• Structural Engineering and Mechanics
• /
• 제66권4호
• /
• pp.423-438
• /
• 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.

• 대한토목학회논문집
• /
• 제34권6호
• /
• pp.1807-1814
• /
• 2014

자연재해는 발생 자체를 막는데 한계가 있기 때문에 피해저감을 위해서는 예방사업을 통해 재해발생을 사전에 예방하는 것이 중요하다. 자연재해발생의 증가와 함께 자연재해와 관련된 예방사업에 대한 관심이 높아지고 있으며, 이와 관련된 투자도 증가하고 있다. 이와 함께 자연재해예방사업에 대한 투자 시, 그 파급효과 등을 검증할 수 있는 평가 역시 중요한 과제로 대두되고 있다. 자연재해예방사업과 같은 국가 공공투자사업을 평가하기 위해서 비용편익분석과 같은 정량적 분석을 통한 연구는 지속적으로 수행되고 있다. 정량적 분석방법만으로 사업의 효과를 충분히 설명하지 못한다는 문제점에도 불구하고 재해관련 분야에서 효과분석이나 평가를 위한 다양한 방법이 제시되지 못하고 있는 것이다. 본 연구에서는 정성적 분석을 통한 자연재해예방사업의 사후평가를 위해서 자연재해예방사업의 사후평가에 영향을 미치는 항목들을 도출하고, 구조방정식모델(SEM : structural equation modeling)을 통해 사후 평가항목과 사업효과 간 인과관계 분석 및 가중치를 산정하였다. 이를 바탕으로 자연재해예방 사업에 대한 사후평가지수 산정식을 제시하였다.

• 정보관리학회지
• /
• 제21권2호
• /
• pp.23-44
• /
• 2004

본 연구의 목적은 사회심리학 이론을 토대로 지역정보 시스템 이용모형을 개발함으로써, 지역주민을 위한 정보통신 서비스의 이용을 효과적으로 설명하는데 있다. 본 연구를 위해 필자는 Ajzen의 계획적 행위 이론(Theory of Planned Behavior: TPB)을 기본모형으로 선택하였는데, 이 이론은 (1) 지역정보 서비스 이용 결과에 대한 기대, (2) 주변 사람들의 권유, (3) 이용을 가능하게 하는 내외적 요인에 대한 자신의 통제 능력의 지각 등을 기본 골격으로 한다. 계획적 행위 이론은 일반적인 사회행동의 설명에 적용되어온 사회심리 이론이므로 필자는 지역정보 시스템 이용의 행동적 특성을 연구 모형에 반영하기 위하여 두 이론 즉, 인터넷 등 매체 이용을 설명하기 위하여 널리 적용되어온 이용과 충족 이론(Uses and gratifications)과 경영정보시스템 이용을 설명하기 위하여 적용되어 온 기술수용모형(Technology Acceptance Model: TAM)을 추가적으로 검토했다. 417명의 지역정보망 시스템 이용자로 부터 수집된 실증자료를 토대로 구조방정식모형(Structural Equation Model: SEM)을 이용하여 제안된 지역정보 시스템 이용모형을 검증한 후 향상된 수정 모형을 제안했다. 그 결과, 지역정보 시스템 이용에 영향을 미치는 주요 요인들로 지역정보를 이용하고자하는 의도, 태도, 주관적 규범, 정보습득에 대한 기대, 사회적 상호작용에 대한 기대, 지역 연계에 대한 기대, 및 개인관련 규범 신념 등을 밝혀 냈다. 이러한 결과를 중심으로 본 연구의 함의와 후속 연구과제가 결론에서 논의되었다.

• Structural Engineering and Mechanics
• /
• 제74권1호
• /
• pp.55-67
• /
• 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
• /
• 제7권2호
• /
• pp.225-240
• /
• 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
• /
• 제5권1호
• /
• pp.42-54
• /
• 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.

• 한국농공학회논문집
• /
• 제63권1호
• /
• pp.49-60
• /
• 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.

• 한국의류학회지
• /
• 제40권1호
• /
• pp.131-147
• /
• 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
• /
• 제84권2호
• /
• pp.207-224
• /
• 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.

• 한국경영과학회지
• /
• 제29권3호
• /
• pp.23-39
• /
• 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.