• Journal of KIISE
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• v.43 no.7
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• pp.827-833
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• 2016

HTTP Adaptive Streaming (HAS) is a technique that adapts its video quality to network conditions for providing Quality of Experience. In the HAS approach, a video content is encoded at multiple bitrates and the encoded video content is divided into several video segments. A HAS player estimates the network bandwidth and adjusts the video bitrate based on estimated bandwidth. However, the segment scheduler in the conventional HAS player requests video segments periodically without considering TCP. If the waiting duration for the next segment request is quite long, the TCP connection can be initialized and it restarts slow-start. Slow-start causes the reduction in TCP throughput and consequentially leads to low-quality video streaming. In this study, we propose a TCP-aware segment scheduling scheme to improve performance of HAS service. The proposed scheme adjusts request time for the next video request to prevent initialization of TCP connection and also considers the point of scheduling time. The simulation proves that our scheme improves the Quality of Service of the HAS service without buffer underflow issue.

• The Journal of the Korea Contents Association
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• v.15 no.3
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• pp.467-476
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• 2015

This study aims to verify mediating effect of ego-resilience and mental health between psychological home environment and adaptation to school of early adolescents in schools with Educational Welfare Priority Project(EWPP). For this purpose, multiple regression analysis and hierarchical regression analysis were conducted on the relationship between psychological home environment and adaptation to school, ego-resilience and metal health of 310 male and female students in fifth and sixth grade in four elementary schools on EWPP located in Busan area. As the result of analysis, three major variables affecting adaptation to school life turned out to be in the order of ego-resilience, home environment and mental health and both ego-resilience and mental health were confirmed to play partial mediating role in the relationship between home environment and adaptation to school life. Since home environment as a psychological variable of adolescents from poor families have an effect on adaptation to school in connection with ego-resilience and mental health as personal variables, this study can be used as base materials for the development of programs to strengthen psychological home environment, ego-resilience, and mental health. In addition, in terms of practical implications, educational welfare policies for alienated class can be practical policy alternative to mitigate social polarization.

• Korean Journal of Child Education & Care
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• v.19 no.3
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• pp.99-113
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• 2019

Objective: This study is a case study on mother's perceived the adaptation process and program of a one-year-old toddlers in daycare center. Methods: This study is a case study of four mothers who live in Seoul, South Korea and whose first child enters in daycare center at 18 or 20 months. The data collection method was applied to group interview and the individual in-depth interview method. Results: After the interview data was analyzed, first, they decided to enroll their child to a daycare center after two mothers were pregnant with the second child or the others received a phone call for admission. The first impression of the teachers had a great influence on the choice of admission when mother first visited the daycare center. mother, as well as toddlers who exhibited anxiety, experienced an adaptation process. Through communication between mother and teacher, mothers could feel the toddler's adaptation. Second, as for the difference of the adaptation program according to the daycare center type through the adaptation process of the one-year-old toddlers, there was a big difference in the program guide, the period, the content and the proceeding method. Conclusion/Implications: Based on the results of this study, it is expected that it will be a basic data for the development of the adaptation program for one-year-old toddlers in daycare center at the national level.

• Proceedings of the Korea Institute of Convergence Signal Processing
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• 2005.11a
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• pp.264-267
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• 2005

본 논문에서는 매 프레임 단위로 노이즈를 추정하는 방법을 적용하는 전처리 기법을 이용하여 적응 지각필터의 연산량을 개선하는 알고리즘을 제안한다. 제안된 전처리 잡음 주정 알고리즘은 잡음에 열화 된 대역으로부터 잡음을 추정하여 적응 지각필터에 적용함으로써 연산량 개선과 동시에 오디오 신호의 음질을 개선하는 알고리즘이다. 이는 처리되는 신호 구간에 따라 잡음에 열화 된 대역으로부터 잡음을 추정함으로써 초기 추정 잡음에 보다 가까운 추정 잡음을 얻을 수 있다. 결과적으로 적응 지각필터의 연산량을 효과적으로 줄일 수 있다. 성능 평가를 위하여 지각필터의 적용 결과와 제안한 알고리즘의 적용 결과로 얻어진 개선 신호의 SSNR, NMR의 비교와 적응 지각필터 적용 횟수, 동작 시간 등을 이용하여 성능의 개선을 확인하다.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.30 no.5
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• pp.782-793
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• 1997

