• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.05a
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• pp.729-732
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• 2003

Security and privacy issues complicate wireless local area network deployment. for a wired network, certain levels of security are maintained since access to the physical medium is restricted to the devices physically connected to the network. Though wireless local area networks offer some built-in security features, security breaches are possible if appropriate precautions are not taken. This paper describes security issues related to wireless local area networks and presents a software approach for restricting and controlling wireless access. The system authenticates users on the basis of identity, privileges and access hardware by distributed software agents that implement security policy and restrict unauthorized access.

• Proceedings of the KIEE Conference
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• 2006.04a
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• pp.258-260
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• 2006

In this paper, we designed a embedded system that will perform a primary role of Tangible Space implementation. This hardware includes function of image capture through camera interface, image process and sending off image information by LAN (local area network) or WLAN(wireless local area network). We define this hardware as a network based Visual Agent Platform for Tangible Space

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.8
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• pp.1486-1491
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• 2017

In this paper, we propose a private multimedia caching scheme based on wireless local area network (WLAN) to improve the quality of service for high capacity and high quality multimedia streaming services which are recently increasing and to reduce the traffic load of core networks. The proposed caching scheme stores multimedia in the storage device mounted on WLAN APs and provides streaming services on its own without Internet connection in accordance with the request from clients. We have implemented a test network based on real commercial networks and measured the performance of the proposed caching scheme in terms of frames per second (FPS) and buffering time. According to the performance measurement results, the proposed caching scheme can reduce the average buffering time by 73.3% compared to the conventional streaming scheme. In addition, the proposed caching scheme can also improve the average FPS by 71.3% compared to the conventional streaming scheme.

• Journal of Korea Society of Digital Industry and Information Management
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• v.10 no.2
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• pp.47-59
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• 2014

In this paper, I propose a new energy efficient clustering scheme to prolong the network lifetime by reducing energy consumption at the sensor node. It is possible that a node determines whether to participate in clustering with certain probability based on local density. This scheme is useful under the environment that sensor nodes are deployed unevenly within the sensing area. By adjusting the probability of participating in clustering dynamically with local density of nodes, the energy consumption of the network is reduced. So, the lifetime of the network is extended. In the region where nodes are densely deployed, it is possible to reduce the energy consumption of the network by limiting the number of node which is participated in clustering with probability which can be adjusted dynamically based on local density of the node. Through computer simulation, it is verified that the proposed scheme is more energy efficient than LEACH protocol under the environment where node are densely located in a specific area.

• Proceedings of the KSME Conference
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• 2001.06b
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• pp.82-86
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• 2001

This papers deals with feasibility study of wireless motion control. Wireless telecommunication advances with development of IT technology and extends more and more areas. So we selected Bluetooth out of the technologies(Bluetooth, SWAP(SharedWireless Access Protocol), IrDA(Infra Red Data Association), WLAN(Wireless Local Area Network)) which was developed for local data communication and set up simple experimental system for wireless data transfer and server and client program for wireless data transfer was wrote. We successfully transferred some data wirelessly with this program.

• Journal of Communications and Networks
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• v.16 no.3
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• pp.311-321
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• 2014

This paper focuses on contention-based medium access control (MAC) protocols used in wireless local area networks. We propose a novel MAC protocol called adaptive backoff tuning MAC (ABTMAC) based on IEEE 802.11 distributed coordination function (DCF). In our proposed MAC protocol, we utilize a fixed transmission attempt rate and each node dynamically adjusts its backoff window size considering the current network status. We determined the appropriate transmission attempt rate for both cases where the request-to-send/clear-to-send mechanism was and was not employed. Robustness against performance degradation caused by the difference between desired and actual values of the attempt rate parameter is considered when setting it. The performance of the protocol is evaluated analytically and through simulations. These results indicate that a wireless network utilizing ABTMAC performs better than one using IEEE 802.11 DCF.

• Proceedings of the KIEE Conference
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• 2007.04a
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• pp.172-174
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• 2007

In this paper, we designed a embedded system that will perform a primary role of Tangible Space implementation. This hardware includes function of image capture through camera interface, image process and sending off image information by LAN(local area network) or WLAN(wireless local area network). We define this hardware as a network based Visual Agent Platform for Tangible Space, This Visual Agent Platform includes the software that is RTLinux and CORBA

• Proceedings of the Korean Society of Computer Information Conference
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• 2008.06a
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• pp.263-268
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• 2008

고도의 정보 사회로의 빠른 변화는 통신 기술의 발달과 통신 정보들의 다양함에 있다. 현대 사회에서 이용자들은 기존의 통신 서비스보다 좀 더 복잡한 기능과 편리한 기능 다양한 서비스를 필요로 하고 있다. 최근 전 세계적으로 '언제나 어디서나'라는 뜻을 가진 유비쿼터스 사회를 이루기 위한 근거리 무선 통신에 대해 관심을 많이 가지고 있으며 그에 따라 연구와 개발이 활발히 진행이 되고 있다. 무선통신 환경이 증가하고 무선 네트워크화의 필요와 수요에 따른 차세대 근거리 무선 통신 기술 중 대표적인 ZigBee 통신과 기능검증에 대한 H/W 플랫폼을 설계하고 구현하였으며 실험을 통하여 ZigBee의 전송도달거리와 송수신 속도를 확인하였다. 근거리 무선 통신 중 ZigBee의 특성을 고찰하였고 근거리 무선 통신의 연구 방향에 대해 제시하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.5 no.4
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• pp.626-648
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• 2011

Energy consumption of wireless access networks is in permanent increase, which necessitates development of more energy-efficient network management approaches. Such management schemes must result with adaptation of network energy consumption in accordance with daily variations in user activity. In this paper, we consider possible energy savings of wireless local area networks (WLANs) through development of a few integer linear programming (ILP) models. Effectiveness of ILP models providing energy-efficient management of network resources have been tested on several WLAN instances of different sizes. To cope with the problem of high computational time characteristic for some ILP models, we further develop several heuristic algorithms that are based on greedy methods and local search. Although heuristics obtains somewhat higher results of energy consumption in comparison with the ones of corresponding ILP models, heuristic algorithms ensures minimization of network energy consumption in an amount of time that is acceptable for practical implementations. This confirms that network management algorithms will play a significant role in practical realization of future energy-efficient network management systems.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.1
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• pp.88-91
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• 2016

In this paper, we have proposed the frequency interference analysis system using both LabVIEW and Universal Software Radio Peripheral(USRP) for performance degradation analysis of Multi Input Multi Output-Orthogonal Frequency Division Multiplexing(MIMO-OFDM) Wireless Local Area Network(WLAN) due to Wireless Local Area Network(WPAN) interferer. The proposed system consists of three part, i.e., victim, channel, and interferer. Both victim and interferer are implemented by LaBVIEW and a USRP board. Then interfering signal and additive white Gaussian noise are combined with the wanted signals of a victim. Measured Bit Error Rate(BER) at the victim receiver is compared with theoretical BER according to various signal to interference plus noise power ratio (SINR) values. Measured and theoretical BER curves show good agreement.