• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.4B
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• pp.305-313
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• 2011

This paper presents a P2P (Peer-to-Peer) overlay multicast tree construction algorithm to support stable multimedia service over the Internet. While constructing a multicast tree, it takes into account not only the link delay, but also peer stability. Since peers actually show dynamic and unstable behavior over P2P-based network, it is essential to consider peer stability. Furthermore, the weighting factor between link delay and peer stability is adaptively controlled according to the characteristics of the multicast tree. Basically, Genetic algorithm is employed to obtain a near optimal solution with low computational complexity. Finally, simulation results are provided to show the performance of the proposed algorithm.

• Korean Journal of Child Studies
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• v.22 no.4
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• pp.17-32
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• 2001

The purpose of this study was to explore the developmental patterns of self-concept of pre-adolescents and adolescents by using the longitudinal data originated by the Korean Institute for Research in the Behavioral Sciences (KIRBS). Specifically, using Structural Equation Modeling (SEM), the effects of parents and peer groups on the stability and change of self-concept were examined across a 9-year-period. The subjects were 62 children(29 boys and 33 girls) from the KIRBS longitudinal data. The results showed that, peer relationships revealed consistent effects on children's self-concept from pre-adolescence to mid-adolescence. In particular, this influence was most evident at 7 years of age and at 16 years of age. However, parental influence was almost non-existent for 7-year-olds, equivalent to peer relationships for 10-year-olds, and decreased for 16-year-olds. On the whole, parental and peer influence on self-concept gradually decrease in adolescence. Nevertheless, parental and peer influence continue to maintain a certain level of influence from childhood to adolescence. This study provides an understanding of developmental change and stability in the self-concept of Korean adolescents.

• Korean Journal of Child Studies
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• v.36 no.4
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• pp.17-32
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• 2015

The purpose of the present study was to explore the stability and changes of participant roles in the bullying process, namely, bullies, victims, followers, outsiders, and defenders. In addition, this study examined associated environmental characteristics of both followers and defenders in sixth graders among peer bystanders in the fifth grade. The participants consisted of 461 children from grades 5 to 6(male: 239, female: 222). Data were collected at one year intervals for two data points. The results indicated a moderate consistency in the participant roles the children take across time. Followers and outsiders tended to change differently in their roles one year later. On the other hand, defenders, bullies, and victims tended to keep the same role. The defenders group generally had higher levels of peer attachment, teacher attachment and community's supervision than the followers group. The implications for future research and intervention in bullying were also discussed.

• Journal of Child Welfare and Development
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• v.16 no.2
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• pp.109-135
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• 2018

The purpose of this study was to analyze the longitudinal causal relationship between caregiver relations and peer relations of children in out-of-home care. We analyzed the three years(2011-2013) of longitudinal data from the Panel Study on Korean Children in Out-of-Home Care. The autoregressive cross-lagged model (ARCL) was used to measure the longitudinal causal relationship between caregiver relations and peer relations. As a result, first, caregiver relations and peer relations showed stability over time. In other words, the results of the measurement at three time points showed that the caregiver relations and peer relations at the previous time had a significant effect on the caregiver relations and peer relations at the later time point. Second, the previous caregiver relations had a significant effect on the subsequent peer relations over time. Third, the previous peer relations had a significant effect on the subsequent caregiver relations over time. This study confirmed the interrelationships of caregiver relations and peer relations of children in care by examining the longitudinal data using the longitudinal analysis method.

• Journal of Korea Multimedia Society
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• v.12 no.5
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• pp.717-727
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• 2009

P2P (Peer-to-Peer) network depends on cooperation of peers considerably. However, some peers do not share files at all and only download files. Peers also share low quality files or unpopular files. These selfish behavior of peers is referred to 'free riding'. The free riding of peer may decrease participation of other peers or the system performance. In this paper, we propose an incentive mechanism, called IcMFS (Incentive Mechanism for File Sharing System), which provides the correct use of incentive mechanism using trust peer, computes contribution values referring behavior of peers and rewards peers. The proposed mechanism assigns bandwidth and TTL(Time-To-Live) to a peer and differentiates the use of service. A case study on simulations shows the service differentiation according to the contribution value of peer, the correct use of incentive mechanism using trust peer and the advantage by use of trust peer. To prove the stability of proposed mechanism, we also show the disadvantage that a peer receives from the incorrect use of incentive mechanism.

