• Human Ecology Research
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• v.54 no.5
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• pp.461-473
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• 2016

The study examined whether children's behavioral problem and self-resilience mediated the association between mothers' democratic parenting and their children's school life adjustment perceived by children. We analyzed data from the fourth Korean Children and Youth Panel Study (KCYPS) that included democratic parenting, behavioral problem, self-resilience, and school life adjustment by 1,971 mothers and fourth grade elementary school children. We identified structural relationships among the variables using SPSS 18.0 and AMOS 18.0 applying structural equation modeling. The measurement model and structure model had a favorable goodness of fit and the results of structure models on each path were as follows. First, school life adjustment had positive correlations with mother's democratic parenting and self-resilience, but there was a negative correlation between school life adjustment and behavioral problems. Second, the relationship between mother's democratic parenting and self-resilience was mediated by behavioral problems and behavioral problems; in addition, self-resilience mediated the relationship between mother's democratic parenting and school life adjustment. The results of this study suggested that children's school life adjustment and children's confidence to control behavioral problems could improve by promoting self-resilience. If fourth grade children could perceive mother's parenting as affection, monitoring children's behavioral problems could be reduced, and children's self-resilience and school life adjustment could be increased.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.2
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• pp.111-118
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• 2020

Recently, bioenergy research using microalgae, one of the most promising biofuel sources, has attracted much attention. Cell disruption, which can be classified as physical or chemical, is essential to extract functional ingredients from microalgae. In this study, we investigated the cell disruption efficiency of Chlorella sp. using low-frequency non-focused ultrasound (LFNFU). This is a continuously physical method that is superior to chemical methods with respect to environmental friendliness and low processing cost. A flat panel photobioreactor was employed to cultivate Chlorella sp. and its growth curve was fitted both with Logistic and Gompertz models. The temporal change in cell reduction by cell disruption using LFNFU was fitted with a Logistic model. The experimental conditions that were investigated were the initial concentration of microalgal cells, relative amplitude of output ultrasound waves, processing volume of microalgal cells, and initial pH value. The optimal conditions for the most efficient cell disruption were determined through the various tests.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11b
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• pp.190-193
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• 2005

The air filter in engine intake system filters the dirt in the breathing air but also it attenuates the noise although the phenomenon has been regarded negligible. For the analysis of the acoustical performance of air filter, an acoustical model is suggested in this paper. The air filter consists of a porous filter element, which catches the particulate dirt, and a plastic filter box, which supports the filter element. Fibrous structure of the filter element is modeled as a micro-perforated panel using the flow resistivity and porosity. The pleated geometry of the filter element is modeled as two coupled ducts and a mathematical model is developed for the analysis of sound propagation. The filter box Is modeled as a rigid rectangular box. By combining two models, a 4-pole transfer matrix for the air filter is derived. The transmission loss calculated using the transfer matrix of the suggested model is compared with the measured data. Reasonably good agreement is observed. The result can be improved by considering the visco-thermal effect in modeling, in particular at a frequency range near the troughs of TL curve.

• Health Policy and Management
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• v.24 no.4
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• pp.357-366
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• 2014

Background: The objective of this study was to evaluate the efficiency of an emergency ambulance system and to investigate socio-economic and clinical characteristics associated with emergency ambulance service. Methods: Based on 2011 Korea health panel, unmet need and inappropriate use of emergency ambulance service were measured by Gibson in 1977. Furthermore, the factors associated with unmet need and inappropriate use of emergency ambulance service were identified by Fisher's exact tests and multiple logistic regression models. Results: Unmet need, defined as the proportion of emergency patients who clinically need ambulance transportation but do not receive it, was found to be 59.8%. Inappropriate use, defined as the proportion of emergency patient receiving ambulance care who did not clinically need it, was found to be 37.2%. There were statistically significant differences between appropriate and inappropriate groups in overall variables of socio-economic and clinical characteristics. Specifically, gender, age, relationship to household, and reasons of visiting emergency department (accident/disease) were statistically significant factors associated with appropriate use of emergency ambulance service. Conclusion: Unmet ambulance need is a useful measure for patients needs assessment, and inappropriate ambulance use is a valid criteria in judging the efficiency of emergency ambulance system. To improve and understand emergency ambulance system, unmet need and inappropriate use of emergency ambulance service should be more concerned.

• Korean Journal of Childcare and Education
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• v.16 no.2
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• pp.161-178
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• 2020

Objective: The purpose of this study was to investigate the effects of parenting stress of mothers, warm parenting behaviors and controlling parenting behaviors on children's social competence. Methods: A total of 1515 mothers of young children(780 boys, 735 girls), who had participated in wave 7 of the Panel Study on Korean Children(PSKC), answered the questionnaires. The questionnaires included items about mothers' parenting stress, parenting behaviors, and their children's social competence. The collected data were analyzed using descriptive statistics, Pearson's correlation and structural equation models using SPSS 23 and AMOS 22. Results: First, there was a significantly negative correlation between mothers' parenting stress and children's social competence. Also, there was a significantly positive correlation between mothers' warm parenting behaviors and controlling parenting behavior and children's social competence. Second, mothers' parenting stress showed a direct negative effect on children's social competence. Third, mothers' warm parenting behaviors and controlling parenting behaviors showed partial mediating roles in the relationship between mothers' parenting stress and children's social competence. Conclusion/Implications: In order to develop positive social competence of children, programs and social support are needed to reduce mothers'parenting stress and induce positive parenting behaviors.

