• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.6A
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• pp.832-844
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• 1999

In this paper, we analyzed mobile-IP protocol of IETF, and propose new method to improve performance in handover environments. In proposed method, cache agent manages mobility binding information for mobile host. Thus, effective support of mobility is possible. Also, when handover occurs, mobile host recognizes change of foreign agent, and transmits registration message to new foreign agent. However, during registration time, data packet loss is occurs in old foreign agent. Thus, we prevent data loss by using data packet buffering and forwarding in old foreign agent.According to simulation results for data packet transmission performance in the case of handover occurring, proposed method has better performance than previous method in the view of transmission delay and throughput. Especially, if handover occurs very often, data buffering and forwarding method in foreign agent could guarantee better performance.

• The Journal of the Korea Contents Association
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• v.4 no.1
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• pp.67-75
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• 2004

In this paper, we design an authentication model based mobile PKI (Public Key Infrastructure). The authentication mood consists of Root-CA Home-network agent and Foreign-network agent. CA will going to gave the delegation ticket to Home-Agent or Foreign-Agent when they request. The authentication mode information security is various characteristic more then high speed, mobile network and low cost more then previous structure of assure information security.

• ETRI Journal
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• v.24 no.1
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• pp.12-22
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• 2002

A Mobile IP allows IP hosts to move between different networks without changing their IP addresses. Mobile IP systems supporting local registration were introduced to reduce the number of times a home registration with the remotely located home agent was needed. The local registration Mobile IP scheme enhanced performance by processing registration requests of mobile nodes at a local agent. The local registration approach may affect other aspects of the Mobile IP systems such as fault tolerance. In this paper, we briefly review previous solutions for supporting fault tolerance in local registration Mobile IP systems and propose a fault tolerance protocol with a backup foreign agent in a hierarchical local registration mobile IP to enhance the efficiency of such systems against foreign agent failures. We also describe the specification of the proposed protocol using LOTOS and perform its validation using MiniLite. Finally, we analyze the performance of our proposed fault tolerance protocol through simulation.

• Journal of the Korea Society of Computer and Information
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• v.4 no.4
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• pp.163-169
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• 1999

Mobile-IP has been designed to have mobile computer users move from place to place without changing their IP addresses. Mobile-IP introduces the following entities to support mobility: Home Agent. Foreign Agent, etc., and it uses the techniques such as Agent Discovery, Registration. and Tunnelling. Mobile-IP route optimization provides a mechanism by which correspondent nodes are enable to know the mobile host's care-of address to alleviate the triangle routing problem. As a further performance improvement, to alleviate the overhead resulted from the frequent local mobility within a site hierarchical foreign agents are presented, and as a foreign agent which is willing to participate in communication maintain a buffering mechanism not to loss packets for mobile host, smooth handoffs is presented. In this paper, the problems to be thought to support host's mobility and the existing method to support it is discussed.

• Proceedings of the Korean Information Science Society Conference
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• 2000.10c
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• pp.414-416
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• 2000

Mobile IP는 OSI7 계층 중 네트워크 계층에서의 이동성 지원을 위한 Protocol이다. Mobile IP의 세 주체 중 Home Agent와 Foreign Agent는 Mobile Node 에게 이동성을 제공하는 서비스 제공자로서의 역할을 수행한다. 본 논문에서는 Mobile IP Protocol의 주체 중 Mobile Agent를 객체지향 개념을 도입하여 설계.구현한다. Linux Kernel 2.2.14의 환경에서 객체지향 언어인 C++을 이용, 기능적인 측면에서의 객체를 구성하고, IP 계층에서의 이동성을 제공하기 위해 Home Agent와 Foreign Agent의 주된 기능인 터널링(Tunneling)을 Linux Kernel의 모듈(Module)을 이용, 설계.구현한다.

