• Proceedings of the Korea Information Processing Society Conference
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• 2008.11a
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• pp.141-144
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• 2008

IPTV, VOD와 같은 스트리밍 서비스와 유료 케이블 TV 방송 채널, 유료 위성방송 채널 등에는 반드시 제한 수신 시스템(Conditional Access System, CAS)이 필요하다. CAS시스템은 인증 받은 사용자에게는 깨끗한 화면을 보여주어야 하고 인증 받지 않은 사용자에게는 정상적으로 화면을 즐길 수 없도록 하여야 한다. 이러한 환경을 만들기 위하여 추가비용이 적은 알고리즘이 필요한데 그 방법으로 암호화를 제안한다. 본 논문에서는 CAS 등의 인증시스템을 위하여 H.264 영상의 선택적 암호화를 구현하였다. 제안하는 방법은 여러 가지 포맷으로 된 콘텐츠를 트랜스코딩하여 YUV 형식으로 변환한 뒤, 이것을 H.264 코덱을 이용하여 압축한 다음 필요에 따라 특정한 부분을 암호화하는 것이다. 실험을 통하여 암호화 키가 없는 미 인증 사용자는 영상을 제대로 볼 수 없었고 암호화의 강도를 강하게 할 경우 재생은 되지만 영상의 확인이 불가능함을 확인하였다. 또한 300프레임의 영상을 암호화 하는데 평균 71.3초가 걸려 속도 역시 빠름을 확인하였다. 제안하는 내용은 IPTV, VOD와 같은 스트리밍 서비스에서의 사용자 인증 및 저작권 보호 등의 분야에 유용하게 사용될 것이다.

• Journal of the Korean Society for information Management
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• v.20 no.3
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• pp.261-276
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• 2003

Seoul City has been operating 17 public libraries to bridge the digital gap in the information society. Digital collection that has used recently, is providing various information services and information sources such as Internet. DVDs, satellite broadcasts and plan to offer service with more contents in the near future. In an attempt to facilitate the use of digital archives in public libraries in Seoul, this study thus applies marketing strategy to Electronic Information Center in the S Library and techniques can contribute a dynamic approach to total strategy development for library professionals that will ensure effective management and the achievement for their goals.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.6
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• pp.574-581
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• 2002

Microstrip $8{ imes}2$ sub-array antennas for a extension to active phased array antennas are designed, fabricated and measured for TX/RX dual operation in satellite communication and a reception of satellite broadcasting. For the frequency range from 11.7 to 12.75 GHz for RX and from 14 to 14.5 GHz for TX, two orthogonal linear polarizations of ${pm}45^{\circ}$ are used to transmit and receive simultaneously with one radiator. They adopt dual resonance between two patches for wideband characteristics in RX band and show isolation characteristics over 20 dB. An electrical beam tilt of $30^{\circ}$ is achieved and a tapered power distribution, narrow element spacing are used for the purpose of low side-lobe characteristics.

• Journal of Digital Contents Society
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• v.8 no.2
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• pp.173-189
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• 2007

This study attempted to analyze factors influencing S-DMB adoption. The theoretical background of this study is 'Technology acceptance model.' Based on this theory and literature review this study set 5 hypotheses. For this research, a survey was conducted by online research lab. from October 25 to 31. Data were collected from 350 subjects. Complete and useable questionnaires were received from 303 respondents. The result and conclusion are as follow: 'Instant accessibility,' 'service quality,' 'Cost,' 'advertising,' 'perceived easy of use' are significant factors influencing 'perceived usefulness'. 'Compatibility,' is a significant variable influencing 'perceived easy of use'. However, 'self efficacy' and 'innovativeness' are not significant factors influencing 'perceived easy of use.' The result of the analysis showed that most of the hypotheses were verified the same as preceding studies, but some results were different with the result of preceding studies. Therefore, it implies the characteristics of S-DMB different with other IT systems and mass media that were research subject mostly before, and it influences the result of this study as well.

