• Proceedings of the KIEE Conference
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• 2004.05a
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• pp.62-64
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• 2004

P2P Systems have grown dramatically in recent years. Now many P2P systems have developed and been confronted by P2P technical challenges. We should consider how to efficiently locate desired resources. In this paper we integrated the existing pure P2P and hybrid P2P model. We try to keep roles of super peer in hybrid and concurrently use pure P2P model for searching resource. In order to improve the existing search mechanism, we present contents-based classification mechanism. Proposed system have the following features. This can forward only query to best peer using RI. Second, it is self-organization. A peer can reconfigure network that it can communicate directly with based on best peer. Third, peers can cluster each other through contents-based classification.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.3 no.1
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• pp.5-25
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• 2009

In recent years the popularity of multi-hop wireless networks has been growing. Its flexible topology and abundant routing path enables many types of applications. However, the lack of a centralized controller often makes it difficult to design a reliable service in multi-hop wireless networks. While packet routing has been the center of attention for decades, recent research focuses on data discovery such as file sharing in multi-hop wireless networks. Although there are many peer-to-peer lookup (P2P-lookup) schemes for wired networks, they have inherent limitations for multi-hop wireless networks. First, a wired P2P-lookup builds a search structure on the overlay network and disregards the underlying topology. Second, the performance guarantee often relies on specific topology models such as random graphs, which do not apply to multi-hop wireless networks. Past studies on wireless P2P-lookup either combined existing solutions with known routing algorithms or proposed tree-based routing, which is prone to traffic congestion. In this paper, we present two wireless P2P-lookup schemes that strictly build a topology-dependent structure. We first propose the Ring Interval Graph Search (RIGS) that constructs a DHT only through direct connections between the nodes. We then propose the ValleyWalk, a loosely-structured scheme that requires simple local hints for query routing. Packet-level simulations showed that RIGS can find the target with near-shortest search length and ValleyWalk can find the target with near-shortest search length when there is at least 5% object replication. We also provide an analytic bound on the search length of ValleyWalk.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.26 no.2
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• pp.201-210
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• 1996

There is increasing attention about radiology teaching files on the Internet in the field of diagnostic radiology. The purpose of this study was to aid in the creation of new radiology teaching file by analysing the present radiology teaching file sites on the Internet with many aspects and evaluating images on those sites, using Macintosh IIci computer, 28.8kbps TelePort Fax/Modem, Netscape Navigator 2.0 software The results were as follow : 1. Analysis of radiology teaching file sites (l) Country distribution was the highest in USA(57.5％). (2) Average number of cases was 186 cases and radiology teaching file sites with search engine were 9 sites (22.5％). (3) At the method of case arrangement, anatomic area type and diagnosis type were found at the 10 sites(25％) each, question & answer type was found at the 9 sites(22.5％). (4) Radiology teaching file sites with oro-maxillofacial disorder were 9 sites(22.5％). (5) At the image format, GIF format was found at the 14 sites(35％). and ]pEG format found at the 14 sites(35％). (6) Created year was the highest in 1995(43.7％). (7) Continuing case upload was found at the 35 sites(87.5％). 2. Evaluation of images on the radiology teaching files (l) Average file size of GIF format (71 Kbyte) was greater than that of JPEG format(24 Kbyte). (p<0.001) (2) Image quality of GIF format was better than that of JPEG format. (p<0.001).

• Proceedings of the Korean Information Science Society Conference
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• 2005.11a
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• pp.454-456
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• 2005

최근에 파일 공유 애플리케이션을 개발하는데 있어 클라이언트-서버(client-sewer) 모델의 문제점을 해결하기 위해 피어-투-피어(peer-to-peer) 모델이 각광 받고 있다. 대표적일 P2P 기반 파일 공유 시스템으로 넵스터, 그누텔라등이 있다. 그러나 이 시스템들은 각각 중앙 집중적 제어, 혹은 브로드캐스팅에 의한 과도한 네트워크 트래픽 발생 등 확장성 문제를 발생시킨다. 이런 문제점을 해결하기 위해 울트라피어 및 동적 라우팅 기법을 사용하지만 여전히 rare 파일에 대한 높은 응답시간과 검색의 낮은 신뢰성 문제점들을 해결할 수 없다. 본 논문에서는 popular 파일과 rare 파일에 대한 검색을 구분하여 popular 파일을 기존의 그누텔라 검색 방법을 사용하고 rare 파일 검색을 제안하는 새로운 DHT 알고리즘을 사용하도록 한다. 특히 제안하는 DHT 알고리즘은 기존의 DHT 알고리즘들과 달리 일반 노드가 아닌 울트라피어들만으로 구성함으로서 검색 비용, 노드 조인과 리브 비용, 핑거 테이블의 엔트리 수를 매우 줄임으로서 효과적이고 확장적이라 할 수 있다.

