Dongsu Seong

Multipoint conference systems in a ubiquitous environment

In a ubiquitous environment, people can communicate with others and have access to various computing services any time, any place. The multipoint conference systems in a ubiquitous environment are expected to be one of the leading applications to connect people. In this paper the various multipoint conference systems are compared for their efficiency in a ubiquitous environment and shows why the endpoint mixing conference scheme performs effectively in an ad hoc environment. However, the endpoint mixing conference scheme has its own drawbacks as well and we propose solutions for them.

Design and implementation of efficient error concealment algorithm using adaptive selection of adjacent motion vectors and data hiding

In this paper, we propose a hybrid error concealment algorithm, which uses data hiding and decoder-based concealment. The algorithm uses the error concealment with data hiding. If the hiding information is lost, the motion vector of the lost macroblock is computed with adaptive selection of the adjacent motion vectors and overlapped block motion compensation (OBMC) is applied with this motion vector. Our algorithm is shown to be more effective in case of continuous GOB (Group of Blocks). The results show more significant improvement than many temporal concealment methods such as Motion Vector Rational Interpolation (MVRI) or existing error concealment using data hiding.

An efficient hierarchical conference to minimize average hops between participants

In the hierarchical conference, the media data between the terminal nodes are exchanged via the neighboring nodes with hierarchical structure. This scheme may cause the transmission delay between terminal nodes in a conference. Since media in a hierarchical conference is delivered within a tree structure, it may experience unacceptable delay, which degrades the QoS between terminal nodes. This paper introduces a algorithm for minimizing average hops between the terminal nodes of participants to consider each terminals computing resources.

The Improvement of SBC for a Multipoint Conference in a Ubiquitous Environment

In a ubiquitous environment, a communication and computing service can be taken without the limitation of the time and space. A conference service is one among the techniques implemented basically and used widely for such environment. The multipoint conference in a ubiquitous environment would be operated mostly in the private network to give the effect of the firewall. In this paper, we introduce SBC method to solve the some problem of the multipoint conference operation in a firewall environment, propose an algorithm to improve the existing SBC method.

Implementation of VoIP in Ubiquitous Fashionable Computer

VoIP (voice over IP) is the technology to transport video and voice over IP networks such as the Internet. Today, the VoIP technology is viewed as the right choice for providing voice, video, and data communication over the next generation network. UFC (ubiquitous fashionable computer) is a human-oriented fashionable computer with which we exploit the ubiquitous computing environment by our intuitive interface. VoIP applications can be used for video or voice communication between UFCs. In this paper, VoIP in UFC is introduced, which supports point-point communications as well as multi-point communications in NAT (network address translator) environments

Design and Implementation of Error Concealment Algorithm using Data Hiding and Adaptive Selection of Adjacent Motion Vectors

In this paper, we propose an error resilience video coder which uses a hybrid error concealment algorithm. Firstly, the algorithm uses the error concealment with data hiding. If the hiding information is lost, the motion vector of lost macroblock is computed with adaptive selection of adjacent motion vectors and OBMC (Overlapped Block Motion Compensation) is applied with this motion vector. We know our algorithm is more effective in case of continuous GOB. The results show more significant improvement than many temporal concealment methods such as MVRI (Motion Vector Rational Interpolation) or existing error concealment using data hiding.