• 한국정보통신설비학회:학술대회논문집
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• 2009.08a
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• pp.99-103
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• 2009

Recently, as wired and wireless communication services have rapidly developed and multimodal mobile devices which have various characteristics have widely spread, the need for new convergence services increases. The growing population of VoIP technologies and the high communication expense yield that the market of IP based telephony such as WiFi phone and IP phone is substituted for one of the conventional PSTN telephony. With the help of this trend, the wireline network operators desire to find a market in mobile networks. Therefore, they focus on Fixed Mobile Convergence (FMC) service as one of the key factors to accomplish this goal. FMC services are able to provide the mobility of voice services between circuit switched and packet switched networks. IP Multimedia Subsystem (IMS) based Voice Call Continuity (VCC) is one of the schemes to embody FMC services. As Application Server (AS) which has this VCC function provides seamless handover of services between heterogeneous networks, FMC subscribers can communicate seamlessly with others m WiFi domain and COMA domain using WiFi-COMA dual phone. Most of enterprises have already introduced IP network infrastructure and IP-PBX (Private Branch eXchange) for telephony. However, the problems of high communication cost and work inefficiency due to frequent outside jobs or business trips have remained. In order to solve these problems, demands for enterprise FMC services increase. In this paper, we introduce a new IP-PBX based VCC model that can provide seamless handover of voice services between WiFi and COMA networks for enterprise users and we investigate some interworking and security issues between Soft Switch (SSW) and IMS, or between IMSs. In addition, we introduce a new service that can provide the continuity of voice sessions as well as video sessions using Multimedia Session Continuity (MMSC) technology which has evolved from VCC. This service is expected to be one of the next-generation personalized services based on user's context.

• Journal of Korea Multimedia Society
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• v.9 no.1
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• pp.89-100
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• 2006

The introduction of GSMP open interface to OBS network can materialize to separate the transport plane and the control plane in OBS network. This makes the implementation of OBS switches simple and provides various flexibility. However, the introduction of open interface will cause the connection setup delay because of the additional processing overhead of open interface protocol. Also, in GSMP based network, the location of network management functions are not defined explicitly and the research result about the OBS network management is almost nothing. This paper proposes a parallel connection setup mechanism using centralized connection control server to minimize connection setup delay in OBS network with GSMP open interface and defines managed objects to support connection, configuration, performance, and fault management for the management of OBS network with GSMP open interface. This paper also proposes a distributed network management model, in which the above managed objects are distributed in a controller and an OBS switch according to network management functions. We verify the possibility of OBS control and network management by implementing network management function using proposed parallel connection setup mechanism and distributed network management model.

• Journal of Korea Multimedia Society
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• v.9 no.10
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• pp.1322-1331
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• 2006

Concurrency control is one of the important factors to maintain consistent conditions of a game because most participants of the game should be shared information to play the game through a distributed network system. replay delay times should establish in every event and the received event should be saved and performed simultaneously for Concurrency Control. However, it is not easy to practice the event with same speed in environment having various moving speed. Therefore, expansion have to be provided. In other words, one of the most important factors of a game's efficiency is the process of bandwidth and delay. the process of concurrency control method based on scalable prediction for Multi-platform games would minimize the loss rate of a event and then would improve the interaction capacity of a game. It also might get reliability between clients. This paper analyzes some problems in terms of a layout of a game that integrates a cable and a wireless system. In addition, this paper provides methods to expand bandwidth and delay that might be an obstacle of a On-line game and to ensure reliability between a server and a client.

• Journal of Korea Multimedia Society
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• v.1 no.1
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• pp.67-79
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• 1998

In this paper, we present the design and analyze the transmission rate of a control algorithm for the client buffer on the VOD systems. The design is based on the server's data transmission rate and clients' data consumption rate. The proposed algorithm stabilizes the client's buffer by reducing the oscillation phenomena of the buffer. And it uses the BCT (Buffer Check Time) to reduce the scheduling load of the client system. The client's data consumption rate and the buffer size are calculated on the basis of BCT. In case that the predicted buffer size operates in the overrun or starvation the buffer. As the load fluctuation of the network, the transmission rate control policy cannot stabilize the client's buffer alone. The media scaling policy, therefore, also performs its complementary part in stabilizing the client's buffer, and performance evaluation of the proposed algorithm is provided through simulation.

