• The Journal of Information Technology
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• v.12 no.1
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• pp.15-20
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• 2009

In this paper, we aim that it solve to problem of the database hoarding because a week connectivity of wireless networks and cutting of link, Consistency of shared data, optimizing of the log include to Mobile Continuous Query Processing System under the mobile client and server environment. and we demonstrate of the superiority for the new Mobile Continuous Query Processing System compare C-I-S(Client-Intercept -Server)model with performance. and we perform to various experiment in order to establishment of superiority compare the index architecture and method for the realtime Continuous Query Processing. in this paper.

• Proceedings of the IEEK Conference
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• 2002.06c
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• pp.235-238
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• 2002

This paper presents a remote mobile robot system that transmits streaming video and audio over the lossy packet networks such as (Wireless) LAN. The error resilient video and audio packets are transmitted on the RTP/UDPfP Protocol stack. The mobile robot can be accessed by a certified user from the remoted area. Thus, the movement of mobile robot can be controlled by the operator observing the working surroundings.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2004.11a
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• pp.95-95
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• 2004

• TTA Journal
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• s.104
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• pp.129-136
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• 2006

TTA는 지난 2월 21일, 프랑스 파리에서 개최된 WiMAX 이사회 회의에서 WiMAX 포럼 공인시험소 자격을 획득하였다. 이런 결과를 바탕으로 TTA는 2006년 9월 Mobile WiMAX 시험장비 도입을 시작으로 시험장비 검증과 모의 인증시험을 거쳐 12월부터 Mobile WiMAX 제품에 대한 WiMAX 포럼 공인 인증시험을 실시할 계획이다. 이에 본 고를 통해 현재 진행 중인 Mobile WiMAX 인증시험 개요 및 동향을 소개하고 자 한다. 1) IEEE802.16-2004 : IEEE Standard for Local and Metropolitan Area Networks-Part16: Air Interface for Fixed Wireless Access Systems

• Proceedings of the Korean Information Science Society Conference
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• 2001.04a
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• pp.301-303
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• 2001

Mobile IP를 기반으로 하는 무선 네트워크의 개념이 확장됨에 따라 Mobile IP의 중요성이 더욱 부각되고 있다. 하지만 Mobile IP에서 수행되는 핸드오프는 심각한 성능 저하를 초래하고 있으며, 이를 해결하려는 연구도 많이 진행되어 왔다. 그러나 기존의 연구들은 데이터 링크 계층의 특성을 전혀 고려하고 있지 않고 있기 때문에 핸드오프에 의한 문제들을 궁극적으로 해결하지는 못하고 있다. 본 논문은 데이터 링크 계층에서 수행되는 로밍 정보를 이용하여 Mobile IP가 핸드오프를 신속하게 처리하는 기법을 제시하고 이를 사용하여 성능 저하를 크게 막을 수 있음을 보인다.

• International Journal of Contents
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• v.1 no.2
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• pp.31-34
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• 2005

The new realtime applications like multimedia and realtime services in a wireless network will be dramatically increased. However, many realtime services of mobile hosts in a cell cannot be continued because of insufficiency of useful channels. Conventional channel assignment approaches didn't properly consider the problem to serve realtime applications in a cell. This paper proposes a new realtime channel assignment algorithm based on time constraint analysis of channel requests. The proposed algorithm dynamically borrows available channels from neighboring cells. It also supports a smooth handoff which continuously serves realtime applications of the mobile hosts.

• ETRI Journal
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• v.41 no.3
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• pp.326-336
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• 2019

A wireless power transfer technique can solve the power capacity problem in wireless rechargeable sensor networks (WRSNs). The charging strategy is a wide-spread research problem. In this paper, we propose a demand-based charging strategy (DBCS) for WRSNs. We improved the charging programming in four ways: clustering method, selecting to-be-charged nodes, charging path, and charging schedule. First, we proposed a multipoint improved K-means (MIKmeans) clustering algorithm to balance the energy consumption, which can group nodes based on location, residual energy, and historical contribution. Second, the dynamic selection algorithm for charging nodes (DSACN) was proposed to select on-demand charging nodes. Third, we designed simulated annealing based on performance and efficiency (SABPE) to optimize the charging path for a mobile charging vehicle (MCV) and reduce the charging time. Last, we proposed the DBCS to enhance the efficiency of the MCV. Simulations reveal that the strategy can achieve better performance in terms of reducing the charging path, thus increasing communication effectiveness and residual energy utility.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.10a
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• pp.153-155
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• 2010

Internet phone (VoIP) services in Korea have achieved noticeable growth year after year since the service launching, and the growth still coninues. The market of mobile internet phone also expands sharply. Therefore, it is crucial to deploy networks which can support mobile internet phone services with excellent quality. For mobile internet phone services, it will be necessary to build and use networks with good mobility and high transmission rate. Current wireless networks for Internet services include 3G, Wi-Fi, and mobile WiMAX networks. 3G provides good mobility but lower transmission rate, whereas Wi-Fi exhibits excellent transmission rate but less mobility. Mobile WiMAX networks taking the merits of both, high mobility and transmission rate, are being deployed widely in recent years. This article examines the recent standardization efforts of WiMAX Forum for VoIP service in WiMAX networks.

• Journal of the Semiconductor & Display Technology
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• v.20 no.3
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• pp.108-112
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• 2021

For smart mobile devices, the wireless communication module is one of the hardware modules that consume the most energy. If we can build a multi-channel multi-interface environment using heterogeneous communication modules and operate them dynamically, data transmission performance can be highly improved by increasing the parallelism. Also, because these heterogeneous modules have different data rates, transmission ranges, and power consumption, we can save energy by exploiting a power efficient and low speed wireless interface module to transmit/receive sporadic small data. In this paper, we propose a power efficient data transmission method using heterogeneous communication networks. We also compared the performance of our proposed scheme to a conventional scheme, and proved that our proposed scheme can save energy while guaranteeing reasonable data delivery time.

• Proceedings of the Korean Information Science Society Conference
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• 2006.06d
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• pp.124-126
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• 2006

Mobile Ad hoc networking is an emerging technology and in these days many applications are being developed to run on these networks. In these networks lookup services are very important because all nodes do not have same resources in term of memory and computing power. Nodes need to use different services offered by different servers. Reliable and efficient scheme should be available for lookup services due to limited bandwidth and low computing power of devices in mobile ad hoc networks. Due to mobility and rapid change in network topology, lookup mechanism used in wired network is not appropriate. Service discovery mechanism can be divided into two main categories Centralized and Distributed. Centralized mechanism is not reliable as there is no central node in these networks. Secondly centralized mechanism leads toward single point failure. We can handle the service discovery mechanism by distributing server's information to each node. But this approach is also not appropriate due to limited bandwidth and rapid change in network. In this paper, we present reliable lookup service scheme which is based on distributed mechanism. We are not using replication approach as well due to low bandwidth of wireless networks. In this scheme service discovery mechanism will be handled through different lookup servers. Reliability is the key feature of our proposed scheme.