• Structural Engineering and Mechanics
• /
• v.15 no.6
• /
• pp.669-683
• /
• 2003

The stochastic optimal nonlinear control of coupled adjacent building structures is studied based on the stochastic dynamical programming principle and the stochastic averaging method. The coupled structures with control devices under random seismic excitation are first condensed to form a reduced-order structural model for the control analysis. The stochastic averaging method is applied to the reduced model to yield stochastic differential equations for structural modal energies as controlled diffusion processes. Then a dynamical programming equation for the energy processes is established based on the stochastic dynamical programming principle, and solved to determine the optimal nonlinear control law. The seismic response mitigation of the coupled structures is achieved through the structural energy control and the dimension of the optimal control problem is reduced. The seismic excitation spectrum is taken into account according to the stochastic dynamical programming principle. Finally, the nonlinear controlled structural response is predicted by using the stochastic averaging method and compared with the uncontrolled structural response to evaluate the control efficacy. Numerical results are given to demonstrate the response mitigation capabilities of the proposed stochastic optimal control method for coupled adjacent building structures.

• Journal of Digital Convergence
• /
• v.7 no.3
• /
• pp.123-135
• /
• 2009

The considerable progress of IT industry has changed the industrial structure and lifestyle of our society. One of the remarkable fields of IT industry is online game industry. It showed rapid growth for the past decade. But in recent years online game industry faced with the limit of its growth for a number of reasons. To overcome such situation, online game companies should improve functions of game and analyze their customer's needs for sustainable growth through increasing customer satisfaction and loyalty. The purpose of the study is to investigate and evaluate the factors of online game service quality and the relation of customer satisfaction and loyalty. SPSS 14.0 and AMOS 7.0 are used for experimental research. Through reliability and validity test, service quality factors influencing the customer satisfaction are appeared to be 5 latent variables(reliability, responsiveness, assurance, empathy, tangibles). In addition, by structural equation model and covariance structural model, the result showed that empathy is the most influenced factor to customer satisfaction and customer satisfaction has positive effect on customer loyalty. The results of this research have important implications for explaining an mechanism for service quality of online game, customer satisfaction and loyalty and they might provide operational guidelines to the online game service company.

• Structural Engineering and Mechanics
• /
• v.86 no.1
• /
• pp.49-68
• /
• 2023

This study investigates the static and dynamic structural analysis of symmetrical and asymmetrical coupled shear walls using the continuous and modified transfer matrix methods by idealizing the coupled shear wall as a three-field CTB-type replacement beam. The coupled shear wall is modeled as a continuous structure consisting of the parallel coupling of a Timoshenko beam in tension (with axial extensibility in the shear walls) and a shear beam (replacing the beam coupling effect between the shear walls). The variational method using the Hamilton principle is used to obtain the coupled differential equations and the boundary conditions associated with the model. Using the continuous method, closed-form analytical solutions to the differential equation for the coupled shear wall with uniform properties along the height are derived and a numerical solution using the modified transfer matrix is proposed to overcome the difficulty of coupled shear walls with non-uniform properties along height. The computational advantage of the modified transfer matrix method compared to the classical method is shown. The results of the numerical examples and the parametric analysis show that the proposed analytical and numerical model and method is accurate, reliable and involves reduced processing time for generalized static and dynamic structural analysis of coupled shear walls at a preliminary stage and can used as a verification method in the final stage of the project.

• Korean Journal of Social Welfare Studies
• /
• v.42 no.1
• /
• pp.279-304
• /
• 2011

The housing is basic need to human life, foundation of family life and structural characteristics to control human life and action. The structural characteristics of housing have various effects on the family life such as family lifestyle, relationship of family members and child development and health by family structure. The purpose of the study is to identify how the housing poverty, defined as sub-minimum standard housing conditions, excess housing expenditure and housing instability, affects the family responsibility burden, the family relationship satisfaction and the family life satisfaction. This study used the third Korean Welfare Panel Study, the analytic method used was the Structural Equation Modeling(SEM), and the model fit had a considerable validity by inspecting the SEM. The findings of the study are as follows. Housing poverty had significant positive effect on family responsibility burden, while had significant negative effects on family conflict action method, family relationship satisfaction, family life satisfaction and health(subjective, mental, physical). The indirect effects on housing poverty had better effect by family conflict action method than effect by health, but the direct effects had the most.

