• The Journal of Korean Association of Computer Education
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• v.5 no.4
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• pp.71-78
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• 2002

The mobile agent is receiving the attention as new technique to retrieve and to share the distributed contents on web-based educational systems. The retrieval using mobile agent uses the method that delivers the agent to accomplish a search in direct server in substitute for it is transmitted a many contents to accomplish an efficient search. This study proposed the model of retrieval system that shares and searches the distributed educational contents of the bulletin board and newsgroup by using the mobile agent. In order to evaluate the efficiencies of the system that is proposed, we did the comparison test on the search model of existing and proposing system. By a test result, we confirmed network traffics of proposed system are diminished. Moreover we gave proof the fact that the optimum search time of the mobile agent-based system is shortened.

• The Journal of the Korea institute of electronic communication sciences
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• v.5 no.2
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• pp.185-192
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• 2010

A P2P technology in distributed environments is very useful in the respect that persons to have resources efficiently share the resources. A P2P system is caused as follows : resource search, resource transmission, resource transmission again and then excessively occurred network traffic. To improve performance about this a lot of studies is proceeding. One of this various study's directions to improve performance is recently come to a field to improve usability as such person. At this point this study is proposed P2P group search algorithm to improve usability.

• Proceedings of the Korea Information Processing Society Conference
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• 2012.04a
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• pp.1288-1289
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• 2012

분산 시스템과 관련하여 P2P 기술은 분산 환경에서 자원을 보유한 개인은 효율적으로 다른 사용자들과 자원을 공유하는 측면에서 활용도 높은 분야이다. 그러나 P2P 시스템은 자원 검색, 전송, 재전송 작업이 이뤄질 때마다 네트워크 트래픽이 과다하게 발생되는 단점을 갖고 있다. 이러한 문제를 해결하여 P2P 시스템의 성능 향상을 목표로 하는 연구가 많은 부분 진행되고 있다. 이러한 성능 향상의 다양한 방향성 가운데 사용자 입장에서의 사용성 개선 측면이 최근 중요한 부분으로 대두되고 있는데 본 연구에서는 사용성을 개선하기 위한 P2P 그룹 관리 검색 알고리즘을 제안한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.5B
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• pp.443-450
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• 2011

The Internet has become an essential part in our modern life by providing useful information. So, the volume of Internet traffic has been increasing rapidly, which emphasizes the importance of network traffic analysis for effective network operation and management. Signature based analysis have been commonly used, but it is shown that the increase of signatures due to the increase of applications causes the performance degradation of real-time traffic analysis on high-speed network links. In this paper, we propose OS fingerprinting method for real-time traffic analysis. The previous problems can be solved by utilizing the OS information. The OS fingerprinting method for real-time traffic analysis, proposed in this paper, conducts under passive mode, and improves the limitation of a previous method such as low completeness and accuracy. In this paper, we enlarged an input data to improve completeness, and used the User-Agent field in HTTP packet to extract various OS signatures. Also, we changed an input data from packet to flow to improve accuracy.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.17 no.7
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• pp.758-766
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• 1992

In this paper, the traffic control scheme used by M-cancel-Get services In CMIS /CMIP, OSI network management protocol, is presented and the performance is analyzed. M -Get service which allows a multiple response functional unit is a service that searches an attribute of the managed sys-tem and the service requires a large quantity of response as its typical characteristics. At the time, management response is transmitted Irrelevant to the network condition In the managed as well as In the management system. The management system requests M Canrel-Get service which informs the canrelation of M -Get service (or Information retrieval. In case of using M-Cancel-Get service for traffic control, the point of time for traffic control is propose by the result of simulation on management response time as the number of multiple response packets is Increased. The result is analyzed by processing ratio of the network workload and the average delay time of packets. As a result, the traffic control parameters proposed in the study show superiority in its processing ratio and the average packet delay time. Especially, its performance improves as the size of background traffic density Increase.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.2B
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• pp.71-79
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• 2006

Address lookup is an essential function in the Internet routers, and it determines overall router performance. In this paper, we have thoroughly investigated the binary-search-based address lookup algorithms and proposed a new algorithm based on binary search on prefix lengths. Most of the existing binary search schemes perform binary search on prefix values, and hence the lookup speed is proportional to the length of prefixes or the log function of the number of prefixes. The previous algorithm based on binary search on prefix lengths has superior lookup performance than others. However, the algorithm requires very complicated pre-computation of markers and best matching prefixes in internal nodes since naive binary search is not possible in their scheme. This complicated pre-computation makes the composition of the routing table and incremental update very difficult. By using leaf-pushing, the proposed algorithm in this paper removes the complicated pre-computation of the Previous work in performing the binary search on prefix lengths. The performance evaluation results show that the proposed scheme has very good performance in lookup speed compared with previous works.

