• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.2
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• pp.75-82
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• 2008

Mobile IP was proposed to overcome identity problem of original IP address system caused by mobility of wireless mobile host. To complete its network handoff procedure, it must receive a mobile advertisement broadcasted by mobile agent. Generally, in a mobile IP system, mean time delay, 500ms, in a network handoff procedure is a critical problem of wireless service such as Voip, multimedia streaming. A caching agent caches a latest mobile advertisement, and replays it by receiving solicitation message from a mobile node finishing link layer detection. But, during the procedure of mobile registration, many packets from service provider to the mobile host would be lost and handoff time delay would be increased. In this thesis, we propose an unproved caching agent technique which can forward data packets while handoff procedure, and CoA pool for fast mobile IP registration.

• The KIPS Transactions:PartC
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• v.13C no.6 s.109
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• pp.709-716
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• 2006

According to the increase of various AV media devices and contents in the digital home, the DLNA becomes to play an important role as the interoperability standard between then Since this guideline only focuses on the interoperability among home networked devices, media players, and media contents existing inside of the homenetwork, there is no retrieval and transmission method for sharing multimedia contents located over several homes via Internet. Additionally, this guideline lets device-detection and notification messages to be transmitted using W multicast methods, and current Internet environment cannot guarantee consistent IP multicast services, it has the limitation that it cannot retrieve and control DLNA devices in other digital homes remotely via the Internet. Therefore, in this paper, we propose the IHM(Inter-Home Media) proxy system and its operating mechanism to provide a way of sharing media contents distributed over multiple DLNA-based homes, through analyzing these limitations and building up a sharing method for A/V media contents distributed over the DLNA homes based on the dynamic or private IP networks. Our method removes the limitation on the user locations through sharing distributed media contents, and also makes cost-downs for storing media contents, from the view point of individual residents.

• Proceedings of the Korea Information Processing Society Conference
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• 2010.04a
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• pp.729-732
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• 2010

통신망의 발달로 다양한 인터넷 기반 기술들이 등장함에 따라 현재는 데이터뿐만 아닌 음성에 대한 부분도 IP 네트워크를 통해 전송하려는 움직임이 발판이 되어 VoIP(Voice Over Internet Protocol)라는 기술이 등장하였다. SIP(Session Initiation Protocol) 프로토콜 기반 VoIP 서비스는 통신 절감 효과가 큰 장점과 동시에 다양한 부가서비스를 제공하여 사용자 수가 급증하고 있다. VoIP 서비스는 호(Call)를 제어하기 위해 SIP 기반으로 구성이 되며, SIP 프로토콜은 IP 망을 이용하여 다양한 음성과 멀티미디어 서비스를 제공하게 되는데 IP 프로토콜에서 발생하는 인터넷 보안 취약점을 그대로 동반하기 때문에 DoS(Denial of Service) 및 DDoS(Distribute Denial of Service)에 취약한 성향을 가지고 있다. DDoS 공격은 단시간 내에 대량의 패킷을 타깃 호스트 또는 네트워크에 전송하여 네트워크 접속 및 서비스 기능을 정상적으로 작동하지 못하게 하거나 시스템의 고장을 유도하게 된다. 인터넷 기반 생활이 일상화 되어 있는 현 시점에서 안전한 네트워크 환경을 만들기 위해 DDoS 공격에 대한 대응 방안이 시급한 시점이다. DDoS 공격에 대한 탐지는 매우 어렵기 때문에 근본적인 대책 마련에 대한 연구가 필요하며, 정상적인 트래픽 및 악의적인 트래픽에 대한 탐지 시스템 개발이 절실히 요구되는 사항이다. 본 논문에서는 SIP 프로토콜 및 공격기법에 대해 조사하고, DoS와 DDoS 공격에 대한 특성 및 종류에 대해 조사하였으며, SIP를 이용한 VoIP 서비스에서 IP 분류와 메시지 중복 검열을 통한 DDoS 공격 탐지기법을 제안한다.

• The Journal of the Convergence on Culture Technology
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• v.7 no.1
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• pp.551-557
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• 2021

With increase of electric vehicle in the road, the number of charging/discharging infrastructure for electric vehicle in public space is also increased rapidly. To charge or discharge the electric vehicle the user of electric vehicle and service provider should verify the each other's identity to minimize security vulnerability. This paper proposes mutual authentication scheme between electric vehicle and charging/discharging service provider with help of hash function and Message Authentication Code(MAC). Also efficient operating scheme for charging/discharging service system is proposed. The analysis shows that the system has robustness against security vulnerability. Also this system can keep the sensitive personal information of service user safely.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.4
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• pp.692-699
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• 2015

Evarything as a Service (XaaS) is a software, platform, infra distribution method which provide users with necessary modules, not entire modules, as a service. To efficiently and securely operate services such as XaaS, it is needed to solve various Internet problems like network congestion, weak security and so on. Future Internet technologies are provided to solve such problems. Specially, named data networking architecture (NDN) proposes that network nodes cache transmitted data, and then they send the cached data if receiving request messages for the cached data. So NDN can efficiently diffuse excessive request messages transmitted toward original contents providers. However, when receiving contents through NDN, receivers can not confirm the practical providers because the practical providers can be different from original contents providers. Hence, it is requested for receivers to verify the received contents and such a verification process can cause service delay of XaaS. In this paper, we improve a content verification scheme of NDN to enhance the performance of services such as XaaS.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.8B
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• pp.797-804
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• 2009

