• Proceedings of the Korea Information Processing Society Conference
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• 2009.11a
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• pp.917-918
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• 2009

This study evaluated the level of performance improvement in the form of a simulated experiment by adding fixed node in the middle of the network as a way to improve mobile ad.hoc network performance. The result showed that the performance level was much higher when fixed node was used together than when mobile node was used only, and the comparison of the mobile speed of mobile node also showed that use of fixed node together had higher performance. Moreover, the evaluation in accordance with the number of fixed node showed that more number of fixed node had shorter time delay. Further study following this on how many fixed node should be added on the ad.hoc network will ensure establishment of more reliable ad.hoc network.

• Proceedings of the Korean Information Science Society Conference
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• 2001.04a
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• pp.547-549
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• 2001

인터넷의 확산과 All-IP망으로의 망의 진화에 대한 논의가 활발하게 이루어지고 있다. 더불어 IPv6[1]망에서의 이동성 지원을 위하여 IETF(Internet Engineering Task Force)에서 Mobile IPv6를 제안하였다. Mobile IPv6[5]의 기본 발상은 Routing Table의 변경에 의에 다른 링크로 이동한 호스트에게 Packet를 전달할 수 있게 하는 것이다. (Triangle Routing[4]). Mobile IPv6을 구성하는 요소 중 Mobile Node의 기본 구조를 제시했다. Mobile Node 자신의 위치 정보를 갱신하는 Move Detection이 핵심적인 부분이다. 본 논문에서는 이 절차에 대한 보다 실제적인 고찰과 이를 의한 설계를 제시한다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.10
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• pp.2529-2547
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• 2012

In this paper, we use a quadrotor-based mobile sink to gather sensor data from the terrestrial deployed wireless sensor network. By analyzing the flight features of the mobile sink node, we theoretically study the flight constraints of height, velocity, and trajectory of the mobile sink node so as to communicate with the terrestrial wireless sensor network. Moreover, we analyze the data amount which the mobile sink can send when it satisfies these flight constraints. Based on these analysis results, we propose a data acquisition approach for the mobile sink node, which is discussed detailed in terms of network performance such as the transmission delay, packet loss rate, sojourning time and mobile trajectory when given the flying speed and height of the mobile sink node. Extensive simulation results validate the efficiency of the proposed scheme.

• Proceedings of the Korean Information Science Society Conference
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• 2006.10d
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• pp.791-795
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• 2006

하이브리드 센서 네트워크에서 static sensor node들이 초기 배치된 후, coverage-hole을 결정하여, hole을 커버할 mobile sensor node들의 필요한 수 및 위치를 결정하고 배치하는 연구는 상당한 수준에 이르렀다. 그러나 mobile sensor node들을 호출하고 배치하는데 너무 많은 에너지를 소모하고 있다. 본 논문에서는 coverage-hole에서 mobile sensor node들을 호출하기 전에 mobile sensor node들을 최대한 coverage-hole에 가깝게 배치하여, 호출하는데 소요되는 에너지를 획기적으로 절감하였다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.12A
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• pp.994-1005
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• 2011

In this paper, we propose a novel approach to optimize the movement of mobile sink node, called AMSP(Adaptive Mobile Sink Path) for mobile sensor network environments. Currently available studies usually suffer from unnecessary data transmission resulting from random way point approach. To address the problem, we propose a method which uses the Hilbert curve to create a path. The proposed method guarantees shorten transmission distance between the sink node and each sensor node by assigning orders of the curve according to sensor node density. Furthermore, The schedule of the sink node is informed to all of the sensing nodes so that the Duty Cycle helps the network be more energy efficient. In our experiments, the proposed method outperforms the existing works such as TTDD and CBPER by up to 80% in energy consumption.

