• Korean Journal of Culture and Social Issue
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• v.20 no.4
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• pp.329-346
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• 2014

Current study examine whether happiness (life satisfaction, positive affect, and negative affect) improves academic achievement (GPA) by longitudinal data. Two surveys were conducted with one year interval and total 112 respondents participated in both surveys. Hierarchical regression analysis was employed to investigate that happiness in the first time have an effect on GPA in the second time after controlling for GPA in the first time as well as demographic variables. We found that life satisfaction and positive affect in the first survey improved GPA after the next semester. Interestingly, GPA did not bring happiness by this longitudinal data. The implication for study were discussed.

• Steel and Composite Structures
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• v.47 no.1
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• pp.19-36
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• 2023

An experimental study of eleven PVC-FRP Confined Concrete (PFCC) column-Reinforced Concrete (RC) beam joints reinforced with Core Steel Tube (CST) under axial compression is carried out. All specimens are designed in accordance with the principle of "weak column and strong joint". The influences of FRP strips spacing, length and steel ratio of CST, height and stirrup ratio of joint on mechanical behavior are investigated. As the design anticipated, all specimens are destroyed by column failure. The failure mode of PFCC column-RC beam joint reinforced with CST is the yielding of longitudinal steel bars, CST and stirrups of column as well as the fracture of FRP strips and PVC tube. The ultimate bearing capacity decreases as FRP strips spacing or joint height increases. The effects of other three studied parameters on ultimate bearing capacity are not obvious. The strain development rules of longitudinal steel bars, PVC tube, FRP strips, column stirrups and CST are revealed. The effects of various studied parameters on stiffness are also examined. Additionally, an influence coefficient of joint height is introduced based on the regression analysis of test data, a theoretical formula for predicting bearing capacity is proposed and it agrees well with test data.

• The Journal of Korean Association of Computer Education
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• v.20 no.3
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• pp.35-46
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• 2017

The purpose of this study is to analyse the longitudinal relations between creativity, academic achievements, and utilization of computer & smartphone of middle school students. For this purpose, multivariate latent growth model was verified, using three year longitudinal panel data of Seoul Educational Longitudinal Study(2013-2015). Results indicated that the more students in their first year used computer & smartphone, the better scores they obtained on the creativity and academic achievements. As their grade goes up, while the growth rates of using computer & smartphone and creativity were related positively, the growth rates of using computer & smartphone and academic achievements -even though it was not statistically significant- were related negatively. In addition, the first year students, who obtained high level of scores on the creativity, obtained high level of scores on academic achievements, but this tendency was not significant as their grade goes up.

• Korean Journal of Childcare and Education
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• v.12 no.5
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• pp.137-155
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• 2016

The purpose of the present study was to investigate the longitudinal relationship between main caregivers' life satisfaction and depression and self-esteem of school-aged children, and to provide plans for improving the lives of the school-aged children. For this purpose, we analyzed the three years'longitudinal panel data (2011-2013) of the Korean Children and Youth Panel Survey (KCYPS) including 2,342 first grade elementary school children employing the latent growth model using SPSS 18.0 and AMOS 22.0. Analysis results were as follows. First, main caregivers'life satisfaction and school-aged children's depression increased as time passes and linear change model was selected. Second, the initial status of main caregivers'life satisfaction had effects on the initial status of their children's depression, but initial status and rates of change of life satisfaction did not have an influence on the rates of change of the depression. However, it was found that the main caregivers' life satisfaction had effects on the school-aged children's self-esteem and it worked as a mediator on the longitudinal relationship between the main caregivers'life satisfaction and the children's depression. School-aged children's self-esteem was a partial mediator on the initial status of their depression and full mediator on these rates of change. These findings suggests that programs improving school-aged children's self-esteem should be developed.

• Journal of the Korean Institute of Navigation
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• v.8 no.2
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• pp.51-70
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• 1984

In the North Pacific Ocean a lot of large waves set up in winter, affected by continued winds and swells owing to severe extratropical cyclones. Under this sea condition, if the ship is about 100,000L/T (in deadweight capacity tonnage), we can't find the danger involved in the ship at sea apparently. But when we compare the seaworthiness of ship's building strength with the stress given to the hull by waves, we can't insist that the former be more stronger than the latter. As a result, VLCC is in danger of destroying and cutting for lack of longitudinal strength in heavy weather. Up to this time, Naval Architects have actively studied the relation between ship's longitudinal strength and waves as a ship's projector; however, actually, they have never made more profound study on the problem of longitudinal strength in relation to navigation. The main puprpose of this thesis is to clarify these vivid actual states of ship's trouble unknown to ship's masters. In this thesis we picked up VLCC Pan Yard, a vessel of Pan Ocean Bulk Carrier company's, as a model ship. And in the North Pacific Ocean, we have chosen for this research the basins where the wind speed and the wave height are greater than average. The data used this thesis are quotes from the "winds and waves of the North Pacific Ocean('64-'73)", and wind speed more than 30 knots was made use of as an ocject of this study. By usinh the ITTC wave spectrum, we found out the significant waves for every 5 knots within the range of 20 knots to 45 knots of wind speed. According to this H1/1000 was calculated. The stress of ship's hull is determined by ship's speed and wave height. We compared the ship's longitudinal strength with a planned wave height by rules of several famous classification societies in the world. In the last analysis, we found out that ship's present planned strength in heavy weather is not enough. Finally we made a graph for avoiding heavy weather, with which we studied safe ship's handling in the North pacafic Ocean in winter.

