• Journal of Korea Spatial Information System Society
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• v.7 no.1 s.13
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• pp.77-89
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• 2005

Recently, application area on the Location Based System(LBS) is increasing because of development of mobile-communication and GPS technique. Previous studies on the index of moving objects are classified as either index for past trajectories or current/future positions. It is necessary to develop a unified index because many applications need to process queries about both past trajectories and current/future positions at the same time. In this paper, the past trajectories of moving objects are represented as line segments and the current and future positions are represented as the function of time. We propose a new index called PCR-tree(Past, Current R-tree) for unification of past, current and future positions. Nodes of the index have bounding boxes that enclose all position data and entries in the nodes are accessed with only one interface. We implement the proposed index and show a feasibility of processing the queries about temporal-spatial domain with the query tool which we develop.

• KIPS Transactions on Computer and Communication Systems
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• v.7 no.8
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• pp.195-202
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• 2018

With the development of location-based applications such as smart phones and GPS navigation, active research is being conducted to protect location and trajectory privacy. To receive location-related services, users must disclose their exact location to the server. However, disclosure of users' location exposes not only their locations but also their trajectory to the server, which can lead to concerns of privacy violation. Furthermore, users request from the server not only location information but also multimedia information (photographs, reviews, etc. of the location), and this increases the processing cost of the server and the information to be received by the user. To solve these problems, this study proposes the EGTC (Enhanced Grid-based Trajectory Cloaking) technique. As with the existing GTC (Grid-based Trajectory Cloaking) technique, EGTC method divides the user trajectory into grids at the user privacy level (UPL) and creates a cloaking region in which a random query sequence is determined. In the next step, the necessary information is received as index by considering the sub-grid cell corresponding to the path through which the user wishes to move as c(x,y). The proposed method ensures the trajectory privacy as with the existing GTC method while reducing the amount of information the user must listen to. The excellence of the proposed method has been proven through experimental results.

• Korean Journal of Social Welfare
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• v.68 no.1
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• pp.225-248
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• 2016

This study explores the effects on development of poor children by community-based orchestra educational activities and the orchestra educational activities factors for promoting the effects using longitudinal data are those collected for "The Evaluation of the Impact of Our Neighborhood Orchestra on Children's Learning" made by the Seoul Philharmonic Orchestra. For these purposes, this study employed a latent growth model analysis of the factors such as depression, aggressive behavior, communality and interpersonal relationship of development of poor children and evaluation, satisfaction, outsiders'attention and participation of facilitative factors. The result shows that they displayed significantly positive development in depression, aggressive behavior, and interpersonal relationship. It appears that the evaluation on music achievement had a positive impact on the rate of change in communality, while the evaluation on attitude had an impact in the initial value of depression, aggressive behavior, and communality, also the sense of satisfaction had a positive impact on the initial value of communality and interpersonal relationship in conditional models. And parents' attention and participation had a negative impact on the initial value of aggressive behavior, while the attention and participation of the community showed a positive impact on the initial value of depression and aggressive behavior. Based on these results, this study attempted to broaden the understanding of the development of poor children taking part in orchestra-based educational activities and provide a practical basis for social workers' direct invention, and look for new ways by shedding light on the merits of the cultural/art education of poor children that engage in the community-based orchestra educational activities.

• Korean Journal of Child Studies
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• v.37 no.6
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• pp.145-155
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• 2016

Objective: The purpose of this study was to investigate trajectories of child peer interaction and to compare the causal effects of their predictors, including child individual variables (i.e., gender, language ability, and cognitive ability) and teacher variables (i.e., teacher efficacy and teacher-child interaction). Methods: The participants of this study were 263 children and their teachers from the forth to sixth waves of longitudinal data from the Korean Children and Youth Panel Survey by the Korea Institute of Child Care and Education. The data was analyzed using Pearson's correlation and latent growth modeling. Results and Conclusion: The findings of this study are as follows: First, there was a linear decrease in child negative peer interaction over the course of 3 years, and significant individual differences were found in the trajectories (intercept and slope). Second, the predictors had significant casual effects on the trajectories of child negative peer interaction. The trajectories of child negative peer interaction involving girls, higher cognitive ability, and greater teacher-child interaction showed lower degree of intercept and a quicker decrease. Finally, the implications of findings are discussed.

• Human Ecology Research
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• v.54 no.6
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• pp.565-574
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• 2016

This research examined the trajectories of peer rejection in preschool children. This study also investigated the gender differences in the intercept and slope of the trajectories for peer rejection along with the influences of aggression, withdrawal and language ability on the trajectories of peer rejection. A latent growth curve model investigated peer rejection in 3 to 5 year olds. Three hundred and thirteen 3-year-old children were recruited from five preschools and 14 daycare centers. The children's language ability was measured by a Wechsler Preschool and Primary Scale of intelligence verbal test and teachers completed measurements for aggression and withdrawal. A peer nomination inventory was used to assess peer rejection. Children were asked to nominate three classmates who they do not like to play with. The research findings showed that peer rejection decreased during the preschool years. Compared with girls, boys showed higher levels of peer rejection and a slower change rate of peer rejection. Girls who were aggressive showed high levels of peer rejection and a slow change rate of peer rejection. Moreover, girls who had a high levels language showed low levels of peer rejection and a slow change rate of peer rejection. These findings imply that language ability could be a protective factor of peer rejection for girls.

