• Computers and Concrete
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• v.23 no.4
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• pp.235-243
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• 2019

The discontinuous Galerkin method (DGM) has become widely used as it possesses several qualities, such as a natural ability to dealing with discontinuities. DGM has its major success related to fluid mechanics. Its major importance is the ability to deal with discontinuities and still provide high order of approximation. That is an important advantage when simulating cracking propagation. No remeshing is necessary during the propagation, since the crack path follows the interface of elements. However, DGM comes with the drawback of an increased number of degrees of freedom when compared to the classical continuous finite element method. Thus, it seems a natural approach to combine them in the same simulation obtaining the advantages of both methods. This paper proposes the application of the combined continuous-discontinuous Galerkin method (CDGM) to crack propagation. An important engineering problem is the simulation of crack propagation in concrete structures. The problem is characterized by discontinuities that evolve throughout the domain. Crack propagation is simulated using CDGM. Discontinuous elements are placed in regions with discontinuities and continuous elements elsewhere. The cohesive zone model describes the fracture process zone where softening effects are expressed by cohesive zones in the interface of elements. Two numerical examples demonstrate the capacities of CDGM. In the first example, a plain concrete beam is submitted to a three-point bending test. Numerical results are compared to experimental data from the literature. The second example deals with a full-scale ground slab, comparing the CDGM results to numerical and experimental data from the literature.

• Journal of Korea Society of Digital Industry and Information Management
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• v.14 no.4
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• pp.135-148
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• 2018

The purpose of this study is to investigate the effect of perceived interactivity on intention to use augmented reality tourism application in mobile environment. The analysis results revealed that perceived interactivity has a positive (+) effect on perceived usefulness and ease, perceived ease has a significant effect on perceived usefulness, perceived usefulness and perceived ease are related to perceived ease of use (+) Effect on the growth rate. This study attempted to expand the theoretical aspects from an integrated point of view as the existing interactions studies have been studied with an intolerant perspective in the online or mobile environment. The results of this study can be summarized as follows: First, the constructivist factors of perceived interactivity are derived through a comprehensive study of previous studies, and the second-order and reflective constructs are measured to confirm that the perceived interactivity consists of five sub-dimensions. Through such verification, the structure of perceived interactivity was systemized by clarifying the relationship between the factors. In addition, the four components of the perceived interactivity derived from the present study have differentiated effects on the TAM, respectively.

• Journal of Power Electronics
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• v.19 no.4
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• pp.869-880
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• 2019

Due to the inherent feedforward of load current, capacitor current (CC) control shows a fast transient response that makes it suitable for the power supplies used in various portable electronic devices. However, considering the effect of the outer voltage loop, the stable range of the duty-cycle is significantly diminished in CC controlled buck converters. To investigate the stability effect of the outer voltage loop on buck converters, a CC controlled buck converter with a proportion-integral (PI) compensator is taken as an example, and its second-order discrete-time model is established. Based on this model, the instability caused by the duty-cycle is discussed with consideration of the outer voltage loop. Then the dynamical effects of the feedback gain of the PI compensator and the equivalent series resistance (ESR) of the output capacitor on the CC controlled buck converter with a PI compensator are studied. Furthermore, the design-oriented closed-loop stability criterion is derived. Finally, PSIM simulations and experimental results are supplied to verify the theoretical analyses.

• Korean Journal of Childcare and Education
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• v.15 no.5
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• pp.87-111
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• 2019

Objective: The purpose of this study is to investigate the effect of the level of communication difficulty between child-care teachers and parents and teachers' job satisfaction on teacher's emotional labor. Methods: The data of 137 questionnaires collected in Y city, Gyeongggi-do were analyzed. The respondents of the questionnaires were teachers of 0-5 year old children. Statistical analyses were performed using frequency analysis, explorative factor analysis, independent t-test, One-way ANOVA, and multiple regression analysis at the p < .05 by SPSS 24.0 program. Results: First, there was no statistically significant difference on child-care teachers' communication difficulties with parents by sociological variables of child-care teachers. Second, there was no statistically significant difference on teachers' job satisfaction by sociological variables of child-care teachers. However, there were significant differences on the sub-factors of job satisfaction by teaching careers, types of workplace, and marital status. Third, these two factors were found to be important predictors of child-care teachers' emotional labor. Conclusion/Implications: In order to reduce the emotional labor experienced by child-care teachers in early childhood care settings, it will be necessary to pursue a multi-faceted approach to improving the working environment.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.22 no.1
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• pp.47-59
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• 2019

This study was composed of four treatments [no treatment, phosphate + limestone layer treatment, phosphate + sodium bicarbonate + cement layer treatment, and phosphate + sodium bicarbonate + limestone layer treatment] for figuring out vegetation effects on the acid drainage slope. Treated acid neutralizing techniques were effective for neutralizing acidity and vegetative growth in order of [first: phosphate + sodium bicarbonate + limestone layer treatment, second: phosphate + sodium bicarbonate+cement layer treatment, third: phosphate + limestone layer treatment and fourth: no treatment] on the acid drainage slope. We found out that sodium bicarbonate treatment was additory effect on neutralizing acidity and increasing vegetaive growth besides phosphate and neutralizing layer treatments. In neutralizing layer treatments, Limestone layer was more effective for vegetation and acidity compared to cement layer treatment. Cement layer showed negative initial vegetative growth probably due to high soil hardness and toxicity in spite of acid neutralizing effect. Concerning plants growth characteristics, The surface coverage rates of herbaceous plants, namely as Lotus corniculatus var. japonicus and Coreopsis drummondii L were high in the phosphate + sodium bicarbonate + limestone layer treatment while Festuca arundinacea was high in the phosphate + sodium bicarbonate + cement layer treatment. We also figured out that soil acidity affected more on root than top vegetative growth.

