• Structural Engineering and Mechanics
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• 제64권4호
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• pp.461-472
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• 2017

The dynamic tests of recycled aggregate concrete (RAC) are carried out, the rate-dependent mechanical models of RAC are proposed. The dynamic mechanical behaviors of RAC frame structure are investigated by adopting the numerical simulation method of the finite element. It is indicated that the lateral stiffness and the hysteresis loops of RAC frame structure obtained from the numerical simulation agree well with the test results, more so for the numerical simulation which is considered the strain rate effect than for the numerical simulation with strain rate excluded. The natural vibration frequency and the lateral stiffness increase with the increase of the strain rate. The dynamic model of the lateral stiffness is proposed, which is reasonably applied to describe the effect of the strain rate on the lateral stiffness of RAC frame structure. The effect of the strain rate on the structural deformation and capacity of RAC is analyzed. The analyses show that the inter-story drift decreases with the increase of the strain rate. However, with the increasing strain rate, the structural capacity increases. The dynamic models of the base shear coefficient and the overturning moment of RAC frame structure are developed. The dynamic models are important and can be used to evaluate the strength deterioration of RAC structure under dynamic loading.

• 대한가정학회지
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• 제50권1호
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• pp.51-63
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• 2012

The purpose of this study was to investigate the effect of appearance management cognition on attitude toward appearance management and the effect of this attitude on appearance management behavior. It also examines how demographic factors affect these relationships. This study gave a questionnaire survey to adults between the ages of 40 and 50 in Seoul, Daegu, and Ulsan, South Korea. Data collected from 368 respondents were analyzed using descriptive statistics, t-test, factor analysis, and structural equation modeling. The study model was tested by structural equation modeling, the results of which revealed a positive effect of appearance management cognition on attitude toward appearance management and a positive effect of attitude toward appearance management on appearance management behavior. The results of t-testing showed that there were significant differences in cognition, attitude, and behavior toward appearance management by gender, age, educational level, and income.

• Structural Engineering and Mechanics
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• 제8권1호
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• pp.27-38
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• 1999

Cables are used in many applications such as cable-stayed bridges, suspension bridges, transmission lines, telephone lines, etc. Generally, the linear relationship is inadequate to present the behavior of cable structure. In finite element analysis, cables have always been modeled as truss elements. For these types of model, the nonlinear behavior of cables has been always ignored. In order to investigate the importance of the nonlinear effect on the structural system, the effect of cable stiffness has been studied. The nonlinear behavior of cable is due to its sag. Therefore, the cable pretension provides a large portion of the inherent stiffness. Since a cable-stayed bridge has numerous degrees of freedom, analytical methods at present are not convenient to solve this type of structures but numerical methods may be feasible. It is necessary to provide a different and more representative analytical model in order to present the effect of cable stiffness on cable-stayed bridges in numerical analysis. The characteristics of cable deformation have also been well addressed. A formulation of modified modulus of elasticity has been proposed using a numerical parametric study. In order to investigate realistic bridges, a cable-stayed bridge having the geometry similar to that of Quincy Bayview Bridge is considered. The numerical results indicate that the characteristics of the cable stiffness are strongly nonlinear. It also significantly affects the structural behaviors of cable-stayed bridge systems.

• Earthquakes and Structures
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• 제8권3호
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• pp.779-799
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• 2015

The slosh height and the possibility of water spill from rectangular Spent Fuel Storage Bays (SFSB) and Tray Loading Bays (TLB) of Nuclear power plant (NPP) are studied during 0.2 g, Safe Shutdown Earthquake (SSE) level of earthquake. The slosh height obtained through Computational Fluid dynamics (CFD) is compared the values given by TID-7024 (Housner 1963) and American concrete institute (ACI) seismic codes. An equivalent amplitude method is used to compute the slosh height through CFD. Numerically computed slosh height for first mode of vibration is found to be in agreement the codal values. The combined effect in longitudinal and lateral directions are studied separately, and found that the slosh height is increased by 24.3% and 38.9% along length and width directions respectively. There is no liquid spillage under SSE level of earthquake data in SFSB and TLB at convective level and at free surface acceleration data. Since seismic design codes do not have guidelines for combined excitations and effect of higher modes for irregular geometries, this CFD procedure can be opted for any geometries to study effect of higher modes and combined three directional excitations.

• Journal of Korean Biological Nursing Science
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• 제20권4호
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• pp.221-227
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• 2018

Purpose: This study aimed to evaluate the effect of illness perception on depression and quality of life in patients with hemodialysis. Methods: This is a cross-sectional study using structural equation modeling. Depression, quality of life and cognitive and emotional illness perceptions were measured by the Center for Epidemiologic Studies Depression-10 (CESD-10), Short Form-36 version 2 (SF-36v2), and Brief Illness Perception Questionnaire (BIPQ) in 272 hemodialysis patients. Results: Prevalence of depression was 76.1%, and higher in female patients on hemodialysis. Cognitive illness perception had effect on depression and quality of life, while emotional illness perception had effect only on depression. Quality of life was explained 69.6% through depression (${\beta}=-.74$, t= -8.17) and cognitive illness perceptions (${\beta}=.21$, t= 3.06), while depression was explained 40.5% through cognitive (${\beta}=-.34$, t= -5.99) and emotional (${\beta}=.59$, t= 9.37) illness perceptions. Conclusion: In the inevitable choice of dialysis, illness perception could decrease depression and improve quality of life in hemodialysis patients.

