• Proceedings of the KIEE Conference
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• 2003.11c
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• pp.592-595
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• 2003

In this paper, we have designed a Home Networking System using an embedded linux board. The system based on the World-Wide-Web is composed of three parts - a Server, a Client and a Simulator. The Home Networking Server is built in an embedded board using an embedded linux kernel. A web-server and Home Networking Server Seryice Demon programming with a Jaya-Language is included in the board. Clients can connect to the server board using a web-browser in the desktop computer, PDA or any other machines which include a web-browser. For this purpose, we made the client program using a Java-Applet. So, the clients who connect to the server for the control of the applications, download the class-file and execute the client-program in the web-browser. So, the clients don't need any other programs to control the applications from a remote place. The size of server board is very small (86.3$\times$74mm), which makes it very useful not only for the Home-Networking-System but also in many other fields, e.g., embedded robot control system, etc. Using an embedded board instead of a desktop computer is good for a simple network environment and it occupies only a small space to make the system.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.908-911
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• 2004

There are various researches on mobile robot systems. Connection method between server and client of mobile robot system is one of them. In the case of mobile robot system, when connection method between server and client is wireless than wire, applications may be expanded. Also in remote monitoring environment using mobile robot system, we are interested in an effective transmission of the image information between server and client. In this paper, Bluetooth is used for connection method between server and client. One of the major applications of Bluetooth is the cable replacement for mobile and peripheral devices. Using Bluetooth, we propose the control method of mobile robot system. Bluetooth offers fast and reliable transmissions of both voice and data over the globally available 2.4GHz ISM (Industrial, Scientific and Medical) band. It has the advantage of small size, low power and low cost. It has the disadvantage of limited range and limited bandwidth. Also in order to transfer effectively image information between remote site(server) and mobile robot system(client) using Bluetooth, we applied to MPEG-2 and MPEG-4 image compression techniques and the results are compared with each other.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.1
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• pp.523-549
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• 2018

The increasing number of subscribers and demand of multiplicity of services has turned Multi-Server Authentication (MSA) into an integral part of remote authentication paradigm. MSA not only offers an efficient mode to register the users by engaging a trusted third party (Registration Centre), but also a cost-effective architecture for service procurement, onwards. Recently, Lu et al.'s scheme demonstrated that Mishra et al.'s scheme is unguarded to perfect forward secrecy compromise, server masquerading, and forgery attacks, and presented a better scheme. However, we discovered that Lu et al.'s scheme is still susceptible to malicious insider attack and non-compliant to perfect forward secrecy. This study presents a critical review on Lu et al.'s scheme and then proposes a secure multi-server authentication scheme. The security properties of contributed work are validated with automated Proverif tool and proved under formal security analysis.

• The Transactions of the Korea Information Processing Society
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• v.7 no.2S
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• pp.577-593
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• 2000

A distributed video-on-demand (VoD) system is one where collection of video data is located at dispersed sites across a computer network. In a single site environment, a local video server retrieves video data from its local storage device. However, in the setting of a distributed VoD system, when a customer requests a movie from the local server, the server may need to interact with other servers located across the network. In this paper, we present three types of presentation plans that a local server must construct in order to satisfy the customer request. Informally speaking, a presentation plan is a temporally synchronized detailed sequence of steps that the local server must perform for presenting the requested movie to the customer. This involves obtaining commitments from other video servers, obtaining commitments from the network service provider, as well as making commitments of local resources, within the limitations of available bandwidth, available buffer, and customer data consumption rates. Furthermore, for evaluating the goodness of a presentation plan, we introduce two measures of optimality for presentation plans: minimizing wait time for a customer, and minimizing access bandwidth is used. We develop algorithms to compute optimal presentation plans for all three types, and carry out extensive experiments to compare their performance. We have also mathematically proved certain results for the presentation plans that had previously been verified experimentally in the literature.

