• Journal of Convergence for Information Technology
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• v.12 no.5
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• pp.100-106
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• 2022

A longitudinal study refers to a research method based on longitudinal data repeatedly measured on the same object. Most of the longitudinal analysis methods are suitable for prediction or inference, and are often not suitable for use in exploratory study. In this study, an exploratory method to analyze longitudinal data is presented, which is to find the longitudinal trajectory after determining the best number of clusters by clustering longitudinal data using self-organizing map technique. The proposed methodology was applied to the longitudinal data of the Employment Information Service, and a total of 2,610 samples were analyzed. As a result of applying the methodology to the actual data applied, time-series clustering results were obtained for each panel. This indicates that it is more effective to cluster longitudinal data in advance and perform multilevel longitudinal analysis.

• The Journal of Korean Association of Computer Education
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• v.23 no.1
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• pp.53-61
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• 2020

In the information society, the ability of learners to use computers to conduct self-directed learning is important. Indeed, the higher the computer's ability to use computers, the more the academic achievement needs to be analyzed. The purpose of this study was to identify longitudinal trajectories of student awareness of ICT literacy and frequency of computer use. We also examined the effects of the longitudinal patterns on academic achievement and college major choice. A non-parametric approach, K-means for longitudinal data(KML) algorithm, was conducted using 9-year longitudinal data from Seoul Education Longitudinal Study (2010-2018). Findings indicated that a pattern presenting a higher awareness of ICT literacy and frequency of computer use showed better academic achievements and was likely to prefer to choose engineering-related majors.

• Proceeding of EDISON Challenge
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• 2016.03a
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• pp.548-553
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• 2016

본 연구는 타원형 물체가 유체 중에서 침강할 때 물체의 형상과 밀도에 따른 침강특성을 분석하는 것이며, 이로 인해 종단속도에 미치는 영향을 평가하는 것이다. 복잡한 형태의 물체를 타원기둥으로 단순화하였고, 낮은 Reynolds 수(=0.5~100)에 대하여 연구를 진행하였다. 또한 침강형태가 종단속도에 미치는 영향을 연구하였다. 수치해석 검증을 통해 정확하고 효율적인 격자 크기를 결정하였다. 정확한 분석을 위해 단순히 종단속도의 변화를 본 것이 아니라 진동하지 않은 물체의 이론적 속도와 비교하여 이와 얼마나 차이가 있는지를 확인하였다. 수치해석 결과 장단축비에 따라 물체의 침강특성이 크게 변하였고 그 경향은 밀도비에 따라 다른 양상을 보였다. 또한 각의 진동에 대한 진폭과 진동수가 물체의 침강속도에 영향을 주는 것을 확인하고 그 원인에 대해서도 연구하였다.

• The Korean Journal of Applied Statistics
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• v.37 no.1
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• pp.61-72
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• 2024

The purpose of this study is to investigate retest reliabilities in longitudinal study, the same test is administered repeatedly over time. Linear mixed models were used to establish various situations of tests occurred in longitudinal study. Combination of two types of true value and three types of systematic error was considered. In order to apply the models to real longitudinal data, height data from the Berkeley growth study and vocabulary score data from the University of Chicago experimental school were used. Using the mixed model, there is an advantage that the reliability can be determined by selecting the covariance structure of the true value and the error separately. However, in order to properly analyze the reliability, researchers need to consider variations that can occur in measurement, such as characteristics of subject, the test, and the the treatment applied in the study. And the proper model should be selected and the quality of the measurement should be evaluated for each trial.

• The Journal of Information Systems
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• v.18 no.4
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• pp.105-130
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• 2009

정교화가능성모형과 기술수용모형에 의해 정보기술 수용의 설득과정을 시도한 연구들이 이론적으로 미친 영향은 매우 크다. 그러나 이들 연구의 대부분은 횡단면적 접근에 기반한 정적 모형을 사용했기 때문에 시간 흐름에 따른 변수 간의 관계 변화를 적절히 설명하지 못하고 있다. 가령, 교육 프로그램을 통한 정보기술 수용은 일정기간의 시간을 요하는데 설득경로가 유용성의 지각에 미치는 영향력은 달라질 수 있다. 따라서 정보기술 수용과정을 충분히 규명하기 위해서는 기존의 연구모형은 종단적으로 확장되어 시간 흐름에 따른 시스템 사용을 평가해야 한다. 한편 정보기술수용 연구에서 내재적 동기의 중요성이 강조되고 있음에도 불구하고 수용 설득과정에서 내재적 동기에 대한 고려는 별로 없었고 대부분의 연구는 유용성과 같은 외재적 동기를 중심으로 이루어졌다. 본 연구의 목적은 정보기술수용 설득과정의 이해를 넓히기 기존 연구에서 제시된 연구모형에 내재된 동기에 관련된 변수를 포함하고 전체적인 모형을 종단적으로 확장했고, 실증적 검증을 위해 정규 대학과정 과목의 학생들을 대상으로 두 번에 걸친 표본 조사를 하였다.