• 한국보육지원학회지
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• 제17권6호
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• pp.149-168
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• 2021

Objective: The purpose of this study was to analyze the structural relationship between fathers' involvement in parenting, mother's parenting stress and smartphone addiction, and children's smartphone addiction. Methods: The subjects of this study were 327 children aged between 3 and 5 who were attending nurseries and kindergartens in Gyeonggido, Gangwondo, and Busan, South Korea, and their mothers, fathers, and teachers. The data collected from the subjects were analyzed based on correlation analysis and structural equation modeling. Results: First, the fathers' involvement in parenting had a direct effect on their children's smartphone addiction, and no direct effect on the mother's parenting stress and smartphone addiction. Second, the mother's parenting stress had a direct effect on the mother's smartphone addiction and direct and indirect effects on their children's smartphone addiction. Third, the mother's smartphone addiction had a direct effect on their children's smartphone addiction. Conclusion/Implications: The findings in this study suggest the fathers' involvement in parenting and the mother's parenting stress and smartphone addiction have effects on their children's smartphone addiction. Based on these results, the study proposed ways to prevent children's addiction to smartphones and provided suggestions for further research.

• 한국보육지원학회지
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• 제18권3호
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• pp.1-18
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• 2022

Objective: The purpose of this study was to analyze the structural relationship between the authentic leadership of the director, social support, and teacher efficacy perceived by early childhood teachers. Methods: The participants of the study were 433 teachers working at kindergartens and daycare centers in Seoul and Gyeonggi Province. The data collected through the survey were analyzed by applying a structural equation model. Results: As a result of the study, it was found that the authentic leadership of the director perceived by early childhood teachers had a positive (+) effect on the early childhood teachers' social support and teacher efficacy, respectively, and social support had a positive (+) effect on teacher efficacy of the early childhood teachers. The results showed that social support had a positive mediating effect in the relationship between the director's authentic leadership and teacher efficacy perceived by early childhood teachers. Conclusion/Implications: The results suggest that it is necessary to establish a social support system through the exercise of the director's authentic leadership in order to improve the teacher efficacy of early childhood teachers.

• Earthquakes and Structures
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• 제22권3호
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• pp.319-330
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• 2022

Retrofit of soft-story buildings due to seismic loads using Gap-Inclined-Brace (GIB) system is considered a new retrofit technique that aims to maintain both strength and stiffness of structure. In addition, it provides more ductility and less P-delta effect, and subsequently better performance is observed. In this paper, the effect of the eccentricity between GIB and the retrofitted column due to installation on the efficiency of the retrofitting system is studied. In addition, a modification in the determination method of GIB properties is introduced to reduce the eccentricity effect. Also, the effect of GIB system on the seismic response of mid-rise buildings with different heights considering soft-story at various heights has been studied. A numerical model is developed to study the impact of such system on the response of retrofitted soft-story buildings under the action of seismic loads. To achieve that goal, this model is used to perform a numerical investigation, by considering five case study scenarios represent several locations of soft-story of two mid-rise reinforced concrete buildings. At first, Non-linear static pushover analysis was carried out to develop the capacity curves for case studies. Then, Non-linear time history analyses using ten earthquake records with five peak ground accelerations is performed for each case study scenario before and after retrofitting with GIB. The results show that large GIB eccentricity reduce the ultimate lateral resistance and deformation capacity of the retrofitting system. Moreover, the higher the retrofitted building, the more deformation capacity is observed but without significant increase in ultimate lateral resistance.

• Structural Engineering and Mechanics
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• 제82권4호
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• pp.517-542
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• 2022

The effect of mean angle of wind attack on the flutter critical wind speed of two generic bridge deck cross-sections, viz, one closed box type streamlined section (deck-1) and closed box trapezoidal bluff type section with extended flanges/overhangs (deck-2) type of section have been studied using Computational Fluid Dynamics (CFD) based forced vibration simulation method. Owing to the importance of the effect of the amplitude of forcing oscillation on the flutter onset, its effect on the flutter derivatives and flutter onset have been studied, especially at non-zero mean angles of wind attack. The flutter derivatives obtained have been used to evaluate flutter critical wind speeds and flutter index of the deck sections at non-zero mean angles of wind attack studied and the same have been validated with those based on experimental results reported in literature. The value of amplitude of forcing oscillation in torsional degree of freedom for CFD based simulations is suggested to be in the range of 0.5° to 2°, especially for bluff bridge deck sections. Early onset of flutter from numerical simulations, thereby conservative estimate of occurrence of instability has been observed from numerical simulations in case of bluff bridge deck section. The study aids in gaining confidence and the extent of applicability of CFD during early stages of bridge design, especially towards carrying out studies on mean incident wind effects.

• 한국식생활문화학회지
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• 제22권3호
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• pp.303-308
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• 2007

The purpose of this study was to measure the mediating effects of sacrifice, value and satisfaction on the relationship between restaurant service quality and loyalty. A total of 273 questionnaires were completed. Structural equation model was used to measure the causal effects of service quality, perceived sacrifice, value, satisfaction and loyalty. Results of the study demonstrated that the structural analysis result for the data also indicated excellent model fit. The influences of service quality and perceived sacrifice on value were statistically significant. The influences of service quality and value on satisfaction were statistically significant. The influences of value and satisfaction on loyalty were statistically significant. As expected, the service quality had a significant effect on loyalty. The results indicated that the effect of service quality on loyally was mediated by value. Moreover, the effect of service quality on loyalty w3s mediated by satisfaction.