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We investigated the heat dissipation in heterostructure field-effect transistors (HFETs) using microRaman measurement of the temperature in active AIGaN/GaN. By varying the gate structure, the heat dissipation through the gate was clearly revealed. The temperature increased to 120 °C at the flat gate device although the inserted gate increased to only 37 °C. Our results showed that the inserted gate structure reduced the self-heating effect by three times compared to the flat gate structure. Temperature mapping using micro-Raman measurement confirmed that the temperature of the near gate area was lower than that of the near drain area. This indicated that the inserted gate electrode structure effectively prohibited self-heating effects.

Hybrid broadcasting utilizing heterogeneous networks can provide not only Audio/Video(A/V)-based unidirectional broadcast services but also various interactive A/V and data services via both broadcast and communication networks. Customers of hybrid broadcasting services can then consume A/V content that is transmitted from broadcasting stations and data services relevant to A/V content through communication networks, such as the Internet. Since interactive data can be widely ingested in various countries and regions, it is advantageous for it to be customized for personalized services depending on consumer preferences and locations. However, the current broadcasting standard has not yet defined a standardized method of inserting content into a broadcasting program. Thus, the research on content insertion technology using heterogeneous networks is actively progressing. The most important technical challenge of inserting content is rendering a smooth replacement of on-air broadcast content with media data through communication networks and an accurate return to the over-the-air broadcast content consistent with the rendering timeline using legacy receivers. Since most legacy receivers have one decoder, both the inserted content and the broadcast content have to be handled by one decoder. When two video streams are processed by one decoder, decoding and rendering problems due to the buffer overflow may occur, and buffer management of the decoder is required to solve this problem. Therefore, this paper proposes a content insertion method of using a frame control-based receiver buffer model to enable smooth and accurate rendering of inserted and on-air content without any blackout scenes.

Advanced Television Systems Committee (ATSC) 3.0 is a more innovative standardization including Ultra High Definition (UHD) broadcasting and mobile High-Definition (HD) broadcasting. It also includes the deployment of a disaster information alarm function as well as the adoption of All-Internet Protocol (IP) based transmission in terrestrial broadcasting networks. Thus, ATSC enables additional technologies such as hybrid broadcasting services by interworking terrestrial broadcasting and internet networks for bidirectional customized services. In addition, there is a growing interest in wider viewing contents, which provide more immersive contents than existing UHD broadcasting mediums. Wider viewing contents can be acquired by using large field of view (FoV) lenses such as fish-eye lenses or by stitching several sub-images. The images captured by large FoV lenses have heavily curved surface distortions, while the distortion of the stitching-based wider viewing contents caused by the synthesizing process on overlapping regions is lower. Provision of wider viewing contents over the traditional broadcasting service has limitations in terms of bandwidth. However, they can be overcome by using hybrid broadcasting platforms such as ATSC 3.0, which transmits a video sequence over an RF channel and other viewing-angle video sequences through the Internet network, where signalling among those video sequences is required. Therefore, this paper proposes a hybrid broadcasting platform for transmitting multiple video sequences over broadcasting and Internet networks, and stitching them for wider viewing.

Point cloud content is widely used to store and represent 3D volumetric objects with a complex and detailed representation from any direction of view. However, the amount of data needed for point cloud content is much larger than that of 2D representations. To overcome this difficulty, MPEG has started to develop a Video-based Point Cloud Compression (V-PCC) that is designed by projecting point cloud content into 2D content and compressing the 2D content using conventional 2D video codecs. Compression efficiency of the V-PCC can be achieved when 3D motion flow and textual conformity on 3D surfaces are preserved through 2D projections that are favorable to the 2D video codec. As mentioned above, point cloud content has a complex geometry, therefore when decomposing a point from 3D coordinates to construct a 2D patch, several situations must be considered in addition to the location of adjacent points. This paper addresses the issues in such complex geometry by proposing a method that preserves 3D homogeneity in 2D patches. Comprehensive experiments are conducted to demonstrate bitrate savings of 0.5%, 0.6%, 7.8%, 7.0% and 5.5% in random access mode and 0.1%, 0.0%, 7.0%, 4.2% and 3.3% in all intra mode for D1, D2, Y, Cb, and Cr, respectively, compared to the reference software.

