• Journal of Broadcast Engineering
• /
• v.25 no.1
• /
• pp.94-104
• /
• 2020

Currently media consumption over fixed/mobile Internet is mostly conducted by adaptive media streaming technology such as DASH (Dynamic Adaptive Streaming over HTTP), which is an ISO/IEC MPEG (Moving Picture Experts Group) standard, or some other technologies similar to DASH. All these heavily depend on the HTTP caches that ISPs (Internet Service Providers) are obliged to provide sufficiently to make sure fast enough Web services. As a result, as the number of media streaming users increases, ISPs' burden for HTTP cache has been greatly increased rather than CDN (Content Delivery Network) providers' server burden. Hence ISPs charge traffic cost to CDN providers to compensate for the increased cost of HTTP caches. Recently in order to reduce the traffic cost of CDN providers, P2P (Peer-to-Peer)-assisted DASH system was proposed and a peer selection algorithm that maximally reduces CDN provides' traffic cost was investigated for this system. This algorithm, however, tends to concentrate the burden upon the selected peer. This paper proposes a new peer selection algorithm that distributes the burden among multiple peers while maintaining the proper reduction level of the CDN providers' cost. Through implementation of the new algorithm in a Web-based media streaming system using WebRTC (Web Real-Time Communication) standard APIs, it demonstrates its effectiveness with experimental results.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.17 no.5 s.108
• /
• pp.461-475
• /
• 2006

In this paper, it is described about the tri-band mobile antenna system design to provide broadband multimedia and direct broadcasting services using goo-stationary Koreasat 3, simultaneously operated in Ka/K/Ku band. The radiating part of the antenna system with a fan beam characteristic in the elevation plane is composed of the quasi-offset dual shaped reflector and the tri-band feeder. The tri-band feeder is also composed of the Ka/K dual band feeder with the protruding dielectric rod, the circular polarizer, the ortho-mode transducer and the circular-polarized Ku band feed array. Especially, the Ka/K dual band circular polarizer was realized firstly using the comb-type structure. For fast satellite-tracking on the movement, the Ku band feed array has the structure of the $2{\times}2$ active phased array which can make electrical beams. And, the circular-polarized characteristic in the feed array was improved by $90^{\circ}$ rotating arrangement of four radiating elements polarized circularly by a $90^{\circ}$ hybrid coupler, respectively. Four beam forming channels to make electrical beams at Ku band are divided into the main beam channel and the tracking beam channel in the output, and noise temperature characteristics of each channel were analyzed on the basis of the contributions of internal sub_units. From the fabricated antenna system, the output power at $P_{1dBc}$ of Ka_Tx channel was measured more than 34.1 dBm and the measured noise figures of K/Ku_Rx channels were less than 2.4 dB and 1.5 dB, respectively, over the operating band. The radiation patterns with co- and cross-polarization in the tri-band were measured using a near-field measurement in the anechoic chamber. Especially, Ku radiation patterns were measured after correcting each initial phase of active channels with partial radiation patterns obtained from the independent excitation of each channel. The antenna gains measured in Ka/K/Ku band of the antenna system were more than 39.6 dBi, 37.5 dBi, 29.6 dBi, respectively. And, the antenna system showed good system performances such as Ka_Tx EIRP more than 43.7 dBW and K/Ku_Rx G/T more than 13.2 dB/K and 7.12 dB/K, respectively.

• Journal of Broadcast Engineering
• /
• v.14 no.4
• /
• pp.463-474
• /
• 2009

By employing the subscriber concept in broadcasting services, IPTV (Internet Protocol Television) operators provide various grades of services to subscribers based on the billing level of the subscribers. With the income from subscribers for a basis, IPTV operators plan to provide high quality services. Since Web browser-based IPTV provides T-commerce and E-commerce services as well as television services, users may frequently visit other service domains to buy goods or content. To provide the user with charged or private services, these service domains request authentication of user. The existing authentication system is not appropriate for the IPTV service environment because the environment unavoidably forces the user to cross from one authentication-based service domain to another. Single sign-on provides a user with transparent authentication services by enabling an authenticated user to move between authentication-based service domains without any re-authentication. Like this distributed environment, since the IPTV service environment also provides a variety of authentication-based services, transparent authentication service needs to be provided to subscribers who want to access charged or private services. In this paper, we propose a new user authentication scheme for the IPTV environment. This scheme integrates the Security Assertion Markup Language (SAML), which is a standard for XML-based single sign on. We validate this scheme using a simple use case scenario.

