• Journal of Korea Society of Industrial Information Systems
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• v.5 no.1
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• pp.16-24
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• 2000

In the distributed multimedia document system, media objects distributed over a computer network are retrieved from their sources and presented to users according to specifed temporal relations. For effective presentation, synchronization have to he supported. Furthermore, presentation in distributed environments is influenced by network band with and delay, so they have to be considered for synchronization. This paper propose a distributed multimedia presentation model that supports synchronization effectively. In this model, when media objects are transfered from servers to a client, network situation and resources are monitored and thus a feedback message for change of them is sent to sever. Then, the sever adjusts the data sending rate to control synchronization.

• The KIPS Transactions:PartB
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• v.9B no.1
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• pp.47-56
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• 2002

In the distributed multimedia document system, media objects distributed over a computer network are retrieved from their sources and presented to users according to specified temporal relations. For effective presentation, synchronization has to be supported. Furthermore, since the presentation in the distributed environment is influenced by the network bandwidth and delay, they should be considered for synchronization. This paper proposes a distributed multimedia presentation system that performs presentation effectively in the distributed environment. And it also suggests a method to supports synchronization, in which, network situation and resources are monitored when media objects are transferred from servers to a client. Then a feedback message for the change of them is sent to the server so that the server might adjust the data sending rate to control synchronization. To monitor the situation of network, we use two methods together. One is to manage the level of the buffer by setting thresholds on a buffer and the other is to check the difference between the sending time of a packet from the server and the arrival time of the packet to the client.

• Journal of information and communication convergence engineering
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• v.8 no.6
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• pp.690-696
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• 2010

Web-based virtual collaboration is increasingly gaining popularity in almost every area in our society due to the fact that it can bridge the gap imposed by time and geographical constraints. However, in medical field, such collaboration has been less popular than other fields. Some of the reasons were timeliness, security, and preciseness of the information they are dealing with. In this paper, we are proposing a web-based distributed medical collaboration system called Virtual Collaboration System for Medicine (VCSM) for medical doctors that meet the needs. The proposed system consists of two parts - multimedia presentation and recordable virtual collaboration. The former supports synchronized multimedia presentation using Synchronous Multimedia Integration Language (SMIL.) It allows synchronization of the contents of a PowerPoint presentation file and a video file. The presentation may be provided to the participants before the discussion begins. Next, in the virtual collaboration stage, participants can use text along with associated symbols during the discussion over the presented medical images. The symbols such as arrows or polygons can be set or removed dynamically to represent areas of interest in digital images using so called layered architecture that separates image layer from annotation layer. XML files are used to record participants' opinions along with the symbols over some particular images

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.1
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• pp.108-116
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• 2005

Synchronizations of intra${\cdot}$intermedia for the lecture presentation in distributed multimedia environments are difficult to guarantee accurate temporal relationship between media, due to the asynchronous errors such as the delay or loss of transferred data or the transmission characteristics of each media. The jitter phenomenon occurs when the network delay has the media arrival rate abnormal because the intra-media synchronization reflects the presentation rate. And the cumulative effective of jitters on a per media stream basis results in a skew. This phenomenon cause confusion to contents recognition of learners due to network delay and can not provide effective interaction of sender and receiver in the distance education. Therefore, this paper can be solution to problems due to network delay by maintaining the requirements of temporal relationship between more than one media. And this paper enables to suggest the inter-media synchronization method that is subject to be influenced by presentation rate, and to implement lecture presentation system for distance education.

• Journal of KIISE:Computing Practices and Letters
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• v.8 no.1
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• pp.25-35
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• 2002

Many multimedia presentation applications involve retrieval of objects from more than one collaborating server. Presentations of objects from different collaborating servers might be interdependent. This implies that objects should be retrieved from remote servers and delivered continuously according to given time constraints. Such applications need an estimate of the avaliable network resources to each of the collaborating servers and local system resources in order to identify a schedule for retrieving the objects composing the presentation. A collaborating server can suggest modifications of the retrieval schedule depending on its load. these modifications can potentially affect the retrieval schedule for other collaborating applications. Hence, a sequence of negotiations has to be carried out with the collaborating servers in order to commit for a retrieval schedule of the objects composing the presentation. In this paper, we propose an application sub-layer protocol, RLCP(Resource Lock Commit Protocol), for handling the negotiation and commitment of the resources required for a collaborative multimedia presentation and apply it to distributed video presentation application.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2001.11a
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• pp.335-354
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• 2001

