• Journal of Korea Multimedia Society
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• v.14 no.12
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• pp.1583-1590
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• 2011

A Certificate Revocation List(CRL) should be distributed quickly to all the vehicles for vehicular communications to protect them from malicious users and malfunctioning equipment as well as to increase the overall security and safety of vehicular networks. Thus, a major challenge in vehicular networks is how to efficiently distribute CRLs. This paper proposes a Multimedia Object Transfer(MOT) protocol based on CRL distribution scheme over T-DMB infrastructure. To complete the proposed scheme, a handoff method, CRL encoding rules based on the MOT protocol, and relative comparison are presented. The scheme can broaden breadth of network coverage and can get real-time delivery with enhanced transmission reliability. Even if road side units are sparsely deployed or, even not deployed, vehicles can obtain recent CRLs from T-DMB infrastructure effectively.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.3
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• pp.15-26
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• 2008

T-DMB, DVB-H, MediaFLO, ISDB-T와 같은 1세대 휴대 이동 방송 기술 개발 및 표준화가 완료된 후 본격적인 서비스가 도입되고 있으며, T-DMB에서는 다채널 및 고품질 AV 서비스, 3D와 같은 신규 미디어 서비스 제공을 위한 기술 개발이 추진되고 있다. 본고 에서는 T-DMB의 신규 기술 개발 동향과 향후의 방송 통신 융합 환경에 대비한 차세대 휴대 이동 방송 기술 개발에 대한 현황을 소개한다. 그리고 해외 휴대 방송 기술 동향을 함께 살펴본다.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.815-816
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• 2008

In this paper, we evaluate depth image preprocessing for 3D data service based on DIBR over T-DMB. We evaluate two preprocessing methods of depth images. These are gaussian smoothing and adaptive smoothing. The results show that adaptive smoothing is more suitable for images with sharp transition of depth.

• The Journal of the Acoustical Society of Korea
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• v.25 no.4E
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• pp.137-141
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• 2006

This paper presents HE-AAC decoder optimization on TMS320C55x fixed-point DSP core using a DSP-C like FFR code, which provides fast and flexible porting to a DSP core. Our optimization efforts are focused on methodologies that include general optimization methods of FFR code suitable for general DSP or RISC platform in high-level language and software optimization methods in assembly language level. The implementation result requires 48 MIPS and 135 Kbytes memory space to decode 48 Kbps stereo using real Korean S-DMB data.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2003.11a
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• pp.418-422
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• 2003

In this paper a dual-band circularly polarized stacked microstrip antenna for Global Positioning System (GPS) service and Digital Multimedia Broadcasting (DMB) service is designed. By stacking two different corner-truncated square microstrip patches, dual-band, dual polarization characteristic is obtained. Experimental results show impedance bandwidth of 60 MHz (3.8%) and axial ratio bandwidth of 6 MHz (0.4%) in GPS and impedance bandwidth of 126 MHz (4.7%) and axial ratio bandwidth of 30MHz (1.1%) in DMB.

• Proceedings of the KAIS Fall Conference
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• 2011.05a
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• pp.421-424
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• 2011

As the demand of the high-speed transmission between fast moving mobile objects is increasing, more ideas are coming out to improve the channel distortion for such cases. WOFDM(Wavelet-based Orthogonal Frequency Division Multiplexing) is the most brilliant one among them, which combines the advantages of wavelet transform technique and OFDM technique, and it has been implemented into the PLC (Power Line communication) system. In this paper, we are trying to describe a comparative study on COFDM (Fourier-base OFDM) and WOFDM in the conventional T-DMB system. From the simulation results, we can see that the performances of COFDM and WOFDM are nearly same under the AWGN channel. However, WOFDM outperforms COFDM under the time-invariant Rayleigh fading channel.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2006.11a
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• pp.161-164
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• 2006

이 논문에서는 AT-DMB (advanced terrestrial digital multimedia broadcasting) 시스템에서 채널정보를 이용하여 Viterbi 복호기의 성능을 향상시키는 방법을 제시하고 그 성능을 살펴보았다. 채널정보는 부반송파를 16-QAM 계층변조한 수신신호로부터 자력적으로 추정한다. 모의실험을 통해 채널정보를 이용한 Viterbi 복호기가 채널정보를 이용하지 않는 복호기에 비해 약 1 dB의 성능향상을 나타냄을 알 수 있었다.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.457-458
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• 2006

This paper propose design and implementation methods of ensemble multiplexer which is the purpose of Terrestrial DMB Conditional Access Service. Also transmit ensemble stream which is scrambled through the proposed ensemble multiplexer, by descrambling or decoding received stream as the scramble mode which is applicated through receiving verfication platform and by desplaying it, verificate the performance of ensemble multiplexer.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2015.11a
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• pp.35-38
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• 2015

OFDM 변조방식의 특징 중 하나가 SFN(Single Frequency Network) 기능이다. 최근 지상파 UHDTV방송을 기대하면서 OFDM 변조방식의 SFN기능을 이용한 가정 내 무선수신 환경에 대한 관심이 높아지고 있다. 그러나 SFN기능이 가능할지라도 송 중계기와 갭 필러 측면에서 보면 프로그램을 전달하는 별도의 백본망 없이 수신과 송신이 동일한 주파수로 이루어지려면 송신된 전파가 다시 자기 안테나로 수신되는 Feedback현상에 대해 좀 더 많은 연구가 요구되고 있다. 본 연구에서는 현재 가정과 사무실 등에서 사용하고 있는 저가의 가정용 T-DMB 갭 필러를 이용한 수신실태와 Feedback 현상에 대해 몇 가지 실험을 실행해 보았다. 가정용 갭 필러의 Feedback현상과 사용 형태를 분석함으로써 향후 UHDTV방송의 원활한 SFN망 구축과 가정 내 무선 수신환경 구축을 위한 방안을 제시하고자 한다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.8
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• pp.1904-1913
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• 2014

Was develop 256bit output stream cipher of improving for same key reuse prohibition and integrity. The developed stream cipher used Salsa20 round function was implemented to hardware of applying a 5-stage pipeline architecture, such as WSN and DMB for real-time processing can satisfy the speed and security requirements.