• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.2
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• pp.96-102
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• 2003

The thermal design of MGSE(Mechanical Ground Support Equipment) panel is performed for thermal vacum thest of Ka-band EQM(Engineering Qualification Model) payload of communications and broadcasting satellite. The thermal environments are predicted to evaluate the performance of transponder equipments in the thermal vacum chamber. SINDA is used to verify the thermal design of the heat pipe layout. Embedded 16 heat pipes in the EQM payload developed for Ka-band trasponder equipments are designded properly. The heat fluz loaded on the external facesheet is 265W/㎡ for the hot platear function test of the traspinder equipments, and the zero heat flux for the cold plateau case. The maxium predicted heat transport capability is 2723 W-cm.

• ETRI Journal
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• v.24 no.1
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• pp.1-11
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• 2002

A video summary abstracts the gist from an entire video and also enables efficient access to the desired content. In this paper, we propose a novel method for summarizing news video based on multimodal analysis of the content. The proposed method exploits the closed caption data to locate semantically meaningful highlights in a news video and speech signals in an audio stream to align the closed caption data with the video in a time-line. Then, the detected highlights are described using MPEG-7 Summarization Description Scheme, which allows efficient browsing of the content through such functionalities as multi-level abstracts and navigation guidance. Multimodal search and retrieval are also within the proposed framework. By indexing synchronized closed caption data, the video clips are searchable by inputting a text query. Intensive experiments with prototypical systems are presented to demonstrate the validity and reliability of the proposed method in real applications.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.3
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• pp.359-364
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• 2016

As cable TV networks have a media feature that is a broadband wire network, they can provide not only TV broadcasting services but also communication services. Accordingly, the cable TV network is mentioned as the optimal network for convergence of broadcasting and communication services. Recently, Available frequencies of the cable TV network have become insufficient as enhancement of video quality, increment of VoD service, and growth of high-speed internet service. This paper presents a new implementation method of switched digital video (SDV) technology that is introduced for obtaining additional frequency band. In the SDV system, only TV channels requested from viewer are sent and non-requested channels are dropped. The presented SDV uses a sharing method of TV broadcasting and communication service in a same frequency band. This method shows increase of spectrum efficient from switching of TV service channels without building a complex system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.10B
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• pp.919-928
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• 2006

A periodic broadcasting is known as an efficient technique for delivering popular videos to reduce bandwidth requirements for transmitting streaming video to viewers in video-on-demand (VoD) services. However, the most periodic VoD schemes approach needs frequency channel hopping, many segments of video managing, and using many channel at the same time. These make it difficult to implement. In this paper, we propose a Staircase Staggered broadcasting scheme which has a simple structure and substantially improved VoD efficiency. The numerical results demonstrate that the viewer's waiting time of the Staircase Staggered broadcasting scheme is close to the staircase broadcasting scheme and the maximum buffer requirements of this can be adapted for demanding rate by adjusting the short front part of a video sizes.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.1648-1653
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• 2003

The paper studies effect of quasi-periodic or airplane flutter phenomenon on television broadcasting signal. Airplane flutter is a very important problem. It causes the receiving antenna to receive both direct signal by the Tx (Transmitter antenna) and reflected signal scattered by the airplane with phase delay. The sum of two signals results in fading, sometime collapse and distortion of picture on TV screen. We performed measurement and modeling this phenomenon on TV signal when the airplane flew across and range Tx and Rx (Receiver antenna). The frequency 60.75MHz (Aural frequency of CH3) is used under tests. A single scatter multipath model is introduced. It is used to duplicate some of the measured data and show the dependence of power variation on the airplane fluttering. The fluctuation of the airplane flutter phenomenon was calculated to be around 2-4dB. The Yaki antenna is used for improving airplane flutter problem because it can make high gain and high directivity.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.8B
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• pp.539-546
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• 2007

For better performance and to avoid member service annoyance that results due to joining-clients' waiting durations and time-outs when there are more than one client wanting to join concurrently for Personal Broadcasting System service, there is a need for improving concurrent member joining mechanism. For a more efficient and better performing, this paper apply Overlay Multicast based mini-Overlay Broadcasting Control Protocol(mOBCP) Algorithm on Personal Broadcasting System. mOBCP proposed is performance-effective mechanism, since it considers the case of how fast will children, concurrently, find and join new parents when paths to existing parents are in Failure. The performance comparison, in terms of tree construction time variation and Latency are done through simulations and the results conclude in favour of the Proposed mOBCP.

