• Journal of Digital Convergence
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• v.5 no.1
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• pp.69-76
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• 2007

This paper presents a study on the introduction of User Model-Based Dialogue System. Also we present a plan-based Korean dialogue system as a natural language database user interface for product search. The system can be characterized by its support for mixed initiative to give user more control over dialogue, employment of user model to reflect user's preferences, alternative solution suggestion if there is no product matched exactly to user's requirements, handling circumlocution which frequently occurs in dialogues. The user modeling shell system BGP-MS is adapted for the system. The system provides for a user-friendly database user interface by managing dialogue intelligently. By its implementation and test, it has been shown that the user model-based dialogue system can be utilized effectively for product search.

• Journal of the Korean Operations Research and Management Science Society
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• v.30 no.4
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• pp.151-161
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• 2005

For Internet service providers (ISPs), there are three common types of interconnection agreements : private peering, public peering and transit. One of the most important problems for a single ISP is to determine which other ISPs to interconnect with, and under which agreements. The problem can be then to find a set of private peering providers, transit providers and Internet exchanges (IXs) when the following input data are assumed to be given : a set of BGP addresses with traffic demands, and a set of potential service providers (Private peering/transit providers and IXs) with routing information, cost functions and capacities. The objective is to minimize the total interconnection cost. We show that the problem is NP-hard, give a mixed-integer programming model, and propose a heuristic algorithm. Computational experience with a set of test instances shows the remarkable performance of the proposed algorithm of rapidly generating near-optimal solutions.

• Proceedings of the Korea Information Processing Society Conference
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• 2003.05b
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• pp.1425-1428
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• 2003

인터넷 서비스의 발전에 따라 보안성이 높고 경제적인 VPN 의 필요성이 대두되었다. 여러 방식의 VPN 구성 방법 중 향후 멀티미디어 실시간 서비스 등에 필요한 QoS 및 트래픽 엔지니어링에 장점을 갖는 MPLS 기반의 VPN기술이 활발히 논의되고 있으며 현재 BGP/MPLS VPN 이 표준으로 정립되고 있다. 본 연구팀은 현재 활성화되고 있는 Mobile computing 기술과 이러한 VPN기술을 접목시켜 MPLS VPN 망에서의 이동성을 지원을 위한 방안을 제시 및 구현한 바 있으며 본 연구에서 기 제안한 방식에서 추가적으로 고려해줘야 할 문제점 및 해결방안에 대해 연구하였다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.8B
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• pp.738-749
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• 2003

Mobile IP protocol introduced in RFC3344 provides a node of the mobility service through IP tunneling mechanism in the IP networks. In this paper, we describe a method to provide a mobility service for VPN(Virtual Private Network) nodes on the MPLS(Multiprotocol Label Switching) network. The MPLS VPN considered here is based on "BGP/MPLS VPNs" presented in RFC2547. PE(Provider′s Edge) routers, which are able to provide VPN services on the MPLS network, are associated with mobility agents to support Mobile IP This proposed mechanism applies when a VPN node moves to other site of the same VPN, or when it moves to other site of a different VPN, or to the ordinary Internet site. We implemented this mechanism in PE routers and analyzed the performance of the MPLS VPN with mobility support on the testbed.

• 한국디지털정책학회:학술대회논문집
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• 2007.06a
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• pp.287-296
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• 2007

In this paper we present a plan-based Korean dialogue system as a natural language database user interface for product search. The system can be characterized by its support for mixed initiative to give user more control over dialogue, employment of user model to reflect user' spreferences, alternative solution suggestion if there is no product matched exactly to user's requirements, handling circumlocution which frequently occurs in dialogues. The user model ing shell system BGP-MS is adapted for the system. The system provides for a user-friendly database user interface bymanaging dialogue intelligently. By its implementation and test it has been shown that the user model-based dialogue system can be utilized effectively for product search.

• Information and Communications Magazine
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• v.16 no.2
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• pp.107-118
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• 1999