• Journal of Gifted/Talented Education
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• v.23 no.5
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• pp.793-815
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• 2013

Research on entrepreneurial gifted youth who have immense potential within the national economy in the near future is critical. The purpose of this article is to establish the proper goal and direction of longitudinal study on entrepreneurial gifted youth and to identify substantial research problems. In order to do a theoretical inspection around preceeding research related with the field, longitudinal study of entrepreneurial youth (including gifted education and entrepreneurship) was executed. As a result, the goal, 'the verification of whether entrepreneurs can be cultivated by educational interventions' was derived as an appropriate research direction. Also, 4 major research problems are presented: (1) Description of the features of entrepreneurial gifted youth and their developmental pattern, (2) Explanation of the effects of educational intervention on intensifying entrepreneurial giftedness, (3) Prediction which identifies the factors that influence the youths' success as eminent entrepreneurs, and (4) Control over promoting talented individuals and refining relevant policy and institutions. Implications and further research directions are also discussed.

• Communications of Mathematical Education
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• v.35 no.1
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• pp.97-118
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• 2021

Since the characteristics of teachers that affect mathematics academic achievement are constantly changing and affecting mathematics achievement, longitudinal studies that can predict and analyze growth are needed. This study used data from middle and high school students from 2013(first year of middle school) to 2017(second year of high school) of the Seoul Education Longitudibal Study(SELS). By classifying the longitudinal changes in mathematics academic achievement into similar subgroups, the direct influence of teachers' characteristics(professionalism, expectations, academic feedback) perceived by students on the longitudinal changes in mathematics academic achievement was examined. As a result of the study, it was found that the characteristics of mathematics teachers(professional performance, expectation, and academic feedback) in group 1(343 students), which included the top 14.5% of students, did not directly affect longitudinal changes in mathematics academic achievement. Students in the middle 2nd group(745, 32.2%) had academic feedback from the mathematics teacher, and the 2nd group(1225 students) in the lower 53%, which included most of the students, showed that the expectations of the mathematics teacher were the longitudinal mathematics achievement. The change has been shown to have a direct effect. This suggests that support for teaching and learning should also reflect this, as the direct influence of teachers' professionalism, expectations, and academic feedback on longitudinal changes in mathematics academic achievement is different according to the characteristics and dispositions of students.

• Korean Journal of Culture and Social Issue
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• v.28 no.3
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• pp.331-352
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• 2022

This study used a latent growth curve models(LGCM) to examine longitudinal changes in youth's game usage, self-control and the longitudinal mediation effect of adaptive game use in the relationship between game usage and self-control. A four-year longitudinal data of 863 adolescents from the Game User Panel Survey, provided through participation in the 2019 Game User Panel Research Conference hosted by the Korea Creative Contents Agency, was used to verify the longitudinal mediation effect of adaptive game use. SPSS 21 was used to verify the normality of variables from each wave, and to conduct correlation analysis. Mplus 6.12 was used to verify the longitudinal mediation effect. The results are as follows. First, game usage, self-control and adaptive game yielded linear temporal growth. Second, latent growth curve models showed that the direct effect of game usage on self-control was insignificant, but game usage had a significant indirect effect on self-control through adaptive game use. Continuous adaptive gaming increased self-control. Third, sobel test results showed that both the initial value and change rate of adaptive game use had a full-mediation effect, confirming the longitudinal mediation effect. This study verified the longitudinal change of self-control affected by change in game usage and adaptive game use.

• Proceedings of the Korean Society of Disaster Information Conference
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• 2015.11a
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• pp.199-200
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• 2015

도시부 교차로의 설계는 지방부 교차로와 근본적으로 달라야 하나, 현행 도시부 교차로 설계는 지방부 교차로 설계기준을 준용하고 있다. 본 연구는 도시부 및 지방부 교차로의 차이점을 비교 분석하고, 국내외 교차로 종단경사 설계기준을 검토한 후 적정 설계기준(안)을 적용한 후, 이를 통계적 분석기법을 활용하여 검증하여 설계기준을 정립하는 순으로 진행 하였다. 분석결과 정면충돌사고율과 차대차추돌사고율이 종단경사와 상관관계가 있는 것으로 나타났다. 이러한 연구를 통해 적정 교차로 종단경사를 적용한 설계가 이루어져야 함을 확인 할 수 있었다.

• Electronics and Telecommunications Trends
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• v.19 no.1 s.85
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• pp.9-21
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• 2004

차세대 통신 시스템은 다양한 IP 멀티미디어 응용을 지원하고, 유비쿼터스 서비스를 제공할 수 있도록 다양한 유무선 통신 시스템들이 IP 기반의 멀티네트워크로 통합될 것이다. 이러한 차세대 통신 시스템에서 IP 기반 멀티미디어 응용을 효율적으로 지원하기 위하여 종단간 QoS 제공이 중요한 문제가 된다. 본 고에서는 3세대 이동통신과 차세대 백본 네트워크(NGN)에서 연구되고 있는 QoS 제공 방안을 살펴본다. 그리고, 3세대 이후의 통신 시스템을 위하여 IP 네트워크에 기반을 두고 이질적인 무선 시스템들의 통합에 대해 연구하고 있는 프로젝트에서 All-IP화에 따른 종단간 QoS 제공 방안을 살펴본다. 그리고, 다양한 통신 시스템들이 IP 기반의 백본 네트워크로 통합되어 All-IP화된 차세대 통신 시스템의 개략적 구조를 제시하고, 이를 기반으로 종단간 QoS 제공을 위하여 연구되어야 할 주요 사항들을 살펴본다.