• 가정과삶의질연구
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• 제30권3호
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• pp.69-82
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• 2012

The purpose of this study was to investigate the degree of sexual behavior. In particular, this study focused on the self-esteem, internet pornography addiction, and relationship satisfaction of freshmen as important predictors of sexual behavior and examined the dynamics of the relationships among the variables. The participants in this research were 1,806 university freshmen: 932 males and 828 females. All respondents submitted their answers on a self-report questionnaire. The data were analyzed with descriptive statistics and Pearson's correlations that used PASW 18.0, and AMOS 18.0, a statistical program for structural equation modeling(SEM), to estimate the hypothesized structural equation model. The major results of this study were as follows: (1) Relationship satisfactions mediated the relationships among self-esteem, internet pornography addiction, and sexual behavior. (2) Sexual behavior between male and female freshmen showed different influences on the test of the structural model invariance across the groups.

• Structural Engineering and Mechanics
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• 제67권6호
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• pp.565-578
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• 2018

This research article reported the nonlinear finite solutions of the nonlinear flexural strength and stress behaviour of nano sandwich graded structural shell panel under the combined thermomechanical loading. The nanotube sandwich structural model is derived mathematically using the higher-order displacement polynomial including the full geometrical nonlinear strain-displacement equations via Green-Lagrange relations. The face sheets of the sandwich panel are assumed to be carbon nanotube-reinforced polymer composite with temperature dependent material properties. Additionally, the numerical model included different types of nanotube distribution patterns for the sandwich face sheets for the sake of variable strength. The required equilibrium equation of the graded carbon nanotube sandwich structural panel is derived by minimizing the total potential energy expression. The energy expression is further solved to obtain the deflection values (linear and nonlinear) via the direct iterative method in conjunction with finite element steps. A computer code is prepared (MATLAB environment) based on the current higher-order nonlinear model for the numerical analysis purpose. The stability of the numerical solution and the validity are verified by comparing the published deflection and stress values. Finally, the nonlinear model is utilized to explore the deflection and the stresses of the nanotube-reinforced (volume fraction and distribution patterns of carbon nanotube) sandwich structure (different core to face thickness ratios) for the variable type of structural parameter (thickness ratio, aspect ratio, geometrical configurations, constraints at the edges and curvature ratio) and unlike temperature loading.

• 응용통계연구
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• 제30권6호
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• pp.827-849
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• 2017

미국의 복지제도의 사회복지정책에서 종종 사용되는 자활(self-sufficiency; SS)은 사회복지학 분야에서 중요한 개념이며 많은 연구가 있어왔다. 이러한 연구들 중에는 심리적 자활(phycological SS; PSS)를 구성하는 자립 의지 척도(employment hope scale; EHS)와 인지된 고용 장벽 척도(perceived employment barrier scale, PEBS)가 미국의 저소득 구직자들의 경제적 자활(economic self-sufficiency; ESS)에 어떻게 영향을 미치는지에 대한 연구도 있다. 이러한 연구는 일반적으로 설문조사 자료를 이용하여 수행되며, 사회과학분야에서 설문조사 자료는 주로 구조방정식모형(structural equation model; SEM)으로 분석된다. 설문조사 자료에서는 일반적으로 측정변수의 개수가 많고 변수들 간에 상관관계가 있는 경우가 대부분이다. 이러한 경우 주성분 분석(principal component analysis; PCA)을 사용할 수 있다. 본 연구의 목적은 사회과학 분야에서 주로 다루는 설문조사 자료를 SEM과 PCA를 사용하여 분석하였을 경우 그 결과를 비교하는 것이다. 우리는 두 가지 분석 방법의 성능을 모의실험을 통하여 비교하였다. 우리는 또한 PSS와 ESS에 대한 실제 설문조사 자료를 이 두 가지 분석 방법으로 분석하고 그 결과를 비교하였다.

• Structural Engineering and Mechanics
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• 제5권6호
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• pp.679-689
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• 1997

The damage of concrete subjected to multiaxial complex loading involves strong anisotropy due to its highly heterogeneous nature and the geometrically anisotropic characteristic of the microcracks. A comprehensive description of concrete damage is proposed by introducing a fourth-order anisotropic damage tenser. The evolution of damage is assumed to be related to the principal components of the current states of stress and damage. The unilateral effect of damage due to the closure and opening of microcracks is taken into account by introducing projection tensors that are also determined by the current state of stress. The proposed damage model considers the different kinds of damage mechanisms that result in different failure modes and different patterns of microdefects that cause different unilateral effects. This damage model is embedded in a thermomechanically consistent constitutive equation in which hardening and the triaxial compression caused shear-enhanced compaction can also be taken into account. The validity of the proposed model is verified by comparing theoretical and experimental results of plain and steel fiber reinforced concrete subjected to complex triaxial stress histories.

• Structural Engineering and Mechanics
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• 제63권2호
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• pp.251-257
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• 2017

A local damage identification method using measured structural static displacement is proposed in this study. Based on the residual force vector deduced from the static equilibrium equation, residual strain energy (RSE) is introduced, which can localize the damage in the element level. In the case of all the nodal displacements are used, the RSE can localize the true location of damage, while incomplete displacement measurements are used, some suspicious damaged elements can be found. A model updating method based on static displacement response sensitivity analysis is further utilized for accurate identification of damage location and extent. The proposed method is verified by two numerical examples. The results indicate that the proposed method is efficient for damage identification. The advantage of the proposed method is that only limited static displacement measurements are needed in the identification, thus it is easy for engineering application.

