• Journal of Technologic Dentistry
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• v.33 no.4
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• pp.517-528
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• 2011

Purpose: In this study, we aim to provide fundamental database for the development of programs that will enhance the satisfactions of the dental technicians' daily life. To this end, we examined various factors that affect the subjects' social and emotional life satisfactions and their overall daily lives. Methods: Out of the random selection of the registered dental offices of Dental Technicians in Seoul, Gyeonggido, and Gangwon-do districts. Four hundred working dental technicians were asked to fill out the questionnaire from the 1st of June to the 25th of August, 2011. We collected the 355 sheets of the questionnaire and took frequency analysis, t-test, analysis of variance and structural equation modeling using SPSS Win 12.0 program. Results: The results of this study is as follows; Firstly, social satisfaction of the subjects turned out 3.71 on average, emotional satisfaction and daily life satisfaction in general were shown 2.77 and 3.19 respectively. Secondly, Age(p<.05), Career(p<.001), Working environment satisfaction(p<.001) showed significant differences in social life satisfaction area, whereas monthly earning(p<.05), working environment satisfaction(p<.001) revealed meaningful differences in the domain of emotional life satisfaction. Thirdly, in the overall satisfaction of daily lives, monthly earning(p<.05), career(p<.01), working environment satisfaction(p<.001) indicated significant difference. Conclusion: Seen from the results of this study, we purport to develop a variety of programs for better working conditions and to further research on the variables affecting the dental technicians' satisfaction of daily lives.

• Geomechanics and Engineering
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• v.14 no.3
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• pp.257-269
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• 2018

Analysis of slope stability failures, as one of the complex natural hazards, is one of the important research issues in the field of civil engineering. Present paper adopts and investigates four soft computing-based techniques for this problem: Patient Rule-Induction Method (PRIM), M5' algorithm, Group Method of data Handling (GMDH) and Multivariate Adaptive Regression Splines (MARS). A comprehensive database consisting of 168 case histories is used to calibrate and test the developed models. Six predictive variables including slope height, slope angle, bulk density, cohesion, angle of internal friction, and pore water pressure ratio were considered to generate new models. The results of test studies are used for feasibility, effectiveness and practicality comparison of techniques with each other, and with the other available well-known methods in the literature. Results show that all methods not only are feasible but also result in better performance than previously developed soft computing based predictive models and tools. It is shown that M5' and PRIM algorithms are the most effective and practical prediction models.

• Structural Engineering and Mechanics
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• v.67 no.3
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• pp.301-310
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• 2018

In this paper, a multi-objective multiparameter optimization procedure is developed by combining rigorously developed metamodels with an evolutionary search algorithm-Genetic Algorithm (GA). Response surface methodology (RSM) is used for developing the metamodels to replace the tedious finite element analyses. A nine-node isoparametric plate bending element is used for conducting the finite element simulations. Highly accurate numerical data from an author compiled FORTRAN finite element program is first used by the RSM to develop second-order mathematical relations. Four material parameters-${\frac{E_1}{E_2}}$, ${\frac{G_{12}}{E_2}}$, ${\frac{G_{23}}{E_2}}$ and ${\upsilon}_{12}$ are considered as the independent variables while simultaneously maximizing fundamental frequency, ${\lambda}_1$ and frequency separation between the $1^{st}$ two natural modes, ${\lambda}_{21}$. The optimal material combination for maximizing ${\lambda}_1$ and ${\lambda}_{21}$ is predicted by using a multi-objective GA. A general sensitivity analysis is conducted to understand the effect of each parameter on the desired response parameters.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.3
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• pp.865-873
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• 2013

This paper proposes a theoretical solution of elastic critical buckling load of infinitely long pipelines with non-uniform thickness under external pressure. The non-uniform cross section of pipelines can be considered as corroded or stiffened pipelines so that this paper can be a fundamental research of pipelines that are essential technology for offshore industries. The theoretical solution of pipelines with non-uniform thickness is derived with an assumption that a cylindrical shell under external pressure can be considered as a simple ring. The eigenfunctions are derived to obtain the critical buckling load. The reduced thickness and the reduced range are considered as variables in parametric analysis. The finite element analysis is performed to verify the theoretical solutions and the results of the analytic method and the finite element method are in good agreement.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.8
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• pp.1046-1055
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• 2000

The flow and thermal phenomena in flat tubes of radiator are analyzed numerically. To predict the characteristics of heat transfer and pressure drop, the flow analysis program for three-dimensional complex geometry is developed, which adopted an non-staggered grid system and Cartesian velocities as dependent variables of the momentum equations. Using the developed program, the effect of tube specifications on the heat transfer characteristics is investigated for various flat tubes. From this study, the following results are obtained; (1) For the same hydraulic diameter($D_h{\doteq}5.2$mm), the Nusselt numbers of three basic modeis(D, J, and H-model) are 8.71, 8.92, and 10.58, respectively, and the pressure drops of D-, J-, and H-model are predicted as $-3.08{\times}10^{-2}\;Pa,\;-3.12{\times}10^{-2}\;Pa,\;and\; -3.98{\times}10^{-2}$ Pa, (2) In case of the same flat tube specification, the fins must be brazed at upper tube surface because the heat is more vividly transferred. Therefore, it is found that the H- model is the most effective tube as a heat exchanger and these results are used as a fundamental data for the design of tube.

