• Human Ecology Research
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• v.52 no.3
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• pp.301-312
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• 2014

The purpose of this study was to examine whether a temporal relationship would develop between the overuse/addictive use of mobile phones and depression in adolescents. For this study, we used the 4-year longitudinal data (2004-2007, Study 1, which measured the overuse of mobile phones and depression) and the 2-year longitudinal data (2010-2011, Study 2, which measured the addictive use of mobile phones and depression) of the Korea Youth Panel study. In addition, the study explored gender differences with respect to the above mentioned relationship. Autoregressive cross-lagged modeling was carried out, along with a multiple group analysis across genders. The findings showed that the overuse/addictive use of mobile phones and depression in adolescents had a significant effect on the future selves of these adolescents over time. Moreover, the overuse/addictive use of mobile phones had a significant influence on subsequent depression, rather than vice versa. This means that as the overuse/addictive use of mobile phones by adolescents increases, their depression intensifies later on; however, as depression among adolescents intensifies, the overuse/addictive use of mobile phones by adolescents' does not increase. Further, the study showed there were significant gender differences in the longitudinal relationship between the overuse/addictive use of mobile phones and depression. Study 1 shows that, prior to the release of smartphones, the overuse of mobile phones had a definite effect on the depression of only males. However, Study 2 shows that, after the release of smartphones, the effect of the addictive use of mobile phones on depression in females was greater than that in males.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2002.09a
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• pp.114-122
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• 2002

The ASCE formula of lifeline.soil interaction force is the basis of semi-analytical relationship for buried pipelines subjected to longitudinal permanent ground deformation due to seismic induced liquefaction. However, since the ASCE formula has been developed based on the stiffness of non-liquefied region, it is needed to modify for the varied stiffness of liquefied region. With this object, the consideration of decreasing effect of soil stiffness in liquefied region is made: i.e. the spatial distributions of pipeline-soil interaction force in liquefied region. It means that the improved formula can reflect various patterns of permanent ground deformation more realistically. Through the comparative analyses using both the improved and ASCE formula, the applicability of the improved and the limitation of the ASCE formula and semi-analytical relationship are discussed. Also, relative influences of various parameters are evaluated for the clarification of behavior of pipeline subjected to longitudinal permanent ground deformation due to liquefaction.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.04a
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• pp.103-106
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• 2000

Nondestructive tests are useful method in rapidly evaluating the condition of existing concrete structures. An objective of this work is to investigate the factors influencing the longitudinal wave velocity-strength relationship, such as w/c ratio, curing temperature, curing condition. Test results show that a change in the w/c ratio ranging from 0.46 to 0.88 and in the curing temperature from 1$0^{\circ}C$ to 3$0^{\circ}C$ did not alter the velocity-strength relationship. however, curing methods had significant effects on the velocity-strength relationship. Therefore, the estimation of compressive strength until 28 day can be accomplished by only a nonlinear equation with consideration of curing condition.

• Steel and Composite Structures
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• v.10 no.4
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• pp.317-329
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• 2010

According to the results of 9 circular concrete filled steel tube (CFT) push-out tests, a new theoretical model for average bond stress versus free end slip curve is proposed. The relationship between verage bond stress and free end slip is obtained considering some varying influential parameters such as slenderness ratio and diameter-to-thickness ratio. Based on measured steel tube strain and relative slip at different longitudinal positions, the distribution of bond stress and relative slip along the length of steel tube is obtained. An equation for predicting the varying bond-slip relationship along longitudinal length and a position function reflecting the variation are proposed. The presented method can be used in the application of finite element method to analyze the behavior of CFT structures.

• Korean Journal of Childcare and Education
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• v.15 no.5
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• pp.23-45
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• 2019

Objective: The purpose of this study is to identify the longitudinal reciprocal relationship between young children's vocabulary ability and physical aggression in young children. Methods: Two waves of panel data(2013/2015) from the Panel Study of Korean Children were analyzed in this study by using an adapted version of Autoregressive cross-lagged modeling. A total of 306 five-year-old and seven-year-old preschoolers, and their mothers participated in the study. Autoregressive cross-lagged modeling for multiple groups was conducted by using AMOS 24.0. Results: First, vocabulary ability and physical aggression showed stability over time. Second, young children's vocabulary ability(t) had a statistically significant effect on physical aggression(t+1). Conclusion/Implications: This study confirmed the interrelationships of young children's vocabulary ability and physical aggression by examining longitudinal data using the longitudinal analysis method. This study highlights the importance of developing interventions to support language development with aggressive children. The results of the present study can be used as a source in developing policies for aggressive children and their parents.

• Korean Journal of Childcare and Education
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• v.20 no.1
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• pp.39-53
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• 2024

Objective: The purpose of this study is to investigate whether emotionality at age three predicts early school-age media overdependence and to examine the potential mediating role of internalizing behavior problems in children. Methods: This study employed data from the 4th and 10th waves of the Panel Study of Korea Children, comprising a sample of 1,270 children. Assessments of emotionality (4th wave), media overdependence (10th wave), and internalizing behavior problems (10th wave) were conducted. Data analysis utilized SPSS and the Process Macro. Results: At age 3, heightened emotionality was found to directly contribute to an increased tendency for media overdependence in early school age. Internalizing behavior problems played a significant mediating role in the relationship between emotionality and media overdependence. Conclusion/Implications: This study validated a significant longitudinal connection between emotionality and the inclination to excessively rely on media, highlighting the role of internalization behavior problems in this relationship. It is essential to provide focused attention, especially to children displaying heightened emotionality in early childhood, in order to proactively prevent internalization behavior problems and the undue dependence on media.

