• Journal of Internet Computing and Services
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• v.10 no.4
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• pp.189-198
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• 2009

Unstructured peer-to-peer systems are most commonly used in today's internet. But file placement is random in these systems and no correlation exists between peers and their contents. There is no guarantee that flooding queries will find the desired data. In this paper, we propose to cluster nodes in unstructured P2P systems using the agglomerative hierarchical clustering algorithm to improve the search method. We compared the delay time of clustering the nodes between our proposed algorithm and the k-means clustering algorithm. We also simulated the delay time of locating data in a network topology and recorded the overhead of the system using our proposed algorithm, k-means clustering, and without clustering. Simulation results show that the delay time of our proposed algorithm is shorter compared to other methods and resource overhead is also reduced.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.16 no.4
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• pp.73-80
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• 2016

Multiplayer Online Games(MOG) using the Internet are typically organized based on a CS(client-server) or P2P(peer-to-peer) architecture. We then propose a method that combines a P2P architecture with a CS architecture in order to utilize their advantages. Most MOGs use a primary-copy replication approach that provides strong consistency control over an object. For each object and character there exists an authoritative copy, called primary copy and all other copies are secondary copies or replicas. Any update to the object has to be first performed on the primary copy. In the proposed hybrid architecture, primary copies may reside on the server or be held by clients. In this architecture, load balancing between a server and clients can be achieved by reducing the number of objects maintained by the server. Games consist of various types of actions with different consistency requirements. A multi-level approach to game consistency is sensible as it provides the best trade-off between consistency and performance. The performance for the hybrid game architecture with the primary-copy model is evaluated through simulation experiments and analysis in this paper.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.4 no.4
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• pp.491-508
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• 2010

In peer-to-peer (P2P) on-demand streaming networks, the alleviation of server load depends on reciprocal stream sharing among peers. In general, on-demand video services enable clients to watch videos from beginning to end. As long as clients are able to buffer the initial part of the video they are watching, on-demand service can provide access to the video to the next clients who request to watch it. Therefore, the key challenge is how to keep the initial part of a video in a peer's buffer for as long as possible, and thus maximize the availability of a video for stream relay. In addition, to address the issues of delivering data on lossy network and providing scalable quality of services for clients, the adoption of multiple description coding (MDC) has been proven as a feasible resolution by much research work. In this paper, we propose a novel caching scheme for P2P on-demand streaming, called Dynamic Buffering. The proposed Dynamic Buffering relies on the feature of MDC to gradually reduce the number of cached descriptions held in a client's buffers, once the buffer is full. Preserving as many initial parts of descriptions in the buffer as possible, instead of losing them all at one time, effectively extends peers’ service time. In addition, this study proposes a description distribution balancing scheme to further improve the use of resources. Simulation experiments show that Dynamic Buffering can make efficient use of cache space, reduce server bandwidth consumption, and increase the number of peers being served.

• Journal of Convergence for Information Technology
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• v.9 no.7
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• pp.48-56
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• 2019

This pilot study is to investigate the effects of peer tutoring on self-leadership, positive psychological capital(PPC) and learning satisfaction of nursing students, and to examine the feasibility of following study through identifying problems in research design. Before the experiments, there was no significant defferences confirming homogeneity of between groups which consisted with 10 and 8 subjects each among general characteristics, and also among their mean ranks by Mann-Whitney U test(Z=-1.40~-.31, p=.160~.754). There was a significant difference in mean rank of 'hope', one of the subdomains of PPC, between groups before and after 10 times of peer tutoring as experiments(Z=-2.27, p=.023), there were positive correlations between self-leadership and confidence, hope and learning satisfaction each before and after experiments(r=49, p=.03), (r=65, p=.01). Finally, the feasibility of experimental study applying this experimental design to investigate the effects of peer tutoring on self-leadership, PPC and learning satisfaction of nursing students was confirmed in this results.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.20 no.3
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• pp.73-81
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• 2020

Today's massively multiplayer online games(MMOGs) can contain millions of synchronous players scattered across the world and participating with each other within a single shared game. The increase in the number of players in MMOGs has led to some issues with the demand of server which generates a significant increase in costs for the game industry and impacts to the quality of service offered to players. In dealing with a considerable scale of MMOGs, we propose a cloud computing and peer-to-peer(P2P) hybrid architecture in this paper. Given the two nearly independent functionalities of P2P and cloud architectures, we consider the possibility of fusing these two concepts and researching the application of the resultant amalgamation in MMOGs. With an efficient and effective provisioning of resources and mapping of load, the proposed hybrid architecture relieves a lot of computational power and network traffic, the load on the servers in the cloud while exploiting the capacity of the peers. The simulation results show that MMOGs based on the proposed hybrid architecture have better performance and lower traffic received compared with MMOGs based on traditional client-server system.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• v.13 no.1
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• pp.177-188
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• 2002

