• Education of Primary School Mathematics
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• v.24 no.1
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• pp.1-20
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• 2021

Factors influencing mathematics academic achievement are constantly changing and have direct and indirect effects on mathematics achievement, so longitudinal studies that can predict and analyze their growth are needed. This study uses longitudinal data on students from 2011 (5th grade of elementary school) to 2015 (2nd grade of middle school) of the Seoul Education Longitudinal Study, and divides them into groups with similar longitudinal changes in mathematics academic achievement. The direct and indirect effects of learning attitudes and achievement goals were examined. As a result of the study, it was found that learning effort and learning attitude had a direct effect on mathematics achievement in 1 group (2277 students, 67.7%), and learning attitude had a direct effect on mathematics achievement in 3 groups (958 students, 28.5%). And it was found that learning effort h ad an indirect effect. In addition, it was found that both learning attitudes, learning efforts, and achievement goals had no effect on the academic achievement of mathematics in the second group (127 students, 3.8%).

• 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.

• The Journal of the Korea institute of electronic communication sciences
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• v.6 no.1
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• pp.49-54
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• 2011

In this paper, End-to-End VoIP(Voice over Internet Protocol) performance over large scale MANET(Mobile Ad-hoc Networks) is evaluated. VoIP implementation model, which can be used for large scale MANET, is suggested through this evaluation. VoIP simulator based on NS-2 network simulator is used for performance measurement. Call connection ratio as a connection performance, MOS and network delay as a transmission performance, packet loss rate as other performance is measured with this simulation. Finally, maximum $10{\sim}15km^2$ as a single MANET, 500 nodes and 100 call connections is suggested for VoIP implementation and operation conditions over large scale MANETs.

• The Mathematical Education
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• v.55 no.4
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• pp.447-465
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• 2016

The purpose of this study is to analyze longitudinal trends of students' mathematical affective domain by use of the data mining method. For this purpose, we used the Korea education longitudinal study(KELS 2005) which was the survey data for students' achievement test, affective domain test, teachers' evaluation, and parents' evaluation from $7^{th}$ grader in the year of 2005 to $11^{th}$ grader in the year of 2010. Subjects of this study is a total of 5040 students who answered to the mathematical affective domain survey in KELS 2005. The result findings are as follows. First, students' affective domain had changed negatively as they went up to higher grade. Second, if students' affective domain had built at a certain level in $7^{th}$ grade, the level did not change easily until $11^{th}$ grade. Third, major factors of students' affective domain were shown to be self-efficacy, intrinsic motivation, efforts and patient, and time management.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.26 no.3
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• pp.281-289
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• 2016

In this paper, a new dynamic model for modal analysis of a rotating cantilever beam with a tip-mass is developed. The nonlinear strain such as von Karman type and the corresponding linearized stress are used to consider the geometric nonlinearity, and Euler-Bernoulli beam theory is applied in the present model. The nonlinear equations of motion and the associated boundary conditions which include the inertia of the tip-mass are derived through Hamilton's principle. In order to investigate modal characteristics of the present model, the linearized equations of motion in the neighborhood of the equilibrium position are obtained by using perturbation technique to the nonlinear equations. Since the effect of the tip-mass is considered to the boundary condition of the flexible beam, weak forms are used to discretize the linearized equations. Compared with equations related to stiffening effect due to centrifugal force of the present and the previous model, the present model predicts the dynamic characteristic more precisely than the another model. As a result, the difference of natural frequencies loci between two models become larger as the rotating speed increases. In addition, we observed that the mode veering phenomenon occurs at the certain rotating speed.