• Journal of Internet Computing and Services
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• v.5 no.5
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• pp.17-26
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• 2004

Mobile multicast schemes are classified into remote subscription and bi-directional tunneling. While the former scheme has much overhead in the maintenances of multicast tree, the latter suffers from inefficient routing. In this paper, we propose dynamic mobile multicast routing (DMMR) scheme, which is operated on the basis of cost functions related with forwarding cost and tree reconstruction cost, Basically DMMR intends to find lower cost between forwarding cost and tree reconstruction cost. Forwarding cost is the cost of tunneling multicast packets from home agent, and tree reconstruction cost is the joining cost of foreign agent to multicast group. In the case that a mobile host moves to the other area, its foreign agent calculates cost functions related with forwarding cost and tree reconstruction cost. If forwarding cost is higher than tree reconstruction cost, foreign agent joins to multicast group and reconstructs the multicast tree. Accordingly, foreign agent can dynamically adapt remote subscription or bi-directional tunneling, Our scheme provides more stable multicast service to the mobile hosts regardless of the movements of mobile host and the number of mobile group members.

• Journal of Internet Computing and Services
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• v.5 no.1
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• pp.25-32
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• 2004

Mobile computing environment makes it possible for computing activities to be maintained during movement even if a user changes its network point of attachment. Mobile IP is a standard protocol designed to be used in such mobile computing environment. However, Mobile IP has a drawback to incur a lot of handoff delays and waste network resources, since CoA(Care of Address) registration packets need to go through a HA(Home Agent) first whenever a mobile node moves. To solve this long-standing problem, this paper proposes a new scheme that, for infra-domain movement, efficiently performs local handoff without notifying the HA Specifically, based on the notion of load balance, the proposed scheme allows every FA(Foreign Agent) in a domain to become the root FA(also known as domain FA) dynamically, thus distributing the registration task into many other foreign agents. The dynamic root assignment through load balancing ultimately leads to fast network response due to less frequent transmission of registration packets.

• Journal of Korea Society of Industrial Information Systems
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• v.13 no.5
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• pp.178-185
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• 2008

This paper proposes a new handover scheme to minimize handover delay and signaling costs, using the fact that a new packet forwarding path could be same or similar to the old one in Mobile IPv4. In the proposed scheme a foreign agent estimates the correlation between the new and old routing paths by using routing costs after receiving a registration request message from a mobile node. If the new packet forwarding path could be same or similar to the old one, the mobile node can receive packets from its old foreign agent without registering its new location with its home agent or correspondent node. The performance analysis shows that the proposed scheme can efficiently reduce handover delay and signaling costs.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.12 s.354
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• pp.89-94
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• 2006

In the Mobile IP, the movement of Mobile Host(MH) causes packets to be transmitted through a long route. A Correspond Node(CN) first communicate with a Home Agent(HA) when a Mobile Host moved from one subnet to another subnet. The HH-MIP algorithm reduces an inefficient transmission of packets by regarding a Foreign Agent(FA) near a mobile host as a Temporary Home Agent(THA). However, The algorithm costs the unnecessary signaling by measuring the distance of route between a FA and a THA for handover in the case that a Mobile host comes from a THA which a current FA never communicated. To solve this problem, we propose a scheme called Hierarchical Home Agent Handover in Mobile IP(HHH-MIP) algorithm. Our HHH-MIP algorithm only searches tables in a router by using the hierarchical structure between a FA and a THA. The simulation results show that the HHH-MIP algorithm reduces the additional signaling cost.

• Journal of Information Technology Applications and Management
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• v.21 no.3
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• pp.65-77
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• 2014

Ubiquitous learning has aroused great interest and is becoming a new way for foreign language education in today's society. However, how to increase the learners' initiative and their community cohesion is still an issue that deserves more profound research and studies. Emotional intelligence can help to detect the learner's emotional reactions online, and therefore stimulate his interest and the willingness to participate by adjusting teaching skills and creating fun experiences in learning. This is, actually the new concept of smart education. Based on the previous research, this paper concluded a neural mechanism model for analyzing the learners' emotional characteristics in ubiquitous environment, and discussed the intelligent monitoring and automatic recognition of emotions from the learners' speech signals as well as their behavior data by multi-agent system. Finally, a framework of emotional intelligence system was proposed concerning the smart foreign language education in ubiquitous learning.