• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.12A
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• pp.1309-1318
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• 2004

The rapid growth of the mobile Internet has enabled its application area to expand, and its users want services that require more bandwidth for multimedia services. There are limits to support the various multimedia service to mobile station provided by existing mobile communications. The wireless MAN called the IEEE 802.16 Broadband Wireless Access systems which the IEEE 802.11 wireless LAN is similar to wireline Internet service being able to supper a various contents is used and is designed to consider a handoff is studying. Especially, TG(Task Group)e of IEEE 802.16 is in progress discussion to support a handoff to higher layer using BS(Base Station) or unit of sector, to UC. Yet a scheme is not detail. This thesis proposes the network model for IEEE 802.16e to support a soft handoff between BSs to use a mobile communication network called cdma2000 Ix EV-DO network. The proposed network model supports soft handoff to add a management skill in MA of each BS for MC(Mobility Controller). The proposed network model has merits that is able to apply existing systems as it is and that is able to use a various multimedia service, when using a wireless Internet.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.1027-1034
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• 2011

Electronic devices in railway vehicle perform various functions such as not only braking and propulsion but also monitoring of vehicle condition, on-line diagnosis, and passenger information service, etc. These devices, distributed in vehicle, should be efficiently connected so as to properly perform the functions. IEC (International Electro-Technical Commission) standardized train communication network (TCN) as IEC 61375-1, -2. TCN can reduce the interconnecting work load by reducing the number of wire-line, compared with existing hard-wire connection, and it brings the efficient control by enabling various devices to share the information. But existing TCN can not satisfy the increasing service demands like passenger internet access and CCTV surveillance, etc. In this paper, we investigate ECN (Ethernet Consist Network) and ETN (Ethernet Train Backbone) which are proposed to satisfy these demands and in the process of standardization by IEC TC9 WG43.

• Electronics and Telecommunications Trends
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• v.15 no.4 s.64
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• pp.52-63
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• 2000

현재 국내 초고속인터넷서비스 시장은 기존통신사업자들의 업역 확대와 신규사업자들의 진입에 따라 초경쟁(hyper-competition)상황에 놓여 있다. 이에 본 고에서는 국내 초고속인터넷서비스 시장의 주요 제품으로 등장하고 있는 ADSL 및 Cable Modem 기술을 이용한 서비스의 시장 경쟁상황을 Porter의 산업구조분석 모형(5-force model)의 측면에서 개괄하고, 현재 사업을 전개하고 있는 각 사업자의 서비스 제공 내용 및 가격 현황을 제시한 후 이들의 가격 및 판촉전략 비교를 통해 향후 사업자들이 취할 수 있는 전략방향을 제시하고자 하였다.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.1113-1114
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• 2008

WiBro(Wireless Broadband) is the standard of high-speed portable internet based on OFDMA/TDD (orthogonal frequency division multiple access / time division duplexing) techniques, and the subset of consolidated version of IEEE802.16e Wireless MAN standard. In this paper, we propose the design method of WiBro system. Proposed method used KSFM neural network blind equalization with Bussgang algorithms.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2003.05a
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• pp.744-748
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• 2003

Developing an interactive satellite multi­media system, such as a digital video broadcasting (DVB) return channel via satellite (RCS) system, is gaining popularity over the world To accommodate the increasing traffic demand we are motivated to investigate an alternative for improving return channel utilization We develop an efficient method for optimal packet scheduling in an interactive satellite multimedia system using hybrid CDMA/TDMA channels. We formulate the timeslot-code assignment problem as a binary integer programming (BIP) problem, where the throughput maximization is the objective, and decompose this BIP problem into two sub-problems for the purpose of solution efficiency. With this decomposition, we promote the computational efficiency in finding the optimal solution of the original BIP problem Since 2001, ETRI has been involved in a development project where we have successfully completed an initial system integration test on broadband mobile Internet access via Ku-band channels using the proposed resource allocation algorithm.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.05a
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• pp.233-236
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• 2008

Wire wireless integrated service of BcN(Broadband convergence Network) is expanding. Information Security issue is highlighted for opposing attack of getting information illegally on wire wireless network. The user of PKI(Public Key Infrastructure) cipher system among Information security technology receives various security services about authentication, confidentiality, integrity, non-repudiation and access control etc. A mobile client and server are loaded certificate and wireless internet cryptography module for trusted data send receive. And data sends receives to each other after certification process through validity check of certificate. Certificate and data security system is researched through PKI on wireless network environment and data security system in this paper.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.8 no.3
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• pp.81-86
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• 2008

The paradigm of information & communication is rapidly changed into ubiquitous environment based electromagnetic wave, and antenna technology in the wireless ubiquitous communication is remarkably developed. Mini chip antenna has its within small card compared to the external AP antenna. Designed and Fabricated WLAN antenna has a broadband characteristics of 2.4~2.5GHz and 4.9~5.85GHz, and can be used triple mode of IEEE 802.11.a,g.b, and it has comparatively a constant performance in the dual frequency band.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.10
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• pp.4865-4886
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• 2017

The user experience of practical indoor power line communication (PLC) applications is greatly affected by the system quality-of-service (QoS) criteria. With a general broadcast-and-multi-access (BMA) relay scheme, in this work we investigate the joint source and relay power optimization of the amplify-and-forward (AF) relay systems used under indoor broad-band PLC environments. To achieve both time diversity and spatial diversity from the relay-involved PLC channel, which is time-varying in nature, the source node has been configured to transmit an identical message twice in the first and second signalling phase, respectively. The QoS constrained power allocation problem is not convex, which makes the global optimal solution is computationally intractable. To solve this problem, an alternating optimization (AO) method has been adopted and decomposes this problem into three convex/quasi-convex sub-problems. Simulation results show the fast convergence and short delay of the proposed algorithm under realistic relay-involved PLC channels. Compared with the two-hop and broadcast-and-forward (BF) relay systems, the proposed general relay system meets the same QoS requirement with less network power assumption.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.05a
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• pp.385-388
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• 2010

A place for the blind people movement restrictions in place on a relatively equal opportunity of education can not be provided. In this paper, blind people, as well as web access to information on the catch of the blind people and their preference for acquiring information on how to analyze the survey and analyze national and international stories. targeting the blind people Internet using Web Services in a high-speed network system design, training and support services, analyze and exchange information in real-time training program to develop a community, remote from the home education support system to revitalize blind people and would like to contribute to the information service.

• Advances in aircraft and spacecraft science
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• v.9 no.6
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• pp.525-536
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• 2022

The current state of telecommunications infrastructure in the Arctic does not allow providing a wide range of required services for people, businesses and other categories, which necessitates the use of non-traditional approaches to its organization. The paper proposes an innovative approach to building a combined communication network based on tethered high-altitude platform station (HAPS) located at an altitude of 1-7 km and connected via radio channels with terrestrial and satellite communication networks. Network configuration and composition of telecommunication equipment placed on HAPS and located on the terrestrial and satellite segment of the network was justified. The availability of modern equipment and the distributed structure of such an integrated network will allow, unlike existing networks (Iridium, Gonets, etc.), to organize personal mobile communications, data transmission and broadband Internet up to 100 Mbps access for mobile and fixed subscribers, rapid transmission of information from Internet of Things (IoT) sensors and unmanned aerial vehicles (UAV). A substantiation of the possibility of achieving high network capacity in various paths is presented: inter-platform radio links, subscriber radio links, HAPS feeder lines - terrestrial network gateway, HAPS radio links - satellite retransmitter (SR), etc. The economic efficiency of the proposed solution is assessed.