• Journal of Digital Convergence
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• v.13 no.8
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• pp.267-279
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• 2015

The study aimed to examine the longitudinal relationship between addictive use of mobile phones and learning activities for elementary school students and to analyze (1)temporal changes of the addictive use of mobile phones and learning activities, (2)temporal relationship between them, and (3)multiple and complex group analysis across gender on the relationship. For the study, 3-year longitudinal data(2010-2012) of the Korean Children and Youth Panel Survey and autoregressive cross-lagged modeling were used. The findings showed that the addictive use of mobile phones and learning activities had a significant positive effect on the future selves of children over time. The addictive use of mobile phones influenced positively subsequent learning activities, but, the learning activities did not affect the addictive use of mobile phones. Further, there were no significant gender differences in the longitudinal relationship. The study provided the useful data to make guidelines on how to protect mobile phone addiction for elementary school students.

• Journal of Digital Convergence
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• v.14 no.12
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• pp.293-302
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• 2016

The study explores how academic strain, unhappiness, and mobile phone dependency among adolescents have changed over time. And we conducted the longitudinal and complex analysis on the influence of academic strain on unhappiness and mobile phone dependency in order to search the ways to prevent a vicious circle among them. We used general strain theory as a conceptual research frame and analysed the data of 1,589 respondents of the 2nd~4th Korean Children and Youth Panel with latent growth modeling. It was found that the levels of academic strain, unhappiness, and mobile phone dependency among adolescents were linearly increased across time. Academic strain initial status positively affected unhappiness initial status and both the initial status and change rate of mobile phone dependency. The change rate of unhappiness positively affected that of mobile phone dependency. Academic strain change rate positively influenced that of mobile phone dependency mediated by unhappiness change rate. We provided useful implications to academic activities, negative emotions, and mobile phone dependency for adolescents and suggested future studies about reasons of the changes of those variables.

• Communications of Mathematical Education
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• v.34 no.4
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• pp.525-544
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• 2020

There are many factors that affect academic achievement, and the influences of those factors are also complex. Since the factors that influence mathematics academic achievement are constantly changing and developing, longitudinal studies to predict and analyze the growth of learners are needed. This study uses longitudinal data from 2014 (second year of middle school) to 2017 (second year of high school) of the Seoul Education Longitudibal Study, and divides it into groups with similar longitudinal patterns of change in mathematics academic achievement. The longitudinal change patterns and direct influence of mood and satisfaction were examined. As a result of the study, it was found that the mathematics academic achievement of the first group (1456 students, 68.3%) including the majority of students and the second group (677 students) of the top 31.7% had a direct influence on the mathematics class attitude. It was found that the mood and satisfaction of mathematics classes did not have a direct effect. In addition, the influence of mathematics class attitude on mathematics academic achievement was different according to the group. In addition, students in group 2 with high academic achievement in mathematics showed higher mathematics class attitude, mood, and satisfaction. In addition, the attitude, atmosphere, and satisfaction of mathematics classes were found to change continuously from the second year of middle school to the second year of high school, and the extent of the change was small.

• Korean Journal of Social Welfare
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• v.63 no.1
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• pp.187-215
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• 2011

This study examined the longitudinal relationship between depressive symptoms and alcohol use based on the tension reduction hypothesis and the intoxication hypothesis considering for path of depressive symptoms on alcohol use and vice versa simultaneously. And this study examined the effect of psychosocial behavior factors (i.e. smoking level, self-esteem, satisfaction with family relationships, and satisfaction with social relationships) on depressive symptoms and alcohol use. Using the data on the Korea Welfare Panel Study for the 1st, 2nd, and 3rd years, this study were estimated using the Latent Growth Curve Model which is helpful for examining differences between the two. The results are as follows: the initial level of alcohol use had a positive impact on the rate of change in depressive symptoms, thereby supporting the intoxication hypothesis. Second, self-esteem and satisfaction with family relationships act as variables with the biggest effect on the initial level and the rate of change in depressive symptoms, whereas other psychosocial behavior factors such as smoking level and satisfaction with social relationship exert the largest influence over the initial level and the rate of change in alcohol use. This study has implications in that it clarified the confused relationship mechanism between alcohol use and depressive symptoms the two. Based on the finding of the study, political and practical implications were discussed.

• Journal of Digital Convergence
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• v.19 no.6
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• pp.373-385
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• 2021

In this study, the Korea Youth Policy Institute applied a self-registering model to verify the patterns of parental stress, multicultural youth psychological maladjustment, and interdependence between three factors by using five-point-time data tracked from middle school to high school. According to the analysis, First, Parent' stress at the time of the five surveys had a significant positive effect on the psychological maladjustment and the risk of academic interruption of multicultural adolescents at that point. Second, the psychological maladaptation of multicultural adolescents at the time of the previous five surveys had a significant positive effect on the risk of academic interruption at that point. Based on these analysis results, various support measures were proposed to cope with the stress of multicultural youth parents, and policy alternatives were proposed to prevent the risk of academic interruption by reducing the psychological maladjustment of multicultural youth.

