• Journal of the Korean Geotechnical Society
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• v.32 no.2
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• pp.53-62
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• 2016

Among several factors controlling soil compaction, temperature is the factor that varies with region and season. Although earthwork is performed in many projects in the cold regions of the earth, studies on quantifying soil compaction associated with temperature are limited. This experimental study investigates the temperature effect on the soil compaction of cohesionless soil. Jumunjin sand was selected for the tests to represent cohesionless clean sand, which is widely used as an engineering fill at petrochemical projects such as northern Alberta of Canada and Russia. The laboratory test program consists of performing a series of standard proctor tests varying temperature of soil samples ranging from $-10^{\circ}C$ to $17^{\circ}C$. Test results indicate that soil specimen volume expansion occurred from bulking and its range was 0% to 6% with zero above temperature. For increasing temperature from $0^{\circ}C$ to $17^{\circ}C$, water content corresponding to maximum volume (minimum dry unit weight) was decreased and water content corresponding to minimum volume (maximum dry unit weight observed after reaching minimum dry unit weight) was slightly increased with increasing temperature. In zero below temperature, dry unit weight gradually decreased with increasing water content. In this case, no bulking effect was found and soil specimen volume increased due to the higher unit volume of ice.

• Journal of the Korean Geotechnical Society
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• v.32 no.4
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• pp.5-14
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• 2016

Numerical simulation of dynamic soil-pile-structure interaction embedded in a dry sand was carried out. 3D model of the dynamic centrifuge model tests was formulated in a time domain to consider nonlinear behavior of soil using the finite difference method program, FLAC3D. As a modeling methodology, Mohr-Coulomb criteria was adopted as soil constitutive model. Soil nonlinearity was considered by adopting the hysteretic damping model, and an interface model which can simulate separation and slip between soil and pile was adopted. Simplified continuum modeling (Kim et al., 2012) was used as boundary condition to reduce analysis time. Calibration process for numerical modeling results and test results was performed through the parametric study. Verification process was then performed by comparing numerical modeling results with another test results. Based on the calibration and validation procedure, it is identified that proposed modeling method can properly simulate dynamic behavior of soil-pile system in dry condition.

• Journal of the Korean Geotechnical Society
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• v.27 no.5
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• pp.85-92
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• 2011

The dynamic behavior of piles becomes very complex due to soil-pile dynamic interaction, soil non-linearity, resonance phenomena of soil-pile system and so on. Therefore, the proper numerical simulation of the pile behavior needs much effort and calculation time. In this research, a new modeling method, which can be applied to the conventional finite difference analysis program FLAC 3D, was developed to reduce the calculation time. The soil domain in this method is divided into a near-field region and a far-field region, which is not influenced by the soil-pile dynamic interaction. Then, the ground motion of the far-field is applied to the boundaries of the near-field instead of modeling the far-field region as finite meshes. In addition, the soil non-linearity behavior is modeled by using the hysteretic damping model, which determines the soil tangent modulus as a function of shear strain and the interface element was applied to simulate the separation and slip between the soil and pile. The proposed method reduced the calculation time by as much as one third compared with a usual modeling method and maintained the accuracy of the calculated results. The calculated results by the proposed method showed a good agreement with the prototype pile behavior, which was obtained by applying a similitude law to the 1-g shaking table test results.

• Journal of Korean Home Economics Education Association
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• v.28 no.1
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• pp.71-85
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• 2016

The purpose of this study was to investigate the mediating effects of stress coping strategy on the relationship between academic burnout and school adjustment in Korea adolescents. A survey was conducted using a convenience sample drawn from 1,232 students from junior high schools in Kunggi Province. Data were analyzed using SPSS package program. The survey results showed that 44.6% of students are dissatisfied with their own academic grade. Antipathy and cynicism showed the most impact on academic burnout. In addition, academic burnout was negatively related with school adjustment. Especially academic burnout exerted inverse relationship with school adjustment, whereas problem oriented and seeking social support coping positively influence on school adjustment. Problem oriented and seeking social support coping partially mediated the relationship between academic burnout and school adjustment. The results indicate that improvement of active stress coping is important to prevent the symptoms of academic burnout and to increase the school adjustment.

