• Journal of Korea Multimedia Society
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• v.7 no.8
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• pp.1097-1106
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• 2004

The typical web cluster architecture consists of replicated real servers and a virtual server that routes client requests among the real servers. In this paper, we proposed an efficient dynamic load distribution method with load prediction for the web cluster systems. The virtual server transmit status request message to real servers in other to get load states. However the load states dose not accurate during load distribution, thus the virtual server predict the load status of real servers and assign a request of the client to the minimum loaded real server. The proposed distribution methods works not related to partial breakdown of real servers, thus the system works with high availability. We also show that the proposed distribution method preserve scalable property and improve the throughput through a set of simulations.

• The Transactions of the Korea Information Processing Society
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• v.7 no.2S
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• pp.721-732
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• 2000

Multimedia communication systems require not only high-performance computer hardwares and high-speed networks, but also a buffer management mechanism to process many data efficiently. Two buffer handling methods, Push and Pull, are commonly used. In the Push method, a server controls the flow of dat to a client, while in the Pull method, a client controls the flow of data from a server. Those buffering schemes can be applied to the data transfer between the packet receiving buffer, which receives media data from a network server, and media playout devices, which play the recived media data. However, the buffer management mechanism in client-sides mainly support either one of the Push or the Pull method. Consequently, they have some limitations to support various media playout devices. Futhermore, even though some of them support both methods, it is difficult to use since they can't provide a unified structure. To resolved these problems, in this paper, we propose an efficient and flexible Push/Pull buffer management mechanism at client-side. The proposed buffer management scheme supports both Push and Pull method to provide various media playout devices and to support buffering function to absorb network jitter. The proposed scheme can support the various media playback devices using a single buffer space which in consequence, saves memory space compared to the case that a client keeps tow types of buffers. Moreover, it facilitates the single buffer as a mechanism for the absorbing network jitter effectively and efficiently. The proposed scheme has been implemented in an existing multimedia communication system, so called ISSA (Integrated Streaming Service Architecture), and it shows a good performance result compared to the conventional buffering methods in multimedia communication environments.

• Proceedings of the KSRS Conference
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• 2004.10a
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• pp.280-282
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• 2004

According as IT environment changes from client/server system to the open system based on web service technologies, the exchange of data and services between independent applications and service servers in web environment is observed Recently. In this points, it is necessary that Geographic Information Systems, Spatial Imagery Information Systems, Intelligent Transportation Systems, and Global Navigation Satellite Systems based on the location and geometry information are inter-related each other. But, the inter-relation of these systems is very difficult because of the closed system architecture, different information format, and the absence of interoperability technologies. In this Paper, we describe 4S integration system based web service technologies that accept the international standard as WFS, WCS, WRS of OGC (OpenGIS Consortium) and UDDI, SOAP, WSDL of W3C. In detail, we study the system architecture design and implementation of traffic information service, routing service, and tracing service. These services are consisting of the data schema based on XML and GML, various functions of each layered service, each server platform, and web server. Specially, we represent that GML is being applied to a wide range of location-based services, telematics, and intelligent transportation

• Journal of Korea Game Society
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• v.2 no.2
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• pp.113-119
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• 2002

With development of internet technology, digital economy that advance rapidly formed much leagues of B2B, B2C, A2B etc, according to the application part. Also, electronic commerce system implementation technology is introduced by Component based on development method in object oriented technique base depending on customer's requirement, and development environment changes by 3- Tiers, Web-Based architecture etc. in existent C/S (Client/Server) environment and is introduced. Thus, In this research, I implemented seat reservation and confirmation system that can be used in electronic commerce in multi-server environment. This, for improve efficiency in distribute environment, relevant importance logic used server component model EJB, and implemented through JSP and Java that use Servlet of Resin Server environment for Main Server. Therefore, through independence component using EJB, I did so that can improved independence between electronic commerce system logic, and reduce server's overhead calling relevant method through discrete EJB server, and manage each logic resources efficiently.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.8
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• pp.1459-1464
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• 2006

