• The korean journal of orthodontics
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• v.39 no.6
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• pp.362-371
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• 2009

Objective: The purpose of this study was to compare the longitudinal treatment effects of facemask with rapid maxillary expansion (FM/RME) and chincup (CC) therapy followed by fixed orthodontic treatment (FOT) in Class III malocclusion (CIII) patients. Methods: The samples consisted of twenty-one CIII patients who had similar skeletal and dental characteristics before FM/RME or CC therapy and good retention results (Class I molar/canine relationship and positive overbite/overjet) after FOT (Group 1, FM/RME, n = 11; Group 2, CC, n = 10). Lateral cephalograms were taken before (T0) and after FM/RME or CC therapy (T1), and after FOT and retention (T2). Skeletal and dental variables were measured. Mann-Whitney U-test and Wilcoxon signed-rank test were used for statistical analysis. Results: During T0-T1, FM/RME therapy induced forward movement of point A, and labioversion of the upper incisors. Both groups showed posterior repositioning of the mandible. FM/RME resulted in increase of the vertical dimension; however, CC caused an increase in articular angle and decrease in gonial angle. During T1-T2, both groups exhibited forward growth of point A. Group 1 showed forward growth and counterclockwise rotation of the mandible and increase of IMPA; however, Group 2, showed increase of ANS-Me/N-Me and decrease of overbite. Conclusions: The key factor for successful FM/RME and CC therapy and good retention results might be a harmonized forward growth of the maxilla that could keep pace with the growth and rotation of the mandible.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.6
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• pp.277-289
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• 2017

The purpose of this study was to compare the visitor's satisfaction factors and causal relationships among the 2010, 2012, and 2016 Korea International Exhibition of Machinery Equipment, Science and Technology for Agriculture. A total of 17 variables to evaluate the level of satisfaction were divided into three factors: contents, publicity and guidance, and environment of convenience facilities. The results were as follows. First, from 2010 to 2016, the Expo showed quantitative and qualitative growth in terms of the number of visitors, firms, and performances. Second, in 2016, the number of visitors aged below 20, foreigners, and new visitors increased year-on-year. Third, the contents, publicity and guidance, and satisfaction were higher than in the last two cases, but the environment of convenience facilities showed no difference among the years. In addition, the revisiting intention in 2012 was higher than that of 2016. Lastly, all three factors had a significant impact on the level of satisfaction in 2016, but publicity and guidance and environment of convenience facilities in 2010 and 2012 were not significant factors on satisfaction. Furthermore, the satisfaction of all three expos was confirmed to be a significant factor for the visitor's revisiting intention.

• Communications of Mathematical Education
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• v.34 no.3
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• pp.325-354
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• 2020

This study utilized longitudinal data from the 2013 year (Secondary Middle School) to 2017 year (Secondary High School) of the Seoul Education Termination Study. Using the latent growth model and the piecewise growth model, we investigated the changes in mathematics academic achievement, internal factors(self-concept, self-control, self-assessment of life satisfaction), and external factors(school climate, guardians) as students' grades increased, and examined whether internal factors and external factors influence the changes in mathematics academic achievement. We examined whether internal and external factors influence the change in academic achievement. As a result of analysis, it was found that mathematics academic achievement remained unchanged from the first grade of middle school to the second grade of middle school, and steadily increased from the second grade of middle school to the first grade of high school, and then decreased slightly in the second grade of high school. The internal and external factors had little change. It has been found that self-concept, self-control as internal factors, and school climate as external factors influence changes in mathematics academic achievement.

• Journal of Digital Convergence
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• v.17 no.8
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• pp.1-13
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• 2019

This study examined the effect of digital technologies on adolescent mental health; attention deficit, aggression, depression. Furthermore, we investigated the role of parenting style and peer attachment as they might have effects on digital technologies. Using two-wave longitudinal data, we conducted longitudinal analysis from the Korean Children and Youth Panel Survey done in 2015 and 2016. Results showed that computer and internet usage for learning purpose has a positive effect on mental health, while computer games and social media have negative effects. Also, the positive effects of learning on depression indicated stronger in adolescents who felt less affection from their parents. On the other hand, the negative effects of computer games and social media could be moderated by both parenting style and peer attachment. Implications of these results and directions for future research are discussed.

• The Journal of the Korea Contents Association
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• v.16 no.6
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• pp.649-661
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• 2016

It was intended to enhance the quality of festival and contribute as image of refined local festival by making an empirical and cross-sectional analysis of effect that the overall quality of service provided in the local festival had on users' satisfaction and revisit intention by using 2013-2014 two-year data for visitors who had enjoyed "Cheonan Heungtaryeong Dance Festival", best festival designated by Ministry of Culture, Sports and Tourism after 2012. The results of analyzing a difference for 2 years are as follows. 1) Among social quality factors, both cultural effect and image effect showed a significant difference with p=.001 and p=.004. 2) Among process quality factors, food and souvenir showed a significant difference with p=.27. 3) Among physical quality factors, both convenience in connection with the visitors' enjoying the festival and facility arrangement didn't show difference between groups with p=.130 and .408. Finally, in the item of whether the overall service quality of festival had an effect on visitor satisfaction and whether visitor satisfaction with festival had an effect on revisit intention, each of these had p=.000. So, it was shown that there was statistically significant difference. In other words, it is proved that the enhancement of service quality lead to high satisfaction, and this arouses revisit intention and produces word of mouth effect.

