• 한국정밀공학회지
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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.

• 한국시뮬레이션학회논문지
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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.

• 한국시뮬레이션학회논문지
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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.

• 대한산업공학회지
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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.

• 한국지진공학회:학술대회논문집
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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.

• 정보처리학회논문지D
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• 제12D권6호
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• pp.905-914
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• 2005

본 논문에서는 센서 및 기기로부터 받은 정보를 이용하여 헬스케어 응용 서비스를 제공하고, 이를 원격에서 모니터링 및 제어할 수 있는 분산객체그룹 프레임워크 기반의 헬스케어 흠 서비스 시스템을 제안한다. 분산객체그룹 프레임워크는 헬스케어 응용의 수행을 위해 수행객체들 및 헬스케어 지원 센서 또는 기기들의 논리적인 서비스별 그룹화와 이들 그룹간의 상호 동적연결 및 실시간 서비스를 지원한다. 제안한 시스템의 구조는 3계층으로 헬스케어 지원 센서나 기기로 이루어진 물리적 계층, 분산객체그룹 프레임워크 지원 계층, 그리고 이들 기반위에서 수행할 헬스케어 응용 구현 계층으로 구성된다. 본 시스템 환경에서 헬스케어 응용으로 위치추적 서비스, 헬스정보 서비스, 그리고 쾌적환경 서비스들을 구현하였고, 각 서비스를 통합하여 수행한 결과를 원격 데스크탑과 이동 단말기를 통해 보였다.

• 한국멀티미디어학회논문지
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• 제4권5호
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• pp.377-389
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• 2001

최근의 웹 환경 확산으로 웹을 기반으로 하는 워크플로우 시스템의 구축경향이 높다. 워크플로우 시스템에서 중요한 기능은 미리 정의된 규칙, 절차 및 조건에 따라 작업흐름을 자동화하는 것으로 정보흐름에 있어서 수동적인 작업을 배제하고 GUI 방식을 지원하며 정보처리의 이동성이 고려되어야 한다. 특히 분산된 업무조직의 작업흐름을 위한 분산워크플로우 시스템은 웹 환경에 있어서 프로세스 로직에 따른 태스크간의 이동제어와 결함허용 및 실시간적 처리가 가능해야 한다. 그러나 기존의 메일 시스템은 전송위주로서 작업흐름을 자동화하려는 경우에 적합하지 못하다. 이러한 문제를 해결하기 위하여 작업흐름 설계가 가능하고 작업흐름제어를 자동화 할 수 있는 분산워크플로우 엔진이 필요하다. 본 논문에서는 웹 메일을 이용하여 작업흐름을 그래픽 인터페이스로 작성하고 이를 절차적 수행이 가능한 스크립트 코드를 생성하는 브라우저를 작성하였으며, 분산환경에서 태스크 처리를 위한 프로세스 스케쥴러 및 서버노드의 결함 발생시 이를 허용하는 전처리기를 지닌 프로세스 엔진을 설계하였다. 이 이스템은 서버의 결함이나 사용자의 부재시 처리를 대행하므로 시스템의 신뢰성과 가용성을 향상시키고, 데이터베이스 기반 워크플로우 시스템보다 비용을 감소시킨다.