• Structural Engineering and Mechanics
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• v.66 no.4
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• pp.423-438
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• 2018

This pioneer study focuses on finite element modeling and numerical modeling of three types of Reinforced Concrete Haunched Beams (RCHBs). Firstly, twenty RCHBs, consisting of three types, and four prismatic beams which had been tested experimentally were modeled via a nonlinear finite element method (NFEM) based software named as, ATENA. The modeling results were compared with experimental results including load capacity, deflection, crack pattern and mode of failure. The comparison showed a good agreement between the results and thus the model used can be effectively used for further studies of RCHB with high accuracy. Afterwards, new mechanism modes and design code equations were proposed to improve the shear design equation of ACI-318 and to predict the critical effective depth. These equations are the first comprehensive formulas in the literature involving all types of RCHBs. The statistical analysis showed the superiority of the proposed equation to their predecessors where the correlation coefficient, $R^2$ was found to be 0.89 for the proposed equation. Moreover, the new equation was validated using parametric and reliability analyses. The parametric analysis of both experimental and predicted results shows that the inclination angle and the compressive strength were the most influential parameters on the shear strength. The reliability analysis indicates that the accuracy of the new formulation is significantly higher as compared to available design equations and its reliability index is within acceptable limits.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.6
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• pp.1807-1814
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• 2014

Natural disaster has been hard to prevent the occurrence of itself, thus in order to reduce the economic damages and loss casualties, it is important to be prepared in cases that the disasters should occur in advance. Interest of the related project to prevent various natural disasters has been grown along with an investment in Korea. Along with this movement, when investments related to natural disaster prevention projects were built on, the post evaluation that can verify the ripple effects of those investments on the community should be emerging as an essential task. For evaluating the effects of public investment projects such as natural disaster prevention projects in this study, the related researches would continue through qualitative analyses, for example, cost-benefit analysis. Even the qualitative analysis alone cannot fully explain the effects of those projects, the diverse methods of analyzing and evaluating those effects might not have been presented in those fields. For the post evaluation of natural disaster prevention projects through the qualitative analysis, this study derived subjects that had effects on the post evaluation of natural disaster prevention projects. Also, employing the structural equation modeling (SEM), the causation between post evaluation subjects and the effects of projects were quantitatively analyzed, and the weighting factors of evaluation items were calculated respectively. Based on these results, post evaluation index formula was proposed for the natural disaster prevention projects in Korea.

• Journal of the Korean Society for information Management
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• v.21 no.2
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• pp.23-44
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• 2004

This study proposed a theoretical framework that could explain the service use of a community informatics. The proposed community informatics use model was developed based on three theoretical models: (1) Ajzen's Theory of Planned Behavior (TPB) from social psychology: (2) Uses and gratifications approaches from media use research; and (3) Technology Acceptance Model(TAM) from information technology use research. The proposed model consists of three basic components: expectations of the outcomes from use, approvals from important others, and perceivied controllability over using the service. The initially proposed model was assessed using structural equation modeling, and then re-sepcified in order to propose a better fitting model. The initially proposed and revised community informatics use models were discussed with their theoretical and practical implications.

• Structural Engineering and Mechanics
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• v.74 no.1
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• pp.55-67
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• 2020

The common practice to predict the characteristic structural load effects (LEs) in long reference periods is to employ the extreme value theory (EVT) for building limit distributions. However, most applications ignore that LEs are driven by multiple loading events and thus do not have the identical distribution, a prerequisite for EVT. In this study, we propose the composite extreme value modeling approach using clustering to (a) cluster initial blended samples into finite identical distributed subsamples using the finite mixture model, expectation-maximization algorithm, and the Akaike information criterion; (b) combine limit distributions of subsamples into a composite prediction equation using the generalized Pareto distribution based on a joint threshold. The proposed approach was validated both through numerical examples with known solutions and engineering applications of bridge traffic LEs on a long-span bridge. The results indicate that a joint threshold largely benefits the composite extreme value modeling, many appropriate tail approaching models can be used, and the equation form is simply the sum of the weighted models. In numerical examples, the proposed approach using clustering generated accurate extrema prediction of any reference period compared with the known solutions, whereas the common practice of employing EVT without clustering on the mixture data showed large deviations. Real-world bridge traffic LEs are driven by multi-events and present multipeak distributions, and the proposed approach is more capable of capturing the tendency of tailed LEs than the conventional approach. The proposed approach is expected to have wide applications to general problems such as samples that are driven by multiple events and that do not have the identical distribution.

• Structural Engineering and Mechanics
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• v.7 no.2
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• pp.225-240
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• 1999

This paper presents a mechanistic approach to uniaxial viscoelastic constitutive modeling of asphalt concrete that accounts for damage evolution under cyclic loading conditions. An elasticviscoelastic correspondence principle in terms of pseudo variables is applied to separately evaluate viscoelasticity and time-dependent damage growth in asphalt concrete. The time-dependent damage growth in asphalt concrete is modeled by using a damage parameter based on a generalization of microcrack growth law. Internal state variables that describe the hysteretic behavior of asphalt concrete are determined. A constitutive equation in terms of stress and pseudo strain is first established for controlled-strain mode and then transformed to a controlled-stress constitutive equation by simply replacing physical stress and pseudo strain with pseudo stress and physical strain. Tensile uniaxial fatigue tests are performed under the controlled-strain mode to determine model parameters. The constitutive equations in terms of pseudo strain and pseudo stress satisfactorily predict the constitutive behavior of asphalt concrete all the way up to failure under controlled-strain and -stress modes, respectively.

