• Journal of the Korea Society of Computer and Information
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• v.12 no.6
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• pp.49-57
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• 2007

The P2P distributed systems are proceeded various studies lively to use the idleness computing resources under the network connected computing environments. It's a general mean to communication from the peer of the shortest downloaded time among same target files to be searched. The P2P search algorithms are very important primary factor to decide a real downloaded time in the criteria to select the peer of a shortest downloaded time. However the peer to give resources could be changed into offline status because the P2P distributed systems have very weakness connection. In these cases. we have a choice to retransmit resources mainly. In this study, we suggested an effective backtracking search algorithm to improve the performance about the request to retransmit the resource.

• Journal of the Korean Institute of Intelligent Systems
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• v.12 no.1
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• pp.73-79
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• 2002

At present, most Electronic Commerce System is made mainstream of Server-Client Commerce. For searching goods information, we must entering the EC sites and search that s information. but, P2P(Peer to Peer) System being escape traditional structure, Server-Client, it enable information transact between users, and resolve the problem of network, add-cost of server-ensurance, etc. Also, it is possible to trade information between person to person, client to provide. In this paper, we investigate on-going p2p models and study on the p2p based control based system.

• Proceedings of the KIEE Conference
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• 2006.04a
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• pp.159-161
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• 2006

The peer-to-peer (P2P) systems have Brown significantly over last few years due to their hish potential of sharing various resources. Super-peer based P2P systems have been found very effective by dividing the peers into two layers, SP (Super-Peer) and OP (Ordinary-Peer). In this paper, we present ISP2P (Intelligent Super-peer based P2P system), which allows us to choose the best SP. Through analyzing capacity and similarity between SP and OP, we can help OPs to select the most appropriate SP respectively. Proposed system can improve the performance of the average response time by superior SP, reduce the bandwidth cost by small path length due to content similarity and solve frequent SP replacement problem by considering similarity of user behavior.

• East Asian mathematical journal
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• v.31 no.5
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• pp.727-735
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• 2015

We introduce the fundamental theorem of upper and lower solutions for a class of singular ($p_1,\;p_2$)-Laplacian systems and give the proof by using the Schauder fixed point theorem. It will play an important role to study the existence of solutions.

• 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.

• International journal of advanced smart convergence
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• v.4 no.2
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• pp.38-45
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• 2015

Peer-to-Peer(P2P) systems are generally classified into two categories; hybrid and pure P2P. Hybrid systems have a single central index server keeping the details of shared information, so that undesirable effects such as heavy load on that server and lack of fault-tolerance can be caused. Pure P2P causes the other problems such as message flooding and scalability although it shows high degree of fault-tolerance. Recently, mobile agent-based distributed computing has been receiving wide attention for its potential to support disconnected operations, high asynchrony, and thus saving network bandwidth. In this paper, a new scheme of peer coordination is proposed for a decentralized P2P network with self-organizing structure. We deployed mobile agents for incorporating the advantages of usage of mobile agents into our P2P network. Proposed P2P network has both advantages of hybrid and pure P2P. The problems of heavy load on the server and lack of fault-tolerance are improved by using multiple special peers called super-peers. And the problems of pure P2P can be reduced by using mobile agents.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.14 no.2
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• pp.35-47
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• 2004

Though P2P network systems are widely used, not so much research has been done on security issues. One of the serious problem in P2P network is the authentication problem. To resolve this problem, we introduce a new concept, a "self-reputation system" in which a user manages her own reputation. We define self-reputation systems by presenting several requirements. We also give one instance of self-reputation system. The proposed instance satisfies the requirement including the prevention of erasing and the platform independence.ependence.

• Journal of applied mathematics & informatics
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• v.29 no.1_2
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• pp.39-48
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• 2011

Some existence theorems are obtained for periodic solutions of nonautonomous second-order differential systems with (q, p)-Laplacian by the minimax methods in critical point theory.

• Journal of the Korea Society of Computer and Information
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• v.17 no.12
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• pp.111-120
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• 2012

As the P2P System is a distributed system that shares resources of nodes that participate in the system, all the nodes serve as a role of server and client. Currently, although systematic, structured P2P systems such as Chord, Pastry, and Tapestry were suggested based on the distributed hash table, these systems are limited to $log_2N$ for performance efficiency. For this enhanced performance efficiency limited, the article herein suggests group routing algorithm. The suggested algorithm is a node-to-group routing algorithm which divides circular address space into groups and uses a concept of pointer representing each group, which is an algorithm where routing is performed based on pointer. To evaluate algorithm performance, a comparative analysis was conducted on average hops, routing table size, and delayed transmission for chord and routing, a signature algorithm in P2P systems. Therefore, enhanced performance is verified for comparative items from the simulation results.

• Journal of KIISE:Information Networking
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• v.34 no.2
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• pp.88-99
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• 2007

P2P systems are distributed data sharing systems, and each node in them plays the role of client as well as server. There are several studies using Distributed Hash Table, such as Chord, CAN, Tapestry, Pastry, but these systems don't consider the physical latency, therefore they have a weakness of difficulty to guarantee stable performance. To improve this problem, we present the TP2P system. This system is a self-organizing hierarchical overlay system and it uses Chord routing mechanism for lookup data. This system is organized by several subnets, each subnet is organized by physically close nodes, and global network organized by all nodes. In each subnet, one node finds a data, it saves in a node in the subnet, therefore it has higher probability to reduce physical lookup latency than Chord system. And each node has global information of some nodes in its subnet, and it is used to lookup data, therefore the number of hops decrease about 25% as well as the physical lookup latecy are reduced.