• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.5
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• pp.115-121
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• 2009

In this paper, we propose an algorithm that reduces channel change delay time in the P2P based IPTV system. Channel change delay time is considered to be one of the most important performance measures in IPTV system. Proposed algorithm presents a method to reduce the channel change delay time effectively. The algorithm eliminates the first channel change delay time and reduces delay time on a continuous channel surfing. We will show the mathematical models to evaluate the performance of proposed scheme with respect to the channel change delay time.

• Proceedings of the IEEK Conference
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• 1998.10a
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• pp.139-142
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• 1998

This paper presents a method to determine the rolloff factors of both the digital terrestrial TV modulator and the bandpass filter (BPF) at the digital TV receiver input, using an analytical power spectral density model satisfying given co-channel and adjacent channel protection ratios for the digital terrestrial broadcasting services. Since the proposed method is very simple and effective to use, also can be used regardless of type of systems or modulation techniques, this method is expected to be applied to select some other digital terrestrial broadcasting system specifications.

• Broadcasting and Media Magazine
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• v.1 no.3
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• pp.16-29
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• 1996

본 논문에서는 지상망 디지털 오디오방송(DAB) 시스템의 출현 배경과 미국 내에서 DAB 시스템의 개발과 성능시험 평가를 위한 NAB, NRSC, EIA, FCC, NASA, Lewis 연구소, 카나다 CRC의 활동상을 소개한다. 구체적으로는 미국에서 개발 중에 있는 USA Digital Radio사, Amati Communications사와 Kintel Technologies사의 FM In-Band On-Channel(IBOC)방식, AT＆T사의 FM In-Band Adjacent-Channel(IBAC)방식과 USA Digital Radio사의 AM IBOC 방식의 원리와 특성, 핵심기술, 개발현황, 성능시험 결과와 각 방식의 장단점을 비교 분석하며 또한 미국의 In-Band 방식과 유럽의 Eureka 147 New-Band 방식을 비교 분석한다.

• Proceedings of the IEEK Conference
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• 1999.11a
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• pp.817-820
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• 1999

In this paper, we describes RF receiver module for IMT-2000 handset with 5MHz channel bandwidth. The fabricated RF receiver module consists of Low Noise Amplifier-, RF SAW filter, Down-converter, IF SAW filter, AGC and PLL Synthesizer. The NF and IIP3 of LNA is 0.8㏈, 3㏈m at 2.14㎓, conversion gain of downconverter is l0㏈, dynamic range of AGC is 80㏈, and phase noise of PLL is -100 ㏈m, at 100KHz. The receiver sensitivity is -110㏈m, adjacent channel selectivity is -48㏈m.

• Journal of the Korea Institute of Military Science and Technology
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• v.11 no.2
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• pp.5-15
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• 2008

Cooperation between the GVWS within a few hundred meters has forced MWRs equipped to have service ranges in such a short ranges as well as the limited numbers of channels are available. This kind of situation often produces the frequency interferences between MWRs due to the easy uses of the common and adjacent frequencies between them. Current work provides the details of the frequency interferences and the possible degrees of detections. It is also described that the effective distances for the operation between the GVWS are investigated when they use the common and the adjacent frequencies each other with the factors as the frequency intervals and the antenna arrangement angles.

• Journal of Electrochemical Science and Technology
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• v.15 no.3
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• pp.373-387
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• 2024

The layout of the cathode flow field largely determines the net output power of the proton exchange membrane fuel cell (PEMFC). To make the normal mass transfer effect best, the longitudinal channel was waved based on four serpentine flow channels, and the effects of sag depth and longitudinal channel width on the output efficiency of the cell were explored. The results show that the wave channel design systematically enhances the forced convection between adjacent channels, which can prevent a large zone of oxygen starvation zone at the outlet of the channel. The increase of the normal velocity in the gas transmission process will inevitably induce a significant enhancement of the mass transfer effect and obtain a higher current density in the reaction zone. For the longitudinal channel width, it is found that increasing its size in the effective range can greatly reduce the channel pressure drop without reducing the output power, thereby improving the overall efficiency. When the sag depth and longitudinal channel width gradient are 0.6 mm and 0.2 mm respectively, PEMFC can obtain the best comprehensive performance.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.30B no.10
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• pp.86-94
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• 1993

This paper presents the two-stage neural network method for efficient channel assignment of cellular mobile radio network. The first stage decomposes the region into non-adjacent groups of cells and the second stage assigns channels to the decomposed groups. The neural network model is tested with an experimental system of eighteen channels dedicated for nineteen hexagonal-cell region. When radom call requests of average density of 2 Erl/Cell to 8 Erl/Cell are presented, the real-time channel assignment method reduces the call-blocking rate up to 16% against the existing SCA(Static Channel Assignment) method.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.1098-1103
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• 2004

In this study, the effect of channel flow in the concave surface on local heat transfer characteristics of array jets was investigated experimentally. A TLC method is employed to determine local heat transfer coefficients on the target plate and also flow visualization has been conducted to investigate the behavior of a row of impinging jets and array of impinging jets. Two different array patterns of impinging array jets devices are tested for Reynolds number(Re=10,000). In a row of impinging jets, secondary vortex is strongly maintained by main vortex at nozzle-to-plate distance of H/d=2. Therefore, the Nusselt number slowly decreased at the mid-way region between adjacent jets. In array jets, the local maximum Nusselt number region move further in the downstream direction due to the increase of channel flow velocity.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.3
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• pp.1336-1340
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• 2011

In this paper, the efficient prevention of cross talk technique for basically avoiding the confusion problem between the overlapped ubiquitous network of the other object is developed within the same area. The intelligent unified wireless network remote meter reading system of the ubiquitous ZigBee base is developed based on this technology. Therefore, in this paper, each meter reading equipments managed the information of its own adjacent ZigBee channel. The intelligent network system steadily transmitting data a relay was developed based upon this information in each region through the flexible channel conversion technique.

• 한국정보통신설비학회:학술대회논문집
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• 2007.08a
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• pp.127-131
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• 2007

본 논문에서 제안하고자 하는 IPTV 채널캐슁 서비스는 IPTV 서비스의 품질요소인 QoE(Quality of Experience)의 개선을 목적으로 하고 있다. IPTV 채널캐슁 방법은 IPTV 서비스가 실시간 방송 및 VOD(Video On Demand)등 다양한 패턴의 서비스를 선택하는 사용자의 채널요구 패턴을 반영한 인접채널(adjacent-channel)을 멀티캐스트하면, 사용자의 채널전환요구시 제어메시지 전송 및 스위칭에 소요되는 대기시간을 줄여 사용자의 채널전환지연시간을 개선할 수 있다. 이를 위하여 본 논문에서는 LRFU(Least Recently Frequently Used) 알고리즘에 기반한 MCA(Multicast Channel Agent)을 제안하며, MCA을 구성모듈에 대한 설명을 기술한다.