• Journal of Korea Multimedia Society
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• v.8 no.9
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• pp.1163-1176
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• 2005

The Web is the largest distributed information space but, the individual's capacity to read and digest contents is essentially fixed. In these Web environments, mining traversal patterns is an important problem in Web mining with a host of application domains including system design and information services. Conventional traversal pattern mining systems use the inter-pages association in sessions with only a very restricted mechanism (based on vector or matrix) for generating frequent K-Pagesets. We extend a family of novel algorithms (termed WebPR - Web Page Recommend) for mining frequent traversal patterns and then pageset to recommend. We add a WebPR(A) algorithm into a family of WebPR algorithms, and propose a new winWebPR(T) algorithm introducing a window concept on WebPR(T). Including two extended algorithms, our experimentation with two real data sets, including LadyAsiana and KBS media server site, clearly validates that our method outperforms conventional methods.

• Journal of Korea Multimedia Society
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• v.8 no.8
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• pp.1088-1098
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• 2005

Context-Aware is a one of the important researches in ubiquitous computing for providing optimal service to users by acquiring user's intentions and environmental information. Diverse researches are focused on the users and its environment facts for Context-Aware base and introduce a sensing based middleware which engages sever/sensor that operates identifier information to provide services. Context-Aware service which is limited by users and environment facts has the problem of overlapping sensing, unnecessary searching and anonymity of users. Also Server-Centric Context-Aware system requires very high cost to manage and operate the services. On this paper, We introduce Autogenous Context service model to simplify the Context-Aware process and design the middleware which performs decentralize management for Context-Aware information of user's portable devices to minimize problems which is occurred during the management and operation of existing Context-Aware system.

• Journal of Korea Multimedia Society
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• v.15 no.7
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• pp.920-930
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• 2012

In this paper, we designed and built a wired temperature controller system which is based on ASIC for a wireless temperature controller system based on FPGA. FPGA devices and wireless controller systems are growing quickly especially for industrial systems for sensing temperature and humidity. FPGA can set up a desired system and a CPU, and directly set up or change a peripheral device based on an IP quickly for an affordable price. This wireless system is easy to install in the field where there are lots of changes and the system is complex. It also has advantages for maintenance. In this study, we are using a 32 bit RISC CPU based on MicroBlaze, with a touch interface, peripheral device, and porting the embedded Linux. Also, we added wireless communication using ZigBee. With this system we provide remote monitoring and control through the web by adding a web server. Compared to the original system, we say not only a performance improvement, but also more efficient development and cheaper costs. In this study, we focused especially on building a better development environment and a more effective user interface.

• Journal of Korea Multimedia Society
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• v.13 no.1
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• pp.102-110
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• 2010

H.264 SVC(Scalable Video Coding) provides the advantages of low disk storage requirement and high scalability. However, a streaming server or a user terminal has to extract a bit stream from SVC file. This paper proposes a bit stream extraction method which can get the maximum PSNR value while date bit rate does not exceed the available network bandwidth. To do this, this paper obtains the information about extraction points which can get the maximum PSNR value offline and decides the spatial/temporal resolution of a bit stream at run-time. This resolution information along with available network bandwidth is used as the parameters to a bit stream extractor. Through experiment with JSVM reference software, we proved that proposed bit stream extraction method can get a higher PSNR value.

• Journal of Korea Multimedia Society
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• v.11 no.8
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• pp.1072-1081
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• 2008

We can categorize the network address allocation mechanism into two types. One is to assign a unique network address using the address allocation server and the other is to make a random address by itself and process the DAD(Duplicate Address Detection) procedure. In this paper we suggest a new address allocation mechanism based on the signal strength for the PLC-based home network. As the combined mechanism of two types this mechanism allocates a unique address for the new node from one of the existing nodes with the simple equation and with the priority based on the signal strength from the new node to the existing nodes. We can use this mechanism for the self-healing function when the packet from the source node may not be delivered to the destination node directly. We developed the simulator for our mechanism using the C# programming and verified the network address assigned uniquely based on the signal strength.

• Journal of The Korean Association of Information Education
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• v.7 no.3
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• pp.263-274
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• 2003

Web based instruction (WBI) has been widely used thesedays because the web has various advantages for instruction. However, most of current WBI systems do not support various requirements from students. It is because of the lack of research for structural instruction method. This paper presents a new method of WBI and designs an instruction model to support various requirements from students by implementing dynamic WBI system using JSP to solve current WBI problems. The developed WBI system uses multimedia based instructions. The implemented system focused on the practical instruction by providing the functions of listening, homework, and test on web site. For the similar effects as in the classroom, it supports functions of electronic white board and multimedia data which is consisted of high-quality sound and video data with high degree of compression. Furthermore, the system supports that instructors can design a test using three kinds of basic forms, a multiple-choice test, brief-answer test, essay test, and evaluate the tests easily. It also supports easy management for homework, lecture registration, and many school affairs.