• Journal of the Korea Society of Computer and Information
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• v.16 no.1
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• pp.101-115
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• 2011

PECOLE (Peer-to-Peer Collaborative Environment) is a P2P-based multimedia distributed collaborative environment supporting a collaborative workspace which is composed of a variety of collaborative applications such as multi-chat, video conferencing, screen sharing and etc. Unfortunately, due to the PECOLE's simple group management, it is impossible to perform collaboration activities while joining multiple groups. In this paper, we present the design and implementation of PECOLE+ which is an extension of PECOLE. PECOLE+ resolves the drawback of PECOLE by providing the Group Management Service and the Workspace Management Service. The Group Management Service provides functionalities such as creating groups, joining multiple groups, and searching groups, and etc. The Workspace Management Service provides each group with an associated workspace, supporting the execution of collaborative applications over the workspace. In addition, any collaborative applications with the provided plug-in interfaces can be executed over the workspace as a PECOLE+ collaborative application.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.10a
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• pp.411-413
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• 2012

It is noticeable that the number of newly registered Android applications increases rapidly. Such a recent trend indicates the Android platform is spreading globally. The ongoing platform upgrade might be one of the main reasons of the popularity of the Android mobile platform. Android platform 4.0 or later provides WiFi-Direct APIs that allow smart devices to communicate with each other without intermediate media. In this paper, we propose design and implementation techniques for small-scale impromptu meeting applications based on WiFi-Direct. The proposed meeting application can be used in a situation when one is difficult to connect the Internet. It also provides meeting data sharing capabilities, noting functionality, real-time remote screen control, and grouping of meeting participants. Our development results have demonstrated that the Android WiFi-Direct APIs can be effectively applied to impromptu conferencing mobile applications.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.7
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• pp.1213-1223
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• 1994

VSATs(Very Small Aperture Terminals) have introduced new concepts in satellite business communications and are typically used in a star network configuration to provide information directly to the user`s premise. The characteristics of this system are low earth station costs, easy in stallation, compact, and very high flexibility for a varierty of applications (Credit Checks, Electronic Mail, Video Conferencing, Reservation System, Database Inquires, Order Entry, etc.). So, the requests of VSAT service have considerably enlarged. The link design of a VSAT network using Korea Sat. is discussed in this paper. This paper is intended to collect in a convient way the principle formula and reference data necessary to make overall performance calcurations and to calcurate antenna size. HPA power size and link margin of earth stations for satellite communications systems. Generally, because the antenna size of the Hub station in the VSAT system is bigger than the Remote station, the method of power allocations of inbound and outbound carriers is utilized in this paper. The size of Hub station and Remote station are assumed to be 3.7m and 1.2m. respectively.

• The Transactions of the Korea Information Processing Society
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• v.6 no.6
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• pp.1493-1501
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• 1999

For the multimedia conference in various networks, international standard works make progress with H and T series. T.120 series are recommended for multipoint data conference in various networks, but its demerit is not supported with video and audio capabilities. H.32X series are recommended for videoconference in various networks. To solve these problems, the combination of H.32X and T.120 are used. But many difficulties exist for consistent control. To solve these problems, T.130, T.131 and T.132 standardizations are made progress, and these are analyzed and implemented over LAN(Local Area Network). Our system introduced in this paper is currently operated on LAN, but can be operated with mixed networks with addition of underlying network dependent protocols.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.11B
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• pp.968-980
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• 2008

Providing handover with guaranteed QoS for real-time multimedia service such as VoIP, video/audio streaming, and video conferencing in wireless LAN is a challenging task. In this paper, we present efficient layer 2 handover mechanism in wireless LAN, which can provide fast handover with guaranteed QoS for real-time multimedia service. To this end, the scanning period and the number of channels per scanning for handover are dynamically adapted to the type of applications and wireless networking environment, so that both the degradation of application service quality and signaling overhead are minimized simultaneously. The performance of the proposed mechanism is verified by the simulation. The simulation results show that the proposed mechanism guarantess QoS of each multimedia application with minimal power consumption.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.1B
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• pp.71-76
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• 2000

