• The KIPS Transactions:PartC
• /
• v.12C no.3 s.99
• /
• pp.437-442
• /
• 2005

The measurement of RTT (Round Trip Time) can be used for the analysis of Internet congestion. However, simple measuring of RTT which measures only hun around time of a packet can not infer a packet forward/backward delay variation. In this thesis, we present a new algorithm which can be used for the estimation of forward/backward delay variation of packets. These delay variations are implication of network congestion state. In this algorithm, the reference forward/backward delay can be determined based on the minimum RTT value. The delay variation of each packet can be calculated by comparing reference delay with the packet delay. We verified our proposed algorithm by NS-2 simulation and delay measuring in a real network.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2009.10a
• /
• pp.116-119
• /
• 2009

In this paper, a P2P streaming system for community TV service which requires realtime interactions was designed and implemented. The proposed system constructs a short delay tree-based P2P network in order to effectively support various community TV services within end-to-end delay bounds. Because a community service based on conversation requires a short delay. The P2P network of this paper was constructed by using an algorithm which utilizes locality and delay information. The implemented P2P streaming system is composed of a Web server and a application, each of which was implemented using Asp.Net and C#.Net respectively.

• The KIPS Transactions:PartB
• /
• v.8B no.5
• /
• pp.507-514
• /
• 2001

In VOD(Video-on-Demand) system, the real-time interactive service is one of the most important factor to determine the degree of QoS(Quality of Service). In this paper, we propose the head-end system consisted of switching agent and head-end node, which needs to receive the only video stream for multiple users which have requested the same video, to serve the unlimited interactive service which has no service delay and block. The unlimited VCR services can be served by storing the video stream with buffer at client and head-end node. And the proposed algorithm presents the method to enhance the efficiency by buffer, offer the true interactive VOD services to users because all of service requested by clients are processed immediately. In this paper, we implemented the VOD system which has the VCR functions without service delay and block. Simulation results indicate that the proposed algorithm has better performance in the number of service request and time interval.

• The Mathematical Education
• /
• v.61 no.2
• /
• pp.359-373
• /
• 2022

This study aims to examine the differences in the longitudinal relationship between academic stress, mathematics self-efficacy, and engagement in mathematics class according to the math achievement level. According to the results, academic stress, math self-efficacy, and math class engagement were stable over time for the high and low groups. Also, In the high group, math self-efficacy had a negative longitudinal mediation effect in the influence of academic stress to math class engagement. Whereas, in the low group math class engagement had a positive longitudinal mediation effect in the influence of academic stress to math self-efficacy. This means that the academic stress affects differently according to the math achievement level, and mathematics teachers should reflect these results in their teaching/learning strategies so that students can increase their mathematics self-efficacy along with their engagement in mathematics classes.

• Proceedings of the Korean Information Science Society Conference
• /
• 2006.10d
• /
• pp.512-517
• /
• 2006

차세대 통신망은 IP 기반 핵심망을 중심으로 무선 액세스망을 비롯한 다양한 액세스망들이 접속되는 형태가 될 것으로 전망되고 있다. 이러한 망 환경에서 사용자가 만족할 수 있는 수준까지 멀티미디어 서비스를 제공하기 위해서는 서비스품질(QoS)이 필수적으로 보장되어야 한다. 특히, 종단간(end-to-end) QoS가 보장되어야 하는데, 이러한 종단간 QoS를 보장하기 위해서는 네트워크 QoS 뿐만 아니라 애플리케이션 계층에서의 QoS도 함께 지원되어야 한다. 본 논문에서는 네트워크에서 혼잡현상이 발생할 경우, 종단간 QoS를 제공하기 위해 송신측에서 가변 멀티코덱(애플리케이션 계층)을 사용하여 트래픽손실 및 지연을 줄일 수 있는 방법을 제안하고, 시뮬레이션을 이용한 성능 분석결과를 제시함으로써 제안된 방식의 타당성을 보인다.

• The Journal of the Korea Contents Association
• /
• v.8 no.1
• /
• pp.177-185
• /
• 2008

Research on media access control (MAC) scheme for Wireless Sensor Network (WSN) has been mainly focused on energy efficiency improvement, while interest on latency is relatively weak. However, end-to-end latency could be a critical limitation specifically in the multi-hop network such as wireless multimedia sensor networks. In this paper we propose a media access control scheme with distributed transmission power control to Improve end-to-end transmission latency as well as reduce power consumption in multi-hop wireless sensor networks. According to the simulation results, the proposed scheme is turned out to be an energy efficient scheme with improved end-to-end transmission latency.