• Journal of Korean Society of Transportation
• /
• v.28 no.3
• /
• pp.109-117
• /
• 2010

The purpose of advanced traffic information system(ATIS) is to help drivers save time and energy in getting to their destinations by providing traffic information through variable message sign(VMS), internet, traffic broadcasting and mobile phones. ATIS does not just provide drivers with benefits in terms of time and energy, but it provides them with psychological benefit as well, i.e., the drivers can relieve their anxiety by getting provided with traffic information. In this study, the efficiency of traffic information system is evaluated and degree of satisfaction of drivers with the system is analyzed by building satisfaction models of various media of traffic information. Each medium has different factors for satisfaction and each factor has different degree of influence, but in general, the efficiency of traffic information in helping drivers choose routes and in providing drivers with peace of mind is considered to have the highest influence on satisfaction of drivers with the system.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.16 no.4
• /
• pp.778-784
• /
• 2012

A symmetric block cryptosystem uses an identical cryptographic key at encryption and decryption processes. HIGHT cipher algorithm is 64-bit block cryptographic technology for mobile device that was authorized as international standard by ISO/IEC on 2010. In this paper, block cipher HIGHT algorithm is designed using Verilog-HDL. Four modes of operation for block cipher such as ECB, CBC, OFB and CTR are supported. When continuous message blocks of fixed size are encrypted or decrypted, the desigend HIGHT core can process a 64-bit message block in every 34-clock cycle. The cryptographic processor designed in this paper operates at 144MHz on vertex chip of Xilinx, Inc. and the maximum throughput is 271Mbps. The designed cryptographic processor is applicable to security module of the areas such as PDA, smart card, internet banking and satellite broadcasting.

• 한국정보통신설비학회:학술대회논문집
• /
• 2009.08a
• /
• pp.31-35
• /
• 2009

현재까지의 국가 정보화 정책은 초고속 국가망, 전자정부 시스템, 유비쿼터스 기술개발 및 산업현장 적용 등 정보화 기반 구축 및 서비스 촉진 중심으로 추진되어 왔다. 유 무선 통합, 전화 인터넷 게임 음악 등 단말의 융 복합, 통신과 방송의 경계 붕괴 등 새로운 기술 환경으로 빠르게 변화 하고 있으며, 전자정부, 인프라산업 등 국가 정보화와 관련된 정책간 시너지를 극대화 하기위한 정책 방향이 필요하다. 이러한 기술 발전과 초고속 멀티미디어 서비스 제공을 가능하게 기반을 제공한 것이 2000년 이후 급속적인 광케이블망 보급 확대와 2006년 하반기부터 FTTH에 대한 투자를 활발히 진행되어 왔기 때문이다. FTTH를 기반으로 하는 다양하고 고품질의 서비스 개발 확대와 지속적인 인프라 투자 증가에 따라 향후 모든 가입자 댁내까지 효율적인 FTTH 구축을 추진하기 위해 그동안 발생되어진 문제점들과 이를 해결하기 위한 대안을 제시 하고자 한다. 특히 FTTH 구축에 따른 국사내 시스템 상면배치 문제를 비롯하여 현재까지 RN(스플리터)의 지하 맨홀 내 광접속함 설치에서 전주 광단자함으로 배치이동에 대한 장점 등 가입자 수요 요구에 탄력적으로 대처하기 위한 경제적이고 지하 맨홀 내 광접속함 설치에서 전주 광단자함으로 배치이동에 대한 장점 등 가입자 수요 요구에 탄력적으로 대처하기 위한 경제적이고 효율적인 구축방법에 대해 분석하였다. 또한, 광단자함의 2차RN 스플리터를 설치하여 가입자를 개통하는 방법에 대한 문제점과 가입자 개통시 적용하는 현장조립커넥터에 대한 사용상의 불편함, 손실증가 문제, 가입자 개통구간 고장발생시의 대처방안 문제점 등에 대해 살펴보았으며, 다양한 가입자 주거 환경에 따른 댁내 망구성에 현재 까지 발생된 문제점과 이를 해결하기 위한 방법을 제시하고자 한다.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.6 no.8
• /
• pp.1358-1364
• /
• 2002

Presently, Multimedia data are increasing suddenly in broadcasting and internet fields. For retrieval of still images in multimedia database, content-based image retrieval system is implemented in this paper that user can retrieve similar objects from image database after choosing a wanted query region of object. As to extract color features from query image, we transform color to HSV with proposed method that similarity is obtained it through histogram intersection with database images after making histogram. Also, query image is transformed to gray image and induced to wavelet transformation by which spatial gray distribution and texture features are extracted using banded autocorrelogram and GLCM before having similarity values. And final similarity values is determined by adding two similarity values. In that, weight value is applied to each similarity value. We make up for defects by taking color image features but also gray image features from query image. Elevations of recall and precision are verified in experiment results.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.34 no.1B
• /
• pp.56-66
• /
• 2009