• Journal of Information Processing Systems
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• v.16 no.3
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• pp.699-717
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• 2020

Propagation time on permissionless blockchain plays a significant role in terms of stability and performance in the decentralized systems. A large number of activities are disseminated to the whole nodes in the decentralized peer-to-peer network, thus causing propagation delay. The stability of the system is our concern in the first place. The propagation delay opens up opportunities for attackers to apply their protocol. Either by accelerating or decelerating the propagation time directly without proper calculation, it brings numerous negative impacts to the entire blockchain system. In this paper, we thoroughly review and elaborate on several parameters related to the propagation time in such a system. We describe our findings in terms of data communication, transaction propagation, and the possibility of an interference attack that caused an extra propagation time. Furthermore, we present the influence of block size, consensus, and blockchain scalability, including the relation of parameters. In the last session, we remark several points associated with the propagation time and use cases to avoid dilemmas in the light of the experiments and literary works.

• Journal of Korean Elementary Science Education
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• v.39 no.3
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• pp.323-337
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• 2020

To achieve effective learning, knowledge must be shared and developed through interaction with peer learners. Therefore, science education emphasizes small group inquiry activities that solves tasks through the interaction of members. The effect of small group inquiry activities depends on how to compose small groups. The way in which a group is composed is a very important factor for improving interaction. In particular, it has been reported that the gender of peer is a very important factor in the interaction between students in the composition of small groups. Meanwhile, studies are being conducted on the types and stability of verbal interactions in small group inquiry activities using social network analysis. The purpose of this study is to analyze the types and stability of verbal interaction types and stability according to gender-grouping in elementary school students' small group activities using social network analysis. To this end, 60 5th graders in elementary school were conducted with different gender in the composition of the group of male, female and mixed-gender students. The study found that the composition of a group by gender had little impact on the type or stability of verbal interaction. However, the frequency of verbal interactions was higher in mixed-gender groups than in other groups. Through this process, the gender-grouping in elementary school students' small group activities suggests a mixed-gender group.

• The Journal of the Convergence on Culture Technology
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• v.6 no.4
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• pp.813-818
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• 2020

Recently, with the rapid increase in technology and users of smart devices, the smart watch market has grown, and its utility and usability are continuously expanding. The strengths of smartwatches are wearable portability, application immediacy, data diversity and real-time capability. Despite these strengths, smartwatches have limitations such as battery limitations, display and user interface size limitations, and memory limitations. In addition, there is a need to supplement developers and standard devices, operating system standard models, and killer application modules. In particular, monitoring and application of user's biometric information is becoming a major service for smart watches. The biometric information of such a smart watch generates a large amount of data in real time. In order to advance the biometric information service, stable peer-to-peer transmission of sensing data to a remote smartphone or local server storage must be performed. We propose a synchronization method to ensure wireless remote peer-to-peer transmission stability in a smart watch system. We design a wireless peer-to-peer transmission process based on this synchronization method, analyze asynchronous transmission process and proposed synchronous transmission process, and propose a transmission efficiency method according to an increase in transmission amount.

• The Korean Journal of Food & Health Convergence
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• v.7 no.2
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• pp.11-24
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• 2021

This study identified the severity of youth gambling behavior and analyzed the impact of stress, impulsivity, peer attachment and social interest on youth gambling behavior. Based on the results of the study, the government sought to help understand teenagers who are addicted to gambling and to help them maintain psychological and social stability and healthy living. A total of 237 high school students were surveyed. According to the analysis, the prevalence rate was found to be 3.4 percent of the problem gambling group and 9.3 percent of the medium-risk gambling group, and a total of 12.7 percent was addiction. Low-risk gambling groups accounted for 16.9 percent and non-problem gambling groups accounted for 70.5 percent. By gender, male students have more serious gambling problems than female students. As a result of dividing the group that experienced gambling more than once and the group that did not experience gambling into gambling group and non-gambling group, the two groups showed significant differences in impulsiveness, avoidant attachment, and interest in others. Furthermore, a correlation analysis was conducted to examine the relationship between these factors and the level of gambling behavior, showing that only impulsivity was significant.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.14 no.4
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• pp.275-284
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• 2010

Deliberate self-harm (DSH) is the act of deliberately harming your own body, such as cutting or burning yourself, without suicidal intent. It has especially become a problem among adolescents and college-age students in institutional settings such as boarding schools, Greek houses, detention centers and hospitals. We focus on contagion of DSH among adolescents and young adults by creating a deterministic epidemiological model. We study the impact of actual peer pressure, virtual peer pressure (the Internet) and treatment analytically in terms of a basic reproduction number through stability analysis of a system of ordinary differential equations. All parameters are approximated and results are also explored by simulations. The model shows that DSH is present in an endemic state in the population considered, and the control strategies are discussed.