• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.10 no.1
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• pp.44-53
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• 1999

In this paper, we propose a pilot based time-averaging channel estimation method and analyze error performances for efficient transmission of OFDM(Orthogonal Frequency Division Multiplexing) in multipath fading environment. Frequency domain channel estimations have been used in OFDM systems to compensate signal distortions due to fading on each subcarrier. The frequency domain estimation scheme uses scattered pilot to estimate channel response by simple interpolation. This implies that the estimated channel response includes signal distortions due to the noise. In this paper, we propose time-averaged channel estimation method to remove the distortion by noise. The proposed scheme can effectively remove noise components by taking time-average of the estimated channel response after estimating frequency domain channel. The computer simulations were performed to evaluate the performance of the proposed channel estimator. For the Rician channel, we compared the performance of the proposed method to that of a conventional one using channel estimation by gaussian interpolation when SER(Symbol Error Rate) = $10^{-4}$, and compared to perfect channel estimation case. The proposed method showed differences of 0.07 dB, 0.6 dB compared to perfect channel estimation and improvements of 1.7 dB, 1.9 dB for 16 QAM, 64 QAM respectively compared to conventional method.

• Journal of Broadcast Engineering
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• v.14 no.6
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• pp.783-795
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• 2009

We analyze the demand and supply in contents for platform differentiation in this paper. The contents provided by new platforms such DMB, IPTV which are introduced by the digital techniques and broadband network are almost same, so it is definitely necessary to differentiate the broadcasting contents for the development of telecommunication industry. To forecast the contents demand needed for each media, we assume 3 scenarios such as maximum, medium and minimum demand for contents considering deregulation of media policy. Also, we include the expected number of channels according to the changeover of policies as a variable for scenario. To predict the supply of contents of each media, we analyze 3 scenarios according to operating rates of production facilities as 100%, 70%, 50% and first-run ratio/rerun ratio of both terrestrial broadcastings and major program providers. The result shows that in case of scenario A, new contents for 453,484 hours are required every year and maximum contents that can be produced in present production facilities are just for 72,852 hours even in condition of 100% operating rate. This means that the unbalance of demand and supply of contents is extremely big and implies that the policies of focusing only on the development of platform and network industry are inadequate. It is time to foster contents business for differentiation of multiplatforms.

• The Journal of the Korea Contents Association
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• v.20 no.2
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• pp.36-50
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• 2020

YouTube as a news channel is gaining popularity because it offers more interesting and in-depth news than traditional news media. However, YouTube has been criticized for its distribution of false information (or fake news) in Korea. Politicians are actively proposing a variety of bills to regulate YouTube's false information and a lot of studies proposed how to regulate YouTube's false information. This study looked at the users' experience and perception of false information and identified factors that affected the regulation of YouTube news. The results showed that the conservatives and the moderate groups were exposed to false information more than the progressives, and those in their 60s believed that false information was distributed on YouTube rather those in their 20s to 50s. The more people value freedom of expression, the more people trust TV Chosun news, the more people tend to oppose the regulation of information on YouTube. On the other hand, it turns out that the more people trust the news on both terrestrial broadcasting networks and JTBC, and the more people value the enlightening aspects on the news, the more they approve of Youtube regulation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.2A
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• pp.172-178
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• 2011

In this paper, the performance of bit interleaved of coded and modulation(BICM) module of the second generation of digital terrestrial television broadcasting system(DVB-T2) is evaluated with the help of computer simulation. The frame error rate performance is studied in AWGN, Rayleigh fading and 15% erasure channels. In addition, iterative receiver is considered that exchanges extrinsic information between the rotated demapper and the LDPC decoder. Through the simulation it is observed that under the flat fading Rayleigh channel, about 1.2dB gain at FER of $10^{-4}$ is introduced when rotated constellation and iterative demapping and decoding are employed. Under the 15% earasure channel, rotated constellation gives performance gain of about 5dB at BER of $10^{-4}$ and when IDD is applied, additional performance gain of about 3dB can be achieved.

• Journal of the Korea Society of Computer and Information
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• v.11 no.5 s.43
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• pp.39-52
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• 2006

As accelerates the technical evolution of high-speed network and progresses the digitalization of broadcasting network, TV channel service through satellite/cable/terrestrial networks becomes more stable and mature. However, TV channel service using IP network such as IPTV is recently emerging. Especially, when it comes to current mosaic EPG(Electronic Program Guide) as a channel guide, the implementation of EPG via IP network is under developing. Furthermore, the personal target mosaic EPG is not provided at all in the IPTV. This paper proposes a construction method of mosaic system which can support fixed and personalized mosaic EPG using IP network for viewers. The fixed mosaic EPG is made several steps as follows ; First, H/E generates several mosaic A/V streams. Then, which are transmitted to the STB in terms of multicasting via IP network. Finally, mosaic EPG is displayed on TV through STB. In addition, this paper describes a construction model of the personalized A/V mosaic EPG that represents each person's favorite channels according to their tastes and interests. As for the contributions. The TV channel guide using IP network enable viewer to select channel more easily with practical adaptation of multi-channel expansibility and sufficient usability. In addition, through personal mosaic EPG, a number of viewers can compose their own mosaic EPG and enjoy a variety of channel easily in accordance with their preferences. Finally, the personal mosaic EPG can prohibit non-adult users from connecting adult-only contents more efficiently.

• Journal of Broadcast Engineering
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• v.24 no.5
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• pp.879-891
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• 2019

This paper provides performance evaluations of various channel estimation schemes for Advanced Television Systems Committee (ATSC) 3.0 multiple-input multiple-output (MIMO) system under a fixed reception environment. ATSC 3.0 MIMO system can obtain high spectral efficiency and improved reception performance compared to conventional terrestrial broadcasting systems. The ATSC 3.0 MIMO defines Walsh-Hadamard and null pilot encoding algorithms and the amplitude and phase of MIMO pilots are different from those of single-input single-output pilots. At the receiver, linear and discrete Fourier transform (DFT)-based interpolations can be used for the channel estimation. This paper provides the various combinations of the interpolation schemes for channel estimation in time and frequency dimensions, and then analyzes the performance of the various combinations through the computer simulation. The results of computer simulation show that the combination of the linear interpolation in the time dimension and then DFT-based interpolation in the frequency dimension can obtain the best performance among the considered combinations.