• Korean Journal of Social Welfare
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• v.64 no.4
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• pp.285-310
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• 2012

This study examined the causal relationship of between stressors and depression using the wave 1~4 of Korean Welfare Panel Study by social stress theory. According to the result, the level of depression and depressed group was decreased in the course of time. As a panel regression analysis, Factors affecting the reduction of depression was upward of the income hierarchy, increase the satisfaction of family and social relationships, and residential satisfaction. Based on the results, the author suggested that social work policies and intervention direction should decrease social stress factors with causality to depression of the men in baby boom generation.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 1999.11a
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• pp.401-405
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• 1999

본 논문은 실시간성 서비스인 버스트 트래픽을 갖는 ATM(Asynchronous Transfer Mode)망에서 실시간 연결 수락 제어를 위한 종단간의 지연보장을 알고리즘을 이용하여 실시간 서비스 트래픽 서비스 품질의 성능에 대해 분석하였다. 셀 손실 확률은 QoS(Quality of Service)의 기준이 되므로 제안된 실시간 알고리즘은 일정한 버퍼 메모리 크기와 연결 요청에 대한 수락 여부 즉, 연결 수락 여부의 결정을 위한 하나의 큐잉 서비스를 필요로 한다. 이러한 트래픽 소스 각 타입에 대한 초과된 셀에 대한 셀 손실 확률은 트래픽 소스 타입 전체에 하나만 존재하더라도 요구를 충족시킬 수 없으므로, 본 논문에서 제안된 버스트 트래픽 특성에 따라 지연보장 알고리즘을 이용한 큐 서비스 방식은 기존의 종단간 지연 보장 알고리즘들에서 사용하던 씬 정렬을 이용하지 않고 몇 개의 FIFO 큐로 구성된 라운드로빈 큐를 이용하여 복잡성을 크게 감소시켰으며 실시간 서비스와 비실시간 서비스의 서비스방식을 효과적으로 결합하여 다양한 QoS를 보장해야 하는 ATM망에 효과적으로 적용할 수 있고 제안된 알고리즘에 산출되는 각각의 셀 손실 확률에 충분한 상한선을 제공하는 전형적인 매개변수를 사용하여 성능을 분석한다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.3D
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• pp.289-294
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• 2010

It is well known that rumble strips contribute to reduce traffic accidents. The present paper provides the reduction effect of traffic accidents under specific highway geometrics after rumble strip installation. Traffic accidents on freeway sections before and after rumble strip installation are compared when conditions of the highway geometric characteristics such as horizontal, vertical geometrics are given. It is shown that rumble strips are effective under highway geometric conditions of down slopes or right curvatures. It is also shown that rumble strips are still effective with shorter length of installation.

• The Journal of the Korea Contents Association
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• v.16 no.5
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• pp.783-801
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• 2016

The purpose of this research is to grasp the influencing factors on the labor market entry of disabled women, and to suggest policy alternatives to support the labor market entry of them. This article utilized the survey data of the 3rd to the 7th Panel Survey of Employment for the Disabled in 2010-2014(by PSED), which is a longitudinal survey for the disabled in Korea. I analyzed the pattern changes of the labor market entry of them with the passage of years, and the influencing factors on that by the event history analysis. The major findings are as follows: First, according to the life table analysis involved in change of the labor market entry, 90% of them continued to remain the longest period of unemployment for four years and the labor market entry rate was only 10% of them. Second, the result of Cox regression analysis shows that public benefit recipient or not, the degree of disability and discrimination experience at the job market were factors to affect the labor market entry. With these results, this study suggested the practical alternatives to improve the labor market entry of disabled women.

• Journal of Science Education
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• v.34 no.1
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• pp.1-11
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• 2010

This study analyzes the factors influencing academic achievement on mathematic and scientific subject and its change in Korean youth by using a sample from KYPS(Korea Youth Panel Survey) data. The results are as follows: First, academic achievement on mathematic and scientific subject of Korean youth shows quadratic curve that their interrelationship between intercept and slope of academic achievement are negative which is statistically significant. Second, analysis of Latent Growth Models shows that parents, teacher, peer group, self esteem, income of family, high school tracks are found to be a statistically significant factor on mathematic. And scientific subject is affected by parents, teacher, peer group, self esteem, income of family, high school tracks. Also, Interesting finding is that father's job is not significant to dependent variables. These findings show that academic achievement on mathematic and scientific subject of the Korean youth are the quadratic curve and influenced by parents, teacher, peer group, self esteem, income of family, high school tracks. To improve youth's mathematic and scientific, Korea educational fields and educators should have policy to care youth's relationship with parents, teachers and self esteem.