• Nuclear Engineering and Technology
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• v.49 no.7
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• pp.1513-1523
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• 2017

Improvement of numerical analysis methods has been required to solve complicated phenomena that occur in nuclear facilities. Particularly, fluid-structure interaction (FSI) behavior should be resolved for accurate design and evaluation of complex reactor vessel internals (RVIs) submerged in coolant. In this study, the FSI effect on dynamic characteristics of RVIs in a typical 1,000 MWe nuclear power plant was investigated. Modal analyses of an integrated assembly were conducted by employing the fluid-structure (F-S) model as well as the traditional added-mass model. Subsequently, structural analyses were carried out using design response spectra combined with modal analysis data. Analysis results from the F-S model led to reductions of both frequency and Tresca stress compared to those values obtained using the added-mass model. Validation of the analysis method with the FSI model was also performed, from which the interface between the upper guide structure plate and the core shroud assembly lug was defined as the critical location of the typical RVIs, while all the relevant stress intensities satisfied the acceptance criteria.

• Proceedings of the Korean Geotechical Society Conference
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• 2002.03a
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• pp.101-110
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• 2002

This article summarises the traditional method of soil-structure interaction based on the modulus of subgrade reaction and shows its weakness. In order to avoid these weakness, a new soil-structure interaction model is proposed. This model considers the soil as a set of connected springs which enables interaction between springs. Its use is as simple as the traditional model but allows to define the soil properties independently from the structural properties and the loading conditions. Thus, the definition of the modulus of subgrade reaction is unnecessary as each component is defined by its own modulii (Young's modulus and shear modulus). The non-linear soil behaviour for the shear stress versus distortion is also incorporated in the model. This feature allows to pinpoint the arching effect in the ground and shows how the stresses concentrate on stiff materials. Based on these principles, three dimensional program has been developed in order to solve the difficult problem of soil improvement by inclusions (stiff or soft). Also the possibility to take into account a flexible mat and/or a subgrade layer has been implemented. Equations used in the model are developed and a parametric study of the necessary data used in the program is presented. In particular, the Westergaard modulus notion and the arching effect are analysed.

• Korean Journal of Childcare and Education
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• v.11 no.1
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• pp.249-267
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• 2015

This study aims to examine the effect of child-centered group play therapy on the improvement of withdrawn preschool children's daily stress, anxiety, peer interaction and EEG variation. The research subjects are 12 children of 3-5 years of age who are over 65T in the social-withdrawal scale of KPRC(Korean Personality Rating Scale for Children). They were recommended by class teachers due to the withdrawal behavior at D kindergarten in Seoul. The experimental group received 12 sessions of the child-centered group play therapy program, twice a week for 35 minutes. But the control group did not receive any of the child-centered group play therapy program. To verify the effects of the program, a Mann-Whitney-U test of the non-parametric was preceded and homogeneity between the two groups was verified. Also, a Wilcoxon's signed-rank test was conducted to check on the pre-to-post changes of daily stress, anxiety, peer-interaction and EEG variation by using SPSS 18.0. The results of this research showed that the child-centered group play therapy program decreases daily stress and anxiety, while it increases positive peer-interaction and the EQ of withdrawal children. The result of this study serves as a baseline data about the effects of child-centered group play therapy for withdrawal children with emotional difficulties.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.9
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• pp.375-386
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• 2016

This study was conducted to investigate the effectiveness of a nonviolent communication program on nurse's interpersonal competence, job stress and spiritual wellness. This study was a inequality similar to the control group experimental design study of repeated measurements before and after. The data for this study were collected from June 1 to October 20, 2013 from 29 clinical nurses. The self-administered questionnaires used consisted of questions regarding general characteristics, interpersonal competence, job stress and spiritual wellness. The results were: 1. For interpersonal competence, the interaction between time and group was significant (F = 7.726, p = 0.002). 2. For job stress analysis, the interaction between time and group was not significant (F = 0.142, p = 0.851). 3. For spiritual wellness, the interaction between time and group was significant (F = 31.355, p < .001). These results suggest that the nonviolent communication program had a positive effect on rejected clinical nurse's interpersonal competence and spiritual wellness, but not on job stress. A follow-up replication study will be necessary.

• Human Ecology Research
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• v.53 no.5
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• pp.475-488
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• 2015

Economic activity and social participation by women has recently increased; however, working mothers raising young children are under new stress due to the simultaneous combination of job and parenting responsibilities. This stress has resulted in social problems of career break and low fertility. This study investigates the effect of clinical art therapy on occupational stress and parenting stress of working mothers. We analyzed 34 working mothers in full-time employment (over 8 hours a day) who have preschool children (0-6 years old). They were divided into 17 subjects in the experimental group and 17 subjects in the control group. For the experimental group, 10 hours and a half sessions of group art therapy were participated in once a week from April to August in 2014. We perform Dan Occupational Stress Index by Ivancevich and Matteson, Parenting Stress Index/Short Form and salivary cortisol test before and after the group art therapy. For qualitative analysis, Kinetic House-Tree-Person (KHTP) drawing test was used. Using SPSS ver. 19.0, paired t -test or Wilcoxon signed rank test compared the pre and post analysis results. The results of this study are as follows. First, scores of 'occupational stress factor' subpart showed significant improvement in the Occupational Stress Index after the clinical art therapy. Second, scores of 'parental distress,' 'parent-child dysfunctional interaction,' and 'difficult child' subpart in Parenting Stress Index also showed a significant improvement. Third, a positive change was observed after the clinical art therapy in the KHTP drawing test. In conclusion, this study suggests that the clinical art therapy can be effective for occupational stress factors and the parenting stress of working mothers.