Accurately predicting the peak wavelength and intensity of the electroluminescence spectrum through the photoluminescence method which can be measured without connecting electrodes is not only practically important for the development of micro-LEDs that cannot be fully inspected for device development, but there is also a fundamental importance in understanding the light emitting mechanism of the LEDs. In this study, the correlation and detailed mechanism between PL and EL are systematically analyzed by considering the effects of carrier escape, carrier accumulation, applied bias, leakage current, incident light wavelength and light absorption in order to provide a clear path for all-optical inspection of light emitting diodes and complete understanding of the luminescence mechanism in GaN-related quantum wells.

The point cloud is a medium that visualizes various information by placing a point having a color value and a geometry value in a three-dimensional space. The point cloud uses dozens and millions of points for visualization of information, and the key point of commercialization of this point cloud video is to efficiently compress a large amount of information of point cloud and transmit it to users. Currently, MPEG V-PCC is conducting dynamic point cloud compression research using the 2D video codec, where motion estimation is conducted in terms of 2D video sequences. Thus, there is a limitation in estimating the motion in 3D point cloud contents. In this paper, we propose the method to use the 3D motion for point cloud video compression. The proposed technology achieves efficient compression rate and improves accuracy in lossy compression.

Recently, the emergence of 3D cameras, 3D scanners and various cameras including Lidar is expected to promote various 3D media applications such as AR, VR and autonomous mobile vehicles. The 3D media can be recently realized by not only 2D pixel and depth information but also points with texture and geometry information. In particular, 3D point cloud data is consisted of hundreds of thousands to millions of 3D points, and thus dramatically increases its data size compared to 2D media data, which brings up the development of an efficient encoding/decoding technology. Also, it is required to develop a scalability function such as Level of Detail (LoD) for both an effective service with different bandwidths, devices and Region of Interest (RoI). In this paper, we propose a new LoD quality parameter considering characteristics of 3D point cloud contents instead of bitrate change based on a video codec in MPEG Video-based Point Cloud Compression (V-PCC). Therefore, the use of LoD table proposed in this paper is confirmed to generate 3D point cloud contents with different point density.

The objective of digital broadcasting has evolved from providing a plain video service to offering a realistic visual experience. Technologies such as 3DTV and UHDTV have been suggested to achieve this new objective by providing an immersive and stereoscopic visual experience. However, owing to the high bandwidth requirements of such services, the broadcasting industry has faced a challenge to find a new transport mechanism for overcoming the bandwidth limitation. The standardization organizations, the Advanced Television Systems Committee, Digital Video Broadcasting, and Telecommunications Technology Association, have been working on the integration of broadcasting and a broadband network (IP) to resolve the bandwidth issue of realistic video services. This paper introduces a frame-level timeline synchronization and transport system target decoder model for providing a stable 3DTV service over a hybrid network. The experimental results indicate that the proposed technologies can be successfully adopted as a reference model in a broadcast-broadband hybrid 3DTV service and other IP-associated hybrid broadcasting services.

As a new hybrid broadcasting service, augmented broadcasting shows enhanced broadcasting content on a large TV screen, while augmented reality (AR) on a mobile device augments additional graphical content onto an input image from the device's own camera to provide useful and convenient information for users. A one-sided broadcasting service using AR has already been attempted in virtual advertisements during sport broadcasts. However, because its augmentation is preprocessed before the video image is transmitted, the viewer at home may have no influence on this formation; and no interaction for the user is possible unless the viewer has a direct connection to the content provider. Augmented broadcasting technology enables viewers to watch mixed broadcasting content only when they want such service and to watch original broadcasting content when they do not. To realize an augmented broadcasting service, the most important issue is to resolve the hybrid content synchronization over heterogeneous broadcast and broadband networks. This paper proposes a novel hybrid content synchronization scheme for an augmented broadcasting service and presents its implementation and results in a terrestrial DTV environment.

