• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.7-8
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• 2006

F-HMIPv6 is protocol that supports fast handovers for Hierarchical Mobile IPv6. Unlike HMIPv6 (Hierarchical Mobile IPv6), it sends FBU(Fast Binding Update) by predicted Router's Information for a potential handover. But, The current version of this protocol doesn't ensure impeccably between mobile node and router. To make up for the weak points of the security, we propose the architecture for F-HMIPv6 protocol to structurally reinforce the security and improve weak security of among mobile node, MAP(Mobility Anchor Point), and routers for binding update when mobile node conducts handovers.

• Proceedings of the Korean Information Science Society Conference
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• 2003.04d
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• pp.644-646
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• 2003

본 논문은 현재 각각의 운영체제에서 운영 및 구현되고 있는 Mobile Node들의 의존성을 최소화하여 설계하고 이를 개발한다. Mobile IP의 RFC 2002를 준수하여 Mobile Node를 운영하는 방법을 설계하여 Mobile Node에 이동성을 제공한다. 여기에는 각각 운영체제만의 특정 코드상의 특징을 제외하고 설계된 기본적인 모듈들을 사용하는 방식을 통해 제안하고, 이에 해당하여 사용되는 이동 에이전트인 HUT code를 수정, 보안한다. 이 설계방식을 가볍게 하여 PC기반의 Linux부터 현재 가장 범용적으로 사용되고 있는 Windows계열의 운영체제 및 휴대성을 강조한 PDA상의 Windows CE에서까지 개발한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.11B
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• pp.1269-1276
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• 2011

In the Proxy Mobile IPv6 (PMIPv6), the data transmission performance may be degraded when the two communicating hosts are located within the same mobile domain, since all the data packet shall be delivered by way of Local Mobility Anchor (LMA). In this paper we propose an extensional scheme of PMIPv6 using binding query. In the proposed Query-based PMIPv6 (Q-PMIPv6) scheme, the Mobile Access Gateway (NAG) of Correspondent Node (CN) sends a binding query to LMA to obtain the Proxy Care-of-Address of Mobile Node (MN). Since then, CN and MN can communicate with each other by using an optimized data path. For comparison, we performed the numerical analysis and the ns-2 simulations for the proposed Q-PMIPv6 scheme and the existing PMIPv6 and PMIPv6 Localized Routing (PMIPv6-LR). From the results, we can see that the proposed scheme outperforms the existing PMIPv6 and PMIPv6-LR schemes in terms of the signaling control and data delivery costs.

• The KIPS Transactions:PartC
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• v.13C no.1 s.104
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• pp.113-120
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• 2006

A node of mobile IPv6 moving foreign networks needs authentication process to support right services against from security threat. AAA is a trust infrastructure that authenticates, authorizes, and accounts nodes receiving a network service. And Mobile IPv6 Working Group recommends use of AAA infrastructure to authenticate mobile nodes. Event though AAA infrastructure provides strong authentication functions, it should exchange a lot of messages to authenticate mobile nodes every movement. The exchange of lots of messages causes latency and it is interfered with realization of real-time communication. This paper proposes an authentication method of improved speed using hash value of mobile node to reduce authentication latency. Directly after movement, a mobile node applying a Proposed method uses extended existing security authentication for a while and deletes the establishment latency of new security authentication. Performance evaluation of a proposed method verifies the efficiency through the analysis of cost comparison with other methods. The conclusion of performance evaluation is that the proposed method gets more 25% performance improvement than a general method when a mobile node moves another subnet.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.5B
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• pp.512-521
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• 2003

In this paper, we introduce our experience of the design and implementation of mobile collaboration system(MCS) that support people using mobile devices to participate in cooperative session. There are considerable differences between desktop PC and mobile devices like PDA in processing ability, resolution of display and color degree. In the case of mobile devices, they use different processors and different operating system and they have even differences in ability of executing application. The mobile collaborative system based on T.120 protocol of ITU-T standard compromised of mobile collaboration server, mobile collaboration client, session node and application. We also define the session node in desktop PC in which session control block and communication block runs. This node provide functions of session control block and communication block to mobile collaboration clients and so lighten load of clients. The mobile collaboration server provides information of candidates for session node, session and user to mobile collaboration client. And this server support clients to configure their own session node and manage sessions. Only the mobile collaboration client module and applications including APE are executed in a mobile device when user using mobile devices would like to participate in cooperative session. We implemented mobile collaboration client and applications with JAVA to support platform independency.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.5B
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• pp.480-488
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• 2009

A mobile ad-hoc network is an autonomous collection of wireless mobile nodes that organizes a temporary network without any network infrastructure. Due to node mobility, it is a challenging task to maintain the network topology. In this paper, we propose a stable clustering algorithm that uses node mobility for cluster formation. In the proposed algorithm, the node mobility is measured by counting the number of nodes entering into/leaving from its transmission range. The node having the lowest mobility is selected as a cluster head. For topology maintenance with reduced control overhead, the cluster head adaptively controls the broadcasting period of hello message to the measured node mobility. Through computer simulations, it is verified that the proposed algorithm outperforms previous clustering algorithms in terms of control overhead, the rate of node mobility changes and the number of cluster head changes.

