• 한국전자통신학회논문지
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• 제4권1호
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• pp.46-52
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• 2009

위성-DMB 영상신호를 수신하는 헤리컬 안테나를 설계하였다. 위성-DMB용 헤리컬 안테나의 위상이 0, 90, 180, 270도 급전 되도록 4중실선(Quadrifilar) 형태로 설계함으로서 원형 편파의 특성을 나타내었으며 QHA 안테나의 상단 갭 간격, 턴 수 및 높이를 가변시켜 최적화시켰다. 최종 설계치는 갭 a=2.2mm, Helix 턴 수 b=0.9 턴 및 길이 c=42mm 이고 입력반사 계수는 주파수 2.62GHz에서 약 -5.8dB 정도이며, 상반평면 방사특성과 0.508dB의 축비특성을 나타내었다. 설계된 이중대역 QHA는 위성-DMB 수신 안테나에 적용되고 있다.

• 한국통신학회:학술대회논문집
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• 한국통신학회 2006년도 하계종합학술발표회 논문 초록집
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• pp.380-380
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• 2006

• 한국인터넷방송통신학회논문지
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• 제10권6호
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• pp.17-22
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• 2010

본 논문에서는 유럽향 지상파 디지털 방송 표준인 DVB-T(Digital Video Broadcasting Terrestrial)와 지상파 모바일 방송 표준인 T-DMB(Terrestrial Digital Multimedia Broadcasting)의 TS(Transport Stream)를 하나의 TS로 역다중화하는 멀티모드 방송의 통합 역다중화기(Demultiplexer)를 제안한다. 제안한 TS통합 역다중화 기능을 수행하는 USB 기반의 통합 수신기는 메모리공유기법에 의해 시스템의 부하를 감소하도록 스트림을 제어함으로서 오디오를 재생하였다. 그 결과로 위도우즈 기반의 통합 역다중화기는 각각 기존의 단일모드 DVB-T 역다중화기에 비해 CPU의 사용 점유율 성능이 향상되었다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권8호
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• pp.3121-3135
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• 2015

Owing to the increase in consumption of multimedia content and the improvement of device capacity, user demand for high-quality content has increased. However, it is difficult to transport such large amounts of content over the existing broadcasting network with limited bandwidth. To provide high-definition broadcasting, some studies suggest methods of transporting multimedia over heterogeneous networks after encoding content hierarchically. MPEG Media Transport (MMT), standardized by Moving Picture Experts Group (MPEG), is a solution that enables large-volume media transport over heterogeneous networks such as digital broadcasting networks and packet-switched networks. In the case of delivering a scalable encoded video over different networks, synchronization of each stream is an important issue. MMT defines a synchronization scheme, but does not contain sufficient functions to implement it. In this paper, we propose a synchronization scheme for media streams that are encoded hierarchically, divided into layers, and transported over heterogeneous networks. We implement our scheme using MMT and HTTP, and experimented using three encapsulated video streams with different durations. As a result, we show that the proposed scheme can reduce the waiting time to display high-quality video, relative to Dynamic Adaptive Streaming over HTTP-Scalable Video Coding (DASH-SVC) by requesting segments of enhanced layers after calculating the transmission time. Additionally, we find out that the selection of durations have a relation to the characteristics of the video.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2008년도 하계종합학술대회
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• pp.799-800
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• 2008

An efficient intra mode selection algorithm is proposed to reduce the computational complexity of inter frames for the H.264|AVC video encoding system. We propose an adaptive thresholding algorithm based on distribution characteristics of the sum of the absolute differences (SAD) of the best inter mode. Through comparative analysis, the proposed algorithm shows better speed up ratio with a negligible quality loss.

• ETRI Journal
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• 제31권1호
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• pp.65-67
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• 2009

We introduce an advanced terrestrial digital multimedia broadcasting (AT-DMB) system that overcomes the limitation of data transmission rates of T-DMB by doubling it with the same frequency bandwidth. In this letter, we propose an efficient algorithm which generates a scalable transport stream in AT-DMB by multiplexing certain types of elementary streams encoded using scalable video coding and an MPEG-surround audio coder for high-quality multimedia services.

• 한국멀티미디어학회논문지
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• 제20권6호
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• pp.853-864
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• 2017

HD padding area is essential redundancy in HD broadcasting. It is possible to use this padding area for the purpose of improving DTV broadcasting services. For utilization of this area, The bit of a service data was converted to black and white $8{\times}8$ block image. Converted block images are compressed with active video and are delivered to a receiver as only DC coefficients in a video stream. video quality is not effected by the proposed method, and service data was perfectly recovered in receiver without errors by using block average and threshold. The proposed utilization of HD essential padding area can possibly overcome the limited transmission stream rate with the bandwidth of HD broadcasting. If service data in transport or video stram were transferred using this padding area, it is possible to improve video quality with expanded video stream rate. Additionally, because the proposed methods are based on well-established standards, it is also useful for world-wide HD broadcasting systems such as ATSC, DVB, and IPTV.

• 한국통신학회논문지
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• 제38C권11호
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• pp.1019-1028
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• 2013

지상파 DMB(digital multimedia broadcasting)의 데이터 방송 서비스인 BWS(broadcast website)는 다수의 수신 단말에서 웹 트래픽 없이 방송을 통한 웹사이트 유사 서비스를 제공할 수 있는 데이터 서비스라는 큰 장점이 있지만, 이동 통신 기술 발달로 인해 스마트 폰이나 패드 등 스마트 기기를 통한 모바일 웹 서비스가 보편화된 환경변화로 그 가치를 인정받지 못하고 있다. 최근 방송과 통신을 융합한 하이브리드 방송을 통해 다양한 하이브리드 서비스를 제공하는 기술이 개발되고 있다. 본 논문에서는 BWS를 계층으로 구분하여 전송하는 계층 연동 구조의 BWS를 제안하고, 하이브리드 DMB 데이터 서비스로의 활용 방안을 제시한다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 학술대회 논문집 정보 및 제어부문
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• pp.530-531
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• 2008

Recently, navigation system is widely accepted for many car users for its versatile facilities. In Korea, many navigation system include DMB (digial multimedia broadcasting) which is mobile TV broadcasting system standard in Korea. However, there is little works on the navigation systems for the European market where the DVB-T can be used for the multimedia broadcasting. Thus, in this work the navigation system with DVB-T is developed and tested for European market resulting increased profits for the navigation manufacturers.

• ETRI Journal
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• 제34권4호
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• pp.492-502
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• 2012

We consider an overlaid broadcast service, where a spread spectrum (SS)-based broadcast signal is overlaid onto the existing terrestrial Digital Multimedia Broadcasting (T-DMB) band. The system is similar to the augmented data transmission in the ATSC DTV, for which it was investigated mostly in terms of link level performance, such as bit error rate. Our focus in this paper is on the system-level performances. More specifically, utilizing both a large scale path loss and a small scale fading channel model, the primary objective is to explore the tradeoff between the coverage and the achievable rate of the overlaid service and, finally, to determine the achievable rate in the overlaid service for marginal coverage reduction in the existing broadcast service. The analytical and simulation results show that an SS-based add-on service of 10 kbps to 20 kbps can co-exist with the T-DMB service while resulting in only a marginal degradation in T-DMB coverage (for example, less than one percent reduction).