• Proceedings of the IEEK Conference
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• 2007.07a
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• pp.45-46
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• 2007

In order to go digital broadcasting in Korea, it is conducted various policies in the country which be expanded network, be increased digital broadcasting hours. And broadcasting stations in the country close down analog broadcasting until 2012. Moreover IPTV is a method of delivering broadcast television and on-demand, rich media content that uses an IP(Internet protocol network) as the medium. And an IP is regarded as a very favorable approach for the future "Medium for Digital TV". However It is not easy to replace the entire digital infrastructure. And there are some problems in the digital infrastructure for Digital TV(i.e. channel zapping delay). Moreover user require service. IPMG is to solve these problems. IPMG is digital converter that allows receive and transmit signal by using many kinds of medium for Digital TV. Moreover IPMG provides users a Network PVR service. In this paper we developing, manufacturing IPMG and analyze its performance.

• Journal of Communications and Networks
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• v.18 no.6
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• pp.892-901
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• 2016

In the multi-user multiple-input multiple-output (MIMO) system, orthogonal random beamforming (ORBF) scheme is proposed to serve multiple users simultaneously in order to achieve the multi-user diversity gain. The opportunistic space-division multiple access system (OSDMA-S) scheme performs multiple weighting matrices during the training phase and chooses the best weighting matrix to be used to broadcast data during the transmitting phase. The OSDMA-S scheme works better than the original ORBF by decreasing the inter-user interference during the transmitting phase. To save more time in the training phase, a partly random multiple weighting matrices selection scheme is proposed in this paper. In our proposed scheme, the Base Station does not need to use several unitary matrices to broadcast pilot symbol. Actually, only one broadcasting operation is needed. Each subscriber generates several virtual equivalent channels with a set of pre-saved unitary matrices and the channel status information gained from the broadcasting operation. The signal-to-interference and noise ratio (SINR) of each beam in each virtual equivalent channel is calculated and fed back to the base station for the weighting matrix selection and multi-user scheduling. According to the theoretical analysis, the proposed scheme relatively expands the transmitting phase and reduces the interactive complexity between the Base Station and subscribers. The asymptotic analysis and the simulation results show that the proposed scheme improves the throughput performance of the multi-user MIMO system.

• Journal of Broadcast Engineering
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• v.11 no.1 s.30
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• pp.130-137
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• 2006

In this paper. we introduce technologies that service multimedia contents (in brief, we call it UCA (Ubiquitous Contents Access)) to end consumer that have various communication terminal on communication & broadcasting convergence environment and propose system that this technologies are applied. Also, we analyzed relative advantage and playfulness of service technology that is looked in consumer side about proposed service technology. When analyzed relative advantage and playfulness in consumer's view point, proposed communication & broadcasting convergence service model could see that is worth service that consumer can prefer.

• Journal of Satellite, Information and Communications
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• v.2 no.2
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• pp.59-63
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• 2007

In this paper, we propose an advanced Ka-band satellite HD broadcasting system using scalable video coding technology. As already known, it is not so easy to achieve reasonable link availability on Ka-band because of the rain-attenuation effect, and in case of HD broadcasting service it's more difficult. To overcome that problem, we propose an hierarchical broadcasting system based on H.264 SVC technology. In this paper, we suggest a few types of system scenario to realize the concept. Those scenarios are including DVB-S and DVB-S2 and spatially scalable video stream is the source stream in all cases.