To study the physiological adaptation (shift-up) of phytoplankton under the simulated upwelling conditions, nitrate uptake capacity of Dunaliella tertiolecta batch culture was measured in the laboratory using the stable isotope $^{15}N-KNO_3$. Contrary to the expected, there was no significant relationship between the maximum $V_{NO3}$ (nitrogen specific nitrate uptake rate) and the initial nitrate concentration. However, there was a strong relationship between the maximum $\rho_{NO3}$ (nitrate transport rate) and the initial nitrate concentration of $<25\;{\mu}M$, which was also influenced by the physiological status of the culture. The increase in $V_{NO3}$ was mainly due to the increase in PON (particulate organic nitrogen) concentration and partly due to the increase in $V_{NO3}$. When the phytoplankton population was severely shifted-down, the physiological adaptation of nitrate uptake was significantly inhibited at high initial nitrate concentrations. The timing of the maximum $V_{NO3}$ or $\rho_{NO3}$ was related to the initial nitrate concentration. At higher initial nitrate concentrations, maxima in $V_{NO3}$ and $\rho_{NO3}$ occurred 1 or 2 days later than at lower nitrate concentrations. This relationship was the opposite to the prediction from the shift-up model of Zimmerman et al. (1987), The shift-up process is apparently controlled by an internal time sequence and the initial nitrate concentration, but the magnitude of $V_{NO3}$ was affected little by changes in nitrate concentration.

• Journal of Digital Convergence
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• v.17 no.6
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• pp.297-305
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• 2019

The purpose of this study was to examine resilience and empathy on the relation between humanity and friendship of the early adolescents using structural equation modeling. The subjects were total 332 students of the 5th and 6th grade in elementary school and 1st and 2nd grade in junior school. The data were collected by means of the self-report questionnaire. The results of this study were as follows: Firstly, the direct effect of humanity on resilience, empathy, and friendship was found. Resilience also influence friendship directly, but empathy did not affect friendship. Secondly, humanity had influence on friendship partially mediated by resilience, but not mediated by empathy. This result shows that resilience was better mediated between humanity and friendship than empathy. Additionally, sex differences were found on empathy, but the differences were not found on resilience. The results revealed that the adolescents who scored high on humanity were better at friendship and when the higher humanity score was, the higher level of resilience was found, and this had an indirect effect on friendship quality.

• 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.

• The Korean Journal of Applied Statistics
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• v.20 no.3
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• pp.605-618
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• 2007

Adaptive sampling design is the selection procedure which depends on observed values of the variable of interest. It is the method which could be applied to the rare and unapproachable population. Adaptive cluster sampling strategies are more efficient than simple random sampling on equivalent sample size. Adaptive sampling with new estimators through the Rao-blackwell method have lower variance than Horvitz-Thompson (HT) and Hansen-Hurwitz (HH). Also, to determine suitable sample size, it was used expected sample and the method finding appropriate sample size by changing initial sample size were studied.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 1999.11b
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• pp.179-183
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• 1999

일반적인 통신 시스템에서 높은 전력을 가지는 출력 신호를 얻기 위하여 고전력증폭기(HPA)의 사용은 필수적이다. 그러나 HPA를 통과한 신호는 AM/AM 및 AM/PM의 비선형왜곡이 발생하는 단점을 가지고 있다. 그 결과 송신신호의 대역내 신호 스펙트럼이 왜곡되고 신호의 대역폭을 확장시켜 인접채널에 간섭을 유발한다. 본 논문에서는 HPA의 비선형 왜곡 특성을 보상하기 위하여 기저대역에서 룩업테이블(LUT)을 이용한 전치왜곡기의 동작 알고리듬을 제안한다. 먼저, LUT의 빠른 초기화를 위하여 송신신호로부터 HPA의 특성을 예측하여LUT를 초기화 시키는 알고리듬을 제안한다. 그리고 통신중에 HPA의 특성이 변화할 경우에 대비하여 평균자승오차를 최소화하는 적응알고리듬을 제안한다.

• Korean Journal of Child Studies
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• v.36 no.1
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• pp.147-162
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• 2015

This study examined the role of after-school caregiver absence in the relationship between school adjustment and mobile phone dependency during early adolescence. Sixth grade students(N=1,863) from the nationally representative Korea Child and Youth Panel Study were analyzed using moderated multiple regression models. The results showed that higher school adjustment may be effective in reducing youth mobile phone dependency. There was also a significant interaction effect between school adjustment and high caregiver absence, indicating that the protective role of school adjustment concerning mobile phone dependency may be less effective among youth of highest risk. Policy implications of the results are also discussed.