• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.11A
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• pp.1101-1112
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• 2006

With the recent growth in demand for high-data rate multimedia services in the wireless environments, the Mobile Broadband Wireless Access (MBWA) technologies, such as WiBro (Wireless Broadband internet) system, are gradually coming into the spotlight. Unlike the conventional mobile communication networks based on cellular system, the WiBro system basically consists of IP based backbone networks that will be ultimately deployed by Ipv6 (IP version six) based backbone networks according to the All-IP trend for the network evolution. In such wireless mobile environments, it is needed to support the mobility management protocol on network layer as well as physical layer and Medium Access Control (MAC) layer in WiBro system. Accordingly, in this paper, we propose a fast handover scheme for improving the handover performance in IPv6 based WiBro system and show that the proposed scheme achieves loss-free and low handover latency during inter-subnet movement of the mobile stations through the simulation.

• Proceedings of the Korea Institutes of Information Security and Cryptology Conference
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• 2002.11a
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• pp.495-498
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• 2002

The need for network protection, accounting and resource management in foreign administrative domain requires appropriate security services. In this paper, we propose an access control protocol to support the authentication between mobile node and visiting subnet. Our hybrid way of approach aims to reduce computational overhead and minimize the use of network bandwidth. We also propose non-certificate based public-key cryptography to provide non-repudiation, which does not require CRL retrieval and certificate validation.

• ETRI Journal
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• v.23 no.4
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• pp.202-204
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• 2001

In this letter, we propose a new multicast scheme, named Xcast+, which is an extension of Explicit Multicast (Xcast) for an efficient delivery of multicast packets. The mechanism incorporates the host group model and a new control plane into existing Xcast, and not only does it provide the transparency of traditional multicast schemes to senders and receivers, but it also enhances the routing efficiency in networks. Since intermediate routers do not have to maintain any multicast states, it results in a more efficient and scalable mechanism to deliver multicast packets. Our simulation results show distinct performance improvements of our approach compared to Xcast, particularly as the number of receivers in a subnet increases.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.17 no.3
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• pp.307-322
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• 1992

For designing the radar integrated data network, we construct the network structure with a spatial hieratchy decomposition scheme. The RIDN can be decomposed into several subent classes, those of which are composed of the several group classes of radar sites, In a group class. The communication nodes of a radar site are modeled by the software modules formulated with the statistical attributes of discrete events. And we get the analysis over the network through the separately constructed infra group level models which were coded with the C language.From the result of the simulation. We could findthe fact that the data integration system;s performance approaches to the theordtically calculated value after being stable. And also we could get the packet processing status of a communication module’s inner processor which is difficult to oberve through the mathematical calculation tin the subnet model of the integrated data network.

• Proceedings of the Korean Information Science Society Conference
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• 2008.06b
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• pp.24-29
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• 2008

여러 개의 작업이 동시에 작동 할 때 서로 다른 작업에서 특정한 로봇이나 장치를 사용하기 위하여 상대방의 작업이 끝나기를 기다리는 상태를 교착상태라 하며 생산공정에서는 효율성과 경제성 제고에 가장 중요한 문제 중 하나다. 지금까지 이러한 교착상태 확인은 도달성(reachability)기법이나 서브넷(Subnet)으로 분리하여 분석하는 기법 등이 가장 많이 사용 되었으나, 분석에 필요한 시간과 노력, 복잡성과 효율성에 있어서 효과적이지 못한 단점을 가지고 있다. 본 연구는 페트리넷(Petri Net)에서 모든 플레이스(Place) 간의 관계를 나타내는 추이(Transitive)행렬을 이용하여 교착상태가 나타날 가능성이 있는 자원공유 플레이스(Place)를 분석하여 교착상태를 검증하는 정책을 제시한다. 이를 위하여 교착상태를 확인할 수 있는 자원공유 플레이스의 관계를 정의하고, FMS(Flexible Manufacturing System) 모델을 이용하여 제안한 알고리즘의 성과를 검증한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.8B
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• pp.719-726
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• 2008

In this thesis investigate the security gateway that manage authorization for user access dynamically by recognizing automatically and comparison & distinction between database and User-information while a terminal unit(PC) trying to access to the network of subnet. Also, it present User-interfaced authorization allowance role model, so administrator can assign united access control between network level(L2) and application level(L7) in relation to system construction.

• Journal of Institute of Control, Robotics and Systems
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• v.10 no.1
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• pp.87-95
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• 2004

We proposed the division algorithm that was aimed at dividing system models. It used a transitive matrix to express the relation between place and transition. And the division algorithm was applied to the scheduling problem, with the division-scheduling algorithm. The division-scheduling algorithm was able to calculate the divided subnet table. And it is able to reduce the analysis complexity. In this study, we applied the proposed division algorithm and division-scheduling algorithm to flexible manufacturing system models. We compared the efficiency and performance of the division-scheduling algorithm with the Hillion algorithm, Korbaa algorithm, and Unfolding algorithm proposed in previous researches.

• Proceedings of the Korean Information Science Society Conference
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• 2006.10d
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• pp.606-610
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• 2006

무선랜(Wireless Local Area Network)의 보급이 증가되고 서비스 지역이 넓어지게 됨에 따라 이동성을 지원하는 VoIP 서비스의 제공에 대한 관심이 고조되고 있다. 그러나 무선랜의 표준 보안기술을 그대로 적용하는 경우 AP간의 Intra-domain handoff와 subnet 간의 Inter-domain handoff 시 사용자가 감내하기 어려운 정도의 끊김이 발생한다. 본 논문에서는 VoIP 서비스 프로토콜 중 하나인 SIP를 기반으로 하여 데이터 서비스와 VoIP서비스에서의 보안적용 방안을 달리하는 방법을 사용하여 보다 효율적으로 이동성을 지원하는 기법을 제안하였다.

• Proceedings of the IEEK Conference
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• 2000.07a
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• pp.88-91
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• 2000

In this paper we approach the problem of congestion control for TCP traffic over ATM-UBR networks by focusing on the fact that to get best performance. We study how to efficiently support TCP traffic in the subnet ATM model, when ATM is only a single link in the whole path. We show that when UBR connection. We analyze the ATM-UBR network service using the BSD 4.3 Reno, Tahoe TCP. However we found the fact that the characteristic of fast recovery algorithm makes a serious degradation of performance in multiple cell loss drop situation. We propose new fast recovery algorithm to solve the problem.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.28B no.9
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• pp.739-746
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• 1991

This paper develops a modified multilayer perceptron architecture which speeds up learning as well as the net's mapping accuracy. In Phase I, a cluster partitioning algorithm like the Kohonen's self-organizing feature map or the leader clustering algorithm is used as the front end that determines the cluster to which the input data belongs. In Phase II, this cluster selects a subset of the hidden layer nodes that combines the input and outputs nodes into a subnet of the full scale backpropagation network. The proposed net has been applied to two mapping problems, one rather smooth and the other highly nonlinear. Namely, the inverse kinematic problem for a 3-link robot manipulator and the 5-bit parity mapping have been chosen as examples. The results demonstrate the proposed net's superior accuracy and convergence properties over the original backpropagation network or its existing improvement techniques.