• Interaction and multiscale mechanics
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• v.2 no.3
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• pp.223-233
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• 2009

This paper presents a new nonlocal stress variational principle approach for the transverse free vibration of an Euler-Bernoulli cantilever nanobeam with an initial axial tension at its free end. The effects of a nanoscale at molecular level unavailable in classical mechanics are investigated and discussed. A sixth-order partial differential governing equation for transverse free vibration is derived via variational principle with nonlocal elastic stress field theory. Analytical solutions for natural frequencies and transverse vibration modes are determined by applying a numerical analysis. Examples conclude that nonlocal stress effect tends to significantly increase stiffness and natural frequencies of a nanobeam. The relationship between natural frequency and nanoscale is also presented and its significance on stiffness enhancement with respect to the classical elasticity theory is discussed in detail. The effect of an initial axial tension, which also tends to enhance the nanobeam stiffness, is also concluded. The model and approach show potential extension to studies in carbon nanotube and the new result is useful for future comparison.

• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.675-678
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• 2008

The effect of wave and current interactions on jet-like current flowing against waves was investigated based on numerical simulations. The numerical simulations are conducted by a combined model system of REF/DIF(a wave model) plus SHORECIRC(a current model) and a Boussinesq equation model, FUNWAVE. In the simulations, regular and irregular waves refracted due to the jet-like opposing current were focused along the core region of current, and the jet-like current was earlier spreaded when the waves had larger wave heights. The numerical results show that the rapid change of wave height distribution in transverse direction near current inlet plays a significant role to spread the jet-like current. In other words, the gradients of radiation stress forcing in transverse direction have a more significant effect on the jet-like current than its relatively small gradients forcing in flowing direction, which tend to accelerate the current, do. In conclusion, it is indispensible to take into account the interaction effect of wave transformation and current characteristics when waves meet the opposing jet-like current such as river mouth.

• Journal of Korean Academy of Nursing
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• v.27 no.3
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• pp.639-647
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• 1997

The purpose of this study was to identify how internal and external coping resources influenced active coping in the process of stress-coping. The model was established theoretically by comparing and integrating the following theories : Stress-Coping, Self-Care, and Resourcefulness. The subjects consisted of sixty eight patients undergoing chemotherapy(experimental group 34, control group 34) at two general hospitals from January to July, 1995. The results were as follows : After self-care education, the active coping score of the experimental group was significantly higher than that of the control group. The active coping score of the high resourcefulness group was significantly higher than that of the low resourcefulness group. The interaction effect between self-care education and resourcfulness was not significant statistically. Specifically as to such scores of seeking social support, problem-oriented strategy and self care behavior, there were significantly higher in the experimental group and high resourcefulness group than in each of the other groups. Considering them both, self-care education and resourcefulness are effective nursing strategies to promote active coping including self-care. Consequently, the synthesis and testing of theories of stress-coping, self-care, and resourcefulness in this study are mostly proven to enhance the explanation and prediction of the change of active coping including self-care. Therefore the result of this study will contribute in the development of practice theory of nursing. A further study is necessary to reevaluate the interaction effect between self-care education and resourcefulness and to identify the difference between resourcefulness and self-efficacy.

• Steel and Composite Structures
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• v.48 no.4
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• pp.461-474
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• 2023

Concrete-filled steel tubes are among the most efficient compressive structural members because the strength of the concrete is enhanced given that the surrounding steel tube confines the concrete laterally and the steel tube is restrained with regard to inward deformation due to the concrete existing inside. Accurate estimations of the ultimate compressive strength of CFT are important for efficient designs of CFT members. In this study, an analytical procedure that directly formulates the interaction between the concrete and steel tube by considering the nonlinear Poisson effect and stress-strain curve of the concrete including the confinement effect is proposed. The failure stress of concrete and von-Mises failure yield criterion of steel were used to consider multi-dimensional stresses. To verify the prediction capabilities of the proposed analytical procedure, 99 circular CFT experimental data instances from other studies were used for a comparison with AISC, Eurocode 4, and other researchers' predictions. From the comparison, it was revealed that the proposed procedure more accurately predicted the ultimate compressive strength of a circular CFT regardless of the range of the design variables, in this case the concrete compressive strength, yield strength of the steel tube and diameter relative to the thickness ratio of the tube.

• Biomaterials and Biomechanics in Bioengineering
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• v.2 no.4
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• pp.197-206
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• 2015

This paper presents three-dimensional finite element method analyses of the distribution of equivalents stress of Von Mises. Induced around a cavity located in the bone cement polymethylmethacrylate (PMMA). The presences and effect of its position in the cement was demonstrated, thus on the stress level and distribution. The porosity interaction depending on their positions, and their orientations on the interdistances their mechanical behaviour of bone cement effects were analysed. The obtained results show that micro-porosity located in the proximal and distal zone of the prosthesis is subject to higher stress field. We show that the breaking strain of the cement is largely taken when the cement, containing the porosities very close adjacent to each other.