• Journal of Korean Society of Industrial and Systems Engineering
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• v.25 no.5
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• pp.31-38
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• 2002

In this paper, we model a two-server queueing system with priority, to which we put a restriction on the number of servers for each customer class. customers are divided into two different classes. Class 1 customers have non-preemptive priority over class 2 customers. They are served by both servers when available but class 2 customers are served only by a designated server. We use a method of generating function depending on the state of servers. We find the generating function of the number of customers in queue, server utilization, mean queue length and mean waiting time for each class of customers.

• Journal of information and communication convergence engineering
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• v.18 no.2
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• pp.82-87
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• 2020

This paper discusses how to design a game server that is scalable, adaptable, and re-buildable with components. Furthermore, it explains how various implementation issues were resolved. To support adaptability, the server comprises three layers: network, user, and database. To ensure independence between the layers, each layer was designed to communicate with each other only via message queues. In this architecture, each layer can have an arbitrary number of threads; thus, scalability is guaranteed for each layer. The network layer uses input/output completion ports(IOCP), which shows the best performance on the Windows platform, it can handle up to 5,000 simultaneous connections on a typical entry-level computer, despite being built with a single-threaded user layer. To completely separate the database from the game server, the SQL code was not directly embedded in the database layer.

• Journal of Korea Game Society
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• v.13 no.2
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• pp.39-48
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• 2013

In MMORPGs(Massively Multi-player Online Role-Playing Games) a large number of players actively interact with one another in a virtual world. Therefore MMORGs must be able to quickly process real-time access requests and process requests from numerous gaming users. A key challenge is that the workload of the game server increases as the number of gaming users increases. To address this workload problem, many developers apply with distributed server architectures which use dynamic map partitioning and load balancing according to the server function. Therefore most MMORPG servers partition a virtual world into zones and each zone runs on multiple game servers. These methods cause of players frequently move between game servers, which imposes high overhead for data updates. In this paper, we propose a new architecture that apply with an arithmetic server dedicated to data operation. This architecture enables the existing game servers to process more access and job requests by reducing the load. Through mathematical modeling and experimental results, we show that our scheme yields higher efficiency than the existing ones.

• Proceedings of the Korean Information Science Society Conference
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• 2002.10d
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• pp.211-213
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• 2002

온라인 게임(online game)은 초고속 통신망의 보급과 기존의 1인용 게임(Single-player game)의 인공지능에서 느낄 수 없었던 즐거움을 제공함으로써 급속도로 보급되었다. 또한 최근의 온라인 게임 시장은 그래픽 기술을 비롯한 하드웨어의 발달로 2D에서 3D로 옮겨가고 있다. 따라서 이러한 추세에 따라 온라인 게임은 보다 많은 멀티미디어 데이터를 필요로 하게 되었다. 이에 Multimedia Storage Sever를 멀티플레이어 온라인 게임(Multi-player online game)에 적용함으로써 보다 효율적인 멀티플레이어 온라인 게임 서버를 구성하고자 한다.

• The KIPS Transactions:PartB
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• v.10B no.1
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• pp.13-20
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• 2003

As it increase electronic commerce user rapidly, it is necessary to study on Improvement of performance for electronic commerce system. This paper suggests electronic commerce system using functionally distributed structure based on multi-agent and evaluate it's performance using prototype. In the suggested system, we use multi-agent using combined reasoning to offer a proper commodity information and meet the customer's requirement. And we can reduce load of the electronic commerce system with distribute agents both main server system and local server system functionally. In experiment result, we can confirm suggested electronic commerce system can prevent customer's unexpected long waiting causes by network traffic and server load, and can improve efficiency.

• Journal of Korean Institute of Industrial Engineers
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• v.42 no.1
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• pp.30-37
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• 2016

A multi-server queueing system with an infinite buffer and impatient customers is analyzed. The system operates in the finite state Markovian random environment. The number of available servers, the parameters of the batch Markovian arrival process, the rate of customers' service, and the impatience intensity depend on the current state of the random environment and immediately change their values at the moments of jumps of the random environment. Dynamics of the system is described by the multi-dimensional asymptotically quasi-Toeplitz Markov chain. The ergodicity condition is derived. The main performance measures of the system are calculated. Numerical results are presented.

• 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.

• Speech Sciences
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• v.9 no.3
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• pp.47-59
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• 2002

A new brilliant service using human-voice and DTMF (Dual Tone Multi Frequency) technique is expected nowadays in order to obtain valuable information on the internet more easily. VoiceXML (Voice eXtensible Markup Language) is the right choice that makes the new service possible. In this paper, the design and implementation of IVR (Interactive Voice Response) server using VoiceXML is described, where it connects with internet and IVR server efficiently. IVR server using VoiceXML is composed of two groups: VoiceXML document handling and VoiceXML execution. Scenario part of IVR server corresponds to VoiceXML document, the execution is performed by VoiceXML execution.

• Journal of the Society of Naval Architects of Korea
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• v.40 no.6
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• pp.69-79
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• 2003

Existing large-scale complex programs usually reside In a single computer, and the user has to be physically in contact with the computer. With the wide spread use of the internet, the need to carry out the design and analysis tasks geographically away from the main computer is increasing. In this paper existing Windows-based propeller design and analysis package is separated into the server-client modules and the protocol program is developed to implement the communication between multi-client computers and a single server computer. A new protocol packet is designed to use the Windows socket and the server/client programs control the receive/send operations using the information transmitted in the packet. Test runs show that the remote user, connected to the server computer through the internet only, can perform the required tasks.

• Journal of Power Electronics
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• v.14 no.5
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• pp.1069-1078
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• 2014

This study presents the design and implementation of a web-based remote laboratory for a multi-mode single-leg power converter, which is a topic in advanced power electronics course. The proposed laboratory includes an experimental test rig with a multi-mode single-leg power converter and its driver circuits, a measurement board, a control platform, and a LabVIEW-based user interface program that is operated in the server computer. Given that the proposed web-based remote laboratory is based on client/server architecture, the experimental test rig can be controlled by a client computer with Internet connection and a standard web browser. Although the multi-mode single-leg power converter can work at four different modes (main boost, buck-boost, boost-boost, and battery boost modes), only the buck-boost mode is used in the experiment because of page limit. Users can choose the control structure, control parameters, and reference values, as well as obtain graphical results from the user interface software. Consequently, the feedbacks received from students who conducted remote laboratory studies indicate that the proposed laboratory is a useful tool for both remote and traditional education.