Recently, SIP(Session Initiation Protocol) is used to set up and manage sessions for multimedia applications such as VoIP(Voice over IP) and IMS(IP Multimedia Subsystem). However, because SIP operates over the Internet, it is exposed to pre-existed internet security threats such as service degradation or service disruptions. Multimedia applications which are delay sensitive even suffers more from the threats mentioned above. The proposed methods so far to detect SIP INVITE flooding are CUSUM(Cumulative Sum), Hellinger distance and adaptive threshold, but among methods only take normal state into consideration. So, it is not capable of adapting the condition of the network congestion which are dynamically changing. In this paper, SIP INVITE flooding detection algorithm considering network congestion which enables efficient detections of such attacks is proposed. The proposed algorithm is expected to detect other types of attacks such as BYE and CANCEL more precisely compared to other methods.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.8A
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• pp.909-917
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• 2004

Mobility support is one of the most important functions to provide seamless data transfer for real-time multimedia services in wireless networks. In this paper, we analyze and compare the handoff delay performances for several architectures such as MIP-RO, SIP, MIP-RO/CIP and SIP/CIP, which are expected to be a promising solution to support IP mobility management. For the analysis, we make the detailed message flows of those architectures in handoffs, and then make an analytical model to compute the handoff delay for each scheme. Numerical results showed that the SIP/CIP approach outperformed other schemes in the viewpoints of the handoff delay.

• Proceedings of the Korea Association of Information Systems Conference
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• 2001.12a
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• pp.348-361
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• 2001

최근 몇 년 사이에 인터넷(Internet) 공간상에서 거래되는 선박매매 사이트의 출현으로 인하여 사이버해운거래 시장이 형성되고 있다. 인터넷은 다양한 정보제공자에 의해 광범위한 분야의 정보를 멀티미디어 형태로 전달한다는 점에서 매우 각광을 받고 있지만 이용자의 증가로 무수한 정보들이 걸러지지 못한 채로 Web상에 존재하게 되었다 따라서, 이러한 정보들을 체계적으로 정리하고, 이용자들의 구미에 맞게 가공된 정보의 필요성이 대두되게 되었다. 이러한 문제를 해결하기 위해서 이용자가 원하는 것을 스스로 인지하고 판단하여 요구사항을 해결해주는 '지능적 대리인' 또는 '지능을 가진 도우미'라고 일컫는 지능형 에이전트(Intelligent Agent)의 필요성이 대두되었다. 지능형 에이전트는 그 다양한 기능으로 인하여 인터넷에서 매우 중요한 요소로 자리잡게 되었다. 우리나라를 비롯해서 선진 해운국에서는 선박매매사이트를 개설하여 사이버 공간상에서 거래를 수행하고 있지만, 사이트별 등록된 선박의 수가 많지 않을 뿐 아니라 거래대상 선박의 표현 방식도 사이트별 국가별로 매우 달라, 선박 매매 시 충분한 매매대상 선박정보를 획득하기 어려운 실정이다. 본 연구는 선박매매 시 고객에게 매매 선박정보를 제공해주는 선박매매용 에이전트 설계를 목표로 하고 있다. Bargainfinder, Bargainboat, Shopboat, Price watch 등 쇼핑몰을 대상으로 하는 비교쇼핑에이전트는 상용화되어 운영되고 있지만 선박매매용 에이전트에 관한 연구는 시도되지 않고 있다. 본 연구는 선박매매용 에이전트를 개발하기 위한 설계연구로서 다음 사항에 대한 연구가 시도되었다. (a) 구매 선박에 대한 요구사항 표현 방법 (b) 관련 선박의 표현, 등록 및 색인방법 (c) 공급 선박의 분류와 표현 방법 (d) 에이전트의 정보 수집을 위한 메시지 표현 방법 (e) 수집된 선박정보의 데이터베이스 저장 표현방법 (f) 요구 선박을 찾아주는 정보제공 서비스가 요구된다.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.10 no.2
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• pp.103-111
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• 2010

For that reason, more and more growing of the internet speed, many kind of the multimedia as if the voice, a letter, a photograph, a moving picture are appearance and integration of the internet as if the wireless internet, the CATV, a satellite is forming. Today, many changes in the communication environment are occurrence. therefore a demands of the user keep up increase. so, in this paper, we developed the SOHO IP-PBX embedded which can automatically exchange the call. the developed IP-PBX have many functions as if the exchange call function, the gateway function, the PSTN backup function, the FAX function, the VPN function, etc. and verified it by an experiment on the rules in KT.

• Journal of Digital Contents Society
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• v.5 no.4
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• pp.283-288
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• 2004

This paper presents research in intelligent massenger technique for Cyber University to support accessing university database. Proposed techniques enables better communication between students and professons by using intelligent messenger. Intranet based massenger support simple message transfer and multimedia chatting service within homogeneous network or members in same group. Using niversity database it provide personalize information for each different user demand needs and through managing technique user could effectively organize members of group. To embody intelligent massenger, JMF(Java Media Frame Work), RMI(Remote Method Invocation), XML techniques were proposed and in result constructing effective community.