• Structural Engineering and Mechanics
• /
• v.65 no.5
• /
• pp.547-556
• /
• 2018

Based on the shaking table tests of a 1:3.52 scale one-bay and one-story ancient wooden structure, a simplified structural mechanics model was established, and the structural state equation and observation equation were deduced. Under the action of seismic waves, the damage rule of initial stiffness and yield stiffness of the joint was obtained. The force hammer percussion test and finite element calculations were carried out, and the structural response was obtained. Considering the 5% noise disturbance in the laboratory environment, the stiffness parameters of the mortise-tenon joint were identified by the partial least squares of singular value decomposition (PLS-SVD) and the Extended Kalman filter (EKF) method. The results show that dynamic and static cohesion method, PLS-SVD, and EKF method can be used to identify the damage degree of structures, and the stiffness of the mortise-tenon joints under strong earthquakes is reduced step by step. Using the proposed model, the identified error of the initial stiffness is about 0.58%-1.28%, and the error of the yield stiffness is about 0.44%-1.21%. This method has high accuracy and good applicability for identifying the initial stiffness and yield stiffness of the joints. The identification method and research results can provide a reference for monitoring and evaluating actual engineering structures.

• Structural Engineering and Mechanics
• /
• v.74 no.1
• /
• pp.1-18
• /
• 2020

For the large deformation of shear walls under vertical and horizontal loads, there are difficulties in obtaining accurate simulation results using the response analysis method, even with fine mesh elements. Furthermore, concrete material nonlinearity, stiffness degradation, concrete cracking and crushing, and steel bar damage may occur during the large deformation of reinforced concrete (RC) shear walls. Matrix operations that are involved in nonlinear analysis using the traditional finite-element method (FEM) may also result in flaws, and may thus lead to serious errors. To solve these problems, a planar four-node element was developed based on vector mechanics. Owing to particle-based formulation along the path element, the method does not require repeated constructions of a global stiffness matrix for the nonlinear behavior of the structure. The nonlinear concrete constitutive model and bilinear steel material model are integrated with the developed element, to ensure that large deformation and damage behavior can be addressed. For verification, simulation analyses were performed to obtain experimental results on an RC shear wall subjected to a monotonically increasing lateral load with a constant vertical load. To appropriately evaluate the parameters, investigations were conducted on the loading speed, meshing dimension, and the damping factor, because vector mechanics is based on the equation of motion. The static problem was then verified to obtain a stable solution by employing a balanced equation of motion. Using the parameters obtained, the simulated pushover response, including the bearing capacity, deformation ability, curvature development, and energy dissipation, were found to be in accordance with the experimental observation. This study demonstrated the potential of the developed planar element for simulating the entire process of large deformation and damage behavior in RC shear walls.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.20 no.2
• /
• pp.190-199
• /
• 2019

This study was conducted to expand the distribution of new technology efficiently by analyzing the structure relationship based on the innovation resistance model and partial least square structural equation model (PLS-SEM). This study selected innovative propensity, relative advantage, compatibility, complexity, trialability, risk, and extension service consisting of educational, technical, and funding services as factors affecting innovation resistance. This study constructed a questionnaire that measured 11 factors including acceptance intention of new technology using 33 indicators. Data was from April to October, 2017, targeting 180 farmers who did not join in projects to spread new technologies of the Rural Development Administration. Results showed the factors positively and significantly affecting innovation resistance include complexity and risk. Innovative propensity did not have any effect on innovation resistance. However, it positively affected acceptance intention of new technology. The service of the extension organizations had a negative effect on innovation resistance, but did not affect acceptance intention of new technology. This study suggests that extension services should promote activities such as education, consulting, publicity and pilot projects related with new technologies in order to minimize the antipathy toward new agricultural technologies.