• Korean Journal of Child Studies
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• v.35 no.5
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• pp.99-111
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• 2014

The purpose of this study was to investigate the relationship between sex role stereotypes and delinquency, and determine if it is mediated by stigma. The data was taken from the fourth wave of the 2010 Korea Youth Panel Survey(KYPS), which was administered by the Korea Youth Policy Institute. The major findings are as follows: First, sex role stereotypes were found to increase stigma and delinquency. Second, the relationship between sex role stereotypes and delinquency is mediated by stigma. Third, the results revealed that there was a significant gender difference in mediating models. As for the female participants, stigma had a mediating effect in the relationship between sex role stereotyping and delinquency. In contrast, for the male participants, the mediating effect of stigma was found to be insignificant. Based on these results, this research suggested that delinquency prevention programs need improvement considering gender difference and sex role stereotypes.

• Journal of Korean Institute of Industrial Engineers
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• v.40 no.3
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• pp.283-290
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• 2014

In the flat panel display industry, to meet production target quantities and the deadline of production, the scheduler and dispatching systems are major production management systems which control the order of facility production and the distribution of WIP (Work In Process). Especially the delivery time is a key factor of the dispatching system for the time when a lot can be supplied to the facility. In this paper, we use survival analysis methods to identify main factors of the delivery time and to build the delivery time forecasting model. To select important explanatory variables, the cox proportional hazard model is used to. To make a prediction model, the accelerated failure time (AFT) model was used. Performance comparisons were conducted with two other models, which are the technical statistics model based on transfer history and the linear regression model using same explanatory variables with AFT model. As a result, the mean square error (MSE) criteria, the AFT model decreased by 33.8% compared to the statistics prediction model, decreased by 5.3% compared to the linear regression model. This survival analysis approach is applicable to implementing the delivery time estimator in display manufacturing. And it can contribute to improve the productivity and reliability of production management system.

• 한국전산유체공학회:학술대회논문집
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• 2007.04a
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• pp.120-124
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• 2007

Helicopters and rotary-wing vehicles encounter a wide variety of complex aerodynamic phenomena and these phenomena present substantial challenges for computational fluid dynamics(CFD) models. This investigation presents the rotor aerodynamic analysis items for the helicopter development and variety aerodynamic analysis methods to provide the better solution to researchers and helicopter developers between aerodynamic problems and numerical aerodynamic analysis methods. The numerical methods to make an analysis of helicopter rotor are as below - CFD Modelling : actuator disk model, BET model, fully rotor model,... - Grid : sliding mesh, chimera mesh / structure mesh, unstructure mesh,... - etc. : panel method periodic boundary, quasi-steady simulation, incompressible,... The choice of CFD methodology and the numerical resolution for the overall problem have been driven mostly by available computer speed and memory at any point in time. The combination of the knowledge of aerodynamic analysis items, available computing power and choice of CFD methods now allows the solution of a number of important rotorcraft aerodynamics design problems.

• The Korean Journal of Applied Statistics
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• v.30 no.6
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• pp.957-981
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• 2017

A generalized linear mixed model is an extension of a generalized linear model that allows random effect as well as provides flexibility in developing a suitable model when observations are correlated or when there are other underlying phenomena that contribute to resulting variability. We describe maximum likelihood estimation methods for logistic regression models that include random effects - the Laplace approximation, Gauss-Hermite quadrature, adaptive Gauss-Hermite quadrature, and pseudo-likelihood. Applications are provided with social science problems by analyzing the effect of mental health and life satisfaction on volunteer activities from Korean welfare panel data; in addition, we observe that the inclusion of random effects in the model leads to improved analyses with more reasonable inferences.

• Journal of Preventive Medicine and Public Health
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• v.40 no.6
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• pp.495-504
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• 2007

Objectives : This study attempts to show how studies using non-experimental data can strengthen causal inferences by applying propensity score and instrumental variable methods based on the counterfactual framework. For illustrative purposes, we examine the effect of having private health insurance on the probability of experiencing at least one hospital admission in the previous year. Methods : Using data from the 4th wave of the Korea Labor and Income Panel Study, we compared the results obtained using propensity score and instrumental variable methods with those from conventional logistic and linear regression models, respectively. Results : While conventional multiple regression analyses fail to identify the effect, the results estimated using propensity score and instrumental variable methods suggest that having private health insurance has positive and statistically significant effects on hospital admission. Conclusions : This study demonstrates that propensity score and instrumental variable methods provide potentially useful alternatives to conventional regression approaches in making causal inferences using non-experimental data.