• Journal of Communications and Networks
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• v.5 no.3
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• pp.197-201
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• 2003

We study in this paper both distributed power control and removal algorithms for multimedia CDMA wireless networks. In our study, users can have different data rates as well as different quality of service (QoS) requirements. We derive a necessary and sufficient condition for the fully distributed power control (FDPC) algorithm to find a feasible power set. We also prove that, if the maximal power level is used at the start, then the distributed constrained power control (DCPC) algorithm is equivalent to the FDPC algorithm. For the connection removal algorithm, we prove that the non-reinitialized removal algorithm finds a feasible power set faster and employs smaller power levels than the reinitialized one does. Performances of some connection removal criteria are also studied. Our simulation results reveal that the smallest normalized CIR (SNC) and largest CIR requirement (LCR) criteria result in smaller outage probability than the smallest CIR (SC) criterion in a multimedia environment.

• Journal of Information Processing Systems
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• v.2 no.2
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• pp.82-87
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• 2006

In spite of the rapid development of the public network, the variety of network-based developments currently raises numerous risks factors regarding copyright violation, the prohibition and distribution of digital media utilization, safe communication, and network security. Among these problems, multimedia data tend to increase in the distributed network environment. Hence, most image information has been transmitted in the form of digitalization. Therefore, the need for multimedia contents protection must be addressed. This paper is focused on possible solutions for multimedia contents security in the public network in order to prevent data modification by non-owners and to ensure safe communication in the distributed network environment. Accordingly, the Orthogonal Forward Wavelet Transform-based Scalable Digital Watermarking technique is proposed in this paper.

• 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 the Korean Institute of Intelligent Systems
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• v.16 no.4
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• pp.402-409
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• 2006

In recent years, several methods in distributed environment have been proposed in which a user-centered multimedia service may be efficiently provided. However, problems such as the improvement of QoS, streaming and the dynamic service of data for distributed service of multimedia data are introduced. In this paper we propose $POX -H_{r}$ structure for user-centered multimedia service in distributed network environment. The proposed $POX -H_{r}$ structure are constructed by disjunct, conjunct, semantic and filtering mapping scheme, and its structure are updated by $M_{filtering}$ scheme. The comparison results shows that the proposed method provides the better than the other methods.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.5
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• pp.987-989
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• 2007

This paper describes a digital convergence platform(DCP) which is implemented based on the MPEG-21 multimedia framework. DCP is a newly proposed solution in this research for the convergence service of future home multimedia environment. DCP is a common platform designed to have the feature of reconfigurability, by means of S/W. which supports to run diverse digital multimedia services. A distributed peer to peer service and transaction model is also a new feature realized in DCP using the MPEG-21 multimedia framework. A prototype DCP is implemented to verify its functions of multimedia service and transactions. The developed DCPs are networked with IP clustering storage systems for the distributed service of multimedia. Successful streaming services of the MPEG-2/4 video and audio are verified with the implemented test-bed system of DCP.

• Journal of Advanced Navigation Technology
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• v.12 no.6
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• pp.666-672
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• 2008

This paper explains late comer and error recovery process for home network environment with session management. This system consists of an ED, ES, and ER. ED is an agent that detects an error by hooking techniques for multimedia distance education based on home network environment with session management. ES is an agent that is an error sharing system for multimedia distance education based on home network environment with session management. ER is a system that is suitable for recovering software error for multimedia distance education based on home network environment with session management. This paper explains a performance analysis of an error recovery system running on distributed multimedia environment using the rule-based DEVS modeling and simulation techniques. The proposed method is more efficient than the other method in comparison with error ration and processing time.

• Journal of Korea Multimedia Society
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• v.3 no.1
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• pp.14-22
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• 2000

We have designed and implemented an educational system based on the distributed virtual environment. The developed system has a client-server architecture: the platform-independent server is implementes by Java machine and the client is composed of VRML, EAI, and general web browser. If a change occurs in this virtual environment, all connected users can perceive the updated environment immediately. the system maintains its virtual environment after it is modified by a user. Also, the system can accommodate many users by minimizing the information exchange. Since users can share multimedia information and virtual objects by overcoming the limitation of time and space, the educational effects can be progressed through the use of the developed system.

• Journal of Korea Multimedia Society
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• v.15 no.10
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• pp.1212-1220
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• 2012

In this paper, a collision-free resource reservation scheme for WUSB (Wireless Universal Serial Bus) networks with WiMedia D-MAC (Distributed Medium Access Control). Since distributed characteristic of the WiMedia D-MAC supporting DRP (Distributed Reservation Protocol) scheme may cause lots of conflicts, overall performances of the WUSB with WiMedia D-MAC can be deteriorated. In addition, when we consider multi-hop environment, "mobile" hidden node problem due to mobility of WUSB devices can be happened, and it is a critical problem to mobile WUSB devices transceiving real-time QoS (Quality of Service) traffic. To tackle the problem, we propose a new DRP reservation mechanism to prevent DRP conflicts for multi-hop mobility support in WUSB networks with WiMedia D-MAC and show its improved performance via simulation results.

• Journal of Korea Multimedia Society
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• v.12 no.7
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• pp.883-892
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• 2009

SOAP using WSDL(Web Service Definition Language) was proposed for effective integration of distributed objects. But the SOAP message and WSDL document automatically generated from development tool are fully dependent on the development environments. So the dependency of SOAP messages and WSDL documents for objects to the development environment is still a big problem to be solved for the integration of heterogeneous distributed objects. In order to support integration of heterogeneous distributed object, we implemented SOAP Bridge called WBSB(WSDL Based SOAP Bridge). As service request message for a particular service object is translated into appropriate SOAP message for the selected service object by WBSB using WSDL repository, a client can use service object without considering the development environment of the service object.

• The Transactions of the Korea Information Processing Society
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• v.7 no.4
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• pp.1050-1061
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• 2000

This paper presents a new object model, LOM(Lightweight Object Model) and an implementation method for the distributed trader in heterogeneous distributed computing environment including mobile network. Trader is third party object that enables clients to find suitable servers, which provide the most appropriate services to client in distributed environment including dynamic reconfiguration of services and servers. Trading service requires simpler and more specific object model than genetic object models which provide richer multimedia data types and semantic characteristics with complex data structures. LOM supports a new reference attribute type instead of the relationship, inheritance and composite attribute types of the general object oriented models and so LOM has simple data structures. Also in LOM, the modelling step includes specifying of the information about users and the access right to objects for security in the mobile environment and development of the distributed storage for trading service. Also, we propose and implementation method of the distributed trader, which integrates the LOM-information object model and the OMG (object Management Group) computational object model.