• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.5
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• pp.957-962
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• 2016

Current terrestrial Digital Multimedia Broadcasting (T-DMB) is conducting the emergency alert broadcast, or can view a variety of broadcasting. However, propagation shadow area is a situation where the service is limited due to limitations of facilities investment. In addition, there is the problem of T-DMB broadcasting is for viewing only a restricted area and a mobile device because the mobile is also T-DMB viewing device impossible. In this paper, it receives a T-DMB broadcasting as a way to solve the problems of the T-DMB system, which was studied the re transmission to the mobile device. Accordingly, by receiving the broadcast may be watched in the mobile device the T-DMB reception impossible. Also provides a one-way/two-way authentication mechanism using a conditional access function, and the system was configured so that the user can watch only the registered broadcasting.

• Journal of Advanced Navigation Technology
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• v.21 no.4
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• pp.359-364
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• 2017

Since the existing analog village broadcasting system has some technical problems in applying and degradations in performance due to its old equipments, it had been required recently to be changed to a wireless digital system and to develop the standardization. However, it is important to analyze the interference between villages in deploying the efficient digital wireless village broadcasting system. In this paper, simulations for co-channel and adjacent channel interference have been carried out considering digital private mobile radio(dPMR) and digital mobile radio(DMR) systems as a representative mobile radio. These results for frequency reuse and channel separation drawn from the separation distance between villages in co-channel interference and the frequency offset in adjacent interference can be helpful to establish a standard and the testing service in the near future.

• ETRI Journal
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• v.36 no.2
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• pp.206-213
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• 2014

This paper presents a novel 90 GHz band 16-quadrature amplitude modulation (16-QAM) orthogonal frequency-division multiplexing (OFDM) communication system. The system can deliver 6 Gbps through six channels with a bandwidth of 3 GHz. Each channel occupies 500 MHz and delivers 1 Gbps using 16-QAM OFDM. To implement the system, a low-noise amplifier and an RF up/down conversion fourth-harmonically pumped mixer are implemented using a $0.1-{\mu}m$ gallium arsenide pseudomorphic high-electron-mobility transistor process. A polarization-division duplex architecture is used for full-duplex communication. In a digital modem, OFDM with 256-point fast Fourier transform and (255, 239) Reed-Solomon forward error correction codecs are used. The modem can compensate for a carrier-frequency offset of up to 50 ppm and a symbol rate offset of up to 1 ppm. Experiment results show that the system can achieve a bit error rate of $10^{-5}$ at a signal-to-noise ratio of about 19.8 dB.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2004.11a
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• pp.253-257
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• 2004

디지털 TV 방송이 본격적으로 보급됨에 따라 2004 년 후반부터 각 방송사들은 디지털 방송네트워크의 설계를 위해 본격적인 전계강도 실측을 실시하고 있다. DTV 신호 측정에는, 가장 기준이 되는 전계강도 측정기를 비롯하여 DTV 복조기(demodulator), 각종 셋톱박스, 위성항법장치(GPS)를 이용한 지형정보시스템(GIS) 등 많은 장비가 필요하고 측정항목도 다양하여, 한 지역을 측정하는데 많은 시간이 소요될 뿐 아니라 측정자의 숙련도에 따라 측정결과의 정확도와 신뢰도가 떨어질 수 있다. 본 논문에서는 이러한 문제들을 해결하기 위해 다양한 계측장비와 운용장비의 제어를 체계적으로 관리하고 측정절차를 일반화하며 측정결과 데이터를 데이터베이스화하여 측정결과를 용이하게 파악할 수 있는 통합 측정 시스템을 제안한다. 또한, 본 시스템은 측정 뿐 아니라 지형정보시스템과 전계강도 예측시스템을 도입하여 측정지점 주변의 수신환경 분석 및 최적 수신위치의 검색정보 등을 제공하며, 다량의 측정결과에 대한 다양한 분석이 가능하여 커버리지 분석 및 송신 네트워크의 설계 등에 활용될 수 있다.

• ETRI Journal
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• v.38 no.5
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• pp.847-857
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• 2016

Broadcasting services such as multi/single channel HDTV and 3DTV/2DTV use a multi-channel encoder that changes the bitrate and composition of the video service depending on the time. However, this type of multi-channel encoder could cause a longer latency owing to the variable bitrate and relatively bigger size of the buffers, which results in the same delay as in 3DTV even for a conventional DTV service. On the other hand, systems built based on separate encoders, each of which is optimized for the target service, might not have such latency problems. Nevertheless, there might be a distortion problem in the image and sound at the time of a switchover between two encoders with different output bitrates and group of picture structures. This paper proposes a system that can realize a seamless video service conversion using two different video encoders optimized for each video service. An overall functional description of the video service change control server, which is a main control block for the proposed system, is also provided. The experiment results confirm the seamless switchover and reduced broadcasting latency of DTV services compared with a broadcasting system composed of a multi-channel encoder system.

