• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.05a
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• pp.575-577
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• 2013

Recently most of the hand-held smart devices have WiFi communication facility. This makes WiFi AP(access point) popular and cheaper than before. These circumstance launches some services with AP providing location based services and device control services. In this paper, we propose a AP based control system. The control system consists of AP's, AP controller and Android application program. The AP can collect MAC address information of the associated smart devices and control connected devices. The AP controller maintains DB for smart device position information and device control information. Finally Android application program provides users location based service and device control service.

• Journal of Korea Society of Industrial Information Systems
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• v.11 no.1
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• pp.69-76
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• 2006

Telematics, which is a compound word of a telecommunication and informatics, provides drivers with useful driving information such as driving path guidance, accident or robbery detection, traffic conditions and other valuable data at real time. This paper proposes and implements how to build a telematics terminal equipped with CDMA and GPS running embedded Linux, to check a vehicle's state through communication between telematics server and vehicle terminals using a cellular phone and to control a vehicle using SMS as shown in Figure 1. In order to do this, we use the SK-VM platform which is mobile terminal platform based on JAVA to design, implement and evaluate it.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.7A
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• pp.973-986
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• 1999

In this paper, we propose MAC protocol that consists of channel access mechanism and transmission mechanism to support effective wireless packet data service. In channel access mechanism, broadcast channel announces status information of random access channel, and mobile station tries random access based on status information. Also, mobile station has access probability to prevent collision increase due to transmission of short message. For effective transmission, mobile station changes transmission rate based on transmission queue status to adapt burst traffic characteristics. In restricted environments of transmission code and bandwidth, proposed protocol shows better performance than cdma2000 system.

• Journal of Communications and Networks
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• v.17 no.3
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• pp.231-240
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• 2015

To facilitate the base station planning in high speed railway communication systems, it is necessary to consider the functional relationships between the base station transmit power and space parameters such as train velocity and cell radius. Since these functions are able to present some inherent system properties determined by its spatial topology, they will be referred to as the power-space functions in this paper. In light of the fact that the line-of-sight path persists the most power of the received signal of each passing train, this paper considers the average transmission rate and bounds on power-space functions based on the additive white Gaussian noise channel (AWGN) model. As shown by Monte Carlo simulations, using AWGN channel instead of Rician channel introduces very small approximation errors, but a tractable mathematical framework and insightful results. Particularly, lower bounds and upper bounds on the average transmission rate, as well as transmit power as functions of train velocity and cell radius are presented in this paper. It is also proved that to maintain a fixed amount of service or a fixed average transmission rate, the transmit power of a base station needs to be increased exponentially, if the train velocity or cell radius is increased, respectively.

• Convergence Security Journal
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• v.9 no.1
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• pp.19-27
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• 2009

In this paper, we propose a safety management system which prevents the occurrence of crime and accident from rising in school neighborhood. This system offers a monitoring method for safety of children which make intelligent space from environment and location sensing data through wireless communication between sensors attached to children and fixed sensor network in school neighborhood. Also, We propose a strategic safety management plan using opportunistic network when node is out of school zone network. Many students can easily receive the service of low cost from WSN-based School zone network than existing service from GPS individually by using our scheme.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.1
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• pp.91-96
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• 2015

Heterogeneous cellular networks support various wireless environments for mobile service. Recently, data services as well as voice services are exponentially increased in cellular networks and the technical transition of LTE-A and IEEE 802.16m so that more base stations are requested to provide suitable service. Base stations consume most of energy in cellular networks, and the energy saving is needed for the base station. In this paper, we propose a saving power scheme by the dynamic energy management. In this paper we consider the simulation evaluations of handover for the low powered base station.

• Journal of Information Processing Systems
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• v.10 no.2
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• pp.176-192
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• 2014

The realization of Wireless Multimedia Sensor Networks (WMSNs) has been fostered by the availability of low cost and low power CMOS devices. However, the transmission of bulk video data requires adequate bandwidth, which cannot be promised by single path communication on an intrinsically low resourced sensor network. Moreover, the distortion or artifacts in the video data and the adherence to delay threshold adds to the challenge. In this paper, we propose a two stage Quality of Service (QoS) guaranteeing scheme called Prioritized Multipath WMSN (PMW) for transmitting H.264 encoded video. Multipath selection based on QoS metrics is done in the first stage, while the second stage further prioritizes the paths for sending H.264 encoded video frames on the best available path. PMW uses two composite metrics that are comprised of hop-count, path energy, BER, and end-to-end delay. A color-coded assisted network maintenance and failure recovery scheme has also been proposed using (a) smart greedy mode, (b) walking back mode, and (c) path switchover. Moreover, feedback controlled adaptive video encoding can smartly tune the encoding parameters based on the perceived video quality. Computer simulation using OPNET validates that the proposed scheme significantly outperforms the conventional approaches on human eye perception and delay.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.05a
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• pp.655-657
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• 2014

In this paper, a lego-type Ultra High Definition(UHD) media platform for cloud service have been proposed. The platform offers you a cloud service, which is freely able to share your UHD media in indoor and outdoor environment. Also, if various media products using the next-generation wireless communication(802.11ac and LTE Broadcast etc.) and proposed platform are utilized, everyone can develop easily because it is the lego-type. Therefore, the platform are expected to lead development of new market and invent industry since it can be applied to various businesses models.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.15 no.3
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• pp.43-52
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• 2005

MIPv4 supports node mobility, manages MN's binding list and provides seamless communication through registration protocol. Since the registration protocol usually operating in the wireless environment involves authenticating MNs, it is a general approach to introduce the AAA infrastructure as key distribution center for the purpose of authentication. In this paper, we propose an efficient registration protocol with lightweight AAA based on domain key. Proposed protocol also withstands various replay attacks, and provides non-repudiation service for the accounts of the usage of the network service.

• Journal of Satellite, Information and Communications
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• v.8 no.4
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• pp.135-141
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• 2013

Subway in Korea, most of a metropolitan public transport use only worth ten million people a day floating population of wireless communication can be considered HOT SOPT. These three operators' 2G/3G/4G / Wi-Fi / T-DMB frequency and the number of services to co-exist, and the subway train passengers and subway party for operation and management of the communication network is also the co-subway passenger safety and for this service for the effects of mutual interference of whether the verification was necessary. This research and testing different frequency / communication interference between services and testing to determine whether, through the subway authorities and mobile operators in each frequency-specific interaction check and there is no interference to the safety and quality of subway passengers communication services that can be verified as the data was found. The verification methods in the metro area, not just from one region to determine whether the interference with a common verification methods can be applied.