• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.8 no.6
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• pp.63-69
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• 2008

In this paper, our goal is to find a power-effective protocol that improves the accuracy of transmission in sensor networks. Therefore we propose a cooperative communication protocol based on MRC(Maximal Ratio Combining) and cyclic code. In our proposal, one sensor node assists two others to communicate with a clusterhead that can get diversity effect and MRC can improve diversity effect also. The proposed protocol with cyclic code can correct error up to 3-bit and reduce decoding complexity compared with convolutional code. Simulation results reveal proposed protocol can save the network energy up to 6dB over single-hop protocol at BER(Bit Error Rate) of $10^{-2}$.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.10a
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• pp.911-916
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• 2007

The home gateway, an equipment which works as an gateway for ubiquitous home network, relays all functions of a home network. The home gateway must always be connected in order to provide seamless services. However it gives unfavorable power consumption. Therefore the needs for working in maximum power saving mode while there is no data traffic and for invoking to the normal function when it is necessary. In this paper we survey the technical papers and the standards documents and provide an overview of power saving mode in the home gateway.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.05a
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• pp.954-956
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• 2013

IOS/IEEE 11073 PHD 표준들은 u-헬스 측정기기와 u-헬스 게이트웨이간의 통신을 가능하게 하도록 설계되어 있다. 모바일 단말기를 데이터 취합을 위한 중계기로 활용하고 별도의 게이트웨이를 구성하여 헬스케어 의료기기를 연동하고 모니터링을 위한 인터페이스를 제공해 왔으나 스마트폰 애플리케이션 단계에서 IEEE 11073 플랫폼을 포함하여 헬스케어 의료기기를 활용하는 u-헬스케어 서비스를 제공하기에는 많은 제약이 있다. 이에 본 논문에서는 Android 4.0.x OS 스마트폰을 대상으로 Bluetooth HDP을 활용하여 u-헬스케어 시스템에서의 게이트웨이/서버 플랫폼 기능을 포함하는 헬스케어 의료기기의 모니터링 애플리케이션 시스템을 설계하였다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.11A
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• pp.1035-1046
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• 2005

This paper analyzes the channel assignment techniques and their performance in the On Board Processing (OBP) satellite communication system. It suggests the new Continuous Rate Assignment (CRA) and Dynamic Rare Assignment (DRA) for improving the efficiency of channel assignment at the OBP switch. Mathematical analysis and simulation are given to evaluate the system performance. Aggregate real-time and non-real-time services are considered as different classes. Higher priority is given to voice and video real-time services to avoid delay variation. Onboard scheduler uses CRA and DRA ways to arrange the capacity allocation dynamically. An improved algorithm is given to make the channel more efficient by doing some evaluation of the switching matrix.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.3A
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• pp.293-302
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• 2004

Wireless LAN is a rather mature communication technology that connects mobile terminals. A typical wireless LAN system is composed of one AP and more than one terminals, which is called a BSS. Terminals near to an AP can receive high rate data but terminals far from an AP may not receive data with guaranteed high speed rate because received signal strength is weakened. This paper proposes a method to allow high speed data transmission by grouping terminals and using part of wireless terminals as repeaters. We compare and analyze proposed grouping algorithms based on Depth First Search and Breadth First Search via simulations. A grouping algorithm based on Breadth First Search is shown to be more effective in term of efficiency and coverage.

• Proceedings of the Korea Information Processing Society Conference
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• 2014.04a
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• pp.210-211
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• 2014

WebRTC(Web Real-Time Communication)는 플러그인의 도움 없이 간단한 웹 표준 API(Application Programming Interface)를 이용하여 웹 브라우저 환경에서 Peer-to-Peer 실시간 통신을 가능케 하고자 하는 기술이다. 실시간 통신으로 오디오, 비디오 스트림은 물론이고 데이터 스트림을 포함한다. 해당 기술은 브라우저간에 직접적으로 Peer-to-Peer 세션을 형성하여 스트리밍을 수행하므로 중계 서버를 이용하는 통신에 비하여 향상된 네트위크 성능을 보이지만 연결을 구성하기 위한 보조 기술들이 요구된다. WebRTC 는 웹 기반 기술이기 때문에 기존의 웹 어플리케이션이 가지는 장단점을 공유한다. 본 논문에서는 WebRTC 기술과 해당 기술을 구성하고 있는 세부 기술들의 구조 및 기능을 분석한다. 또한 해당 기술을 이용하여 간단한 컨퍼런스 시스템을 설계하고 구현한 예제를 보인다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.1
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• pp.183-188
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• 2008

Satellite DMB(Digital Multimedia Broadcasting) uses the Cap Filler(GF) that provides a service to the wave shade area of the satellite signal that is a non-line of sight area. The GF is the repeater and the Satellite DMB Systems certainly must construct the GF Network toguarantee the movement reception of the terminal. As the coverage of the GF is formed the Cell or Sector, when the multiple GF is established to be contiguous, the problem of the interference will be able to occur. This paper describes the Satellite DMB system and the GF, and it investigate the design fundamentals plan of the GF Network that it will be able to reduce this problem. As a result, in case of the distance that GF and terminal unit is above 4.6Km, service is not provided because of quality degradation according to mutual interference.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.10a
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• pp.848-850
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• 2014

Mobile Ad hoc Networks(MANET) is consist of node that has mobility, MANET build cluster formation for using energy efficient. In existing LEACH algorithm elect cluster head node in coverage area by distribution function. However, when the cluster head node, that elected by distribution function, is divided coverage area unevenly, the network can't consumption energy efficiency. To solve this problem, we proposed CSWC(Coverage Scheduling Weight-value Control) algorithm. When the coverage area is divided nonchalance, proposed algorithm increased number of hops, that determines coverage area, for balance coverage area. As the result proposed algorithm is set balance coverage area, the network consumption energy efficiency.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.10a
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• pp.1049-1052
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• 2009

This paper develop a intelligent personal emergency call system using the wireless sensor network to resolve that a portable problem of established emergency call system. The proposed system is composed of a transmitter nodes for individuals, routing nodes for multihop communications, and a server part. The transmitters for patients are monitored for both low battery and operational status. The transmitters provide location of the person activating an emergency call using RSSI. The efficacy of the proposed system is verified by means of experiments. Experimental results are presented that show the effectiveness.

• Journal of the Korea Society of Computer and Information
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• v.27 no.1
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• pp.33-41
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• 2022

This paper describes a planar microstrip patch antenna designed on dielectric substrate. Two types of planar microstrip patch antennas are studied for the 5G wireless applications, one type is conventional microstrip structure, the other type is stacked microstrip structure fed by coaxial probe. Using electromagnetically coupling method, stacked microstrip patch antenna employing a multi-layer substrate structure was designed. The results indicate that the proposed stacked microstrip patch antenna performs well at 5G wireless service bandwith a broadband from 3.42GHz to 3.70GHz. The impedance bandwidth(VSWR≤2) is 360MHz(10.28%) from 3.42GHz to 3.78GHz. In this paper, through the designing of a stacked microstrip patch antenna, we have presented the availability for 5G wireless repeater system.