• Proceedings of the Korea Multimedia Society Conference
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• 2012.05a
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• pp.430-430
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• 2012

• Proceedings of the Korea Multimedia Society Conference
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• 2012.05a
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• pp.171-171
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• 2012

• Journal of Communications and Networks
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• v.13 no.5
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• pp.494-498
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• 2011

Satellite digital multimedia broadcasting (S-DMB) systems use gap fillers (GFs) to provide wireless multimedia services to non-line-of-sight locations. GFs act as repeaters, and S-DMB systems require GF networks in order to guarantee mobile reception. Each GF covers a cell or sector. In order to provide contiguous coverage of an area comprising two or more cells or sectors, multiple GFs are needed. However, when multiple GFs are situated close to each other, interference is likely to occur. As a result, in this study, we have investigated system-level environments for planning the design of interference-free GF networks in S-DMB systems. Our investigations revealed that S-DMB services are unavailable because of quality deterioration caused by interference when the delay attributable to a GF and the satellite signals exceeds ${\pm}$256 chips and the distance between the GF and its reception terminal is greater than 4.6 km. On the basis of this analysis, we conducted a field test that confirmed that the above-mentioned time delay can be controlled in such a way as to ensure high quality S-DMB services.

• Proceedings of the Korean Information Science Society Conference
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• 2002.04a
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• pp.439-441
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• 2002

The number of users and applications of the Internet is increasing and network traffic is increased in proportion to that enormous]y. Application and services, which are provided from a relatively long distance away, running on wide area network are not independent of the current network state. As a multimedia service is provided to a lot of users over the Internet, network status is one of factors to be considered in providing high quality of multimedia service. In this parer, one of methods to get network information is discussed and it is applied to a multimedia service.

• ETRI Journal
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• v.35 no.4
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• pp.726-729
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• 2013

For secure multimedia communications, existing encryption techniques use an online session key for the key exchange, for which key size is limited to less than 10 digits to accommodate the latency condition caused by user devices only being able to handle low computational loads. This condition results in poor security of recorded encrypted data. In this letter, we propose a packet key scheme that encrypts real-time packets using a different key per packet for multimedia applications. Therefore, a key of a relatively small size can provide after-transmission confidentiality to data of a real-time session.

• Annual Conference of KIPS
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• 2007.05a
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• pp.1279-1282
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• 2007

무선 인터페이스 CDMA, WCDMA(HSDPA) 그리고 WiBro 는 대용량의 멀티미디어 컨텐츠를 제한된 무선자원에서 각 사용자에게 효율적으로 제공하기 위하여 Multicast 및 Broadcast 형태로 서비스를 제공하고 있으며, 이러한 서비스는 CDMA 에서는 BCMCS(Broadcast Multicast Service), WCDMA 에서는 MBMS(Multimedia Broadcast Multicast Service) 그리고 WiBro 에서는 MBS(Multicast Broadcast Service)라 불리고 있다. 본 논문에서는 각 서비스들의 DMB(Digital Multimedia Broadcasting)와 같은 방송형 서비스 및 다양한 멀티미디어 컨텐츠를 제공해 주기 위한 각 무선인터페이스의 Multicast 및 Broadcast 형태를 비교 및 분석하여 그에 따른 서비스의 확장성을 비교 분석하였다.

• Annual Conference of KIPS
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• 2000.10a
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• pp.11-14
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• 2000

대부분 기존의 Multimedia 시스템은 응용프로그램이나 사용자에 의해 발생되는 Operation 을 수동적인 형태로 처리를 한다. 개발자는 시스템의 목적이나 전략에 따라 시스템을 구성하는 각각의 Module에 대해 작업을 해야 하지만 목적이나 전략이 변경되면 해당되는 각각의 Module을 찾아서 수정을 해야만 한다. 이러한 일은 상당히 번거롭고 Error를 발생시킬 수 있는 가능성을 내포하고 있다. 또한 Multimedia 시스템은 적절한 정보를 관리하고 다양한 응용프로그램을 지원하기 위해서 많은 기능을 가져야 한다. 이 논문은 Event-Condition-Action(ECA) rule의 Active특성을 Multimedia 시스템에 적용하는 것을 제안하고 있다. 이러한 접근 방법을 통해 코드를 효과적으로 관리할 수 있다. 또한, Operation으로부터 rule을 정의하고 관리하는 것을 분리함으로써 Multimedia 시스템에 대해 상위 계층의 새로운 개념을 제시한다. 이렇게 Multimedia 시스템 상에 Active Rule시스템을 계층화시킴으로써 진보된 Multimedia 서비스를 제공할 수 있다. 시스템의 모든 기능은 Event에 의해 발생되고 Rule의 Condition이 만족할 때 해당하는 Rule의 Action이 실행된다. 여기서 제안한 Interactive Group Teaching System (IGTS) 시스템은 Active Rule 시스템인 Active Rule Management System(ARMS) 상에서 구현되었고, Active 속성을 가진 IGTS 을 설계하는 것을 목적으로 하고 있다. 본 시스템은 ECA Rule 개념이 적용 가능함을 보여준다.

• Proceedings of the Korea Multimedia Society Conference
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• 2012.05a
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• pp.429-429
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• 2012

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.1
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• pp.183-195
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• 2014

Multicasting is an efficient way of group communications because one sender can transmit data to multiple receivers with only one transmission. Furthermore, multicasting is considered an appropriate transmission method for multimedia services. Multimedia applications are expected to become more prevalent over mobile ad-hoc networks in the near future. Therefore, achieving reliability in multimedia communications is an important task. In this paper, we propose a leader-based reliable multicast medium access control layer protocol for multimedia applications to enhance video quality. We present a Markov chain model and numerical formulation of our proposed system.

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.991-994
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• 2005

In the uni-directional broadcasting environments, almost TV programs are scheduled depending on the viewers' popular watching time, and the advertisement contents in these TV programs are mainly arranged by the popularity and the ages of the audience. However, the advertisement programs which support the TV programs the audiences want are not served to the appropriate audiences efficiently. In this paper, we propose the prototype of target advertisement system for the appropriate distribution of the advertisement contents. The proposed target advertisement system estimates the audience's profile without private information and provides the target advertisement contents by using his/her inferred profile. And we show the accuracy of the proposed algorithm, Multistage Classifier, for the target advertisement system and the implementation of our target advertisement system.