• The KIPS Transactions:PartD
• /
• v.10D no.3
• /
• pp.521-530
• /
• 2003

Various multimedia application services have been developed with techniques of high speed networks and computer. Among these services, a video-conference system over internet is useful and important, and its standardization has been shown in ITU-T H.323 and IETF SIP. H.323 standardization is currently used in many products, but two standardizations will coexist for a long time. Since the interoperability is needed between two standardizations, H.323-SIP gateway is developed for it. In audition, a video-conference system supporting two standardizations is necessary to be developed. We have implemented the video-conference terminal supporting both ITU-T H.323 and IETF SIP standardizations over internet. The system implementation has been designed using the common modules of two standardizations maximally, and the interoperability among different systems is satisfied through experiments.

• The KIPS Transactions:PartD
• /
• v.10D no.7
• /
• pp.1177-1188
• /
• 2003

In this paper, a cyber space for multimedia conference is designed and implemented using gatekeeper and web service which satisfies H.323 standards. The implemented gatekeeper manages a registration and a call control for H.323 video conference terminals. The implemented gate-keeper can manage registered users efficiently with directory services using web service. Also, software maintenance of video conference system is established by service provider instead of users using control download on web. finally, we present the practical use of video conference through various applications of directory services.

• The KIPS Transactions:PartD
• /
• v.9D no.3
• /
• pp.501-510
• /
• 2002

A various multimedia application services should be developed with techniques of high speed networks and computer. Among these, video-conference system over Internet is useful and important, and the standardization for it should be showed in ITU-T H.323. H.323 standardization consists of four components such as Terminal, MCU(Multipoint Control Unit), Gatekeeper, and Gateway. Among these, the functions of Gatekeeper are as follows, firstly the address translation service to translate the alias address into the IP address, secondary conference admission control service to control of conference start and termination, thirdly bandwidth management service for H.323 terminals. In this paper, we implemented the Gatekeeper for an efficient management of video-conference components in Internet environment, and will introduce our system. As the experimental results with CUSeeMe and Netmeeting which are well-known H.323 terminal, it is known that our gatekeeper should be satisfied with H.323 standardization.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 1998.11a
• /
• pp.520-524
• /
• 1998

인터넷상에서 실시간 영상회의 시스템을 구축하기 위해 MBone망을 구성하고 RTP에 의해 영상 및 음성정보의 고속전송이 가능하게 하였다. 이를 기반으로 멀티미디어 영상회의 프로토콜인 H.323을 탑재하여 다자간 회의 시스템을 구현하고, 더불어 영상사서함 기능을 부가하여 녹화, 재생이 가능하게 한다. 구현결과 기존의 시스템보다 속도가 향상됨을 확인했다.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2002.11b
• /
• pp.1459-1462
• /
• 2002

본 논문에서는 H.323 영상회의 표준을 만족하는 영상회의 영역을 관리를 위한 게이트키퍼를 구현하고, 기본적인 영상회의 시스템에서의 단점인 등록된 사용자 정보에 대한 일반 사용자의 접근 미비로 인한 불편함과 사용자가 모든 제어를 직접 해서 생기는 오류 등을 해결하고자 웹 서비스와의 연동을 통한 사이버공간을 구현한다 또한, 웹 서비스를 이용함으로써, 영상회의 소프트웨어의 유지 보수를 사용자가 아닌 서비스 제공자가 직접하게 하여 보다 더 효율적인 영상회의 시스템의 관리를 위한 방향을 제시한다.

• Journal of Korea Multimedia Society
• /
• v.5 no.3
• /
• pp.239-248
• /
• 2002

International Standard Organizations such as ITU(International Telecommunication Union) and IETF (Internet Engineering Task Force) are proceeding standardization for various applications and protocols to provide video-conference and multimedia conference services on a variety of networks. Remote device control among these protocols is provided with various capabilities as well as device control to multimedia conference. This protocol for remote device control is standardizing as H.282 recommendation which is specified as core service for the configuration and control of remote device to multimedia conference. The H.282 recommendation does not specify the use of a particular transport protocol. That is, T.120 multimedia conference uses T.136 and H.323 video conference uses H.283 for the transport of H.282 protocol. The introduced system in this paper is based on H.282 and is implemented to be capable of remote device control within the framework of H.323 using H.283. Also, it is shown that a variety of services in the specification of the standard are satisfied through experiments.