• Journal of KIISE:Computing Practices and Letters
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• v.5 no.4
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• pp.405-415
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• 1999

웹의 성장은 점차 복잡한 응용에 대한 요구를 가중시켰으며, 데이타베이스와 웹과의 효율적인 연동 역시 중요한 문제가 되었다. 본 논문에서는 이와 같은 환경을 효율적으로 지원하기 위한 웹 응용 서버 WATS를 설계하고 구현하였다. WATS에서 응용 프로그램은 컴포넌트 단위로 작성된 후 동적으로 링크되고 요청을 처리할 응용 서버가 대기 상태로 존재하는 확장 API 응용 서버 방식으로 구현되었으며, 이러한 웹 서버와 응용 서버의 분리 구조는 대량의 요청을 처리하기에 적합하다. 또한 컴포넌트를 특성에 따라 분류한 후 각 특성에 적합한 특성 기반 스케줄링 알고리즘을 적용하여 프로세스 부하 균형을 이루었으며, 이 기법이 일반적인 라운드 로빈 스케줄링 알고리즘보다 좋은 성능을 나타냄을 성능 측정을 통해서 보인다.Abstract The increasing popularity of the World-Wide-Web (WWW) has resulted in demand for more complex applications, and web gateways to database became core component in such applications. In this paper, we have designed and implemented WATS in order to support these environments. In WATS, application components are dynamically linked with application server processes. And it is implemented as extensible API application server architecture and is able to process a large amount of requests through separating web server from application server. Also we classify the components into various categories according to its own properties and devise process load balancing algorithm by using property-based scheduling. We show WATS using this algorithm performs better than those using general round-robin algorithm.

• Proceedings of the Korean Society of Computer Information Conference
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• 2017.01a
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• pp.195-196
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• 2017

본 논문에서는 멀티미디어 서버에서 특정 서버를 즉시 종료함으로써 에너지를 절약하는 기법을 제안한다. 본 논문에서 제안하는 서버 데이터 배치 기법은 현재 시스템의 부하를 파악하여 부하가 줄어들게 되어 특정 서버를 종료하여도 요청 부하를 충분히 서비스 가능할 경우 서버를 종료한다. 반대로 부하가 증가하게 되어 추가의 서버 사용이 필요하게 되면 서버의 전원을 켬으로써 서비스가 가능하도록 한다. 따라서 멀티미디어 서버의 성능을 최대한 유지하면서 에너지 소비를 크게 절약할 수 있다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.7 no.4
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• pp.895-909
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• 2013

Distributed Denial-of-Service (DDoS) attacks towards name servers of the Domain Name System (DNS) have threaten to disrupt this critical service. This paper studies the vulnerability of the cache server to the flooding DNS query traffic. As the resolution service provided by cache server, the incoming DNS requests, even the massive attacking traffic, are maintained in the waiting queue. The sojourn of requests lasts until the corresponding responses are returned from the authoritative server or time out. The victim cache server is thus overloaded by the pounding traffic and thereafter goes down. The impact of such attacks is analyzed via the model of queuing process in both cache server and authoritative server. Some specific limits hold for this practical dual queuing process, such as the limited sojourn time in the queue of cache server and the independence of the two queuing processes. The analytical results are presented to evaluate the impact of DDoS attacks on cache server. Finally, numerical results are provided for further analysis.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.134-138
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• 2005

There are several application have been developed on internet-based speech recognition. Internet-based speech recognition is a distributed application and there were various techniques and methods have been using for that purposed. Currently, client-server paradigm was one of the popular technique that been using for client-server communication in web application. However, there is a new paradigm with the same purpose: mobile agent technology. Mobile agent technology has several advantages working on distributed internet-based system. This paper presents, applying mobile agent technology in internet-based speech recognition which based on client-server processing architecture.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 1996.06b
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• pp.7-12
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• 1996

This research is on an interactive animation prototype which can be used by many users from different computers, that means a network with one server and many clients. In our research, a complete motion is represented by simple motion characteristics. We establish databases which contain all kinds of human motion characteristics. Using flexible connection and appropriate time control, we are able to recompose a sequential serial motion data. Moreover, an interactive application system is needed among the uses with a server from animator. In this research, we also investigate three methods of“connect motion database”. We are planing to use the method of connecting motion database under networks with a client-server application system.

• Proceedings of the KIPE Conference
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• 2005.07a
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• pp.621-623
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• 2005

OPC has made it to improve the development of control and monitoring software. But it is difficult to understand COM/DCOM model that is a base technology of OPC and complex communication setting between OPC Server and OPC Client. Therefore, in this paper, we design and implement ActiveX based components that are enable to solve these problems. Implemented components provide a method for simple communication between OPC Server and OPC Client and a GUI environment for easy and fast setting of communication information. Also, they provide the architecture for efficient management of OPC Server's data. By using implemented component, easy development and efficient maintenance of OPC Client can be supported.