• Korean Journal of Culture and Social Issue
• /
• v.22 no.4
• /
• pp.567-593
• /
• 2016

This study examined longitudinal mediated effects of informal labeling on the relationship between adolescent abuse and academic achievement using autoregressive cross-lagged modeling. Data were obtained from the second, third, and fourth waves of the middle school student cohort (N=3,168) of the Korean Youth Panel Survey. The major longitudinal findings of this study are as follows: First, adolescent abuse was found to have a positive association with future informal labeling. Second, informal labeling was found to have a negative association with future academic achievement. Finally, the longitudinal relationship between adolescent abuse and academic achievement was partially mediated by informal labeling. Based on these results, this study suggests directions for adolescent abuse prevention. The need for education and prevention of informal labeling was discussed, as well as the direction of intervention programs for adolescents with experience of informal labeling. Furthermore, this study may provide empirical evidence for labeling theory and contribute to increasing awareness on the longitudinal influence of adolescent abuse and informal labeling.

• Korean Journal of Social Welfare Studies
• /
• v.48 no.3
• /
• pp.29-55
• /
• 2017

This study aims to examine how children's life satisfaction is interrelated with parents' life satisfaction longitudinally. Autoregressive cross-lagged model was employed to analyze the interrelationship between children's and parents' life satisfaction. This study used 6 waves (Elementary school 4th year to Middle school 3rd year) from the Korean Children and Youth Panel Study (KCYPS). The sample size was 1,963 families with child and parent. Key findings are as follows: First, children's and parents' life satisfaction, respectively, was found to influence each other during the study period. Second, parents' life satisfaction were found to have positive and significant cross-lagged impacts on children's life satisfaction. Third, similarly, children's life satisfaction was positively related to parents' life satisfaction longitudinally. The findings suggest that children's and parents' life satisfaction are interrelated in an autoregressive cross-lagged model. This study concludes with implications for enhancing children's and parents' life satisfaction.

• Proceedings of the Korean Society of Broadcast Engineers Conference
• /
• 2010.07a
• /
• pp.349-352
• /
• 2010

본 논문에서 우리는 DiffServ 환경에서 멀티미디어 서비스가 요구하는 품질 수준을 고려하는 QoS-aware AQM(Active Queue Management) 방안을 제안한다. 지연과 손실에 민감한 IPTV 및 VoIP와 같은 실시간 멀티미디어 서비스의 사용 증가로 인해 QoS 제공은 필수적이며, 이에 따라 응용계층에서 명시된 QoS 요구 수준을 네트워크 계층에서 인식하여 전달망에서 QoS를 제공할 수 있는 큐 관리 방안이 필요하다. 기존 DiffServ의 수정된 DSCP 필드를 이용하여 요청된 QoS 품질 정보를 네트워크 장비에 전달하고 해당 서비스의 지연 및 손실률 요구 수준에 대한 threshold margin을 도출하고 이 범위 내에서 큐의 임계값을 능동적으로 제어함으로써 종단간 IPTV 및 VoIP와 같은 멀티미디어 서비스의 QoS를 보장할 수 있다.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2007.05a
• /
• pp.1356-1358
• /
• 2007

데이터 병합은 무선 센서 네트워크에서 발생하는 통신량 축소로 에너지 소비의 최소화를 달성하기 위해 적용되는 기법이다. 이런 데이터 병합의 시간 제어는 종단간 지연시간을 최적화하면서 병합 시간의 적응적인 조절로 WSNs의 성능을 크게 향상시킬 수 있다. 따라서 본 논문은 WSNs에서 데이터 정확성과 종단간 지연시간 사이에 발생하는 상충조건의 최적화를 위해 무선 손실을 고려한 적응성 있는 타이밍 제어 프로토콜을 설계하였다. 이 프로토콜은 무선 손실의 변화에 적응성을 있는 데이터 병합을 수행할 수 있도록 선택적 참여율과 중요도를 결정함으로써 네트워크 전체에 패킷 전송 횟수를 균등하게 분배하여 전체 네트워크 안정성을 높일 수 있도록 하였다.