• Structural Engineering and Mechanics
• /
• v.76 no.1
• /
• pp.141-151
• /
• 2020

This manuscript tends to investigate influences of nanoscale and surface energy on a static bending and free vibration of piezoelectric perforated nanobeam structural element, for the first time. Nonlocal differential elasticity theory of Eringen is manipulated to depict the long-range atoms interactions, by imposing length scale parameter. Surface energy dominated in nanoscale structure, is included in the proposed model by using Gurtin-Murdoch model. The coupling effect between nonlocal elasticity and surface energy is included in the proposed model. Constitutive and governing equations of nonlocal-surface perforated Euler-Bernoulli nanobeam are derived by Hamilton's principle. The distribution of electric potential for the piezoelectric nanobeam model is assumed to vary as a combination of a cosine and linear variation, which satisfies the Maxwell's equation. The proposed model is solved numerically by using the finite-element method (FEM). The present model is validated by comparing the obtained results with previously published works. The detailed parametric study is presented to examine effects of the number of holes, perforation size, nonlocal parameter, surface energy, boundary conditions, and external electric voltage on the electro-mechanical behaviors of piezoelectric perforated nanobeams. It is found that the effect of surface stresses becomes more significant as the thickness decreases in the range of nanometers. The effect of number of holes becomes significant in the region 0.2 ≤ α ≤ 0.8. The current model can be used in design of perforated nano-electro-mechanical systems (PNEMS).

• Korean Journal of Child Studies
• /
• v.34 no.1
• /
• pp.87-102
• /
• 2013

This study examined the effects of paternal participation in child care and social support on planning for a second childbirth, focusing on the mediating effect of the mother's parenting stress. The 887 subjects studied in this paper were mothers who have a first child, and were selected from a sample of the 2nd Panel Study of Korean Children(PSKC) by the Korea Institute of Child Care and Education(KICCE), conducted in 2009. Data was analyzed using a Structural Equation Model(SEM) to identify a structure and relationships among factors. The significance of indirect effects to test the mediating effect of maternal parenting stress was identified via bootstrapping. Results indicated that maternal parenting stress partially mediated the relationship between the father's participation in child care and planning for a second childbirth, and absolutely mediated the relationship between social support and planning for a second childbirth. The findings reveal the importance of reducing parenting stress, given its substantial impact on planning for a second childbirth.

• Korean journal of food and cookery science
• /
• v.22 no.2 s.92
• /
• pp.213-221
• /
• 2006

Although motivation and information search have both been studied continuously and separately as important marketing strategies, the relation between cause and effect has received little research attention. Therefore the objective of this study was to research the causal relationships between motivation and information search method. Frequency analysis and reliability analysis, factor analysis, and SEM(Structure Equation Model) were adopted to analyze the data. Motivation was divided into 5 factors which significantly influenced information search method. Factor 1, 'Reception and congratulation', influenced information search positively through 'newspaper, magazine', and 'word of mouth' but negatively through 'TV-advertising' and 'Flyer, Press copy'. Factor 2, 'Change of dietary life', influenced positively 'TV-advertising'. Factor 3, 'Economic saving', influenced positively 'newspaper, magazine', and 'the e-mail's advertising' Factor 4, 'Preference motivation', influenced negatively 'word of mouth' Factor 5, 'Advertisement and companion's need', influenced positively 'newspaper, magazine', and 'the e-mail's advertising' but negatively 'TV-advertising' As a result, customers appeared to choose various information search methods according to their eating-out motivation. 'The e-mail's advertising', and 'word of mouth' are popular among customers' information search methods. Therefore, food-service corporations need to try eliminating negative images of various advertisements and activate positive word of mouth marketing, promotion through internet.