a test and verifying the validity and reliability for measuring a effectiveness of e-earning course in cyber university. Twenty-five items were developed based on literature review and were examined by experts in the field. For item analysis, EFA(Exploratory Factor Analysis) was performed with 768 students in first study. In order to validate the test, CFA(Confirmatory Factor Analysis) was conducted with 791 students in second study. The result of the study yielded five factors with 25 items: 1) contents and design, 2) instructor, 3) system, 4) evaluation, and 5) overall course satisfaction. And this research reports the reliability and validity of new test.