.Next Generation Multimedia Streaming Technology Massive Scale Support $\rightarrow$ Clustered Solution Adaptive to Heterogeneous Network daptive to Heterogeneous Terminal Capability Presentation Technique .SMART Server Architecture .HERMES File System .Clustered Solution . High Speed Storage Interconnect .' Content Partitioning . Load Management . Support for Heterogeniety . Adaptive End to End Streaming Transport: Unicast vs. Multicast '. Scalable Encoding

• Journal of the Korea Institute of Information and Communication Engineering
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• v.1 no.2
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• pp.145-158
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• 1997

Method for synchronizing multimedia data is needed to support continuous transmission of multimedia data through a network in a bounded time and it also required for supporting continuous presentation of multimedia data with the required norminal playout rate in distributed network environments. This paper describes a new synchronization method for supporting delay-sensitive multimedia Presentation without degration of Quality of services of multimedia application. It mainly aims to support both intermedia and intermedia synchronization by absorbing network variations which may cause skew or jitter. In order to remove asynchonization problems, we make use of logical time system, dynamic buffer control method, and adjusting synchronization intervals based on the quality of services of a multimedia. It might be more suitable for working on distribute[1 multimedia systems where the network delay variation is changed from time to time and no global clock is supported. And it also can effectively reduce the amount of buffer requirements needed for transfering multimedia data between source and destination system by adjusting synchronization intervals with acceptable packet delay limits and packet loss rates.

• The Transactions of the Korea Information Processing Society
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• v.5 no.6
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• pp.1441-1456
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• 1998

The concept of a hyperpresmtation, as an extension of a hypermedia, is the presentation in which time-varying multimedia presentations are dynamically linked together and a hyperlink's context can be changed over time at any time during a continuous presentation. Problems caused by integrating the hyperpresentation into an existing multimedia system which handles a sequential presentation only are, how to describe the hyperprcsentation, how to set up a hyperlink on a continuous media, and how to check the consistency of the synchronized presentations. In this paper. a new synchronization description method for the hyperpresentation and a method for setting a hyper link on a continuous media during" presentation are proposed after havin!; SHrvey of existing methods, The proposed method deals with only the DC value in a stream ut a DCT based compressed data for checking a condition of te link. Finally, the method for checking the consistency of mixed presentations before actual play of the hnlerpresentation is described. Proposed methods are implemented on MuX(Multimedia IO Server) where a sample scenario is tested.

• The Transactions of the Korea Information Processing Society
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• v.7 no.12
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• pp.3785-3793
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• 2000

Effective synchronization specification model which can specify temrxlral relationship among media resolving asynchronous problem due to variable network delay is necessary in a distributed multimedia system. Therefore in this paper, we propose RTPN(Real- Time Petri Net) synchronization specification model based on Petri Net for multimedia application in a distributed real time environment. The proposed RTPN model supplies a tlexible decsription of the temporal relationship among various media objects by defining primary key media and relative key media according to delay and importance among media. Firing rule is instantly executed by firing function based on QoS values which supports intra-media and inter-media syncbronization. And asynchronous control algorithm for resynchronization of presentation level is possible more effective supporting of QoS.

• The KIPS Transactions:PartC
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• v.9C no.6
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• pp.953-960
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• 2002

Rel-time application programs have constraints which need to be met between media-data. It is client-leading synchronization that is absorbing variable transmission delay time and that is synchronizing by feedback control and palyout control. It is the important factor for playback rate and QoS if the buffer level is normal or not. This paper, The method of maintenance buffer normal state transmits in multimedia server by appling feedback of filtering function. And synchronization method is processing adaptive playout time for smooth presentation without cut-off while media frame is skip. When audio frame which is master media is in upper threshold buffer level we decrease play out time gradually, low threshold buffer level increase it slowly.