• Journal of Practical Engineering Education
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• v.7 no.1
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• pp.31-37
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• 2015

Terrestrial digital multimedia broadcasting (TDMB) is a method of bringing multimedia images, radio, internet, and television to portable devices through terrestrial digital radio transmissions. TDMB related educations being carried out in colleges are focusing on developing firmware which enables users to choose a wanted service. TDMB transmission frame is made up of synchronization channel (SC), fast information channel (FIC), and main service channel (MSC). Services such as video, audio and date are transmitted in the form of subchannel in the MSC. FIC carries information related to each services and subchannels. This paper presents a TDMB frame analysis simulator for analyzing and displaying FIC data on PC. TDMB frame analysis simulator contains functions such as controlling TDMB receiver through USB, establishing the frequency, bringing FIC to PC, displaying ensemble ID and levels, and displaying informations related to services and subchannels. In addition to that, this simulator has a function of being able to store FIC date and subchannel data. This simulator being developed with C++ is expected to be used to view those data visually so that it helps students to understand the TDMB system better and bring about the educational motivation.

• Proceedings of the IEEK Conference
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• 2000.09a
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• pp.229-232
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• 2000

Orthogonal frequency division multiplexing(OFDM) has meanwhile become part of several telecommunicati ons standards, such as satellite and terrestrial digital audio broadcasting(DAB), digital terrestrial TV broad casting(DVB), asymmetric digital subscriber line(ADSL) for high-bit-rate digital subscriber services on twisted-pair channels, and broadband indoor wireless systems. In his paper, we show that OFDM signals contain sufficient structure to accomplish blind channel estimation using second order statistics only. This method doesn't require redundancy as cp in transmitter. And the result is compared with PSAM channel estimation as least square, linear minimum mean square, singular value decomposition.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.179-180
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• 2008

본 논문에서는, 고품질 AT-DMB 시스템을 위해서 각 계층 ES(Elementary Stream)을 MPEG-4 over PEG-2 시스템과 Eureka-147 DAB 시스템을 통해 서로 다른 채널로 전송한다. 계층별 전송으로 인한 시간 지연에 대처하여 수신 입력부에서는 각각의 계층으로 전송된 ES들이 동기화 되어 복호화 되도록 SVC의 계층적 비트스트림 구조와 적응적으로 동작되는 다중화 시스템 구조를 제작하였다.

• Electronics and Telecommunications Trends
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• v.21 no.4 s.100
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• pp.22-33
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• 2006

방송의 디지털 전환은 기존의 아날로그 방송에 비해 획기적으로 새로운 HD 화질과 3D입체음향의 방송 서비스가 가능하게 하였을 뿐만 아니라, 아날로그 방송에서는 불가능하였던 이동멀티미디어 방송이라는 새로운 서비스가 출현하게 하였다. 이동멀티미디어방송은 TV를 집 밖으로 이끌어내어 차를 타고 갈 때, 걸어갈 때 및 자리를 옮겨 다닐때도 휴대단말기를 통해서 언제 어디서나 원하는 TV 시청 및 음악 청취를 할 수 있는방송 서비스를 실현함으로써, 방송과 통신의 컨버전스를 유도하는 역할 및 나아가서 유비쿼터스 방송망 구성에 적용성을 제시하는 등 우리의 삶에 새로운 시대를 열어가고 있다. 현재 지상파 이동멀티미디어 방송 시스템은 세계적으로 매우 활발하게 연구 및 서비스가 추진중이며, 대표적인 예로는 크게 World DAB를 중심으로 한 T-DMB, DVB를 중심으로 한 DVB-H 그리고 Qualcomm을 중심으로 한 Media FLO 등이 있다. 본고에서는 지상파 이동멀티미디어 방송시스템에 대한 소개와 각 시스템의 표준화 및 서비스 추진 현황에 대해 소개한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.3A
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• pp.327-334
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• 2008

Conventional on-channel-repeaters (OCRs) have a crucial problem that the power of a re-transmitted signal is highly limited by a feedback signal due to antenna coupling. The power limitation problem in OCRs has been solved by incorporating a demodulation-type feedback canceller which eliminates unwanted feedback signals by estimating a feedback channel. In applying the demodulation-type feedback canceller to T-DMB repeaters, there is a troublesome problem of unfrequent known pilot symbols, resulting in poor convergence performance of channel estimation. To solve this problem and enhance the accuracy of estimation, we propose a partitioning method of the Phase Reference Symbol (PRS) transformed in time domain. Since filter coefficients are updated every one partitioned subgroup, the number of updates is increased by the number of partitioned subgroups and thus the convergence speed is enhanced. The improved performance of feedback-channel estimation is directly connected with the feedback-cancellation performance. Simulation result shows that the feedback canceller incorporating the proposed partitioning method has a good performance in terms of residual feedback power.