• Journal of Korea Society of Digital Industry and Information Management
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• v.7 no.4
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• pp.15-22
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• 2011

U-Healthcare service is a real-time service using the vital signs which are continuously transferred from monitoring sensors attached to mobile patients under the wireless network environments. It should monitor the health condition of mobile patients everywhere at any time. In this paper, we have improved two features of the three layered mobile patient monitoring system with load balancing ability. First, the simulation process has been improved by allowing the number of related nodes to be changed. Secondly, we have modified S node to which queue is added to reduce the loss rate of collecting data from patients during the delay of S node process. And the data from the patient with high priority can be transferred to the server immediately through the filtering function. Furthermore, we have solved the problem of redundancy in sharing information among S nodes by differentiating process time to each S node. By performing a DEVS Java-based system simulation, we have verified the efficiency of this improved system.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.16 no.4
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• pp.1373-1391
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• 2022

We investigate mobile multiple-input multiple-output (MIMO) molecular communication via diffusion (MCvD) system which is consisted of two source nodes, two destination nodes and one relay node in the mobile three-dimensional channel. First, the combinations of decode-and-forward (DF) relaying protocol and network coding (NC) scheme are implemented at relay node. The adaptive thresholds at relay node and destination nodes can be obtained by maximum a posteriori (MAP) probability detection method. Then the mathematical expressions of the average bit error probability (BEP) of this mobile MIMO MCvD system based on DF and NC scheme are derived. Furthermore, in order to minimize the average BEP, we establish the optimization problem with optimization variables which include the ratio of the number of emitted molecules at two source nodes and the initial position of relay node. We put forward an iterative scheme based on block coordinate descent algorithm which can be used to solve the optimization problem and get optimal values of the optimization variables simultaneously. Finally, the numerical results reveal that the proposed iterative method has good convergence behavior. The average BEP performance of this system can be improved by performing the joint optimizations.

• The KIPS Transactions:PartC
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• v.15C no.1
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• pp.37-44
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• 2008

In order to minimize the signaling delay for a resource reservation on the new routing path after the handover of Mobile Node(MN) is completed, it is important to discover the crossover node where the old and new routing paths meet. With the 크로스오버 노드 being found, the signaling messages only need to be transferred on the changed part of the end-to-end path. The crossover node is generally discovered using the end-to-end Session ID(SID) of the established session between MN and Correspondent Node(CN). However, in the Hierarchical Mobile IPv6(HMIPv6) network, if the Mobile Anchor Point (MAP) reserves the resource by aggregate with the Home Agent(HA), the crossover node discovery cannot be performed in the general way since the aggregate SID that has established between the previous MAP and HA is different from the that of the current MAP and HA after MN's handover. In this paper, we propose a mechanism to discover the crossover node within the tunnel between the MAP and the HA in an HMIPv6 network, assuming that the Next Steps in Signaling(NSIS) is deployed for the resource reservation and the aggregate reservation is applied over the MAP and HA tunnel. The local repair required for the change of path is performed upon the crossover node discovery. The simulation results show that the proposed scheme reduces the signaling delay for the reservation and outperforms the existing scheme with respect to throughput during the handover.

• Proceedings of the Korean Information Science Society Conference
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• 2002.04a
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• pp.166-168
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• 2002

본 논문에서는 Mobile IP에서 핸드오프 중에 발생하는 패킷손실을 제거하기 위한 신뢰성 있는 핸드오프 기법을 제안하였다. 기존에 제시된 핸드오프 기법은 핸드오프 중에 발생하는 패킷손실을 줄여주지만 여러가지 문제점을 가지고 있었다. 본 논문에서는 캐쉬 에이전트(Cache Agent)가 대응 노드(Correspondent Node)를 대신하여 바인딩 캐쉬를 관리하며 대응 노드가 이동 노드(Mobile Node)에게 전송한 패킷을 버퍼링함으로써 핸드오프 중에 발생하는 패킷손실을 제거한다.