• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.8B
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• pp.1197-1203
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• 2010

A strength of BitTorrent, which is widely used for file sharing today, is due to its peer selection mechanism which is designed to encourage peers to contribute data. In the peer selection phase in BitTorrent, peers to upload the file in a swarm are selected by determining which peers upload the most to themselves. However, the number of peers to upload (i.e., number of unchoked peers) is fixed to four in its peer selection mechanism of BitTorrent, which yields inefficiency because the situation of the swarm may vary frequently (e.g., number of peers in the swarm, download rates, and upload rates). In this paper, we analyze the swarming system performance when the number of unchoked in BitTorrents is not static, but dynamic. For empirical investigation, we established a testbed in Seoul National University by modifying an open-source BitTorrent client, which is popular. Through our experiments, we show that an adaptive mechanism to adjust the number of unchoked peers considering the situation of the swarm is needed to improve the performance of BitTorrent.

• Journal of the Korea Society for Simulation
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• v.15 no.4
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• pp.97-105
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• 2006

Popular content stored within the Internet may be convenient to download via modern 3G connections, but costly due to a fee charged by telecommunication providers on the basis of the amount of data transferred. This paper presents a network in which several mobile devices, called the peers, cooperate to download their assigned portion of the content using a 3G connection in order to reduce the overall cost. Then, the peers exchange their assigned portion of the content with other peers via a wireless ad hoc network and the peers reconstruct the whole content using the exchanged portion. This paper focuses on the per-peer based distribution method, and presents the performance comparison with a similar method, called the per-packet distribution method. Both methods are designed to reduce packet collisions while content is exchanged. The simulation result indicates that the per-peer based method outperforms the per-packet based method, and approximately 90% of the telecommunication cost is saved with as few as 10 peers.

• Journal of Families and Better Life
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• v.22 no.1
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• pp.45-54
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• 2004

To examine group differences among four groups divided by asgression/victimization status, 655 4th graders living in Seoul reported their perceptions of peer aggression, peer victimization, personality traits, parent attachment, and their parents' marital conflict. Peers of the subjects also reported their perceptions of peer aggression and peer victimization. Based on the scores of peer aggression and peer victimization, each child was classified into one of the four groups: nonvictimized aggressors, aggressive victims, passive victims, and normative contrasts. For boys, nonvictimized aggressors were more sociable/active than both aggressive and passive victims. Aggressive victims were more shy/emotional than nonvictimized aggressors and normative contrasts, and were exposed to the highest parental marital conflict. For girls, passive victims were the least sociable/active among the four groups, and showed lower attachment to fathers than normative contrasts. Both aggressive and passive victims were more shy/emotional than nonvictimized aggressors and normative contrasts, and normative contrasts were exposed to the lowest parental marital conflict.

• Korean Journal of Child Studies
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• v.38 no.1
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• pp.217-231
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• 2017

Objective: The purpose of this study was to examine the influence of affective and cognitive empathy, and peer competence on behavioral problems among young children. Methods: The participants were 224 4- to 5-year-olds attending daycare centers in Gyeonggi-do. Children's empathy, peer competence, and behavioral problems were reported by their teachers. The collected data were analyzed using simple regression and three-step hierarchical multiple regression analyses. Results: The results showed that children who exhibited low affective empathy scored higher on peer acceptance and behavioral problems than children who had high affective empathy. This pattern of results was similarly found with cognitive empathy. Additionally, the effect of children's affective empathy on behavioral problems was fully mediated by peer competence, whereas the effect of children's cognitive empathy on behavioral problems was partially mediated by peer competence. Conclusion: These results suggest the need for peer-competence training based on affective empathy and training for both peer competence and cognitive empathy in reducing behavioral problems among young children.

• Journal of the Korean Home Economics Association
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• v.48 no.10
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• pp.25-35
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• 2010

This study examined the potential mediating mechanisms underlying the association between peer victimization and school adjustment. 521 children in the fifth and sixth grades were recruited from primary schools in Korea. Peer nomination and self-reports were used to measure peer victimization, cognitive representations, and school avoidance. Academic achievement records were obtained from official school records. The findings indicated that peer victimization contributed to school avoidance and academic achievement by different pathways. The association between peer victimization and school avoidance was indirectly mediated by perceptions of the self and peers. In contrast, peer victimization was directly associated with academic achievement.

