• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.5A
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• pp.828-835
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• 2001

인터넷 이용이 폭발적으로 증가하고, 음성, 데이터는 물론 영상을 포함한 멀티미디어 정보의 요구가 급증함에 따라 21세기의 통신 네트워크는 통신과 방송의 융합, 과대역화, 고속화, 대용량화, 지능화, 개인화로 바뀌고 있다. 이와 같은 초고속 서비스 망의 중심에는 ATM 기술이 위치하고 있으며, 아직까지 ATM과 같이 진정한 의미의 QoS를 보장할 수 있는 기술은 없는 것으로 알려져 있고, 또한 ATM은 네트워크 응용의 타입을 스스로 인식해 가장 알맞은 대역폭을 제공하므로 실시간 전송 데이터에 대해 가장 효율적으로 대응할 수 있는 기술이다. 이 논문에서는 초고속 위성통신과 발전전망의 세계적인 동향을 분석하고 이에 적합한 응용 서비스를 제공하는 모형을 제시한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.8A
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• pp.1133-1140
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• 1999

In order to provide high-speed wide-band multimedia services via Low earth(LEO) mobile satellire, power and bandwidth efficient digital transmission technique should to employed. This paper analyzes the performance of Trellis-soded 16QAM and 8PSK-2AM which can transmit twice as much inforemation as QPSK in nonlinearly amplified LEO mobile satellite channel. In the analysis the nonlinear mobile satellite channel is modelled by Rician fading channel amplified by Fujitsu's GaAs FET HPA. Our simulation result shows that 8PSK-2AM is less sensitive to the satellite channel nonlinear distortion and its BER performance is better than that of 16QAM. The BER performance of 8PSK-2AM is further improved by optimizing its signal constellation. Accocordingly it is found that Trellis-coded 8PSK-2AM could provide multimedia services such as Satellite Internet, DBS, DAB and ISDB more efficiently in the power and bandwidth limited mobile satellite channel.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.13 no.2
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• pp.41-46
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• 2013

In this paper, low pass filters(LPF) using corrugated waveguide for satellite communication is proposed. To design the proposed LPF, the corrugated waveguide and impedance transformers are combined. The corrugated waveguide is formed by arrangement of T-junction. To obtain low insertion loss and high isolation propriety, T-junction is designed by using Chebyshev function. Impedance transformers is designed by combining T-junction with different heights at both ends of the corrugated waveguide to get high return loss. The measured results of the proposed LPF have a return loss of over 35.4 dB, a insertion loss of less than 0.1 dB from 12.25 GHz to 12.75 GHz and a isolation propriety of over 54.5 dB from 14 GHz to 14.5 GHz. From these results, it is confirmed that the proposed waveguide LPF can be used for satellite communication.

• Proceedings of the Korea Technology Innovation Society Conference
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• 2001.05a
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• pp.93-103
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• 2001

전력선 이용 통신(PLC : Power Line Communication)는 전화선, CATV망, 위성에 이어 제4의 통신망 산업으로 급부상하고 있다. 본 연구에서는 젤라인 및 피엘콤의 PLC를 중심으로 기술특성 및 인터넷 접속가격 비교을 통해 PLC 와 다른 대체상품과의 경쟁력을 분석하였다. PLC는 기술적인 측면에서 제한된 전송전력, 높은 부하 간섭, 가변감쇄, 그리고 임피던스 레벨등의 단점을 가지고 있다. 그러나 PLC는 다른 대체상품에 비해 속도 및 가격측면에서 절대 및 비교우위를 가지고 있다. 따라서 기술적인 문제점들을 해결하여 상용화에 성공할 경우 기존의 인터넷접속 서비스 상품과 경쟁하는 제3의 유선통신망으로 등장하면서 기존 통신서비스 시장의 구도를 크게 바꾸어 놓을 것으로 전망된다.