• Journal of Digital Convergence
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• v.19 no.9
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• pp.361-371
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• 2021

This study investigated the longitudinal effect of peer play behavior (PPB) during toddlerhood on social competence (SC), followed by the effect on adaptation to elementary school. Data were collected from the 4th to 9th Panel Study on Korean Children between 2011 to 2016, of which the data collected from 114 boys and 94 girls were finally analyzed. Multi-Mediator Model Analysis were performed using SPSS and PROCESS macro programs. First, PPB observed at the age of three significantly predicted PPB observed at ages four and five. It significantly affected SC observed at the age of six after transitioning through PPB at each stage. Second, PPB observed at the age of three significantly impacted the degree of adaptation in the first and second grades of elementary school. The medium identified in this second finding was PPB observed after the age of three and SC observed at the age of six.

• Proceedings of the Korea Water Resources Association Conference
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• 2018.05a
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• pp.436-436
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• 2018

하천의 조도계수는 하상 입자들의 크기 및 형상, 식생, 수로의 만곡 등 흐름특성에 영향을 주는 복합적인 경험적 매개변수이므로 그 값을 정확히 산정하는 것은 매우 어렵다(Chow, 1959). 제주도 산지하천은 하상이 매우 불규칙하고 조도계수의 불확실성으로 인해 정확한 홍수위, 홍수량 산정이 어렵다. 또한 하상경사가 매우 급하여 상류와 사류가 복합적으로 발생하므로 수치모의 시 수위차가 크게 발생할 우려가 있다. 따라서 현장실측 기반의 하천 조도계수 산정을 통한 홍수위, 홍수량 산정에 정확도를 향상시킬 필요가 있다. 이 연구에서는 제주도 북부지역의 건천(한천, 병문천, 독사천, 산지천)을 대상으로 하상재료를 직접 실측하여 하상 입경을 이용한 조도계수를 산정하였다. 실측 방법은 대상하천의 현장답사 및 현장조사를 사전에 실시하였으며, 하천의 종단 방향으로 1km 간격, 100개 이상의 하상재료를 표본으로 취하고 선격자법을 적용하였다. 대상하천 하류부의 좌안, 우안은 대부분 하천 정비에 의한 제방 구축이 되었으며, 상류부는 경사가 급한 암질로 구성되어 있으므로 하상을 중심으로 구성물질의 입경과 조고를 측정하여 상류 흐름의 영향범위를 고려한 조도계수를 산정하였다. 표본 측정시 점 사주, 여울, 웅덩이 등 국부적으로 하상재료의 변화가 심한 구역은 피하고 가급적 해당 구역에서 보편적으로 산재된 하상재료를 선택하였다. 향후 부정류 모형인 HEC-RAS를 이용하여 실측 유량과 수위를 적용한 조도계수를 산정한다면 보다 정밀한 조도계수를 산정할 것으로 판단된다.

• Journal of Digital Convergence
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• v.18 no.6
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• pp.459-466
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• 2020

This study aimed to analyze characteristics and factors affecting of depression by households type of elderly with disabilities. Data were analyzed using chi-square test, logistic regression analyses according to the PSED. Data were 608 individuals. First, The one-person households group showed significantly female, non-capital, severe disorder, lower health status, lower economic level, higher help for daily life, higher experience of discrimination, lower satisfaction with relationship, lower participation in social activities. Second, Factors affecting depression included experience of discrimination, participation in social activities. Multi-person group included gender, occupied area, health status, economic level and one-person group were help for daily life. In order to reduce depression, it is necessary to reduce experience of discrimination, improve awareness of disability, health care, economic supports and so on. This study is meaningful in that it classifies households types. In the future, there is a need to longitudinal studies.

• Journal of Digital Convergence
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• v.19 no.1
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• pp.99-105
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• 2021

This study aimed to verify the positive effect of work meaningfulness(WM) on flourishing(FL) with the successive positive effects of work engagement(WE) and job performance(JP) as dual mediators. We conducted an online survey of 395 incumbents working in the companies of different types and statistically analyzed data using SPSS and SPSS Process macro for hierarchical regression and bootstrapping. The results are as follows: 1. correlation coefficients of all combinations from four variables are significant, 2. simple mediation effects(WM-WE-FL and WE-JP-FL) are significant, 3. dual mediation effet(WM-WE-JP-FL) is verified. This study showed practical guide for the efficient management of employees in recent autonomous work environment and further studies with longitudinal method will be needed in order to verify substantially the dual mediation.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.12 no.1
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• pp.19-26
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• 2000

A numerical model is applied for predicting two-dimensional beach and dune erosion during severe storms. The model uses equation of sediment continuity and dynamic equation, governing the on-offshore sediment transport due to a disequilibrium of wave energy dissipation. And the model also uses sediment transport rate parameter K from dimensional analysis instead of that recommended by Kriebel. During a storm, a beach profile evolves to a form where the depth at the surf zone is related to the distance seaward of the waterline. In general, the erosion in the beach profile is found to be sensitive to equilibrium profile parameter, sediment transport rate parameter, storm surge level and breaking wave height.