• Geomechanics and Engineering
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• v.35 no.4
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• pp.411-424
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• 2023

Reasonable estimates of tunnel lining dislocations in the operation stage, especially under longitudinal differential settlement, are important for the design of waterproof gaskets. In this paper, a modified shell-joint model is proposed to calculate shield tunnel dislocations under longitudinal differential settlement, with the ability to consider the nonlinear shear stiffness of the joint. In the case of shell elements in the model, an elastoplastic damage constitutive model was adopted to describe the nonlinear stress-strain relationship of concrete. After verifying its applicability and correctness against a full-scale tunnel test and a joint shear test, the proposed model was used to analyze the dislocation behaviors of a shield tunnel in Shanghai Metro Line 2 under longitudinal differential settlement. Based on the results, when the tunnel structure is solely subjected to water-earth load, circumferential and longitudinal joint dislocations are all less than 0.1 mm. When the tunnel suffers longitudinal differential settlement and the curvature radius of the differential settlement is less than 300 m, although maximum longitudinal joint dislocation is still less than 0.1 mm, the maximum circumferential joint dislocation is approximately 10.3 mm, which leads to leakage and damage of the tunnel structure. However, with concavo-convex tenons applied to circumferential joints, the maximum dislocation value reduces to 4.5 mm.

• Journal of the Korean Home Economics Association
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• v.38 no.5
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• pp.15-24
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• 2000

The purpose of the study was to explore the causal relationships between delinquency and self-esteem among adolescents. The subjects of this study were 497 adolescents attending middle schools in Pusan. The data was collected by longitudinal research design of 9 month interval In first, second wave, the participants completed the delinquency scale and the multidimensional self-esteem inventory that includes home self, peer-related self, teacher-related self, academic-general serif, physical appearance self, physical competence self, and personality self, respectively The major findings of this study were as follows: these causal relationships differed among subdimensions of self-esteem, 1)the causal relationship between delinquency and home self was bidirectional, 2)the causal relationship between delinquency and peer-related self, teacher-related self, academic-general self, and personality self was unidirectional, 3)the causal relationship between delinquency and physical appearance self, physical competence self was not statistically significant.

• Journal of Preventive Medicine and Public Health
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• v.43 no.3
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• pp.193-204
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• 2010

Objectives: The objective of this study was to analyze the causal relationship between smoking and depression using longitudinal data. Methods: Two waves of the Korea Welfare Panel collected in 2006 and 2007 were used. The sample consisted of 14 426 in 2006 and 13 052 in 2007 who were aged 20 and older. Smoking was measured by smoking amount (none/$\geq$ two packs). Depression was defined when the summated CESD (center for epidemiological studies depression)-11 score was greater than or equal to 16. The causal relationship between smoking and depression was tested using logistic regression. In order to test the causal effect of smoking on depression, depression at year 2 was regressed on smoking status at year 1 only using the sample without depression at year 1. Likewise, smoking status at year 2 was regressed on depression at year 1 only using those who were not smoking at year 1 in order to test the causal effect of depression on smoking. The statistical package used was Stata 10.0. Sampling weights were applied to obtain the population estimation. Results: The logistic regression testing for the causal relationship between smoking and depression showed that smoking at year 1 was significantly related to depression at year 2. Smoking amounts associated with depression were different among age groups. On the other hand, the results from the logistic regression testing for the opposite direction of the relationship between smoking and depression found no significant association regardless of age group. Conclusions: The study results showed some evidence that smoking caused depression but not the other way around.

• Journal of Korean Academy of Nursing
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• v.49 no.1
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• pp.69-79
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• 2019

Purpose: This study aimed to identify the directionality of the causal relationship and interaction between depression and amount of smoking over time in hardcore smokers using longitudinal descriptive analysis. Methods: Secondary data from the Korean Welfare Panel Study were analyzed using autoregressive cross-lagged modeling. Participants included 342 hardcore smokers who participated in the 8th to 11th waves of the panel study. Results: Analyses revealed that change(s) in depression levels according to time had a significant positive relationship with the total amount of smoking per day (${\beta}=.29$, ${\beta}=.19$, ${\beta}=.17$, p<.001), while change(s) in total amount of smoking per day according to time had a significant positive relationship with depression (${\beta}=.43$, ${\beta}=.50$, ${\beta}=.38$, p<.001). Analysis of the cross-lagged effect between depression and total amount of smoking per day showed that depression at one time point had a significantly positive relationship with the total amount of smoking per day at the next time point (${\beta}=.14$, ${\beta}=.13$, ${\beta}=.13$, p=.021), and that the total amount of smoking per day at one time point had a significant positive relationship with depression at the next time point (${\beta}=.04$, ${\beta}=.04$, ${\beta}=.03$, p=.044). Conclusion: The findings in the present study confirmed a cross-interaction between depression and total amount of smoking per day in hardcore smokers. The present findings could be used to develop appropriate smoking-related interventions.