• Electronics and Telecommunications Trends
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• v.31 no.3
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• pp.91-100
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• 2016

뉴스와 신문, 라디오, 인터넷에 이르기까지 기상정보를 제공하지 않는 매체가 없는 시대가 되었다. 그만큼 기상정보는 세계적이며 동시에 개인적인, 무엇보다 생활에 밀접한 정보이다. 국민은 보다 정확하며 신속한 정보를 요구하며, 이에 답하기 위해 국가기상위성센터에서는 유관기관들과 천리안의 뒤를 이을 후속 기상위성 개발에 착수하였다. 자연재해 대비에서부터 수많은 산업과 서비스업에 이르기까지, 기상정보는 관련 분야에 엄청난 영향을 끼친다고 볼 수 있다. 본고에서는 대한민국 최초의 기상위성 천리안과, 일본 Himawari-8호의 위성자료 서비스 현황을 소개한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.2B
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• pp.59-68
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• 2008

In order to activate the digital broadcasting in Korea, the analog broadcasting will have been closed down until 2012. Recently IPTV(Internet Protocol TV) thorough internet has been regarded as the fourth media following the terrestrial, satellite, and cable for the digital broad casting. And it has been the important medium for the communication and broadcasting system. However IP is not easy to replace the entire broadcasting system with the digital - type broadcasting system. For the digital broadcasting, we should replace all TV sets, install the settop-boxes to receive the various IP media, solve problems about time delaying when changing channels, and support communication and broadcasting consolidation service for such as PVR and Network CCTV. IPMG is the digital converter that is able to solve these problems. In this paper, I'll develop and analyze IPMG converter's performance which sends and receives both the analogue and digital broadcasting signals through various media gives the Network PVR service.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.9 no.6
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• pp.175-185
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• 2009

In this paper, performance of OFDM systems with turbo code is analyzed and simulated in a satellite broadcasting channel. The performance is evaluated in terms of bit error probability. The satellite channel is modeled as a combination of Rayleigh fading with shadowing and Rician fading channels. As turbo decoding algorithms, MAP (maximum a posteriori), Max-Log-MAP, and SOVA (soft decision Viterbi output) algorithms are chosen and their performances are compared. From simulation results, it is demonstrated that Max-Log-MAP algorithm is promising in terms of performance and complexity. It is shown that performance is substantially improved by increasing the number of iterations and interleaver length of a turbo encoder. The results in this paper can be applied to OFDM-based satellite broadcasting systems.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.16 no.2
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• pp.93-99
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• 2016

In this paper, higher order coupler using small size waveguide which applicable for mobile Ku-band multimode monopulse satellite tracking antenna system, has been designed, implemented and tested. Proposed higher order mode coupler adopts a coaxial structure for low profile characteristic considering installation property to mobile satellite terminal system. In addition, by using proposed coupler, extracted tracking error signal pattern has measured and confirmed that required tracking accuracy is satisfied in desired frequency band. In the future, proposed coupler could utilize for multimode monopulse satellite tracking system for high tracking accuracy.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.19 no.2
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• pp.67-71
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• 2019

In this paper, we derive a reference error probability performance in the environment where mobile satellite terminal is operated. When the satellite terminal moves, shadowing occurs due to the surrounding obstacles and the BER is lowered. We use the Lutz model simulating the environment in which mobile satellite terminals operate The Lutz model combines the Rician distribution with the Suzuki model. The error probability is derived from the numerical analysis of two distribution functions. The simulated results using the measured results in the Korean Peninsula forest area were similar to the BER results obtained using the Lutz model. Intuitively, the approximated results are similar to the measured results. Numerically, the BER error is about 3e-4 or less at an SNR of 30dB.

• The Science & Technology
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• v.33 no.5 s.372
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• pp.22-23
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• 2000

90년대 중반 국내 최초로 컴퓨터에 전화기능을 부여한 CTI서버를 개발한 (주)로커스는 새로운 정보통신문화의 소개와 정착을 위해 매진하고 있다. 94년 사내에 정보통신연구소를 설립하여 6개 연구팀을 운영하고 있는 (주)로커스는 CTI에 인터넷을 통합한 CITI그리고 CITI에 텔레비전ㆍ위성통신을 하나의 커뮤니케이션 세계로 통합하는 mCITTI 기술개발도 진행하고 있다.