• Journal of the Korean Society for Precision Engineering
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• 제23권5호
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• pp.111-118
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• 2006

Better understanding and sharing information are getting important to manage interdisciplinary product development team in a globally-distributed company. This study proposes a solution to implement RPD(Rapid Product Development) system for the distributed development teams using SOAP(Simple Object Access Protocol). And a new approach is introduced for the better understanding of product geometry among the development members in different place and the easy sharing of product information. An application example shows that SOAP operates in distributed environment more efficiently than other RPC(Remote Procedure Call) techniques and it does not respond sensitively to firewall. And SOAP is an excellent RPC and messaging technique to exchange structured data. Procedures developed with use of SOAP are worked together with web, and users can use remote services as an application program in their local computer.

• Journal of Communications and Networks
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• 제14권6호
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• pp.597-605
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• 2012

With the smart grid coming near, wide-area supervisory control and data acquisition (SCADA) becomes more and more important. However, traditional SCADA systems are not suitable for the openness and distribution requirements of smart grid. Distributed SCADA services should be openly composable and secure. Event-driven methodology makes service collaborations more real-time and flexible because of the space, time and control decoupling of event producer and consumer, which gives us an appropriate foundation. Our SCADA services are constructed and integrated based on distributed events in this paper. Unfortunately, an event-driven SCADA service does not know who consumes its events, and consumers do not know who produces the events either. In this environment, a SCADA service cannot directly control access because of anonymous and multicast interactions. In this paper, a distributed security framework is proposed to protect not only service operations but also data contents in smart grid environments. Finally, a security implementation scheme is given for SCADA services.

• Journal of the Korea Society for Simulation
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• 제13권4호
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• pp.43-53
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• 2004

The distributed OCSP (Online Certificate Status Protocol), composed of multiple responders, is a model that enhances the utilization of each responder and reduces the response time. In a multi-user distributed environment, load balancing mechanism must be developed for the improvement of the performance of the whole system. Conservative load balancing algorithms often ignore the communication cost of gathering the information of responders. As the number of request is increased, however, fail to consider the communication cost may cause serious problems since the communication time is too large to disregard. We propose an adaptive load balancing algorithm and evaluate the effectiveness by performing modeling and simulation. The principal advantage of new algorithm is in their simplicity: there is no need to maintain and process system state information. We evaluated the quality of load balancing achieved by the new algorithm by comparing the queue size of responders and analyzing the utilization of these responders. The simulation results show how efficiently load balancing is done with the new algorithm.

• Journal of the Korea Society for Simulation
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• 제2권1호
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• pp.91-106
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• 1993

Load sharing in distributed systems improves systems performance. Research in the field has been focused on steady state performance for load sharing algorithms. However, transient characteristics of such algorithms may be important in a distributed system in which workload for some node is changing. Simulation is the only means to analyze such characteristics. This paper presents a simulation-based analysis of the transient characteristics of four load sharing algorithms ; forward probing, reverse probing, symmetric probing, and multi-threshold symmetric probing algorithms. Discrete event system models for execution of the algorithms in a distributed system has been developed in a SIMSCRIOT II.5 environment. Simulation results indicate that the MSYM algorithm shows the shortest response time in the transient period.

• ETRI Journal
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• 제30권4호
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• pp.618-620
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• 2008

A distributed virtual environment (DVE) allows multiple geographically distributed objects to interact concurrently in a shared virtual space. Most DVE applications use a non-replicated server architecture, which dynamically partitions a virtual space. An important issue in this system is effective scalability as the number of users increases. However, it is hard to provide suitable load balancing because of the unpredictable movements of users and hot-spot locations. Therefore, we propose a mechanism for sharing roles and separating service regions. The proposed mechanism reduces unnecessary partitions of short duration and supports efficient load balancing.