There are two approaches to construct mobile GIS, Vector and Raster methods, according to the map data transformation format from server to mobile client. Each method requires a different implementation architecture of server and client modules for mobile map services. And each have advantages and disadvantages at the different aspects. This thesis implements these two approaches, thus, compares the each merits, by experiments. They include the transmission performance, map quality, and so on.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 2001.11a
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• pp.36-41
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• 2001

감성공학이 G7과제의 하나로 시작되면서 다양한 감성평가 실험들이 수행되어 수많은 실험데이터가 생성되었지만, 효율적인 관리체계의 부재로 인해 많은 노력과 비용이 투자된 가치있는 감성평가 데이터가 자료의 공유 및 활용이라는 측면에서 여러 가지 문제점을 내포하고 있는 실정이다. 본 연구에서는 주거ㆍ사무환경에서 인간의 감성을 지표화하는 6개 분야의 감성기반기술개발 연구과제에서 생성된 피험자의 생리신호 및 주관적 감성평가 데이터를 통합 관리할 수 있는 종합적인 감성정보관리시스템을 설계하였다. 이 정보 시스템은 사용자에게 정교한 GUI와 높은 대화성(interaction)을 제공하기 위해 2계층 클라이언트/서버 구조로 설계하였다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.10a
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• pp.464-467
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• 2003

There are two approaches to construct mobile GIS, Vector and Raster methods, according to the map data transformation format from server to mobile client. Each method requires a different implementation architecture of server and client modules for mobile map services. And each have advantages and disadvantages at the different aspects. This thesis implements these two approaches, thus, compares the each merits, by experiments. They include the transmission performance, map quality, and so on.

• Proceedings of the Korea Database Society Conference
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• 1999.10a
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• pp.175-181
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• 1999

Edelstein(1994)이 제시한 플라이언트/서버 아키텍쳐가 표준으로 자리잡은 가운데 최근 국내에서는 김영걸, 박영면[1995]과 문태수, 정윤[1997]교수가 클라이언트/서버 채택을 위한 상황모델을 제시하였다. 그런데 최근 정보기술의 급속한 발전 상황(특히, 데이터베이스 관리 시스템 분야, 클라이언트/서버 기술 등)은 현재 클라이언트/서버 아키텍쳐와 클라이언트/서버 채택을 위한 상황모델을 설명하는 데 있어서 약간의 어려움을 주고 있다. 따라서 본 논문에서는 클라이언트/서버 아키텍쳐의 보완을 제안하고, 현재까지의 상황 모델에 대한 해석에 있어서의 오류를 지적하여 새로운 모형과 그 해석을 제시하고자 한다. 그 전에 현재까지의 구조와 모델을 고찰 및 비판할 것이다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.10
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• pp.2205-2218
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• 1997

We implement the CARMA-M (Collision Avoidance Radio Multiple Access-Mobile) protocol and DMP (Data-radio Multiplex Protocol) with a client/server architecture for a wireless communication netowrk. These protocols support a data transfer function between a remote computer and a mobile portable computer with a wireless modem which are proposed by dataradio in U.S.A. With the review and analysis of the proposed protocol, the impelementation methods of DMP, CARMA-M and LLC to interface the protocols are presented. Moreover the FEC technique is added to find and correct the errors generated in communication. The simulation method of a wireless network using wires is also shown to verify the implemented protocols.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.6 no.6
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• pp.915-922
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• 2002

This paper presents an implementation of an Remote Examination System on Internet using Java and SWING GUI API. The system is consisted of three parts: generating examination part that is Java application, answering questions part that is Java Applet, reviewing results part that is Java Applet. The first part is implemented with the 2-tier client/server architecture and the last two parts is implemented the 3-tier client/server architecture. Database programming is done using Java JDBC API for database independence and portability. This system can be used the evaluation of lectures, and substituted for pen-and-pencil examinations or adopted to survey applications based on Internet.