On multimedia teleconferencing system existing a number of participants, face of the participants can beperceived by visual image. However, differentiation of each participant's voice and spaciousness sense are very hard since voice of all participants is processed with one dimensional data. In this paper, we implemented three dimensional audio rendering system using the HRTF(Head Related Transfer Function) and distance sense reproduction method and determined the optimal location of the participants for teleconferencing system. In the results of the listening test using elevation and azimuth angle, we showed that directional perception of the azimuth angles were better than that of the elevation angles. Specially, we showed that participant location using the HRTFS of the azimuth angle 10" , 90" , 270" and350" was efficient in teleconferencing system existing four participants. We also proposed that distance cue was used for enhancement of the reality and location of many participants more than five.ipants more than five.

• Journal of the Korean Institute of Intelligent Systems
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• v.18 no.2
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• pp.187-192
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• 2008

The Intelligent Space(ISpace) provides challenging research fields for surveillance, human-computer interfacing, networked camera conferencing, industrial monitoring or service and training applications. ISpace is the space where many intelligent devices, such as computers and sensors, are distributed. According to the cooperation of many intelligent devices, the environment, it is very important that the system knows the location information to offer the useful services. In order to achieve these goals, we present a method for representing, tracking and human Jollowing by fusing distributed multiple vision systems in ISpace, with application to pedestrian tracking in a crowd. This paper describes appearance based unknown object tracking with the distributed vision system in intelligent space. First, we discuss how object color information is obtained and how the color appearance based model is constructed from this data. Then, we discuss the global color model based on the local color information. The process of learning within global model and the experimental results are also presented.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.41 no.3
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• pp.11-16
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• 2004

Recently, collaborative works are increased more and more over the distributed heterogeneous computing environments. The availability of high-speed wide-area networks has also enabled collaborative multimedia applications such as video conferencing, distributed interactive simulation and collaborative visualization. Distributed high performance computing and collaborative multimedia applications, it is extremely important to efficiently perform group communication over a heterogeneous network. Typical group communication patterns are broadcast and Multicast. Heuristic algorithms such as FEF, ECEF, look-ahead make up the message transmission tree for the broadcast and multicast over the distributed heterogeneous systems. But, there are some shortcomings because these select the optimal solution at each step, it may not be reached to the global optimum In this paper, we propose a new heuristic algerian that constructs tree for efficiently collective communication over the previous heterogeneous communication model which has heterogenity in both node and network. The previous heuristic algorithms my result in a locally optimal solution, so we present more reasonable and available criterion for choosing edge. Through the performance evaluation over the various communication cost, improved heuristic algorithm we proposed have less completion time than previous algorithms have, especially less time complexity than look-ahead approach.

• Journal of the Korean Institute of Intelligent Systems
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• v.18 no.1
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• pp.66-71
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• 2008

Recent multimedia technology has supported various application services based on the development of effective movie compression and network techniques. On-line video conference system is a typical example that use theses two technologies effectively. On-line video conference system can be characterized into an effective conferencing method for long-distanced on-line conference members. But, unfortunately, off-line conference with face-to-face meeting is more frequent than on-line conference and their support systems have not been sufficiently considered. In this paper, we propose a recording support system for off-Line conference using face and speaker recognition. This system finds the speaker in the conference by using three microphones and three webcam cameras. And analysis is done with face region information that gathered by currently active webcam camera, and recognizes the identity of face. Finally, the system tracks speaker and records conference with extract speaker information.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.2 no.4
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• pp.81-87
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• 2009

In this paper, the reduction amount of CO2 due to the virtual international video-conference organized by ITU in order to reduce the greenhouse gas (GHG) is calculated. The comparison is made with the case of off-line conference. In the symposium organized by ITU, "The power of ICTs to save The planet", held on September 2009 the participants were highly encouraged to attend the symposium through video-conferencing for the reduction of GHG. As a result, 46 foreign participants and 16 among 170 domestic participants have attended at virtual video-conference, which resulted in about 94.7 ton of CO2 emission reduction. This international symposium firstly tried in conjunction with online and off-line has drawn a big attention in the aspect of global warming. Definitely such ITU's trial will make significant impacts on the holding of other international symposiums and forums.