• Convergence Security Journal
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• v.22 no.4
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• pp.119-127
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• 2022

A movie information program has a positive effect on the viewer's intention to watch the movie by providing an indirect experience of the movie based on trust. In order to increase the effectiveness of a movie information program, a data service that provides the additional information on the movies introduced in a movie information program has been studied. However, since the study limited the data service to one movie information program, it was difficult to apply it to the actual environment of general cable broadcasting companies or satellite broadcasting companies that transmit multiple movie information programs. Therefore, this study expanded the existing research limited to one movie information program to provide additional information of several movie information programs. This study is meaningful in that it suggests a data service that can be operated in the realistic environment of a broadcaster that actually transmits several movie information programs.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.10 no.6
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• pp.552-557
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• 2017

Wire, wireless digital broadcasting has sharply expanded with the birth of high definition TV since 2010, the use of duplex contents as well as simplex contents has rapidly increased. Currently, our satellite communications system adopted DVB by European digital broadcasting standardization organization as a standard of domestic data broadcasting, the method how to use selective contents has been studied variously according to the development of IPTV. Digital broadcasting utilizes the method using Transport Stream Packet(TSP) by the way of multiplexing of information in order to send multimedia information such as video, audio and data of MPEG-2, this streams include detail information on TV guide and program as well as video and audio information. In order to understand these data broadcasting system, this study realized TS analyzer that divides transport stream (TS) by packet in Linux environment, analyzes and prints by function, it can help the understanding of TS, the enhancement of stream parsing ability.

• KIISE Transactions on Computing Practices
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• v.21 no.12
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• pp.798-803
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• 2015

DGPS is a technology that can improve the positioning precision of the existing GPS based on the correction information regarding reference station. Although the country is currently building infrastructure for DGPS correction information to be transmitted, it is being used only in limited areas for which DGPS expensive equipment is required. By enabling the development of the DGPS device using the smart phone, this limitation can be overcome, DGPS can be applied for various location-based services, and the implementation of the new model of location-based services may be enabled. In this paper, we introduce the development of a DGPS device for which high-precision positioning is possible using DGPS correction information received via the DMB network or mobile network in the smart phone environment.

• Journal of Satellite, Information and Communications
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• v.4 no.2
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• pp.28-33
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• 2009

In this paper, we evaluate the performance of various diversity techniques which can contribute to provide efficient multimedia broadcasting services via hybrid/integrated satellite and terrestrial network. Space-time coding can achieve the diversity gain in a multi-path environment without additional bandwidth requirement. Recent study results reported that satellite systems can achieve high diversity gains by appropriate utilization of STC and/or forward error correction. Based on these previous study results, we present various cooperative diversity techniques by combing STC and rate compatible turbo codes in order to realize the transmit diversity for the mobile satellite system. The satellite and several terrestrial repeaters operate in unison to send the encoded signals, so that receiver may realize diversity gain. The results demonstrated in this paper can be utilized in future system implementation.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.2 no.2
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• pp.69-77
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• 2009

Small size and low profile antenna for mobile vehicular-top-mounted is needed in satellite communication services such as DBS, Satellite Internet and VSAT. In middle latitudes, the development of an array antenna which has the conformal, low profile and 45 degree beam tilted configuration, and has the high gain with sharp beamwidth, low sidelobe and low loss is required for Ka band satellite communication. In this paper, in order to meet with these performances, an array antenna consisting of the vertical polarized waveguide longitudinal slots based on the leaky-wave mode of traveling wave antenna is proposed. Especially, for the lower sidelobe level the radiation power control using a design method of the different slot width is proposed. An array antenna consisting of 32 leakywave elements is showing 34.4 dBi of gain, 3.6 degree of beamwidth, below than -25 dB of sidelobe level, 43 degree of beam tilt angle in center frequency 20.0 GHz. Feed network designed by waveguide cooperated feed shows good performance of wideband and low loss.

• Journal of Broadcast Engineering
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• v.9 no.4 s.25
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• pp.305-321
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• 2004

With the advent of the digital broadcasting, the audiences can access a large number of TV programs and their information through the multiple channels on various media devices. The access to a large number of TV programs can support a user for many chances with which he/she can sort and select the best one of them. However, the information overload on the user inevitably requires much effort with a lot of patience for finding his/her favorite programs. Therefore, it is useful to provide the persona1ized broadcasting service which assists the user to automatically find his/her favorite programs. As the growing requirements of the TV personalization, we introduce our automatic user preference learning algorithm which 1) analyzes a user's usage history on TV program contents: 2) extracts the user's watching pattern depending on a specific time and day and shows our automatic TV program recommendation system using MPEG-7 MDS (Multimedia Description Scheme: ISO/IEC 15938-5) and 3) automatically calculates the user's preference. For our experimental results, we have used TV audiences' watching history with the ages, genders and viewing times obtained from AC Nielson Korea. From our experimental results, we observed that our proposed algorithm of the automatic user preference learning algorithm based on the Bayesian network can effectively learn the user's preferences accordingly during the course of TV watching periods.