ATSC is currently working on standardization of hybrid 3DTV broadcasting service in heterogenous network environment after completion of service-compatible 3DTV broadcasting service standard based on broadcasting channel. This paper proposes a convergence 3D video broadcasting method on broadcasting and IP network while guaranteeing a Full-HD 3D quality without degrading the image quality of legacy DTV. Specifically, this paper describes transmission of the 3D additional video using the ISO/IEC 23009-1 DASH, robust synchronization method under heterogenous network environments and system target decoder model for hybrid 3DTV receiver. Based on experimental results, we confirm that proposed technologies can be used as a core technology in the hybrid 3DTV standardization and a reference model for a development of hybrid 3DTV encoder and receiver. Keyword : 3DTV, ATSC, Hybrid, Stereoscopic, DTV, STD 정규논문 (Regular Paper) 방송공학회논문지 제19권 제5호, 2014년 9월 (JBE Vol. 19, No. 5, September 2014) http://dx.doi.org/10.5909/JBE.2014.19.5.687 ISSN 2287-9137 (Online) ISSN 1226-7953 (Print) 688 방송공학회논문지 제19권 제5호, 2014년 9월 (JBE Vol. 19, No. 5, September 2014) 그림 1. 이종망 연동형 3D 비디오 방송서비스 개념도 Fig.1. Conceptual diagram of hybrid network associated 3D video broadcasting service I. 서 론 사용자의 몰입감과 현장감을 극대화할 수 있는 실감 미 디어는 “스마트”로 대표되는 정보통신 분야의 개발 방향과 함께 사회의 키워드로 점차 자리 매김하고 있다. 실감 미디 어는 공간과 시간의 제약을 극복하고 인간에게 자연감과 사실감을 극대화 할 수 있는 미디어로서 현장감/입체감을 제공하는 3D 분야 및 초고화질을 제공하는 UHD 분야를 중심으로 핵심기술을 선점하기 위한 노력이 전 세계적으로 진행되고 있다 . 특히 3D 영화의 성공은 3D 미디어를 극 장과 같은 특화된 환경이 아닌 댁내와 같은 일반 시청환경 하에서도 현장감과 입체감을 제공하기 위한 노력이 지속적 으로 이어지고 있으며, 이와 같이 시청자에게 대용량의 고 화질 3D 콘텐츠를 제공하는 하나의 방법으로 다양한 네트 워크의 융합을 통한 서비스로 발전되고 있다 . ATSC(Advanced Television System Committee), DVB (Digital Video Broadcasting) 및 TTA(Telecommunications Technology Association) 등 전 세계 표준단체를 중심으로 제정된 서비스호환 3DTV 방송방식은 기존 DTV와 호 환성을 유지하면서 3D 비디오를 한 프레임 내 다중화한 단 일 영상을 서비스하는 프레임호환 3DTV 방송서비스에 비하여 고화질의 3DTV 방송서비스가 가능하나 기존 방송 망 대역폭을 통하여 좌우영상을 제공함으로써 Full HD 화 질을 제공하지 못하는 단점이 있다 . 이를 반영하듯 ATSC 는 2012년 12월 방송망기반 서비스호환 지상파 3DTV 방 송서비스 표준 완료 이후 현재 방송망 및 IP망을 결합한 하 이브리드 3DTV 방송서비스에 초점을 맞추어 표준화를 추 진 중에 있다. 하이브리드 3DTV 방송서비스는 스마트TV 환경 하에서 기존 DTV 화질 열화 없이 시청자에게 FULL HD 3D 비디오 제공이라는 핵심 요구사항을 토대로 이종망 연동 3D 비디오 전송에 따른 시그널링, 좌우영상 동기화 및 수신기 내에서 안정적인 3D 비디오 재생을 위한 시스템 타겟 디코더 모델이 핵심기술로 요구되고 있다 . 이에 본 논문에서는 이종망기반의 하이브리드 3DTV 방 송서비스를 위하여 필수적으로 요구되는 시그널링, 동기 화 및 시스템 타겟 디코더 모델을 제시하고 이를 기반으로 한 하이브리드 3D비디오 방송시스템을 제안한다. 이를 위 해 본 논문의 II장에서는 제안한 이종망 융합형 3D 비디오 방송서비스 개요, 서비스 시그널링 구조, 이종망기반 3D 비디오 동기화 및 시스템 타겟 디코더 모델 등 핵심기술을 설명하고, III장에서는 제안한 기술을 토대로 3D 비디오를 송수신하기 위한 방송시스템 개발 및 실험결과를, 마지막 으로 IV장에서 결론 및 향후 연구에 대하여 기술한다. II. 이종망 연동형 3D 비디오 방송서비스

This paper introduces a novel repetitive delivery scheme for the left and right views in service-compatible (SC) 3D video that provides full backward compatibility to a legacy DTV system while retaining HD 3D visual quality without additional bandwidth or a codec over the legacy broadcasting channel. The proposed SC delivery scheme transmits individual view sequences of a 3D video in interlaced form, that is, a left-view sequence of a 3DTV program to be used repeatedly is transmitted first and stored locally, and the right-view sequence of the 3D program is then transmitted. This paper specifically describes the signaling, synchronization, and storage format methods used to validate the proposed SC delivery scheme. The experiment results show that the proposed SC delivery scheme can be effectively applied for an SC 3DTV service without degrading the DTV quality using only legacy DTV platforms.