• International Journal of Internet, Broadcasting and Communication
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• v.14 no.4
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• pp.104-120
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• 2022

In severe disaster situations, Emergency alert provide information for people to survive. However, the only device that can receive the Cell Broadcasting Service (CBS) of the Korean Public Alert System (KPAS), the Public Warning System (PWS), is Smart Phone and Receiving the disaster information is very limited. Therefore, this paper proposes a solution to the problem. First, we discover problems through the analysis of KPAS, and second, we propose Smart Watch and Navigation as devices to receive Emergency alert. The devices can receive disaster information through Bluetooth communication from Smart Phone and provide content such as disaster-related images and videos. Based on the proposed items, the application was developed, and as a result of the test, Smart Phone provided more disaster information like images and videos than current emergency alert, and the method of notification of emergency alert was varied. And Smart Watch and Navigation received disaster information successfully through Smart Phone, which also provided various disaster information like images and videos. The developed application has expanded functionally than the existing emergency alert and can benefit many people in emergency situations.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• fall
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• pp.62-64
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• 2021

최근 코로나 19의 확산으로 인하여 코로나 감염으로 인한 외부 방송 촬영에 제약이 생기면서, 제작환경은 실외에서 실내의 가상 환경 제작 수요가 크게 증가하고 있다. 이에 확장현실 제작 기술이 방송 제작에 적극 활용되고 있다. 확장현실은 외부의 제작 환경을 몰입형 LED월 시스템 기반으로 가상의 그래픽으로 내부 스튜디오 제작환경에서 제작 할 수 있어 방송에서는 확장현실 관련 시스템 및 그래픽 콘텐츠, 운영기술 개발이 요구되고 있다. 이에 본 논문은 확장현실 콘텐츠를 제작 할 수 있는 '몰입형 혼합현실 시스템'을 제안한다. 특히, 확장현실 환경에서 원격으로 AR과 VR 콘텐츠의 동기를 맞추어 운영할 수 있도록 개발된 '원격제어 타임라인 디렉터'를 통해 AR/VR 콘텐츠를 재생 및 입출력을 제어할 수 있다. 본 시스템을 통하여 그래픽 기반의 AR/VR 시험 그래픽 콘텐츠 및 실사 기반의 360 콘텐츠 기반 확장현실 시험 콘텐츠를 개발하였으며, 상용카메라 추적시스템과 연개하어 자연스러운 추적 및 합성 그리고 타임라인 디렉터의 사용자 인터페이스를 이용하여 확장현실 콘텐츠를 제작 및 운영 할 수 있음을 확인하였다.

• Proceedings of the Korea Multimedia Society Conference
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• 2001.11a
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• pp.75-79
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• 2001

near VOU 시스템의 주기적 브로드캐스팅 방식(periodic broadcasting system)으로 여러 가지방법이 제시되었다. 그러나, 대부분 CBR 비디오를 전송하기 위한 방법이다. 요즘의 비디오들은 주고 VHR방식으로 압축되어 있어 VBR 비디오의 브로드캐스팅 기법이 필요하다. 하지만, 이에 대한 연구가 미미한 상태이다. 본 논문에서는 CBR 비디오의 브로드캐스팅 방식의 하나인 SB(Skyscraper Broadcasting)을 수정하여 VBR 비디오를 브로드캐스팅 하는 방법을 제시하였다. 관 논문에서 제시한 방식의 성능 평과 결과, 짧은 초기지연시간과 적은 버퍼가 필요함을 보였다.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2004.11a
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• pp.149-149
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• 2004

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.12 no.5
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• pp.83-90
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• 2012

This paper is a research on the design and implementation of a small real-time radio broadcasting system by using smart phone based on Android. It was designed as the server-client structure, and used the progressive download of HTTP as methods of transferring data to further simplify the system. In order to realize the real-time broadcasting, the original audio source was divided with a short interval and captured to be compressed and stored into files. Then the client receives and plays the compressed files sequentially as it is downloaded. However, this method occurs two problems each of which is the loss of capturing the original source in the server and the discontinuity of playing the files in the client. We solved the problem in the server by separating the thread into two parallel threads of which is each captured and compressed/stored, also by using the double buffering method. The problem in the client was solved using MediaPlayer in Android and the file queue to store the multiple files.