인터넷 사용자가 급진적으로 증가함에 따라 오늘날의 인터넷 트래픽의 양 또한 폭발적으로 증가하였으며 기존의 라우팅 기법을 이용하는 라우터를 사용하는 경우에는 라우팅 시의 지연으로 인해 고속 서비스를 요구하는 사용자의 욕구를 충족시키기는 어려울 것이다. 이와 같은 문제는 앞으로의 인터넷 사용자의 수요 및 요구 서비스를 예측할 때 조속히 해결해야 할 중요한 문제라고 할 수 있다. 고속 인터넷 서비스를 제공할 수 있을 것으로, 예상되었던 IPOA, MPOA, IP Switching, Tag Switching, MPLS 등의 기술 중에서 MPLS는 ATM 교환기를 이용하여 사용자의 요구에 부응할 수 있는 양질의 서비스를 제공할 수 있을 것으로 기대하고 있다. IETF에서는 MPLS 표준화가 활발히 진행중이다. 본 고에서는 ATM 교환기를 기반으로 MPLS 기술을 이용하여 ATM 기반의 인터넷 서비스를 제공할 수 있는 방법에 대해 기술한다. 본 시스템은 ATM 교환기와 연결된 MLSP 상에서 LDP, BGP 등의 프로토콜을 구현함으로써 LER 및 LSR로서 동작할 수 있도록 하여 대용량의 인터넷 트래픽을 고속 처리할 수 있는 기능성을 제시한다.

• International Journal of Internet, Broadcasting and Communication
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• v.13 no.4
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• pp.1-10
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• 2021

The purpose of the study is to contribute to the positive development of blockchain technology by providing data to examine security vulnerabilities and threats to blockchain-based services and review countermeasures. The findings of this study are as follows. Threats to the security of blockchain-based services can be classified into application security threats, smart contract security threats, and network (P2P) security threats. First, application security threats include wallet theft (e-wallet stealing), double spending (double payment attack), and cryptojacking (mining malware infection). Second, smart contract security threats are divided into reentrancy attacks, replay attacks, and balance increasing attacks. Third, network (P2P) security threats are divided into the 51% control attack, Sybil attack, balance attack, eclipse attack (spread false information attack), selfish mining (selfish mining monopoly), block withholding attack, DDoS attack (distributed service denial attack) and DNS/BGP hijacks. Through this study, it is possible to discuss the future plans of the blockchain technology-based ecosystem through understanding the functional characteristics of transparency or some privacy that can be obtained within the blockchain. It also supports effective coping with various security threats.

• Journal of Internet Computing and Services
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• v.11 no.2
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• pp.85-98
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• 2010

An advanced and proactive response mechanism against diverse attacks on All-IP network should be proposed for enhancing its security and reliability on open network. There are two main research works related to this study. First one is the SPIE system with hash function on Bloom filter and second one is the Sinkhole routing mechanism using BGP protocol for verifying its transmission path. Therefore, advanced traceback and network management mechanism also should be necessary on All-IP network environments against DDoS attacks. In this study, we studied and proposed a new IP traceback mechanism on All-IP network environments based on existing SPIE and Sinkhole routing model when diverse DDoS attacks would be happen. Proposed mechanism has a Manager module for controlling the regional router with using packet monitoring and filtering mechanism to trace and find the attack packet's real transmission path. Proposed mechanism uses simplified and optimized memory for storing and memorizing the packet's hash value on bloom filter, with which we can find and determine the attacker's real location on open network. Additionally, proposed mechanism provides advanced packet aggregation and monitoring/control module based on existing Sinkhole routing method. Therefore, we can provide an optimized one in All-IP network by combining the strength on existing two mechanisms. And the traceback performance also can be enhanced compared with previously suggested mechanism.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.10
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• pp.2733-2740
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• 2009

An advanced and proactive response mechanism against diverse attacks on All-IP network should be proposed for enhance its security and reliability on open network. There are two main research works related to this study. First one is the SPIE system with hash function on Bloom filter and second one is the Sinkhole routing mechanism using BGP protocol for verifying its transmission path. In this study, we proposed an advanced IP Tracing mechanism based on Bloom filter and Sinkhole routing mechanism. Proposed mechanism has a Manager module for controlling the regional router with using packet monitoring and filtering mechanism to trace and find the attack packet's real transmission path. Additionally, proposed mechanism provides advanced packet aggregation and monitoring/control module based on existing Sinkhole routing method. Therefore, we can provide an optimized one in All-IP network by combining the strength on existing two mechanisms. And the Tracing performance also can be enhanced compared with previously suggested mechanism.

• Journal of Korea Multimedia Society
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• v.3 no.2
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• pp.148-156
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• 2000

This paper proposed that an MPLS-based VPN using next-generation If switches and appropriate set of traffic engineering algorithms is the best way to implement QoS-capable IP VPNs. While ATM-based solution would not rely scalable the number of connections becomes too large, MPLS-based VPNs’ efficiency could be confirmed network delay time through performance evaluation. And we evaluated the performance about the If VPN based on proposed MPLS, at the result of evaluation. We figured out that delay increased more slowly in case of VPN based on MPLS comparing with the VPN based on ATM which has rapid delay increasement. Therefore we confirm that the VPN based on MPLS has high speed of packet processing and high degree of network efficiency through the performance evaluation.