• Journal of Korean Home Economics Education Association
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• v.22 no.2
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• pp.155-169
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• 2010

This study aims to design practical problem-focused instruction by applying universal design of "Housing" unit of Technology Home Economics in the 10th grade and examine the students' perception on the lesson. The lesson is composed of the following procedures: thinking, problem recognition, problem understanding, information search & alternative search, consideration of the result, and practice plan. To solve problem such as 'What should one do for everyone's convenient and comfortable residential life' practically, we chose the major concern of 'understanding the universal design', 'analysis of cause for environmental change', 'creation of human-concerned residential culture'and performed alternative experience program for the old, the pregnant and the disabled. The students perceived teaching methods and contents positively with interest. They also understood the lesson easily by experiential activity and discussion thus enabling their active participation. It was also found out that the students felt considerable change of their consciousness of living environment of residence and the local community, thus it is concluded that the practical problem-focused instructional design method is very effective.

• Journal of the Korean Geotechnical Society
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• v.29 no.8
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• pp.75-84
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• 2013

Soil freezing is a phenomenon arising due to temperature difference between atmosphere and ground, and physical properties of soils vary upon the phase change of soil void from liquid to solid (ice). A heat-transfer mechanism for this case can be explained by the conduction in soil layers and the convection on ground surface. Accordingly, the evaluation of proper thermal properties of soils and the convective condition of ground surface is an important task for understanding freezing phenomenon. To describe convection on ground surface, simplified coefficient methods can be applied to deal with various conditions, such as atmospheric temperature, surface vegetation conditions, and soil constituents. In this study, two methods such as n-factor and convection coefficient for the convective ground surface boundary were applied within a commercial numerical program (TEMP/W) for modeling soil freezing phenomenon. Furthermore, the numerical results were compared to laboratory testing results. In the series of the comparison results, the convection coefficient is more appropriate than n-factor method to model the convective boundary condition.

• Journal of the Korean Geotechnical Society
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• v.29 no.8
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• pp.37-51
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• 2013

An energy pile encases heat exchange pipes to exchange thermal energy with the surrounding ground formation by circulating working fluid through the pipes. An energy pile has many advantages in terms of economic feasibility and constructability over conventional Ground Heat Exchangers (GHEXs). In this paper, a coil-type PHC energy pile was constructed in a test bed and its thermal performance was experimentally and numerically evaluated to make a preliminary design. An in-situ thermal response test (TRT) was performed on the coil-type PHC energy pile and its results were compared with the solid cylinder source model presented by Man et al. (2010). In addition, a CFD numerical analysis using FLUNET was carried out to back-analyze the thermal conductivity of the ground formation from the Ttype PHC energy RT result. To study effects of a coil pitch of the coil-type heat exchange pipe, a thermal interference between the heat exchange pipes in PHC energy piles was parametrically studied by performing the CFD numerical analysis, then the effect of the coil pitch on thermal performance and efficiency of heat exchange were evaluated. Finally, an equivalent heat exchange efficiency factor for the coil-type PHC energy pile in comparison with a common multiple U-type PHC energy pile was obtained to facilitate a preliminary design method for the coil-type PHC energy pile by adopting the PILESIM2 program.

• Journal of Korean Home Economics Education Association
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• v.29 no.4
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• pp.49-64
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• 2017

The purpose of this study was to explore ways to help improve adolescents' happiness by exploring the influences of emphatic ability and family strengths on happiness. This subjects were 514 middle school students living in Gwangju. Data were collected from self-report questionnaires and analyzed with SPSS 22.0 program. The major findings were as follows; First, the adolescents' emphatic ability('viewpoint', 'identity', 'emphatic interest'), family strengths('family respect and affection', 'role sharing and problem solving', 'communication and bonds', 'financial stability') and happiness scores were higher than the median(3.00). Emphatic ability('viewpoint', 'identity', 'emphatic interest', 'personal suffering') and family strengths('communication and bonds') showed significant difference according to gender. Second, the adolescents' happiness was influenced by 'family respect and affection', 'role sharing and problem solving', 'financial stability', 'personal suffering', 'identity', and 'emphatic interest'. Adolescents' happiness was explained about 39% by these variables. In other words, the higher family respect and affection, both higher role sharing and problem solving and higher financial stability, with lower personal suffering and higher identity and higher emphatic interest showed the higher happiness. These findings demonstrate the emphatic ability and family strengths in adolescents influence on the level of happiness. As such, in order to improve the happiness of adolescents, it is necessary to energize those programs focus on the forming healthy family relationships and to design finance assistance programs that could attempt to minimise financial gap. Additionally, it is necessary to develop programs aimed to enhance emphatic ability and continue such programs in homes as well as at schools. Finally, it is necessary to implement curriculum that may improve family strengths and emphatic ability, which have influenced on the happiness in adolescents. Since the subject "Technology & Home Economics" helps to enhance family strengths, emphatic ability and eventually amplifies the happiness, it is necessary to expand and reinforce it as well as to make it a mandatory subject.