• The Journal of the Korea Contents Association
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• v.7 no.3
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• pp.50-59
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• 2007

IP address lookup is one of the most important and complex functions in the router. In this paper, we propose an improved technique of LC-trie to increase the performance of IP address lookup in the high performance router. We effectively apply the prefix pruning method, which is used for the compression of the forwarding table in TCAM((Ternary Content Addressable Memory), to the LC-trie. This technique can decrease the number of memory accesses and upgrade the lookup speed. Moreover, through the real forwarding table and the real traffic distribution, we evaluate the performance of our scheme in terms of the lookup time and the number of memory access, comparing with that of the previous LC-trie.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.11B
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• pp.1277-1284
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• 2011

Today, many applications use 80 port, which is a basic port number of HTTP protocol, to avoid a blocking of firewall. HTTP protocol is used in not only Web browsing but also many applications such as the search of P2P programs, update of softwares and advertisement transfer of nateon messenger. As HTTP traffics are increasing and various applications transfer data through HTTP protocol, it is essential to identify which applications use HTTP and how they use the HTTP protocol. In order to prevent a specific application in the firewall, not the protocol-level, but the application-level traffic classification is necessary. This paper presents a method to classify HTTP traffics based on applications of the client-side and group the applications based on providing services. We developed an application-level HTTP traffic classification system and verified the method by applying the system to a small part of the campus network.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.19 no.3
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• pp.107-117
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• 2009

Network administrator recognizes the abnormal phenomenon in the managed network by using the alert messages generated in the security devices including the intrusion detection system, intrusion prevention system, firewall, and etc. And then the series of task, which searches for the traffic related to the alert message and analyzes the traffic data, are required to determine where the abnormal phenomenon is the real network security threat or not. There are many alert messages to have to inspect in order to determine the network security situation. Also the much times are needed so that the network administrator can analyze the security condition using existing methods. Therefore, in this paper, we proposed an efficient method for analyzing network security situation using visualization. The proposed method monitors anomalies occurred in the entire IP address's space and displays the detail information of a security event. In addition, it represents the physical locations of the attackers or victims by linking GIS information and IP address. Therefore, it is helpful for network administrator to rapidly analyze the security status of managed network.

• Proceedings of the Korea Information Processing Society Conference
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• 2008.11a
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• pp.1363-1366
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• 2008

최근 Skype의 인기와 더불어 P2P기반의 VoIP에 대한 관심이 높아지고 있다. 이에 표준 콜 셋업 프로토콜인 SIP와 동등 계층 간 통신망 구성의 P2P 기술을 결합하여 분산된 VoIP 서비스를 제공하려는 연구가 활발하게 진행 중에 있다. P2P에서는 중앙 엔티티가 존재하지 않으므로 사용자의 위치정보를 효율적으로 분산시키고 신속한 검색 방법을 제공하는 것을 중요한 문제로 다루고 있다. P2PSIP에서는 파일공유 목적의 P2P 서비스와는 다르게 특정 사용자의 각종정보(위치, 프로파일 등)를 빠르고 정확하게 찾아내야한다. 분산된 사용자의 위치정보를 검색하기 위하여 주로 DHT를 사용하고 있다. 하지만 매번 새로운 접속마다 사용자의 위치를 다시 찾아야 하기 때문에 오버레이 네트워크의 트래픽을 증가시킨다. 또한, 오버레이 네트워크에 참여하는 노드의 수가 증가함에 따라 사용자의 검색시간이 길어지는 단점을 가지고 있다. 본 논문에서는 DHT로 찾아낸 사용자의 접속패턴 히스토리 정보를 캐쉬로 저장하여 호 설정 지연을 감소시키는 방안을 제안한다.