Objectives：The major goal of this study was to investigate and compare the behavior problems and mothers' rearing pattern between adolescent psychiatric patients either neglected or rejected by peer and those who were neither neglected nor rejected by peer. Methods：Adolescent psychiatric patients(N=25) performed peer neglect scale, peer reject scale. And their mothers performed the part of Child Behavior Checklist(CBCL), Maternal Behavior Research Instrument(MBRI), the scale for the maternal concern about the social life of their own patients, and the scale for maternal concern about the friendship of their own patients. According to the score of the peer neglect scale and the peer reject scale, we divided the patients into 'peer neglect-reject' group(n=15) and ‘on-loneliness’ group(n=10), and compared the scores of other scales between each group. Also, we investigated the correlation among all scales. Results：1) The scores of the part of CBCL(p<.05), depressed/anxious subscale of CBCL(p<.05) and thought problem subscale of CBCL(p<.01) in peer neglect-reject group were significantly higher than those in non-neglect group. The score of peer neglect scale was significantly correlated with that of the part of CBCL(r=.516), depressed/anxious subscale of CBCL(r=.483), thought problem subscale of CBCL (r=.651), social problem subscale of CBCL(r=.517). And the score of peer reject scale was significantly correlated with that of attention subscale of CBCL(r=.414), thought problem subscale of CBCL(r=.446), social problem subscale of CBCL(r=.531). 2) But, each group was not significantly different on the scores of MBRI, the scale for the maternal concern about the social life of their own patients, and the scale for maternal concern about the friendship of their own patients. And there were no significant correlation between the scores of peer neglect / peer reject scale and those of scales for maternal rearing pattern. Conclusion：The thought problem and depression/anxiety problem of adolescent psychiatric patients neglected or rejected by peer were estimated more higher than those of adolescent psychiatric patients neither neglected nor rejected by peer. But, from the view of maternal rearing pattern, each 2 groups seemed not to be different. Further research using more subjects will be needed.

• The KIPS Transactions:PartA
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• v.11A no.4
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• pp.257-266
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• 2004

Mobile agents are defined as processes which can be autonomously delegated or transferred among the hosts in a network in order to perform some computations on behalf of the user and co-operate with other agents. Currently, mobile agents are used in various fields, such as electronic commerce, mobile communication, parallel processing, search of information, recovery, and so on. In pure P2P network environment, if mobile agents that require computing resources rashly migrate to another peers without consideration on the peer's capacity of resources, the peer may have a problem that the performance of the peer is degraded due to lack of resources. To solve this problem, we propose resource reservation based load balancing scheme of using RMA(Resource Management Agent) that monitors workload information of the peers and that decides migrating agents and destination peers. In mobile agent migrating procedure, if the resource of specific peer is already reserved, our resource reservation scheme prevents other mobile agents from allocating the resource.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.23 no.3
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• pp.99-106
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• 2023

In this paper, we propose subregion-based area of interest management techniques for MMORPG(massively multiplayer online role playing games) integrating P2P(peer-to-peer) networking and cloud computing. For the crowded region, the proposed techniques partition it into several subregions and assign a player to manage each subregion as a coordinator. These techniques include a load balancing mechanism which regulates communication and computation overhead of such player below the specified threshold. We also provide a mechanism for satisfying the criterion, where subregions overlapped with each player's view must be switched quickly and seamlessly as the view moves around in the game world. In the proposed techniques where an efficient provisioning of resources is realized, they relieve a lot of computational power and network traffic, the load on the servers in the cloud by exploiting the capacity of the players effectively. Simulation results show that the MMORPG based on cloud and P2P architecture can reduce the considerable bandwidth at the server compared to the client server architecture as the available resources grow with the number of players in crowding or hotspots.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.5
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• pp.115-121
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• 2009

In this paper, we propose an algorithm that reduces channel change delay time in the P2P based IPTV system. Channel change delay time is considered to be one of the most important performance measures in IPTV system. Proposed algorithm presents a method to reduce the channel change delay time effectively. The algorithm eliminates the first channel change delay time and reduces delay time on a continuous channel surfing. We will show the mathematical models to evaluate the performance of proposed scheme with respect to the channel change delay time.

• Journal of the Korea Society of Computer and Information
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• v.17 no.1
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• pp.151-159
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• 2012

In this paper, we propose a new peer grouping scheme to consider locality among peers using TTL values in P2P-based IPTV systems. This scheme can select neighbor peers to minimize the number of intermediate routers between each pair of peers. Thus, it can save the network bandwidth as much as the amount of data that the reduced number of routers should transmit In addition, we have conducted various simulation experiments to show that our proposed TTL-based peer grouping scheme can outperform the conventional RTT-based grouping scheme. The experimental results show that our proposed scheme can reduce the jitter ratio as well as the number of data and control packets that all routers should transmit.