• The Journal of the Korea Contents Association
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• v.10 no.1
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• pp.46-58
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• 2010

The user valence of VoIP services with SIP protocol is increasing rapidly because of cheap communication cost and its conveniency. But attacker can easily modify the packet contents of SIP protocol as SIP header is transmitted by using UDP methods in text form. The reason is that SIP protocols does not provide an authentication function on the transmission session. Therefore, existing SIP protocol is very weak on SIP Packet Flooding attack etc. In order to solve like this kinds of SIP vulnerabilities, we used SIP status codes under the monitoring module for detecting SIP Flooding attacks and additionally proposed an advanced protocol where the authentication and security function is strengthened about SIP packet. We managed SIP session spontaneously in order to strengthen security with SIP authentication function and to solve the vulnerability of SIP protocol. The proposed mechanism can securely send SIP packet to solves the security vulnerability with minimum traffic transmission. Also service delay in SIP proxy servers will be minimized to solve the overload problem on SIP proxy server.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.5A
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• pp.526-535
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• 2008

Recently, several MAC protocols using the directional antennas have been proposed for wireless mobile ad hoc networks. In the theory, it can improve spatial reuse and communication throughput in the Mobile Ad-hoc networks. But, or However even though direction transmissions using the Directional MAC protocol(D-MAC) are expected to provide significant improvements, they causes other problems such as deafness problem and fairness problem. In this paper, we analyze the D-MAC protocol in Mobile Ad-hoc network for Vehicle to vehicle(V2V) communication. Through the results of the analysis, We the fundamental problem of D-MAC protocol and finally we suggest new D-MAC protocol for V2V networks.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.5
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• pp.1189-1197
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• 2011

To manage sensing information such as temperature, humidity and so on efficiently, it is need to use special purpose protocol. In this reason, IETF WG proposed CoAP protocol, and it is on Internet draft. If it is possible to work on a specific protocol, sensor end-nodes and network devices will be managed efficiently. However, end-nodes have restricted resources, it is hard to applying to CoAP protocol directly. In this paper we analyse a CoAP protocol stack for USN. To verify this protocol quickly, at first we implemented CoAP protocol stack over PC environments. After the logical verification, we applied this protocol to the USN environment. To do this, we ported CoAP protocol to Cygwin environment, and proposed solutions for hardware dependencies, and it is verified through experiments.

• Journal of KIISE:Computing Practices and Letters
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• v.11 no.4
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• pp.312-333
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• 2005

SIP(Session Initiation Protocol) has been proposed for session control protocol of Internet multimedia communication system like VoIP(Voice over IP). SIP has complicated session control steps to support various kinds of audio and video formats and to assure service quality of real time data communication. Up until now, existing protocol analyzers can not provide such detailed information of SIP based communication system. In this paper, therefore, we propose a new protocol analyzer as a tool that can analyze and diagnose SIP based multimedia communication system throughout the session initiation, data exchange and session change steps. The propose traffic analyzer, which is called STAT(SIP based Traffic Analysis Tool), Is implemented on Winder's environment so that it is generally usable and extensible. Since STAT analyze low level packets captured via Ethernet broadcasting property, it is able to provide session status and real time traffic monitoring information without any affection to the communication system. The STAT which is implemented in this paper. therefore, is expected to be a useful tool for developing and managing of a SIP based multimedia communication system.

• Convergence Security Journal
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• v.21 no.1
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• pp.129-135
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• 2021

Greedy protocols show good performance in Vehicular Ad-hoc Networks (VANETs) environment in general. But they make longer routes causing by surroundings or turn out routing failures in some cases when there are many traffic signals which generate empty streets temporary, or there is no merge roads after a road divide into two roads. When a node selects the next node simply using the distance to the destination node, the longer route is made by traditional greedy protocols in some cases and sometimes the route ends up routing failure. Most of traditional greedy protocols just take into account the distance to the destination to select a next node. Each node needs to consider not only the distance to the destination node but also the direction to the destination while routing a packet because of geographical environment. The proposed routing scheme considers both of the distance and the direction for forwarding packets to make a stable route. And the protocol can configure as the surrounding environment. We evaluate the performance of the protocol using two mobility models and network simulations. Most of network performances are improved rather than in compared with traditional greedy protocols.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.15 no.1
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• pp.41-55
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• 2005

A group key agreement protocol allows a group of user to share a key which may later be used to achieve certain cryptographic goals. In this paper, we propose a new scalable two-round ID-based group key agreement protocol which would be well fit to a Pay-TV system, additionally. to the fields of internet stock quotes, audio and music deliveries, software updates and the like. Our protocol improves the three round poop key agreement protocol of Nam et al., resulting in upgrading the computational efficiency by using the batch verification technique in pairing-based cryptography. Also our protocol simplifies the key agreement procedures by utilizing ID-based system. We prove the security of our protocol under the Computational Diffie-Hellman assumption and the Bilinear Decisional Diffie-Hellman assumption. Also we analyze its efficiency.