• 아동학회지
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• 제33권1호
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• pp.81-92
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• 2012

The main purpose of this study was to analysis of the structural relationship between early adolescents' social relationships, self esteem, life satisfaction, and school adjustment. Data harvested from the Korean Youth Panel Survey 2010 was analyzed by means of Structural Equation Modeling (SEM). The results indicate that the model is appropriate in terms of goodness of fit and significant path based on the validation procedure. According to the model, the social relationships have some degree of influence upon self esteem which then goes on to have a subsequent effect on life satisfaction; which in turn have a further influence on school adjustment. Social relationships also have a direct influence on life satisfaction, school adjustment, and self esteem has a direct influence on school adjustment. The paper concludes with an outline of the implications of the present study for future studies on this subject.

• Structural Engineering and Mechanics
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• 제18권6호
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• pp.709-729
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• 2004

This paper presents numerical and experimental investigations on damage detection of mono-coupled multistory buildings using natural frequency as only diagnostic parameter. Frequency equation of a mono-coupled multistory building is first derived using the transfer matrix method. Closed-form sensitivity equation is established to relate the relative change in the stiffness of each story to the relative changes in the natural frequencies of the building. Damage detection is then performed using the sensitivity equation with its special features and minimizing the norm of an objective function with an inequality constraint. Numerical and experimental investigations are finally conducted on a mono-coupled 3-story building model as an application of the proposed algorithm, in which the influence of modeling error on the degree of accuracy of damage detection is discussed. A mono-coupled 10-story building is further used to examine the capability of the proposed algorithm against measurement noise and incomplete measured natural frequencies. The results obtained demonstrate that changes in story stiffness can be satisfactorily detected, located, and quantified if all sensitive natural frequencies to damaged stories are available. The proposed damage detection algorithm is not sensitive to measurement noise and modeling error.

• Structural Engineering and Mechanics
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• 제83권6호
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• pp.729-744
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• 2022

In this paper, an analytical formulation is proposed to predict the vertical vibration response due to the pedestrian walking on a footbridge considering the human-structure interaction, where the footbridge and pedestrian are represented by the Euler beam and linear oscillator model, respectively. The derived coupled equation of motion is a nonlinear fourth-order partial differential equation. An uncoupled solution strategy based on the combined weighted residual and perturbation method) is proposed to reduce the tedious computation, which allows the separate integration between the bridge and pedestrian subsystems. The theoretical study demonstrates that the pedestrian subsystem can be treated as a structural system with added mass, damping, and stiffness. The analysis procedure is then applied to a case study under the conditions of single pedestrian and multi pedestrians, and the results are validated and compared numerically. For convenient vibration design of a footbridge, the simplified peak acceleration formula and the idea of decoupling problem are thus proposed.

• 대한토목학회논문집
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• 제33권6호
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• pp.2483-2491
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• 2013

교통사고를 감소시키고 안전성을 향상시키기 위해, 사고에 영향을 미치는 요인들을 분석하여 교통사고를 예측하는 모형은 지속적으로 개발되어 왔다. 교통사고 감소와 사고 사망자 감소에 대한 문제는 선진국과 후진국 모두 중요한 문제로서, 우리나라에서는 매해 교통사고 감소를 위한 정책 및 방안을 제시하고 있다. 주 5일제 시행과 여가활동에 대한 관심의 증가로 주중과 주말의 통행패턴은 다른 형태를 지니고 있으며, 교통사고의 특성도 마찬가지로 다르게 나타난다. 본 연구에서는 주중과 주말의 사고 심각도에 미치는 요인이 다름에 대하여 분석하였으며, 이는 고속도로에서 발생한 5년 동안의 사고자료를 구조방정식 모형을 이용하여 분석하였다. 모형의 추정결과 주중 사고 심각도 모형은 도로 요인이 사고 심각도에 가장 큰 영향을 미치는 것으로 나타났으며, 주말 사고 심각도 모형은 운전자 요인이 사고 심각도에 가장 큰 영향을 미치는 것으로 나타나 주중과 주말 사고의 원인 차이를 나타냈다.

• 한국인터넷방송통신학회논문지
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• 제20권2호
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• pp.289-297
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• 2020

본 연구의 목적은 대학생의 혁신성향이 융합학문에 수용의도에 영향을 미치는 효과를 검증하는 데 있다. 이를 위해 기술수용모형에 기초하여 대학생의 개인적 혁신성, 사회적 기대, 지각된 유용성, 융합학문 수용의도를 변인으로 한 구조방정식모델을 설계하고 LISREL을 사용하여 이를 분석하였다. 연구 결과는 다음과 같다. 첫째, 개인적 혁신성은 융합학문 수용의도에 직접적인 양(+)의 예측요인이며, 지각된 유용성을 매개로 한 간접적인 요인임을 확인하였다. 둘째, 사회적 기대 요인은 지각된 유용성을 매개로 융합학문 수용의도에 간접적인 영향을 미치는 것으로 나타났다. 제안된 연구모형은 적합도에서 χ²의 값이 22.638(d.f=29, p=.793)로 나타나 통계적으로 수용할 만한 결과를 보였다. 연구 결과를 토대로 대학생의 혁신성과 융합학문의 유용성을 경험할 수 있도록 다양한 교과 및 비교과 프로그램 개발의 필요성을 제안하였다. 특히 교양 교과의 역할과 위상의 변화가 요구됨을 제안하였다.