• Journal of KIISE:Information Networking
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• v.31 no.5
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• pp.482-489
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• 2004

Paging extensions for Mobile IP was proposed to avoid unnecessary registration signaling overhead of Mobile IP. In order to support the paging function in Mobile IP, the slates of a mobile node arc divided into active on, active off, idle. The active on state means when any incoming or outgoing data session arrives to a mobile node. After data session is completed, the state of the motile node is changed into active off from active on. At this moment, the active timer starts to be operated. If the active timer expires, the mobile node moves to idle state. If a mobile node has very frequently data sessions at the same cell, the mobile node is better to move slowly into idle state. The other way, if the mobile node very frequently moves into new cell area and receives or sends little data, the mobile node is better to move earlier into idle state. In this raper, the active timer is adaptively set by the mobile nodes traffic and mobility characteristics and the paging scheme using this active timer is proposed to reduce the location registration cost.

• Proceedings of the Korean Information Science Society Conference
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• 2002.04a
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• pp.205-207
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• 2002

컴퓨터의 이동성을 지원하기 위해 1996년 IETF (Internet Engineering Task Force)에서 mobile IPv4 를 제정하였고 이에 따른 구현 사례가 등장하였다. 그러나 현재까지 국내외 대학에서 발표된 구현 사례는 주로 유닉스 기반의 플랫폼(리눅스, BSD)에서 개발되었으며 가장 보편적으로 사용되고 있는 운영체제인 윈도우에서, 라우팅 정보가 변경되면 재부팅을 해야 하는 결함때문에 개발에 어려움이 있었다. NT 기반의 윈도우즈가 출시됨에따라 윈도우 플랫폼에서 Mobile IP의 구현이 가능하게 되었으며 본 연구실에서는 윈도우즈 2000 플랫폼에서 Mobile IPv4를 위한 mobile node를 설계하여 POSTECH MIP mobile node를 개발하였다. FOSTECH MIP mobile node는 확장성과 효율성을 목표로 설계되어 커널 스페이스(kernel space)와 유저 스페이스 (user space)에서 동작하도록 구현되었다.

• The Journal of Engineering Research
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• v.8 no.1
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• pp.97-106
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• 2006

Chord system, structured P2P system based on distributed hashed table, didn't consider the mobility of mobile device. Mobility of mobile node may cause performance falloff of both mobile node and P2P network. Not only Chord system but also the greater part of P2P system didn't consider the mobility of mobile node. Recently it is researched on mobility in P2P system. In this paper, it proposed the method of the supporting mobility in chord system. Mobile node joins to the P2P network through the stationary node meaning the parents node. Mobile node require or offer the service for the parents node.

• The KIPS Transactions:PartC
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• v.17C no.2
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• pp.153-158
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• 2010

Mobile IPv6 is one of method can keep Mobile node's session. To solve legacy Mobile IPv4's triangular routing problem, in Mobile IPv6, Mobile Node could directly communicate with Correspond node by Binding Update. But, attacker could interfere Return Routability Procedure that is Correspond node check Home address and Care of address reachable. At this result, Attacker is able to hijack Session to correspond node from Mobile node. In This paper, We propose new Binding Update scheme for solving that problem. Our approach is that MN gives association both home token and care of token using onewayness of keyed hash fuction. From security and performance analysis, we can see that proposed binding Update Scheme can achieve stronger security than legacy scheme and at the same time requires minimal computational overhead.

• The KIPS Transactions:PartC
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• v.13C no.2 s.105
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• pp.211-218
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• 2006

The Mobile IPv6 provides the enhanced internet services to user by supporting a node's mobility. In Mobile IPv6(MIPv6), the mobile node sends the binding message which binds home address(HoA) with care-of address(CoA) to the home agent whenever it changes its point of attachment to the internet. To reduce the mobility management signal message the Paging Hierarchical Mobile IPv6(PHMIPv6) is proposed. The mobile node does not send the binding message within the domain if the mobile node's state is idle. Therefore the mobility signal message cost can be reduced. However, when the mobile node's session arrival rate is high the many mobility management signal cost are needed because the paging cost is very high. In this paper, we analysis the drawback of PHMIPv6 and propose the scheme which can reduce the mobility management signal cost. The proposed scheme works independent of the number of subnet in the domain. Therefore the proposed scheme can improve the mobile node's mobility management scheme.