• Korean Journal of Child Studies
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• v.31 no.3
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• pp.17-32
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• 2010

In this study, I examined the direct or indirect paths among the intra-personal factors as well as extra-personal factors affecting on children's peer competence. Subjects were 514 5-year-old children, their mothers, teachers. The teachers rated each children using Peer Competence Scale (Park, 2001) and completed emotion regulation and Student-Teacher Relationship Scale. The mothers responded to a questionnaire, including Parental Involvement Checklist (Cohen, 1989), parenting behaviors, and Children's Temperament. The data were used for path analysis with Amos 6.0 program. Results of this study were : (1) Children's temperament have an influence on children's peer competence through children's emotion regulation via mothers' parenting behaviors. (2) Children's temperament have an influence on children's peer competence through teacher-child relationship. (3) Mothers' parenting behaviors have an influence on children's peer Competence through mothers' management strategies of peer relations.

• Journal of Korea Multimedia Society
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• v.7 no.7
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• pp.922-933
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• 2004

In recent years, peer-to-peer network have a greate deal of attention for distributed computing or collaborative application, and work of ID-based public key systems have been focusing on the area of cryptography. In this paper, we propose ID-based group key management protocols for secure communication in autonomous peer group. Each member obtains his public/private key pair derived from his identification string from Private Key Generator. No central server participates in group key management protocol instead, all group members share the burden of group key management by the collaboration of themselves, so that our scheme avoids the single point of failure problem. In addition, our scheme considers the nature of dynamic peer group such as frequent joining and leaving of a member.

• English Language & Literature Teaching
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• v.18 no.3
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• pp.149-174
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• 2012

This research aims at exploring what Korean teachers of English need for their effective professional development, particularly from the perspectives of peer trainers who are school teachers as well as teacher trainers. The research is based on an assumption that despite the critical roles of peer trainers in the changing process of English education, very little attention has been paid to listening to their voices. Having an awareness of the meaningfulness of their voices in teacher education, the researcher collected and analyzed the data, employing a questionnaire responded by 32 peer trainers and in-depth group interview with 6 peer trainers who responded the questionnaire. The research findings suggest that the majority of peer trainers believe that the priority should be put on teaching practice rather than language competence for Korean English language teacher development. It has been found that they believe that teacher learning within the workplace with some support from outside experts is the most effective way of making classroom change possible and keeping teachers' professional development sustainable. Finally, the research suggests school-based professional development as an alternative strategy to satisfy their needs on effective and sustainable professional development.

• Korean Journal of Child Studies
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• v.19 no.1
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• pp.43-53
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• 1998

This study investigated the relations among maternal cognition, maternal supervisory/monitoring behaviors, and their children's peer competence. The participants were 40 kindergarten children and their mothers. The mothers completed a questionnaire concerning maternal beliefs about children's social skills. Also their supervisory/monitoring behaviors were observed in the context of child-peer interactions. Children's peer competence was measured using a sociometric status measure and a peer acceptance rating scale. Maternal beliefs were related both to the quantity/quality of maternal supervisory/monitoring behaviors and to children's peer competence. Maternal supervisory/monitoring behaviors were also related to children's actual peer competence.

• Journal of the Korean earth science society
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• v.25 no.3
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• pp.129-141
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• 2004

A peer assessment method was implemented as part of an action research project where the primary goal was to create constructivist science classrooms. Student reflective writings, which had been created in the process of action research, were analyzed to examine the perceptions of the students concerning the peer assessment method employed in their earth science classrooms. Five perception categories and thirteen statements were developed from the student writings. These indicated that the students appreciated the positive nature of peer assessment and the effects of it as an alternative method for promoting learning. It was also revealed, however, that some students displayed inappropriate behaviors toward peer assessment which led to negative perceptions of the new assessment method. Implications for future use of peer assessment in science classrooms are discussed. Limitations founded in the present study as well as possible solutions are provided.