• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.6A
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• pp.1041-1050
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• 2001

본 논문에서는 MPOA(multi-protocol over ATM) 망에서 인터넷 차등화 서비스를 지원하기 위한 구조를 설계하고 이를 분석하였다. ATM(asynchronous transfer mode) 기반 서비스로는 UBR(unspecified bit rate)을 확장한 방안을 적용하였고 이에 따라 변화되어야 할 MPC(MPOA client)와 MPS(MPOA server)의 전달 및 제어 구조와 신호 제어 절차를 설계하였다. 또한 시뮬레이션을 통해 제안된 구조의 ATM 스위치에서 차등화서비스의 지원 가능성을 고찰하고, 트래픽 특성에 따른 차등적 처리 성능을 검증하였다.

• Proceedings of the Korea Information Processing Society Conference
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• 2001.10b
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• pp.1257-1260
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• 2001

본 논문에서는 클라이언트(Windows)/서버(Linux) 환경에서 Java와 C/C++ 언어를 이용한 원격 제어 시스템을 설계 구현하여 Windows 기반의 그룹 내에(기업, 학교 등) 연결된 컴퓨터사이의 통신, 원격 제어, 모니터링, 시스템의 사양, 사용되고 있는 응용프로그램 등의 관리가 가능한 시스템을 개발하였다.

• Proceedings of the Korean Information Science Society Conference
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• 2005.11a
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• pp.664-666
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• 2005

본 논문에서는 적외선을 기반으로 하는 가정용 정보가전기기들을 실내 또는 실외에서 원격으로 제어 및 감시할 수 있는 가정용 정보가전기기 제어 시스템을 구현하였다. 무선 인터넷 접속이 가능한 PDA에 본 논문에서 구현한 클라이언트 응용 프로세서를 동작시키고 가정용 홈 서버에는 정보가전기기를 제어하기 위한 서버 응용 프로세서 및 필요한 제어용 하드웨어 장치들을 부착하였다. 클라이언트 및 서버의 구현구조, 응용 프로세스 간 제어 메시지 등 구현의 세부 내용을 기술하였다. 본 구현의 세부 내용은 차세대 인터넷 프로토콜(IPv6)을 지원할 수 있도록 쉽게 수정 보완될 수 있으므로 IPv6용 가정용 정보가전기기 제어시스템의 개발에 쉽게 적용될 수 있다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.12B
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• pp.2283-2291
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• 1999

Most of collaborative applications use the Server-Client paradigm where all requests of clients will be delivered first to server and that server distributes again the requests to the rest of clients. This server-oriented operation and data transmission mechanism always presents end-to-end communications between the server and clients that can notably decrease the overall performance of applications. In this paper, we propose a new design approach to inhibit the inefficiency of applications using active networking concepts. We propose the ASM service that offers an application-specific in-network multicast functions, the AMTC service and its tree algorithm that builds anon-core based shared tree for multicast. These proposed services locate in active nodes performing its services as part of the overall system to improve the performance of collaborative applications.

• Journal of Institute of Control, Robotics and Systems
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• v.9 no.4
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• pp.340-346
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• 2003

Driven by the growth of the Internet and the increasing ubiquity of embedded computing systems, the embedded system is exploding in terms of it proliferation of products and the number of complex applications. Intelligent dedicated systems and appliances used in interface, monitoring, communications, and control applications increasingly demand the services of a sophisticated, state-of-the-art operating system. In the case of industrial controller, it is required to use a real-time operating system (RTOS) as a good building block to enable Internet connectivity. However, commercial RTOSes are increasingly less desirable due to their lack of standardization and their inability to keep pace with the rapid evolution of technology. In order to overcome these problems, we consider using embedded Linux and embedded web server. Availability of source code, reduced licensing, reliability, open source community support, as well as others, are key reasons for the use of embedded linux by embedded developers. In this paper, we develop embedded linux platform to control the industrial inverter with the Internet connecting feature. The method of web-based management is also proposed by using the embedded web server and Java applet. We show the feasibility of remote management for the commercial inverter controller with the proposed three-tier web-based remote management system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.12B
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• pp.1115-1123
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• 2003