• Agribusiness and Information Management
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• v.5 no.1
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• pp.42-54
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• 2013

Information System (IS) Success Model proposed by DeLone and McLean is applied as a successful operation tool of information system, with its basic assumption of symmetric relationship between independent variables and dependent variables of the structural equation modeling. However, because previous studies have proved asymmetry of quality factors' influence structure on dependent variable by applying three-factor analysis, this study examined asymmetry of impact structure of quality factors introduced in IS Success Model on user satisfaction. Also the study applies structure equation modeling (SEM), three-factor analysis and importance and performance analysis (IPA) to develop resource allocation strategy for IS success. The study is able to provide IS practitioners with strategic implications for allocating and managing limited resources more effectively.

• Journal of The Korean Society of Agricultural Engineers
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• v.63 no.1
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• pp.49-60
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• 2021

This paper analyzes causal relationship between rural experience and settlement. Structural Equation Modeling is the combination of factor analysis and multiple regression analysis which can explain causal relation between factors. Rural perception factor has conceptualized positive sector (attitude, values) and negative sector (perceived risk, sentiment). Statistically significant causality results are as follows. People think about migration into rural when they have high level of attitude about rural but fear of rural life make avoid migration into rural. When people have fear of rural life, they also have bad feeling about rural infrastructure and facility. Attitude of rural, values of rural and low fear of rural life gives positive influence to satisfaction. Satisfaction gives positive influence to migration into rural.

• Journal of the Korean Society of Clothing and Textiles
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• v.40 no.1
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• pp.131-147
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• 2016

This study investigated the relationship between fashion behavior, impression management behavior, and career success. A conceptual model and hypotheses were established based on theoretical linkages between the constructs. Thereafter, empirical data were collected using a set of questionnaires. For this reason, the sample was taken from 720 office workers' who worked at 14's Korea Enterprise, 697 of which was used for an empirical analysis (sample: men over 30 years of age and more than three years continuous service). This study conducted an exploratory factor analysis and confirmatory factor analysis for the validity test. Cronbach's alpha test is used for the reliability test. Moreover, PLS structural equation modeling (SEM) was employed to test hypothesized relationships in the conceptual model (SPSS 20.0 window/Smart PLS 3.0). This study shows that the proposed model is reasonably fit to the actual data. The following results were obtained from the analyses. First, fashion behavior and impression management behavior is positively related to career success. The result shows that economics of the fashion behaviors sub-types were statistically more significant to influence career success. The self-focused of the impression management behavior sub-types were more than statistically significant to influence career success. This finding has great implications to understand self-management behavior and the career success of male office workers.

• Structural Engineering and Mechanics
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• v.84 no.2
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• pp.207-224
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• 2022

The mechanical behavior of prestressed concrete haunched beams (PSHBs) was investigated in depth using a finite element modeling technique in this study. The efficiency of finite element modeling was investigated in the first stage by taking into account a previous study from the literature. The first stage's findings suggested that finite element modeling might be preferable for modeling PSHBs. In the second stage of the research, a comprehensive parametric study was carried out to determine the effect of each parameter on PSHB load capacity, including haunch angle, prestress level, compressive strength, tensile reinforcement ratio, and shear span to depth ratio. PSHBs and prestressed concrete rectangular beams (PSRBs) were also compared in terms of capacity. Stochastic analysis was used in the third stage to define the uncertainty in PSHB capacity by taking into account uncertainty in geometric and material parameters. Standard deviation, coefficient of variation, and the most appropriate probability density function (PDF) were proposed as a result of the analysis to define the randomness of capacity of PSHBs. In the study's final section, a new equation was proposed for using symbolic regression to predict the load capacity of PSHBs and PSRBs. The equation's statistical results show that it can be used to calculate the capacity of PSHBs and PSRBs.

• Journal of the Korean Operations Research and Management Science Society
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• v.29 no.3
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• pp.23-39
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• 2004

This paper focused on empirically testing the ESM(Electronic-Store Success Model). The model was developed by basing upon the ‘Updated D&M(DeLone and McLean) IS Success Model(2003)’ and reflecting the characteristics of marketing and e-business, and composed of the six dimensions including system quality, information quality, service quality, trust, customer loyalty and financial performance. The research model consisting of five dimensions, excluding financial performance, was proposed and empirically verified by structural equation model with respect to data from 224 customers on 69 Electronic-Stores. The results show that system quality and information quality significantly influence service quality, and that service quality also significantly influence trust and customer loyalty, and that trust has significant influence on customer loyalty.