• KEPCO Journal on Electric Power and Energy
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• 제1권1호
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• pp.55-59
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• 2015

Denial of Service (DoS) attack is to interfere the normal user from using the information technology services. With a rapid technology improvements in computer and internet environment, small sized DoS attacks targeted to server or network infrastructure have been disabled. Thus, Distributed Denial of Service (DDoS) attacks that utilizes from tens to several thousands of distributed computers as zombie PC appear to have as one of the most challenging threat. In this paper, we categorize the DDoS attacks and classify existing countermeasures based on where and when they prevent, detect, and respond to the DDoS attacks. Then we propose a comprehensive defense mechanism against DDoS attacks in Control System to detect attacks efficiently.

• Journal of Korean Institute of Industrial Engineers
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• 제39권4호
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• pp.278-289
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• 2013

Up-to-date market dynamics and intense competition have forced a production system to be more widely distributed and decentralized than ever, and the production system itself can be regarded as a collaborative network of autonomous production resources in which the responsibility of decision making is also decentralized into individual autonomous entities. The conventional resource management models, however, are not suitable for the distributed and decentralized environment because of their centralized nature. In this paper, an agent-based resource management model is proposed. The proposed model applies employment relation-driven fractal organization (FrOrg) into organizational model for distributed production resources and presents a resource management framework based on employment contracts. The fractal organization is a structured association in which a self-similar pattern recursively appears, and employment relations between production resources are recursively constructed throughout the entire production system.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 한국지진공학회 2006년도 학술발표회 논문집
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• pp.563-570
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• 2006

Distributed control architecture is based on sharing control and data between multiple nodes on a network Communication and task sharing can be distributed between multiple control computers. Although many communication protocols exist, such as TCP/IP and UDP, they do not have the determinism that realtime control demands. Fiber-optic reflective shared memory creates the opportunity for realtime distributed control. This architecture allows control and computational tasks to be divided between multiple systems and operate in a deterministic realtime environment. One such shared memory architecture is based on Curtiss-Wright ScramNET family of fiber-optic reflective memory. MTS has built seismic and structural control software and hardware capable of utilizing ScramNET shared memory, opening up infinite possibilities in research and new capabilities in Hybrid and Model-In-The-Loop control.

• The KIPS Transactions:PartD
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• 제12D권6호
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• pp.905-914
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• 2005

This paper suggests a healthcare home service system based on the distributed object group framework that can not only provide healthcare application services using the information obtained from the physical healthcare sensors and devices, and but also monitor and control these services remotely. The distributed object group framework supports the object group service, the interaction service between object groups and the real-time service in order to execute the healthcare application. Here object group means the unit of logical grouped objects or healthcare sensors and devices for a service. Our suggested system consists of 3 layers. The first layer presents the physical sensors and devices for healthcare, as a physical layer. The second layer lays the distributed object group framework, and the third layer, the upper's one, implements healthcare applications based on lower layers. With healthcare applications providing for this system, we implemented the location tracking service, the health information service and the titrating environment service. Also the integrated executing results of these services can be monitored and controlled via remote desktop systems or PDAs.

• Journal of Korea Multimedia Society
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• 제4권5호
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• pp.377-389
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• 2001

It has a tendency to build Workflow Systems based on the web with the spread of web environment. The important function in Workflow Systems are to automatize job flow according to the predefined regulations, procedures or conditions. Hence, there needs to consider excluding passive jobs, supporting GUI and a migratory information processing for information flow. Distributed Workflow System for workflow of a distributed service system should perform transfer control and Fault-Tolerance between tasks based on process logic, and real time processing. However, the existing mail systems being used are just for transmission and it doesn't fit to automatize job flow. To solve the matter, there needs a Distributed Workflow Engine to design workflow and automatize its control. In this paper, we design a web browser with graphic interface using web mail, a browser creating a script code for a procedural performance. Also, we design a Process-engine has a Preprocessor which tolerates process scheduler for task transaction or server node's faults on distributed environment. The proposed system enhances the reliability and usability of a system reduces the cost rather than a workflow system based on database, for they execute as proxy for a server's fault or suers' absence.