• Korean Journal of School Psychology
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• v.16 no.1
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• pp.1-15
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• 2019

The purpose of this study was to explore the concurrent and lagged effects of parental neglect and abuse on longitudinal changes in late childhood school adjustment. This study utilized survey data from the fourth through seventh iterations of the Korean Child Youth Panel Study conducted on fourth-year elementary school students through first-year middle school students. The data was analyzed using latent growth modeling. The results were as follows. First, the level of school adjustment decreased gradually. Second, both neglect and abuse had concurrent effects on school adjustment. Third, neglect had lagged effects on school adjustment but abuse did not. The paper discusses the implications of these results. The results of this study can be used to better understand and support children who have suffered neglect or abuse adjust to school during late childhood.

• The Journal of Korean Association of Computer Education
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• v.15 no.3
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• pp.71-80
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• 2012

The purpose of this study is to find out the changing trajectory of online game use as the development of early adolescences. It is also to explore whether the self-control has a current and a lag effect on the game use while development of students. We found these results: (a) There is a statically significant individual variability in initial levels and rates of change in online game use over time. The change of trajectory is declined. (b) Boys also have higher rate of the change in using game than girls over time. (c) Both initial state and changing rate of online game use affects negatively the academic achievement. (d) Current effect always supports, but lag effect does not support except the period from last elementary school grade to middle school grade as explanations for the developmental relation between self-control and online game use in young adolescents.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.9
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• pp.190-198
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• 2020

The purpose of this study was to investigate the changing trajectory of self-esteem and to explore contemporaneous and lagged effects of social supports(family, friends, and teacher) of 4th graders in elementary school to 9th graders in middle school. The subjects were 1,296 multiethnic students, who participated in the Multicultural Children and Adolescents Panel Study(MCAPS) from 2011 to 2016. The results of piecewise growth function showed that students' self-esteem was increased during upper grade in elementary school but soon deceased during middle school. Individual differences were found at initial, 1st and 2nd changing status. Students with higher level at initial status in self-esteem showed less increased pattern during elementary school but greater decreased pattern during middle school. In addition, supports from family and teacher showed contemporaneous effects across all 6 years while supports from friends showed such effects only for 5 years except 9th grade. Lagged effects of family were found in elementary school and significant lagged effects with supports from friends were found at 6th and 8th grade. The results of this study imply that the social support of family, friends, and teacher has an important role to encourage the self-esteem of multicultural adolescents.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.1
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• pp.72-82
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• 2009

In OFDMA systems, cyclic delay diversity can improve the system performance due to diversity effects. However, applying cyclic delay diversity to block-hopping SC-FDMA systems can affect the performance in two contrary ways: positive effect due to increased frequency diversity and negative effect caused by increased frequency selectivity. Hence, the delay value for cyclic delay diversity should be carefully selected to maximize the system performance. This paper discusses these two contrary effects and proposes a method of determining the delay value of cyclic delay diversity for block-hopping SC-FDMA systems.

• Proceedings of the Korean Information Science Society Conference
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• 1998.10a
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• pp.468-470
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• 1998

최근 영상회의 시스템과 관련하여 해결해야 할 문제 중 데이터 전송시 발생하는 지연에 관한 연구가 진행되고 있다. 본 논문에서는 영상회의 구성을 설명하고 영상회의 시 발생하는 전송 지연을 최소화 방법에 대해서 논한다. 전송 지연을 최소화하기 위해서 근원적으로 오디오와 비디오 데이터를 분리 시켜 전송하므로 전송 시 발생하는 지연을 최소화 시켰다. 또한 이를 효과적으로 지원할 수 있는 동시화 알고리즘을 제안하고, 이 알고리즘을 기반으로 영상회의 시스템을 설계하였다.

• Journal of the Korean Home Economics Association
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• v.48 no.6
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• pp.71-82
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• 2010

This study examined the effects of parent-, peer-, and teacher-attachment on development of career maturity via the mediating effects of self concept. There were 2844 elementary school students, ages 12 to 13 years old, who participated in the Korean Youth Panel Survey. All data were used for the analyses. Gender differences were found in most of the variables, including attachment, self concept, and career maturity. The Structural Equation Modeling technique applied to the data revealed that there were both concurrent and lagged effects of attachment and self concept on career maturity. It was found that self concept played a mediating role on career maturity.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.9C
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• pp.643-651
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• 2008