• Journal of Korea Multimedia Society
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• v.10 no.10
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• pp.1328-1337
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• 2007

We describe a method for streaming specific section using the section information among peers on P2P network. As peers tend to extract only the part of contents in which they are interested, an indexed file is created based on the section information of multimedia contents and registered in the search server. If a peer requests the streaming of specific parts of the contents to other corresponding peer using the section information that the server returns, the peer streams only separated section of the multimedia contents according to the information. For this process, we implement a function that a peer's PC can play a role as a server, and the peer streams the separated content based on the section information that the server supplies.

• Journal of KIISE:Computing Practices and Letters
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• v.8 no.5
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• pp.598-606
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• 2002

We suggest a distributed communication and management methodology using PC to PC Query multicasting strategy for efficient management of medical images produced by DICOM(Digital Imaging and Communications in Medicine) Modalities. It is absolutely necessary to reduce strict degradation of PACS system due to large sire of medical images and their very high transport rates. DICOM PC to PC Component is composed of a Service Manager to execute requested queries, a Communication Manager to take charge of file transmission, and a DICOM Manager to manage stored data and system behavior Each Manager itself is a component to search for requested file by interaction or to transmit the file to other PCs. Distributed management and transformation of medical information based on PC to PC Query multicasting methodology will enhance performance of central server and network capacity, reducing overload on both. We organize three major components for system operation. Each component is implemented as Agent. Communication between agents uses XML encoded Agent Communication Language.

• Journal of Intelligence and Information Systems
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• v.13 no.1
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• pp.59-79
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• 2007

P2P (Peer to Peer) techniques have been well applied to file sharing due to its cost-effectiveness and convenience. Dynamic network evolution is another good thing for P2P according to addition and deletion of nodes and change of files a node has. Our research proposes a P2P-based KMS (Knowledge Management System). Knowledge of enterprises spreads all over sub-organizations like oversea factories and sales departments and is changed in dynamic manner. P2P techniques are, therefore well matched with knowledge management domain. In order to increase search efficiency, we introduce social network theory into P2P-based KMS. Social network technique makes the most similar nodes (in KMS domain, nodes which has the most similar knowledge) its own neighbors, which makes eventually search efficiency increase. We developed our prototype system P2P-SN-KMS and evaluated by simulation.

• 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.

• Journal of Information Processing Systems
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• v.10 no.4
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• pp.628-645
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• 2014

In past few years, distributed hash table (DHT)-based P2P systems have been proven to be a promising way to manage decentralized index information and provide efficient lookup services. However, the skewness of users' preferences regarding keywords contained in a multi-keyword query causes a query load imbalance that combines both routing and response load. This imbalance means long file retrieval latency that negatively influences the overall system performance. Although index replication has a great potential for alleviating this problem, existing schemes did not explicitly address it or incurred high cost. To overcome this issue, we propose, in this paper, an integrated solution that consists of three replication schemes to alleviate query load imbalance while minimizing the cost. The first scheme is an active index replication that is used in order to decrease routing load in the system and to distribute response load of an index among peers that store replicas of the index. The second scheme is a proactive pointer replication that places location information of each index to a predetermined number of peers for reducing maintenance cost between the index and its replicas. The third scheme is a passive index replication that guarantees the maximum query load of peers. The result of simulations indicates that the proposed schemes can help alleviate the query load imbalance of peers. Moreover, it was found by comparison that our schemes are more cost-effective on placing replicas than PCache and EAD.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2006.05a
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• pp.81-90
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• 2006

The GNUnet proposed a file encoding method by 1KB block size to support anonimity of files, decentralizes encoded block to peers through unstructed mode and original data decoding method a block searching or encoded blocks. but, the encoding and block decentralizing method with $600\sim700MB$ large multimedia file appered two problems. First problem, it need addition R block and I block, which make about 4% of storage resource. Second problem, unstructured model added network load by broadcasting decentralizing method. Third problem, The critical point of keyword search function. This paper suggest variable encoding block size and structured model by block decentralizing solution. Suggested encoding method reduced block request supplementary block generation from 4% to 1%, network load by proposal structured model sending answer through dedicated peer to decentralize block and we defined content-based keyword and identifier of sharing file.