• The Journal of Asian Finance, Economics and Business
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• v.7 no.4
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• pp.29-39
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• 2020

The purpose of this study is to investigate the determinants of blockholder presence in the Korean stock market. This study examines previous theories and studies, points that previous studies did not examine, and proposes two hypotheses. To verify two hypotheses, fundamental data were collected from firms listed on Korea Exchange from 2005 to 2017. As explanatory variables, we use the factors and characteristics of the firms used in the previous studies. Logistic regression analysis was conducted to test the determinants of blockholder presence. We find that firm size is the most distinctive factor determining the presence of blockholder, and firm idiosyncratic risk is the most similar factor determining the existence of each blockholder. Tobin Q shows significant value in family and government, and R&D intensity appears to be a negative related to the presence of blockholder in financial institutions. We also find that the determinant of blockholder presence differs from the mechanisms that govern each individual blockholder type when all blockholders grouped together. This suggests that there is blockholder heterogeneity within Korea listing firms. Our findings contribute to investors and policy makers who interested in the determinants of the presence of blockholder and blockhoder heterogeneity in Korea stock market.

• Korean Journal of Human Ecology
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• v.17 no.6
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• pp.1115-1124
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• 2008

Although parent-child relationships are fundamental aspects of human development across all societies, this relationship is also shaped in significant ways by culture. Therefore, the present study sought to determine whether adolescent autonomy was predicted in a similar or differential manner by several parent-adolescent variables consisting of parenting behavior, parental authority, and parents' educational attainment in samples of Chinese and American adolescents. The sample for this study included 418 Chinese adolescents and 226 American adolescents. Utilizing structural equation modeling, the results revealed that the effect of paternal authority on adolescent autonomy development is indirect, with the indirect effect being mediated by the authoritative parenting behaviors for both cultural groups. Therefore, the analyses for Chinese and European American youth generated similar association patterns, such that parenting behaviors served as a mediator in the relationship between paternal authority and adolescents' autonomy development. The significance of this present study is to contribute to existing knowledge in the field of adolescent development and to the literature on how parental behaviors and authority in collectivistic societies and individualist societies influence adolescent development.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2017.05a
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• pp.180-181
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• 2017

This study aims to analyze the high strength mortar's fundamental properties and autogenous shrinkage properties by taking into consideration the result of the previous study in which it was found that ERBO(Biodiesel) exercises greatest effect on the expansion effect of mortar, and changing the time and rate of mixing the ERBO. A total of five levels were set as experimental variables: the three levels of the rate of ERBO, 0, 0.5, 1.0%, and the two levels of the time of mixing the ERBO: first, adding the ERBO with the mixing water and mixing it before, and second, mixing it after the mortar is completely mixed. It was found that the rate of length change decreased as the rate of ERBO increased, and the rate of length change was lower when the ERBO was mixed sooner.

• Journal of Korea Foundry Society
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• v.24 no.2
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• pp.94-100
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• 2004

Gas porosity which is a common defect in aluminum alloy casting, is also thought to be severer in aluminum alloy castings produced by lost foam process due to the pyrolysis of the polystyrene foam pattern during pouring. Fundamental experiments were carried out to evaluate the effect of process variables such as the melt treatment, the cooling rate and pouring temperature on the density and mechanical properties in A356.2 castings with simple bar shape. The density of grain refined specimen was slightly lower than that of degassed one, but was higher than that of no treated one and that of shot ball packed specimen was higher than the other specimens. The tensile strength and elongation were in the ranges of $200{\sim}230MPa$ and $0.5{\sim}1.5%$ respectively. The density and hardness of lost foam cast specimens decreased with increase in pouring temperature.

• The Journal of Asian Finance, Economics and Business
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• v.4 no.1
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• pp.39-49
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• 2017

This study develops an early warning system (EWS) to prevent the banking crisis. The proposed system incorporates both the perspective of crises and fundamental characteristics of the banking system in each economy. A fuzzy logic method with data from 1990-2009 is employed to construct the EWS of banking crisis based on 21 pre-determined variables from the aspect of total economy, financial and banking sectors. Our results show: Firstly, South Korea recorded higher probability to have a banking crisis in 1997 as there was large foreign debt in dollars. Secondly, China, Australia and New Zealand banking systems appear to be vulnerable to the crisis in 2007. The surge of China export, FDIs and booming stock market were signs of a heated economy. Australia with high commodity prices was also vulnerable to crisis. Thirdly, Australia, China, Japan and New Zealand banking systems appear to be exposed to the higher chance of a crisis in 2010. Japan with deflation coupled with expensive yen did not augur well for its export. Overall, the findings show that in Asian Financial Crisis 1997/98 and Global Financial Crisis 2008/09, many economies are exposed to a higher probability of having the crisis and this shows an urgent need of having surveillance in these economies.