In this paper, a remote control system called TeleRemote system which can be applied to existing wireless mobile networks or public telephone networks for remote control is designed and implemented. The proposed design employs program technology based on the theory of signal detect control and enables the EPG(Electronic Program Guide) functions such as recording reservation of bidirectional video signals with TV reception card on PC. It can also control recording reservation using remote control program through telecommunication network The PC-EPG system is implemented in Web programs with Server/Clinet architecture and the server system that provides EPG functionalities is in charge of recording reservations and data communications by means of the scheduler program. Data storing to client PCs is performed through TCP/IP and finished by client programs implemented using Visual C++/MFC programs. As remote control system, the developed system can be used for unmanned security system using the Web camera. Building intranet and making connection to internet, the TeleRemote system is believed to create potential for commercial communication system.

• The Journal of Information Systems
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• v.11 no.1
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• pp.175-198
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• 2002

This paper is to develop a security module for electronic approval systems. Electronic documents are created, transmitted and saved in the company's intranet computer network. Transmitting electronic documents, however, brings us a security problem. Communications among various computer systems are exposed to many security threats. Those threats are eavesdropping, repudiation, replay back etc. The main purpose of this paper is to develop a module which provides the security of electronic documents while they are passed from one place to another This paper applies Multi-Level security to the electronic approval system that guarantees security of electronic documents from many threats. Multi-Level security controls the access to the documents by granting security level to subject users and object electronic documents. To prevent possible replay back attacks, this paper also uses one time password to the system. The security module is composed of client program and server one. The module was developed using Microsoft Visual Basic 6.0 and Microsoft SQL Server 7.0. The code uses Richard Bondi's WCCO(Wiley CryptoAPI COM Objects) library functions which enables Visual Basic to access Microsoft CryptoAPI.

• Journal of applied mathematics & informatics
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• v.41 no.6
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• pp.1155-1171
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• 2023

This paper investigates a non Markovian M/G/1 queue with retrial policy, different kind of service rates as well as unsatisfied clients which is inspired by an example of a transmission medium access control in wireless communications. The server tends to work continuously until it finds at least one client in the system. The server will begin its maintenance tasks after serving all of the clients and if the system becomes empty. Provisioning periods in regular working periods and maintenance service periods should be evenly divided. Using supplementary variable technique, the amount of clients in the system as well as in the orbit were found. Further few performance measures of the system were demonstrated numerically.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.8B
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• pp.535-540
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• 2005

This paper presents a scalable caching algorithm of proxy server with the finite storage size minimizing client's buffer size and constant-bit-rate channel bandwidth. Under the general video traffic condition, it is observed that the amount of decreased client's buffer size and channel bandwidth after caching a video frame depends on the relative frame position in the time axis as the frame size. Based on this fact, we propose an effective caching algorithm to select the cached frames by using the normalized buffer size. Finally, experimental results are provided to show the superior performance of the proposed alghrithm.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.1B
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• pp.56-66
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• 2009

In the traditional Server/Client architecture, the client connects to the known servers and gets information through web searching. However, nowadays, diverse internet devices providing services (get) working on internet easily. The update interval of the services or information provided by the devices is relatively short. And also they tend to be both a server and a client. In this situation, the way of the traditional information searching such as web searching is not appropriate. In this paper we propose a service push model, where it pushes its service profiles to all the other network devices by broadcasting them on the network. When a device connects to the network newly, it can get all service profiles in the network and it gets service profiles newly pushed by service providers in prompt. Also it can call any service among the service profiles within itself. We implemented a prototype system for the service push model on the JXTA platform based on P2P network. Also we measured the service profile pushing delay, the service discovery time, and the response time of service execution by running test applications written on the prototype system.