• Journal of the Korean Chemical Society
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• v.24 no.4
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• pp.280-287
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• 1980

The interactions of chemical carcinogens, such as polycyclic aromatic hydrocarbons, dimethylaminoazobenzene (DAB) and its derivatives and heterocyclic compounds with tissue components, especially with deoxyribonucleic acid (DNA), were examined by means of simple Huckel method. Assuming that the formations of a loose molecular complex between the carcinogens and the tissue components are the first step of chemical carcinogenesis, the most proble orientation between the chemical carcinogens and adenine-thymine (A=T) pair or guanine-cytosine $(G\equivC)$ pair is determined. It has been found that, in the case of the formation of molecular complex between chemical carcinogens and A=T pair, the two atoms of K-region of the carcinogens and the atom of L-region in the proximity of their K-region are combined correspondingly with C-l' carbon atom in the sugar that is attached to thymine, N-1 nitrogen atom and C-5 carbon atom in the thymine part of A=T pair, while, in the case of that between the carcinogens and $G\equivC$ pair, the above three atoms of the carcinogens are combined correspondingly with C-8 carbon atom, N-9 nitrogen atom and N-3 nitrogen atom in the guanine part of $G\equivC$ pair.

• Spatial Information Research
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• v.15 no.1
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• pp.15-23
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• 2007

Recently, Korea became the first country which started Terrestrial-DMB service. The DMB service is still at a very early stage throughout the world. At this stage, it is an important issue to develop DMB contents which distinguish DMB from traditional broadcasting by utilizing DMB's mobility. In this paper, we will propose outline of map service through DMB along with related services such as traffic and location information. This outline includes the map service protocol and map data structure for DMB. There is little research at the moment related to it, and this preliminary research enables map service through DMB. A map service would bring DMB a distinct advantage over traditional broadcasting. Moreover, further services based on broadcasting network and mobility would contribute to rapid growth of DMB.

• Korean journal of communication and information
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• v.26
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• pp.135-156
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• 2004

Policymakers' active support as well as broadcasting and telecom industries' endeavors seeking new business opportunities speed up the introduction of a new medium called DMB in Korea. Meanwhile, discussions from a critical perspective concerning the policy rationale, cultural and social implications of DMB and policy processes are rather scanty. The discussion of policy rationale focuses upon whether the rationale to introduce DMB is sufficiently valid. The discussion of DMB's cultural and social bearings is concerned with whether the implications of new media and technology are properly considered in policymaking and that of policy processes questions whether the initial conditions of DMB are appropriately structured. This study explores such issues associated with the introduction of DMB in Korea.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.8B
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• pp.1188-1196
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• 2010

In this paper, worldwide standards and regulations on in-band/out-of-band emission characteristics of DMB broadcasting equipments are reviewed, and emission mask requirements of terrestrial low power DMB repeater under 10mW/MHz are analyzed. Out-of-band emission mask drafts suitable for single/multiple block low power repeaters are proposed. Validity and usefulness of the proposed drafts is evaluated and verified in the several experiments. Using the proposed standard, small-sized and cost-effective DMB repeater can be easily implemented to broaden DMB broadcasting coverage by reducing weak signal areas.

• Journal of Broadcast Engineering
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• v.13 no.2
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• pp.172-178
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• 2008

Orthogonal Frequency Division Multiplexing (OFDM) is one of the most promising technologies for high data rate wireless communications. OFDM has been adopted in wireless standards such as digital audio/video broadcasting. The combination of OFDM and cooperative diversity techniques can provide the diversity gain and/or increased capacity. In this paper, the cooperative coding using cyclic delay diversity (CDD) for multiuser OFDM systems is introduced. To improve the beneficial effects of relays's cooperation, CDD is adopted in cooperative transmission of relays. Simulation results show the bit error rate (BER) for various consideration. The proposed scheme provides improved performance compared to delay.