• Computers and Concrete
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• v.23 no.5
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• pp.321-327
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• 2019

Experimental isotherm compressive tests show that concrete behaviour is dependent on temperature. The aim of such tests is to reproduce how concrete will behave under environmental changes within a moderate range of temperature. In this paper, a novel constitutive elastic damage behaviour law is proposed based on a free energy with an apparent damage depending on temperature. The proposed constitutive behaviour leads to classical theory of thermo-elasticity at small strains. Fixed elastic mechanical characteristics and fixed evolution law of damage independent of temperature and the material volume element size are considered. This approach is applied to compressive tests. The model predicts compressive strength and secant modulus of elasticity decrease as temperature increases. A power scaling law is assumed for specific entropy as function of the specimen size which leads to a volume size effect on the stress-strain compressive behaviour. The proposed model reproduces theoretical and experimental results from literature for tempertaures ranging between $20^{\circ}C$ and $70^{\circ}C$. The effect of the difference in the coefficient of thermal expansion between the mortar and coarse aggregates is also considered which gives a better agreement with FIB recommendations. It is shown that this effect is of a second order in the considered moderate range of temperature.

• Stress
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• v.26 no.4
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• pp.290-295
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• 2018

Background: The aim of this study were to investigate the effect of unstable attachment on subjective well-being and to identify mediator effects of decentering and self-compassion. Methods: A total of 255 college students participated in this study by completing the following questionnaires: Experience in Close Relationship Scale, Subjective Well-being Questionnaire, Decentering Scale, and Self-Compassion Scale. Results: Mediated Regression Analysis was used for the purposes of study. The results are as the following. First, unstable attachment had significant negative correlation with subjective well-being and decentering and self-compassion. Second, decentering had a partial meditational effect on the relation between unstable attachment and subjective well-being. Third, self-compassion had completely meditational effect on the relation between unstable attachment and subjective well-being. Conclusions: These results suggested that it is important to enhance students' level of decentering and self-compassion in order to increase their subjective well-being effectively.

• Journal of the Korea Fashion and Costume Design Association
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• v.23 no.3
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• pp.87-98
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• 2021

Due to the influence of COVID-19, many changes have been made in the education methods in universities. In respomse, this study intendsto present an efficient learning method by identifying the impact of professor images on learning immersion and the learning satisfaction of classes taught with blended learning for university students majoring in beauty at H University in Seoul. For final analysis, 232 of the 234 questionnaires administered from May 17, 2021 to June 2, 2021 were analyzed. For statistical analysis, SPSS 21.0 was utilized; frequency analysis was conducted to identify demographic characteristics, factor analysis was used to verify the research model, and regression analysis was conducted to verify the hypothesis. First, images of professors have been shown to affect learning immersion. Second, the professor image were shown to affect learning satisfaction. Third, education immersion has been shown to affect educational satisfaction. In order to overcome the limitations of online lectures in universities that suddenly began with onset of COVID-19, it is believed that students' satisfaction can be increased by applying blended learning as a way to improve the quality of classes.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.34 no.5
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• pp.59-67
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• 2018

G-SEED's evaluation of existing buildings is an important point because the energy consumption and CO2 emissions of existing buildings are continuously increasing due to the aging of buildings over time. However, as G-SEED certification is concentrated on new buildings and the standards are not yet available, we will make improvements to evaluate the existing buildings of G-SEED. In order to improve G-SEED for EB, two research procedures were carried out. First, LEED EBOM and LEED for NC compare and analyze evaluation items and methods, and LEED EBOM focuses on evaluation of existing buildings. Second, we analyzed the certification evaluation contents of eight domestic LEED EBOM accredited buildings and obtained items that can be applied or need to be applied when revising G-SEED for EB. LEED EBOM is focused on improving the performance and utilization of data that track and manage the energy and environmental effects of building operations. As a result of the case analysis, the evaluation of G-SEED for EB requires quantitative evaluation items such as environmental management of buildings, energy performance status of building, improvement plan and improvement of performance according to tracking value. Although G-SEED for EB is not structured yet and there are few cases of certification, it is expected that quantitative evaluation of existing buildings will be made through continuous research.

• Journal of Family Relations
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• v.23 no.2
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• pp.29-45
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• 2018

Objectives: The purposes of this study were to investigate the influence of stress cognition of adolescents in a single-parent family on their problem-focused coping behaviors, and to verify the mediating effect of family cohesion between stress cognition and their problem-focused coping behaviors. Method: A survey was conducted on middle school students in Gwangju, and the responses of 404 participants were used in the analysis. The data were analyzed using the SPSS 21.0 program. Results: The results of this study were as follows: First, stress cognition had a negative influence on the problem-focused coping behaviors of the adolescents of single-parent family. Second, family cohesion completely mediated the effects of stress cognition on this problem-focused coping behaviors. Conclusions: This study suggests that it is necessary to improve the function of family cohesion in order to improve the problem-focused coping behaviors of adolescents in single-parent families.