• 한국노년학
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• v.28 no.4
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• pp.797-813
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• 2008

The purpose of this study is to analyze the trends and to achieve in-depth understanding about the research on families in later life. The journal articles related to the elderly and family studies published between 1980 and 2008 were analyzed for theories, research subjects and methodology. A total of 181 research articles were published focused on the elderly and families during this period of time. The results are as follows; there has been a steady increase in the number of research articles analyzing the elderly and families since 1980. However, there was little effort to integrate empirical findings with theories. With regards to the methodology, the majority of the studies used quantitative methods, although the number of the qualitative studies increased after 1990. The size of samples in most of the quantitative studies was large enough to test inferential statistic techniques. The research subjects such as family relations(parent-adult child, grandparent-grandchildren), family conflict, support system were studied in depth; however, the practical use of these research findings in welfare policies and service programs was not so effective. In future, researchers should be expected to play important roles in the practical fields and the policy implementation process utilizing their research findings.

• Proceedings of the Korean Information Science Society Conference
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• 2002.10e
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• pp.442-444
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• 2002

본 논문은 인터넷 전화 (Internet Telephony)의 대표적 프로토콜인 SIP의 이동성과 효율적인 네트워크 대역 이용에 관한 연구이다. 이동성을 제공하기 위해 모바일 IP를 사용하기에는 삼각 라우팅, 캡슐화 오버헤드와 같은 단점이 있다고 알려진 것에 비해 이러한 모바일 IP 기반 SIP 애플리케이션의 가능성과 적합성을 보인 기존의 연구 〔1〕에서 더 나아가 무선통신에서 발생하는 핸드오프 동안에도 패킷 손실을 최소화 할 수 있는 패킷 당 오디오 프레임 수의 상관관계를 설계하고, 무선통신 종단 간 물리적 거리 변화에 따라 동적으로패킷 당 프레임 수를 조절하여 적용할 수 있는 적응적 애플리케이션 개발을 위한 표준을 제시한다.

• Proceedings of the Korea Water Resources Association Conference
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• 2008.05a
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• pp.893-896
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• 2008

본 연구의 목적은 저수지내에서 유사거동 현상 중 실제 저수지가 운영되는 조건하에서 소류사가 어떻게 거동하는가를 대표적인 소류사 공식을 통해 분석하고자 한다. 이를 위해 소류사 모의시 적용되는 하류단 경계조건 즉 저수지 수위와 저수지내 소류사 퇴적형상과의 관계를 모의할 수 있도록 대표적인 소류사 공식을 이용한 유사해석모형을 개발하고 분석하였다. 본 연구에서는 비교적 규모가 큰 다목적댐을 대상으로 과거의 저수지운영 실적을 근거로 하류 단 경계수위와 홍수량에 대해 일단위 평균자료를 적용하여 소류사를 모의하고 그 소류사의 퇴적 형상이 저수지 종단상에서 1차원적으로 시간에 따른 어떻게 거동하는 가를 고찰하였다.

• 한국노년학
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• v.32 no.4
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• pp.1063-1086
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• 2012

The purpose of this study is to understand the current state of the older people's social exclusion by identifying patterns of the change in social exclusion level through a longitudinal analysis with an aim of exploring the predictors of changes. To this end, this study has adopted the panel data, the English longitudinal Study of Ageing(ELSA). The data of 7631 respondents who aged over 50 were used for the final analysis. The social exclusion of the older people was analyzed into five different sub-dimensions: social relationship; cultural activities; access to health services; financial security; and sense of loneliness. The person-centered approach that focuses on the various patterns of the trajectories of change has used semi-parametric group based model in order to estimate different trajectories among individuals. The data was analyzed using Spss 18.0 and SAS 9.2 proc traj. In results, First, semi-parametric group-based model analysis has shown that the older people are not 'homogeneous' group with similar exclusion level in every individual with same trajectories of change, but can be divided into various categories with diverse intercept and slope. Second, different trajectories in change of exclusion level help to confirm that the older people's social exclusion level increases gradually over time or remains unchanged. Third, this analysis has provided the useful guidelines to identify the high-risk groups of social exclusion. Forth, the variables that make difference in more than three dimensions include gender, age, self-perceived health, physical activity, weekly income, marital status, family relation, and beneficiary status. Implications and further suggestion were discussed.

• Korean Journal of Social Welfare Studies
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• v.47 no.4
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• pp.309-332
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• 2016

This research attempts to calculate the vertical equity of National Health Insurance Contribution of locally provided policy holders by abilities to pay. Also, this longitudinal study examined the influence of abilities to pay and demographic characteristics on the health insurance premium. Using data from the Korea Welfare Panel Study, this study followed the self-employed households who continued to participate in the survey from 2011 to 2015. Kakwani's index of progressivity was measured as a measure of vertical equity and panel regression analysis was conducted by STATA program. The results of this research are as follows. First, from 2011 to 2015, the values of kakwani's index were negative according to composite income, which meant some levels of regressiveness of contribution. Secondly, panel regression analysis showed that the lowest household of composite income had a significantly negative effect on premiums, which also meant regressiveness. Based on the results, the author suggested political discussions on reorganizing the system of imposing the National Health Insurance contribution.