• KEPCO Journal on Electric Power and Energy
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• v.7 no.2
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• pp.277-283
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• 2021

Power plant simulators have been used for operator training, control verification and engineering verification. In general, simulators can be used in the place where they are installed by only single user group at a time. Considering high cost of simulator development, a lot of available scenarios, the diversity of user level and accessibility based on users' work location, development of simulator system that can be used by multiple user groups regardless of location is required in order to enhance utilization of simulators. In this paper, the simulator system that can be used by multiple user group simultaneously without location limitation is proposed. The simulator system is composed of simulator servers, database servers, HMI servers, a web server, web clients. Simulator server consists of control model, process model that are developed for Circulating Fluidized Bed power plant located overseas. A web server manages user accounts, operation procedures, multiple server access between web client group and simulator server group. In other words, a web server makes a user group select a simulator server at a time. The developed simulator system is integrated after implementing process model, control model, HMI, and web server. Web client systems are installed on local site where power plant is located, while simulator servers, HMI servers, database servers, and a web server are located in KEPCO RI. The developed simulator system is verified by steady-state test, malfunction test and so on via remote access.

• Proceedings of the IEEK Conference
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• 2003.11b
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• pp.231-234
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• 2003

This paper designs and implements fault-tolerant server of meta server for shared filesystem (SANfs) in SAN environment. SANfs is the filesystem that many clients can share data in Network-attached storage in SAN environment and meta server is the server that processes file operation in SANfs. The focus of this paper is the implementation of fault-tolerant server of meta server in SANfs. In the event of a meta server, meta server failovers to a fault-tolerant server where its processing continues seamlessly. If meta server doesn't restore, fault-tolerant server searches reliable client and makes another fault-tolerant server and work as meta server. Heartbeat monitors meta server and shadow server and controls them.

• Proceedings of the Korea Institute of Convergence Signal Processing
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• 2001.06a
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• pp.49-52
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• 2001

In this paper, the design and implementation of the Geographic Information Retrieval System for the ArcView is described. The environments for the system configurations include a PC server under Linux Operating System, Apache Web-server, and Oracle as database engine. In addition, JSP(Java Server page) and Servlet is used to view database and Map-Image.

• The Journal of Information Systems
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• v.4
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• pp.85-104
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• 1995

In a loosely-coupled distributed database server system, a server failure and/or a communication failure can be masked by a resiliency mechanism. Recognizing that a distributed transaction executes at several servers during its lifetime, we propose a resiliency mechanism which allows continuous transaction processing in distributed database server systems in the presence of a server failure. The resiliency mechanism for transaction processing is achieved by keeping redundant information using a primary/backup approach. The purpose of this paper is to analyze the performance improvement opportunities with the resiliency mechanism and to present the design of the proposed system.

• Journal of the Korea Society of Computer and Information
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• v.23 no.9
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• pp.73-80
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• 2018

In this paper, we propose a new type of client server environment to improve the architecture vulnerable to hacking in an existing client server environment. On the server side, move the existing Web server to the client side and This is a way for clients to communicate only the data they need and suggests a structure that completely blocks the web attack itself to the server. This can completely prevent a server from being hacked, spreading malicious code and hacking data on a server. It also presents a new paradigm that will not affect servers even if malware is infected with client PCs. This paper validates the proposed environment through BBS (Big Bad Stick) hardware in the form of USB on the client side. This study proof that secure services are provided through encryption communication with server-side security equipment, indicating that this study is a system with new security.

• Proceedings of the IEEK Conference
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• 2001.06c
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• pp.209-212
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• 2001

In this paper, an intelligent notification system has been presented. The system operates on both wired and wireless internet. When a new message has been uploaded in a bulletin board systems(BBS) on HTTP web server, it sends the same message to their cellular phones of all members of a given group at the same time via SMS(Short Message Service). In addition, on reading SMS message, those who read them respond to a WAP server using pulling technique via wireless internet. Therefore, the HTTP server does know the members who did not read the message yet. Two different web servers, the HTTP server and the WAP server, running on a single system has been implemented. They share the single database which covers al1 related information about the BBS. The set of experiments shows that the notification system works well as we have expected Thus, we conclude that the proposed system that operates on both wired and wireless internet is the one of successful model for such environments.

• Journal of Korea Multimedia Society
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• v.17 no.6
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• pp.706-715
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• 2014

It is used to lead to serious structural vulnerability of the system security of security-critical system when we have quickly developed software system according to urgent release schedule without appropriate security planning, management, and assurance processes. The Data Set and Provider of DataSnap, which is a middleware of Delphi XE2 of the Embarcadero Technologies Co., certainly help to develop an easy and fast-paced procedure, but it is difficult to apply security program and vulnerable to control software system security when the connection structure Database-DataSnap server-SQL Connection-SQL Data set-Provider is applied. This is due to that all kinds of information of Provider are exposed on the moment when DataSnap Server Port is sure to malicious attackers. This exposure becomes a window capable of running SQL Command. Thus, it should not be used Data Set and Provider in the DataSnap Server in consideration of all aspects of security management. In this paper, we study on the verification of the security vulnerabilities for Client and Server DataSnap in Dlephi XE2, and we propose a secure coding method to improve security vulnerability in the DataSnap server system.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2007.11a
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• pp.253-256
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• 2007

The web server for the embedded Linux system(ELS), unlike the ones for the usual Linux or Windows, has some disadvantages such as small number of installable applications, low compatibility and limited extensibility. This fact raises some problems when data are transferred in real-time via the web server, which are mainly caused by a poor performance of the processor and small-sized memory. Conventional user interfaces adopted for the usual web servers are unsuitable for the ELS because they are platform-limited and their installations are done by the form of plug-ins. If the web server for the ELS has an Ajax engine that can be utilized without any installation procedure, the advantages of usability, accessibility and quick response time can be obtained. This paper presents the Ajax interface for the ELS web server. The efficiency of the proposed technology in the real-time remote monitoring is shown through an implementation.

• Journal of the Korean Institute of Intelligent Systems
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• v.10 no.2
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• pp.168-174
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• 2000

All the visiting customers makes a queue and then can be served at an unoccupied server, in the queueing system of multi-server. The customer and server, however, have a conflictive feeling of satisfaction at all times. To solve the problem, in this paper, it is proposed that new design method of server number to maximize the satisfaction level of customer and server by the hzzy concept which is applied to the queuing system.

• International journal of advanced smart convergence
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• v.12 no.3
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• pp.25-31
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• 2023

This paper designs a real-time video playback system using a web camera in the RTSP server. It designs a function to play the video data of the web camera in the client in real time using the web camera in the server and using the RTSP protocol. It consists of a server module function that produces real-time video information using a web camera and a client module function that plays video received from the server in real time. The experiment was conducted by establishing an environment for designing a real-time video playback system using a web camera. As a result of the experiment, it was confirmed that real-time video playback from the server's web camera worked well.