In the traditional Server/Client architecture, the client connects to the known servers and gets information through web searching. However, nowadays, diverse internet devices providing services (get) working on internet easily. The update interval of the services or information provided by the devices is relatively short. And also they tend to be both a server and a client. In this situation, the way of the traditional information searching such as web searching is not appropriate. In this paper we propose a service push model, where it pushes its service profiles to all the other network devices by broadcasting them on the network. When a device connects to the network newly, it can get all service profiles in the network and it gets service profiles newly pushed by service providers in prompt. Also it can call any service among the service profiles within itself. We implemented a prototype system for the service push model on the JXTA platform based on P2P network. Also we measured the service profile pushing delay, the service discovery time, and the response time of service execution by running test applications written on the prototype system.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2008.06a
• /
• pp.231-231
• /
• 2008

최근 인터넷의 보급과 함께 고화질 및 양방향 TV, VOD 방송, 화상 전화 등의 멀티미디어 시대가 열리면서 초고속 통신 시스템에 대한 관심이 증가되고 있다. 특히 화상이나 동영상 같은 대량의 정보가 졸은 품질 및 빠른 속도로 전달될 수 있는 통신 시스템의 필요성이 대두됨에 따라 가장 효율적인 고속 전송 수단으로 광통신이 이용되고 있으며 그에 따른 광통신 능 수동 소자 개발에 관한 연구도 활발히 이루어지고 있다. 이러한 광통신 소자 중 원하는 빛을 선택적으로 투과하고 반사할 수 있는 flat-band pass(FP) filter의 역할이 중요한 부분을 차지하고 있다. 본 논문에서는 IR 영역에서 투과성이 우수한 칼코게나이드 물질을 이용해 l 차원 광자결정구조의 FP-filter를 설계, 제작하고 그에 대한 특성을 평가하였다. 시료는 5N의 순도를 갖는 As, Se, Te 물질을 준비하고 $As_xSe_yTe_z$를 조성비에 맞추어서 석영관에 진공 봉입한 후 용융 혼합하여 $As_{33}Se_{67}$과 $As_{40}Se_{25}Te_{35}$ 조성의 두 가지 비정질 벌크를 제작하였다. 제작된 시료의 굴절률은 ellipsometer을 사용하여 측정하였고, 본 연구진이 자체 개발한 계산툴에 따라 다중층막 구조를 설계하였다. 열 증착법을 이용하여 설계된 구조에 맞게 기판에 올리는 방법으로 1차원 광자결정 구조의 다중층막 샘플을 제작하였고 UV-Vis-IR Spectroscopy를 사용하여 반사도와 투과도를 측정하였다. 광통신용 L/C 밴드 주파수 범위에서 투과성이 우수한 칼코게나이드 박막의 1차원 광자결정 구조는 FP-filter등의 소자로써 유용하게 사용될 수 있다.

• Journal of Broadcast Engineering
• /
• v.11 no.1 s.30
• /
• pp.116-129
• /
• 2006

The progress of data transmission technology through the Internet has spread a variety of realistic contents. One of such contents is multi-view video that is acquired from multiple camera sensors. In general, the multi-view video processing requires encoders and decoders as many as the number of cameras, and thus the processing complexity results in difficulties of practical implementation. To solve for this problem, this paper considers a simple multi-view system utilizing a single encoder and a single decoder. In the encoder side, input multi-view YUV sequences are combined on GOP units by a video mixer. Then, the mixed sequence is compressed by a single H.264/AVC encoder. The decoding is composed of a single decoder and a scheduler controling the decoding process. The goal of the scheduler is to assign approximately identical number of decoded frames to each view sequence by estimating the decoder utilization of a Gap and subsequently applying frame skip algorithms. Furthermore, in the frame skip, efficient frame selection algorithms are studied for H.264/AVC baseline and main profiles based upon a cost function that is related to perceived video quality. Our proposed method has been performed on various multi-view test sequences adopted by MPEG 3DAV. Experimental results show that approximately identical decoder utilization is achieved for each view sequence so that each view sequence is fairly displayed. As well, the performance of the proposed method is examined in terms of bit-rate and PSNR using a rate-distortion curve.