In this paper, we propose a method to determine the optimal cyclic delay value of cyclic delay diversity(CDD) in orthogonal frequency division multiplexing(OFDM) systems. As the cyclic delay value increases, we can get signal to interference and noise ratio(SINR) gain by diversity effect, while SINR loss increases because of channel estimation errors. If the optimal delay value obtained by the proposed method is applied to CDD scheme, we can minimize the required SINR for a given FER(frame error rate) under the above mentioned trade-off.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.12
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• pp.49-57
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• 2008

In distributed-allocation OFDMA systems, cyclic delay diversify can improve the system performance by increasing frequency diversity. However, applying cyclic delay diversify to distributed-allocation SC-FDMA systems can affect the performance in two contrary ways: positive effect due to increased frequency diversity and negative effect caused by increased frequency selective channels. This paper addresses these two contrary effects and discusses about when cyclic delay diversity is useful and when it is not very useful for distributed-allocation SC-FDMA systems.

• The Korean Journal of Financial Management
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• v.17 no.1
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• pp.203-226
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• 2000

본 연구는 주가지수 선물시장이 도입된 1996년 5월 3일부터 1998년 12월 5일까지 1분 간격 KOSPI 200 선물가격과 현물가격의 거래자료를 이용하여 각 선물가격과 기초자산가격간의 관계와 상호작용을 검토하는데 있다. 특히 본 연구는 차익거래자나 초단기 투기자(scalper)들이 거래체결을 위해 촌각을 다투는 선물시장의 거래행태에서 볼 때, 경제적 의미를 부여할 수 있는 1분 간격 수익률 자료를 이용함으로써 시장참여자의 실제 거래에서 표출되는 정형화된 현상을 정확히 파악한다는 점에서 중요하다. 본 연구의 주요 결과를 제시하면 다음과 같다. 첫째, 주가지수 선물시장과 현물시장간에 체계적이고 긴 선도-지연 관계가 발견되었다. 주가지수 선물가격의 변화가 현물가격의 변화를 대략 26분 정도 선도하고 있으며, 대략 5분 정도 현물시장의 선도효과도 발견된다. 따라서 KOSPI 200 선물수익률과 현물수익률간의 선도-지연 관계는 한 시장에서 다른 시장으로의 일방적인 것이 아니라 시장간의 피드백(feedback)효과가 존재하며, 선물의 선도효과가 지배적인 것으로 보인다. 이러한 선도-지연 현상은 노이즈에 의한 비동시거래보다는 거래비용과 공매제약 차이 등 각 시장의 제도적 차이에 의해 발생하는 것으로 보여진다. 둘째, 약세시장 하에서 선물의 선도효과가 더욱 크게 나타났다. 이러한 현상은 약세시장 하에서 현물시장의 공매제약이 선물가격과 현물가격간의 괴리를 더욱 크게 하여 선물가격이 현물지수를 더욱 선도하게 하는 요인이 될 수도 있음을 나타내는 것이다. 셋째, 만기별 하위기간 중 97년 6월과 97년 12월을 제외한 기간은 선물과 현물가격간에 장기 안정적인 균형관계가 성립함을 발견하였다. 넷째, ARMA(p, q) 여과를 거친 선물과 현물수익률을 이용하여 97년 6월과 12월은 백터자기회귀(VAR)모형, 그 외의 기간은 오차수정(EC)모형으로 추정하였다. 표본전체기간동안 장기균형오차에 대한 조정은 선물과 현물시장에서 동시에 이루어지고 있으며, 시장간에 발생하는 불균형 상황은 아비트라지 거래로 조정되고 있음이 발견되었다. 각 만기별 모든 하위기간에 있어서는 시장간의 장기 불균형 상황이 현물시장을 통해서 조정되고 있으며, 시장이 성숙된 최근의 만기 98년 12월 하위기간에서는 선물의 15분 선도효과와 현물의 1분 선도효과가 발견되어 선물의 선도효과가 지배적임을 발견하였다.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2003.05a
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• pp.38-40
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• 2003

본 연구에서 적용한 저 NOx 연소법의 NOx 저감 효과를 비교해 보면 다단 연소법이 지연연소 효과와 국부적인 최고 화염온도 감소, 고온부에서의 산소농도 감소효과 등이 동시에 나타나 저 과잉공기 연소법, 배기가스 재순환법, 이단 연소법 보다 더 큰 NOx 저감효과를 얻을 수 있음을 알 수 있었다. 다만, 총 공급공기 량에 대한 분할 공급공기량의 비가 일정수준 이상으로 커지면 CO 발생량 증가로 효율저하 등의 문제점이 우려되므로 연소상태를 저하시키지 않는 공급비를 산정하는 것이 중요할 것으로 생각된다.