• Human Ecology Research
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• v.56 no.2
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• pp.157-165
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• 2018

Using data from the Panel Study on Korean Children, this study investigated whether children with high levels of problem behaviors adjusted more poorly on the $1^{st}-grade$ than children with low levels of problem behaviors, and whether there was evidence of intra-individual stability in behavior problems over time. Data were analyzed by use of the Latent Growth Model and group differences analyses. Three findings were noteworthy. First, there was evidence of intra-individual and inter-individual variability in behavior problems between poor- and non-poor household children. Second, children with higher initial levels of internalizing and externalizing behaviors at 4 years had lower school readiness scores at 6 years. Finally, children with lower levels of school readiness at 6 years had lower school adjustment scores in $1^{st}$ grade. The results discuss implications for future research and policies for preschool children. With mediating effect of school readiness, developmental trajectories of child's problem behavior have been found to be predictors of delayed achievements in school. The results show that intervention programs are necessary for children with high levels of problem behavior. This study also showed that children who experienced poverty at home could have more difficulties in school readiness and school adjustment.

• Korean Journal of Health Education and Promotion
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• v.32 no.5
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• pp.43-51
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• 2015

Objectives: Socioeconomic factors are one of the significant factors explaining drinking problems in our society. From the poverty and inequality perspective, not only absolute poverty but perceived level of poverty or inequality has a direct effect on one's health and health behaviors. The purpose of the study is to explore the growth trajectories of problem drinking in Korea in relation to poverty and perceived income. Methods: Data from 13,414 adults were analyzed using 4 years of data (2010 to 2014) from the Korea Welfare Panel. Main variables included poverty status, perceived income inequality, and problem drinking. A latent growth modeling was employed for the analysis. Results: The non-poverty group had higher initial level of problem drinking; however, the poverty group showed higher rate of increase in problem drinking rate. The perceived income inequality had no significant influence on the initial level, but over time, those with higher level of perceived income inequality showed higher rate of increase in problem drinking. Conclusions: Findings showed that poverty and inequality affect changes in problem drinking. Efforts to prevent and decrease problems related to alcohol should not only focus on changing individuals' behavior but also on decreasing the inequality gap.

• The Journal of the Korea Contents Association
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• v.21 no.4
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• pp.278-291
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• 2021

This study performed a longitudinal research on the causal relationship between multidimensionality of problem drinking and poverty, and multidimensional deprivation meaning the inequality, focusing on gender difference. For this, this study examined the latent group of problem drinking change trajectory through the latent class growth analysis targeting total 3,770 men and 5,632 women by using the 6th-year Korea Welfare Panel Study data from 2013 to 2018, and then conducted the multinominal logistic regression analysis to verify the influence of multidimensional deprivation factors on this latent group. The main results of this study are as follows. First, the latent group of problem drinking change trajectory according to gender was classified into three latent groups in both men and women while the development aspect was different from each other. The male latent group with 'moderate level' or higher showed higher level of problem drinking than women. However, in case of 'drinking group with high level' according to gender, as time passed, the men tended to maintain it while the women tended to increase it. Second, in the results of examining the effects of multidimensional deprivation on the latent group of problem drinking change trajectory, the men with more experiences of social deprivation and the women with more experiences of social security deprivation showed the higher possibility to belong to the 'drinking group with high level' compared to the 'drinking group with low level'. Based on such results above, this study discussed the preventive/intervention measures for problem drinking according to gender.

• Korean Journal of Childcare and Education
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• v.10 no.6
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• pp.333-346
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• 2014

This study looked into changes in the parenting stress and the depression of mothers whose children at the age of three or younger have been suffering from developmental risk, and discussed how the parenting stress would constantly influence the depression. In order to achieve the research goal, the study used the data from the Panel Study of Korean Children. According to the findings of the study, first of all, the parenting stress increased significantly for the next four years after the childbirth. The study also understood that there are personal differences among the mothers in relation to how much the stress gets worse overtime. Second, more severe the parenting stress during the year of the childbirth, the greater the depression during the same year, and this parenting stress's being intensified even more greatly for the four years right after the childbirth turned out to have a significant effect on how much the depression develops. What this study has found out so far confirms that the depression of the mothers will get reduced when the mothers of the children with the developmental risks before the age of three try to efficiently deal with their parenting stress.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.05a
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• pp.768-771
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• 2008

컴퓨터를 활용한 제어 기술이 발달함에 따라 무인화 시스템이 증가하고 있는 현실이다. 이 논문에서는 현재 많은 연구가 활발히 이루어지고 있는 무인화 시스템들 중의 하나인 무인 자동 주차 시스템을 위한 기법을 제안하고 시뮬레이션 실험을 통하여 그 가능성을 보였다. 제안한 자동 주차 시스템에서는 센서 정보를 입력으로 하고 퍼지 함수에 의한 추론 결과를 활용하여 조향 장치를 제어하는 방식을 제안하였다. 성능 평가를 위하여 그래픽 시뮬레이션 환경을 구축하고 제안한 기법을 이용한 가상자동차의 주차 과정을 보였으며 그 결과를 분석하였다.