• Korea Journal of Hospital Management
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• v.5 no.1
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• pp.232-271
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• 2000

The introduction of a team system to any organization is usually to improve that organizations dynamics, by increasing the proper adaptation to rapidly changing environments, by reducing approval procedures, and by promoting power authorization. In this regard, this study was carried out in an attempt to determine (1) whether or not the introduction of a team system can be as effective in hospital organizations as it has been in business organizations, and (2) what behavior factors influence such effectiveness. For the current study, questionnaires were distributed to the employees of a university hospital in Pusan. Four hundred eighty three of them(94.7%) were retrieved and analyzed through statistical processes. The three types of variables that were found to influence team effectiveness were: (1) independent variables of team organization characteristics, such as communication, organizational atmosphere, leadership and team knowledge, (2) intervening variables of team organization characteristics. such as job autonomy, technological variety, task subjectivity, task feedback and task importance, and(3) the dependent variables of team level effectiveness, such as job satisfaction and commitment to team organization. The gathered data were processed by using the 6.12 version of the statistical program SAS(Statistical Analysis System), and the reliance coefficient of those measured variables was then evaluated as an average of 0.78. The influence of team level effectiveness was analyzed by using multiple regression analysis. These differences in effectiveness were then analyzed on the basis of related mean values, while the differences among demo-sociological characteristics were analyzed by using the dispersion analysis(ANOVA) and the t-test. The results of the study can be summarized by the following. First, regarding the relationship between team organization characteristics and team level effectiveness, all of the factors including communication, organizational atmosphere, leadership and team knowledge were found to have a significant influence on effectiveness. Second, the factors of team job characteristics, such as technological variety, task importance and job autonomy, had significant effects on job satisfaction and organizational commitment among the teams members. Team level effectiveness was generally high, while team job satisfaction was higher the teams organizational commitment. Third, regarding the demo-sociological characteristics, team level effectiveness was found to be higher among those who were older, who had more job experience, and who had a higher position. Comparing the differences among job types, the effectiveness was relatively higher in the fields of nursing and administration/management then in other fields. Further study should be done towards the setting of variables for characteristics of hospital organization, developing suitable methods of measurement, and researching individual level effectiveness.

• Korea Journal of Hospital Management
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• v.25 no.2
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• pp.1-13
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• 2020

Purpose: The purpose of this study is to identify the effect of the disease duration on depression change in cancer survivors between the middle and old age groups. Methodology: To that end, we analyzed 275 patients using the Korea welfare panel survey from 2011 to 2016 jointly developed by the Korea Institute for Health and Social Affairs and Seoul National University. The duration of the elapsed and the experienced was measured as a independent variable. CES-D was used as a dependent variable. Frequency, paired t-test, ANOVA, and logistic regression analysis were conducted using Stata 14.0 for statistical analysis. Findings: Studies have shown that as the duration of the elapsed and the experienced increases, people under 65 are 1.17 times and 1.84 times each more likely to be included in depression-increase group than in depression-reduction group. The group that has been maintaining economic activities continuously since 2011 was significantly less likely to belong to the depression-increase group than the group that did not have economic activities in 2016. For those aged 65 and older, there was no significant difference in the duration of the elapsed and the experienced. The higher the likelihood of low-income households being included in the family of depression was 2.58 times higher than for ordinary households. Practical Implications: It is suggested that close policy management of the employment and working environment of cancer survivors is necessary, as both cancer survivors of productive age as well as older cancer survivors are analyzed to be beneficial to depression management. In addition, a systematic management program related to the mental health of cancer survivors is believed to be necessary for normal social recovery in the future.