• Proceedings of the Korean Information Science Society Conference
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• 2006.06d
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• pp.241-243
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• 2006

업무환경이 다양해지면서 사람들은 원거리에 있는 사람과 협업을 하는 경우가 많아지고 있다. 원거리의 사람들과 협업을 하기 위한 컴퓨터 도구로서 협업지원 시스템을 사용하고 있다. 웹데브는 웹상의 분산 저작활동을 지원하기 위한 표준프로토콜로서 원거리에 있는 사람들 간에 웹상의 자원을 편집하고 관리할 수 있도록 해주는 HTTP/1.1의 확장이다. 협업지원 시스템을 구성할 때 웹데브를 사용한다면 효과적인 시스템을 구성할 수 있을 것이다. 현재 개발된 협업지원시스템 중에서 리눅스 기반으로 동작 협업시스템은 부재한 상대이다. 본 논문에서는 리눅스 기반에서 웹데브 프로토콜을 이용하여 동작하는 협업시스템의 설계에 대하여 기술한다. 본 시스템의 서버는 웹데브 서버로 널리 사용되고 있는 Jakarta Slide 서버를 확장하여 협업을 지원할 수 있는 구조로 설계 하였다. 서버에는 협업작업을 용의하게 할 수 있는 팀작업장을 지원하며 또한 개인적인 자료를 관리할 수 있는 개인작업장을 지원하는 기능을 지원하게 된다. 클라이언트는 사용자가 서버에 등록한 자원을 관리 하는 기능과 팀원들 간의 상호작용을 원활하게 지원하는 사용자 인터페이스를 설계 하였다. 또한 협업지원 시스템을 사용하는 사용자가 새로운 팀작업장을 만들 수 있는 기능을 구성하고 다른 사용자를 초대하거나 다른 팀작업장에 참가요청을 할 수 있는 기능을 설계하였다.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.10 no.2
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• pp.81-88
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• 2006

The advent of supercomputers contribute greatly in overcoming scientific and academic problems that were previously difficult to solve. However, the supercomputer itself suffers from the problem of being considerable cost. In response, the concept of grid computing, to use the resources of distribute computers connected with each other, was created. This system uses connection oriented protocols to integrate and manage the resources of different types of distributed systems, yet it has the problem of compatibility between protocols of other types. In this paper, a system to manage grid network performance through XML-based SOAP web service which is platform-independent, is proposed.

• The Journal of the Korea institute of electronic communication sciences
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• v.8 no.12
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• pp.1803-1810
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• 2013

In a warehouse, because there exist frequent changes of stock status and the quality of some contents are influenced by the environment such as temperature, fast and accurate management of the warehouse's environment is very important for Warehouse Management Systems. However, due to the absence of a unified standard for the communication protocol between RFID nodes and centralized MAC schemes for RFID communications in previous studies have severe problems. Therefore, in this paper, we propose a WiMedia MAC based RFID cooperative relay transmission scheme for warehouse management system applications.

• The Journal of Korean Association of Computer Education
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• v.4 no.2
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• pp.51-61
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• 2001

With the advance of computer and communication technologies, a lot of virtual schools provide web-based classes that provide learning environments out of temporal and spatial constraints and many research works on the web-based classes have been proposed. Various techniques are required to build the virtual schools efficiently. One of them is the scheme for transaction management. However, existing transaction management schemes have inappropriate features for supporting web-based classes. In this paper, we propose a new locking-based transaction processing protocol that satisfies the requirements after presenting the requirements for transaction management to support web-based classes. In the protocol, a new method, called mark, is adopted to satisfy the requirements. The proposed protocol also eliminates unnecessary delays or abortions and thus, the proposed protocol can improve the performance of database systems.