• Journal of the Korean Data and Information Science Society
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• v.28 no.1
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• pp.1-10
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• 2017

Longitudinal data of Korean child academic achievement have been used to find the significant exploratory variables under the assumption of independent repeated measured data. Using the exploratory variables in previous research works, we analyze the linear mixed model incorporating the fixed and random effects for child academic achievement to detect the significant exploratory variables. Korea welfare panel study data observed three times between 2006 and 2012 by additional survey for children. The child academic achievement is evaluated by the sum of academic achievements of Korean, English and Mathematics. We also investigate the multicollinearity and the missing mechanism and select some popular correlation matrices to analyze the linear mixed model.

• The Journal of the Korean dental association
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• v.54 no.11
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• pp.850-864
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• 2016

The Generalized Estimating Equations (GEE) approach is a widely used statistical method for analyzing longitudinal data and clustered data in clinical studies. In dentistry, due to multiple outcomes obtained from one patient, the outcomes produced from an individual patient are correlated with one another. This study focused on the basic ideas of GEE and introduced the types of covariance matrix and working correlation matrix. The quasi-likelihood information criterion (QIC) and quasi-likelihood information criterion approximation ($QIC_u$) were used to select the best working correlation matrix and the best fitting model for the correlated outcomes. The purpose of this study is to show a detailed process for the GEE analysis using SPSS software along with an orthodontic miniscrew example, and to help understand how to use GEE analysis in dental research.

• Journal of Korean Home Economics Education Association
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• v.34 no.3
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• pp.49-65
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• 2022

This study aims to examine the mutual influences of negative parenting attitudes, self-esteem, and life satisfaction perceived by adolescent children through longitudinal perspective. Data from the first to third years of the panel of the first year middle school students were used among the 2018 data of the Korean Children and Youth Panel Survey (KCYPS) of the Korea Youth Policy Institute. The longitudinal correlation was analyzed by applying the autoregressive cross-lagged model which can determine the direction of longitudinal causality between variables. As a result of the analysis, it was found that the negative parenting attitudes, self-esteem, and life satisfaction perceived by adolescents had a positive effect on the negative parenting attitude perception, self-esteem, and life satisfaction at later times, respectively. In addition, the higher the negative parenting attitude at the previous point was, the lower the self-esteem or life satisfaction afterward. The higher the life satisfaction, the lower the negative parenting attitude of the parents, and the higher the self-esteem. Recognition of negative parenting attitudes of parents lowered the self-esteem of adolescents, whereas the cross-delay coefficient from self-esteem to negative parenting attitude perception was not significant. Through these results, the longitudinal relationship between negative parenting attitude perception of adolescence, self-esteem, and life satisfaction was confirmed and efforts to form positive self-esteem and improve life satisfaction were discussed.

• 한국노년학
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• v.29 no.2
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• pp.729-742
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• 2009

The purpose of this study was to examine the changes of emotion experiences in old age and confirm the effects of emotional characteristics on the subjective well-being in old age by the longitudinal study. This longitudinal study started from 2003 and every two year we performed panel study. We analysed the data from old participants who participated tree-times(2003, 2005, 2007)and over 65 year-old. Finally, 844 old participants(male, 340; female, 504)' data were analysed. The elderly experienced more positive emotions than negatives and these results represented affective optimization. We performed mixed ANOVA method and confirmed significant change of emotion experiences during 6 years. Positive emotion experiences and negative emotion experiences were decreased as they get older. We also examined the effects of emotional experiences on the subjective well-being. In results, emotion experiences were more effective than the demographic variables for maintaining subjective well-being in old age. Decreasing negative emotion experiences and increasing positive emotion experiences can keep happy life up in old age. The importance of the quality of emotional life in old age and the necessity of longitudinal study of aging were discussed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.10
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• pp.509-516
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• 2020

Since the 1960s, many rivers have been polluted and destroyed due to river repair projects for economic development and the covering of small rivers due to urbanization. Many studies have analyzed rivers using measured river topographic factors, but surveying is not easy when the flow rate changes rapidly, such as during a flood. In addition, the previous research has been mainly about the cross section of a river, so information on the longitudinal profile is insufficient. This research used informational entropy theory to obtain an equation that can calculate the average river slope, river slope, and river longitudinal elevation for a river basin in real time. The applicability was analyzed through comparison with measured data of a river's characteristic factors obtained from a river plan. The parameters were calculated using informational entropy theory, nonlinear regression analysis, and actual data. The longitudinal elevation entropy equation for each stream was then calculated, and so was the average river slope. All of the values were over 0.96, so it seems that reliable results can be obtained when calculating river characteristic factors.