• The KIPS Transactions:PartC
• /
• v.9C no.3
• /
• pp.343-350
• /
• 2002

This paper describes the implementation of H.235 protocol for authentication and media stream encryption of multimedia conference systems. H.235 protocol is recommended by ITU-T for H.323 multimedia conference security protocol to prevent from being eavesdropped and modified by an illegal attacker. The implementation in this paper has used password-based with symmetric encryption authentication. Media streams are encrypted using the Diffie-Hellman key exchange algorithm and symmetric encryption algorithms such as RC2, DES and Triple-DES. Also, 128-bit Advanced Encryption Standard and 128-bit Korean standard SEED algorithms are implemented for the future extension. The implemented authentication and media stream encryption has shown that it is possible to identify terminal users without exposing personal information on networks and to preserve security of multimedia conference. Also, encryption delay time and used memory are not increased even though supporting media stream encryption/decryption, thus the performance of multimedia conference system has not deteriorated.

• Proceedings of the Korean Information Science Society Conference
• /
• 2001.10b
• /
• pp.403-405
• /
• 2001

한정된 대역폭의 통신망에서 다른 매체에 비해 자료량이 많은 화상의 압축은 중요한 문제로 떠올랐다. 대표적인 영상 압축방법으로 MPEG 시리즈와 H.26x 시리즈가 있다. 그중 H.263은 화상회의 표준안인 H.323와 최근 진행중인 차세대 이동통신이라 일컬어지는 IMT-2000에서 영상압축방법중의 하나로 채택되었다. 또한 현대에 이르러 Desktop상에서의 영상회의구축은 더 이상 불가능한 일이 아니며, 또 하나의 영상회의 활용분야로 급속히 떠오르고 있다. 이는 internet의 보급과 함께 internet방송, 다대다 화상회의, 원격 의료 진료 등, 수없이 많은 분야에 활용될 수 있는 계기가 마련되었다. 이에 본 논문에서는 H.261과 H.263, 그리고 H.263 version 2의 Desktop상에서의 실제적인 구현 및 비교를 기술한다.

• Proceedings of the Korean Information Science Society Conference
• /
• 2001.10a
• /
• pp.718-720
• /
• 2001

본 논문에서는 ITU-T 영상회의 프로토콜 표준안(H.323)에서 보안 프로토콜로 권고된 H.235를 기반으로 하여 사용자 인증, 비디오 및 오디오 데이터의 암호화, 암호키의 보호에 대하여 구현한다. 인증 방법으로는 패스워드 기반의 대칭키 암호 인증을 사용하고, 비디오 및 오디오 데이터의 암호화에 사용되는 암호키의 보호를 위해서는 DES와 Diffie-Hellman의 키 분배 방법을 사용한다. 또한, DES를 사용한 비디오 및 오디오 데이터의 암호화/복호화를 보여준다.

• The Transactions of the Korea Information Processing Society
• /
• v.7 no.7
• /
• pp.2041-2049
• /
• 2000

A various multimedia application services are developed wiht techniques of high speed networks and computer. Especially the videoconference system is important and useful in a remote discussion with multiple users. A vidoconferencing system in local area network used in corporation and university is useful and important. A standardization for it should be showed in ITU. Recommendation H.323 describes terminals, equipment, and services for videoconference over communication networks which do not provide a guaranteed Quality of Services for videoconference over communication networks which do not provide a guaranteed Quality of Service. In this paper, we introduce ITU-T H.323 which is the standardization over internet, and show a multipoint videoconferencing system and peer to peer videophone system using the ITU-T H.323.