• Proceedings of the KSRS Conference
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• 2002.10a
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• pp.844-849
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• 2002

A provision of spatial information is expected to make a market explosion in various fields. A distribution of spatial data on wireless mobile environments indicates a huge expansion of mobile technology as well as a spread of geospatial applications. For high quality spatial information, 4S technology project integrating 4 kinds of spatial systems is currently being executed with the goal of nationwide integration of spatial data and spatial information systems. In terms of network environments, a mobile ad hoc network where mobile terminals communicate with each other without any infrastructures has been standardized for the next generation mobile wireless network. With respect to the future technologies for spatial information, it is necessary to design 4S applications on mobile ad hoc networks. This paper addresses the issue, which is proposing design points for distributing 4S spatial data on mobile ad hoc networks and ad hoc styled 4S applications.

• Journal of Communications and Networks
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• v.7 no.2
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• pp.192-206
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• 2005

Integration of mobile networks and Internet has started with 2.5 generation of mobile cellular networks. Internet traffic is today dominant traffic type worldwide. The hanger for higher data rates needed for data traffic and new IP based services is essential in the development of future wireless networks. In such situation, even 3G with up to 2 Mbit/s has not provided data rates that are used by Internet users with fixed broadband dial-up or through wired local area networks. The solution to provide higher bit rates in wireless access network has been found in wireless LAN although initially it has been developed to extend wired LAN into wireless domain. In this paper, we propose and describe a solution created for interoperability between mobile cellular network and WLAN. The integration between two networks, cellular and WLAN, is performed on the authentication, authorization, and accounting, i.e., AAA side. For that purpose we developed WLAN access controller and WLAN AAA gateway, which provide gateway-type access control as well as charging and billing functionalities for the WLAN service. In the development process of these elements, we have considered current development stadium of all needed network entities and protocols. The provided solution provides cost-effective and easy-to-deploy PLMN-WLAN Internetworking scenario.

• Journal of Institute of Control, Robotics and Systems
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• v.7 no.4
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• pp.326-333
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• 2001

This paper focuses on a method to connect mobile devices such as mobile robot. Automated Guided Vehicle (AGV) and Unmanned Container Transporter(UCT) to a fieldbus. In this paper, the IEEE 802.11 wireless LAN is used to extend a Profibus network for the mobile devices. In order to integrate these two networks, a gateway is developed using two threads and an internal buffer. Furthermore, a polling algorithm is applied at the gateway in order to satisfy real-time requirements on data communication, Finally, the performance measures such as data latency and throughput are experimentally evaluated on a wirelessly-extended Profibus network. The results shows the feasibility of the wireless extension of Profilbus for various mobile device.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.23 no.9A
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• pp.2230-2239
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• 1998

Recently, mobility support of connectionless mobile ATM data service has been mainly studied in wireless ATM communication network. this paper shows the network model for the mobility support of connectionless data service in ATM network, and proposes the methods to minimize COIP (care of IP address) acquisition processing time for MH(mobile host)migration. Th echaracteristics of proposed methods, COIP acquisition probability and IP data communication sequence of proposed model, are discussed in this paper.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.9 no.4
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• pp.39-45
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• 2009

With the rapid growth of recent wireless mobile computing application technology and handheld mobile terminal device development technology, one of the big issue in these fields is to design online games in wireless mobile ad hoc network environment. Online games in mobile computing environment have lots of constraints for developing online games because mobile terminals have many limitations such as low performance of processor, limited memory space, small bandwidth of wireless communication, and confined life of battery power. Therefore, most of mobile games are restrictive in the function of online and multi-play up to date. In this paper, the online MMORPG game, capable of multi-play with many other mobile users using mobile terminals in wireless mobile computing environment, is designed and implemented. Proposed mobile online game uses bluetooth to construct temporary wireless mobile ad hoc network with other mobile clients, and designed to carry out online MMORPG game with these clients. It also supports multi-play among them.

• The Transactions of the Korea Information Processing Society
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• v.6 no.11S
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• pp.3332-3339
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• 1999

TCP protocol is originally designed for the wired network in which the packet loss in mostly caused the network congestion, and thus the performance of protocol can be decreased in mobile Internet environment due to the comparatively high error rate of wireless link. This paper analyzes the influence of retransmission interference that is a major factor to the TCP performance decrease. We first build a model in order to simulate the mobile Internet environment that includes the wireless network, and then we implement a program using PARSEC simulation language and finally executed the program. Based on the simulation results, we suggest a method that reduce the effect of the retransmission interference.

• Journal of Korea Society of Digital Industry and Information Management
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• v.4 no.1
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• pp.33-40
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• 2008

This paper presents a new scheduling scheme in wireless distributed network. To overcome the limited information about unfamiliar mobile nodes and to reduce the required system performance, we propose a scheduling algorithm of job allocation based on the trust model. The suggested scheduler evaluate an unfamiliar mobile node's trust and make reference to the trust value of neighboring scheduler. This scheduling algorithm can avoid malicious or selfish mobile nodes by assigning low trust values. We also present a trust evaluation metric and show the efficiency of suggested scheduling algorithm by performance evaluation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.11
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• pp.2585-2593
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• 1997

Recently a new wireless communication architecture, a Virtual Cellular Network(VCN) was proposed in order to improve the preformance of a wireless network. Unlike a conventional cellular network, the VCN does not use a conventional frequency reuse concep. In the VCN, however, each mobile can use the entire system bandwidth. There is no pre-determined border of cells nor fixed based station for a mobile to communicate with. The performance of the VCN is improved by allowing any mobile to communicate with any port which residues in the virtual cell of the mobile. In this paepr, the Multi Packet Encoding (MPE) is proposed for the VCN uplink in order to improve the unfair throughput and delay caused by the position of the mobiles, and its performance is investigated via computer simulations. The Minimum Group(MG) is proposed for downlink protocol.

• Journal of Institute of Control, Robotics and Systems
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• v.16 no.2
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• pp.114-119
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• 2010

Network technology has been developed rapidly for digital service in these days. ZigBee, one of the IEEE 802.15.4 protocols, supporting local communication has become the core technology in the wireless network area. In this paper we designed an integrated fire monitoring system using a mobile robot and the ZigBee sensor nodes which are deployed to monitor fires. When a fire breaks out, the image information of the scene of a fire is transmitted by an autonomous mobile robot and we also monitor the current position of the robot. Furthermore, the data around the place where the fire breaks out and the positions of the sensor nodes can be transmitted to a server via the multi-hop communication in the real time.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.05a
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• pp.425-428
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• 2002

To understand and forecast the wireless internet market in Korea, we will analyse the network externalities in wireless internet market into communication network externalities and hardware/software network externalities. The wireless market has two competing streams, one is mobile internet and the other is wireless fan internet. Both are characterized by strong network externalities which lead to increasing return to stale. Mobile internet is supposed more suitable for communication and WLAN for data. However these two system will compete in some area, and the critical factor to deride the winner is supposed to be the network externalities as in so many other high-tech industries had showed.