• 한국시뮬레이션학회:학술대회논문집
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• 한국시뮬레이션학회 2001년도 The Seoul International Simulation Conference
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• pp.425-434
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• 2001

In this paper we introduce a general framework for the modeling, analysis and costing of logistic networks including supply chains (SCs). The employed modeling notation, the so-called Process Chain paradigm, is specifically developed for the application field of logistic networks which includes SCs. We view SCs as discrete event dynamic systems (DEDS) and apply corresponding simulative techniques in order to derive performance measures of the Process Chain model under investigation. For this purpose Process Chain models are automatically transformed into the input language of the simulation tool HIT. Subsequently, a cost accounting model using the performance measures is applied to obtain costs which are actually subject of interest. The usefulness and applicability of the approach is illustrated by a typical supply chain example. We investigate the impact of an additional SC channel between a manufacturer and web-consumers on the overall supply chain costs.

• 한국정밀공학회지
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• 제12권6호
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• pp.128-136
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• 1995

The problem addressed in this paper is that of the on-line computational burden of time-optimal control laws for quick, strongly nonlinear systems like revolute robots. It will be demonstrated that a large amount of off-line computation can be substituted for most of the on-line burden in cases of time optimization with constrained inputs if differential point-to- point specifications can be relaxed to cell-to-cell transitions. These cells result from a coarse discretization of likely swaths of state space into a set of nonuniform, contiguous volumes of relatively simple shapes. The cell boundaries approximate stream surfaces of the phase fluid and surfaces of equal transit times. Once the cells have been designed, the bang- bang schedules for the inputs are determined for all likely starting cells and terminating cells. The scheduling process is completed by treating all cells into which the trajectories might unex- pectedly stray as additional starting cells. Then an efficient-to-compute control law can be based on the resulting table of optimal strategies.

• 제어로봇시스템학회논문지
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• 제7권8호
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• pp.689-696
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• 2001

Large-scale Multi-disciplinary Systems(LMS) such as transportation, aerospace, defense etc. are complex systems in which there are many subsystems, interfaces, functions and demanding performance requirements. Because many contractors participate in the development, it is necessary to apply methods of sharing common objectives and communicating design status effectively among all of the stakeholders. The processes and methods of systems engineering which includes system requirement analysis; functional analysis; architecting; system analysis; interface control; and system specification development provide a success-oriented disciplined approach to the project. This paper shows not only the methodology and the results of model-based systems engineering to Automated Guided Transit(AGT) system as one of LMS systems, but also propose the extension of the model-based tool to help manage a project by linking WBS (Work Breakdown Structure), work organization, and PBS (Product Breakdown Structure). In performing the model-based functional analysis, the focus was on the operation concept of an example rail system at the top-level and the propulsion/braking function, a key function of the modern automated rail system. The model-based behavior analysis approach that applies a discrete-event simulation method facilitates the system functional definition and the test and verification activities. The first application of computer-aided tool, RDD-100, in the railway industry demonstrates the capability to model product design knowledge and decisions concerning key issues such as the rationale for architecting the top-level system. The model-based product design knowledge will be essential in integrating the follow-on life-cycle phase activities. production through operation and support, over the life of the AGT system. Additionally, when a new generation train system is required, the reuse of the model-based database can increase the system design productivity and effectiveness significantly.

• 한국경영과학회:학술대회논문집
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• 한국경영과학회/대한산업공학회 2005년도 춘계공동학술대회 발표논문
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• pp.1033-1039
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• 2005

Parallel and distributed simulation is concerned with the efficient execution of large-scale discrete event simulation models on multiprocessors and distributed platforms. After the development of WWW, many efforts in the parallel and distributed simulation have been made for modeling, particularly building simulation languages and creating model libraries that can be assembled and executed over WWW. However, web-based parallel and distributed simulation is restricted by heterogeneous computing environments. Recently, the advent of XML and web services technology has made these efforts enter upon a new phase. Especially, the web services as a distributed information technology have demonstrated powerful capabilities for scalable interoperation of heterogeneous systems. This paper aims to develop and evaluate the parallel and distributed simulation using the web services technology. In particular, a prototype multi-pass simulation framework is implemented using Java-based web services technology. It focuses on the efficiency of multi-pass simulation used for optimization through the distribution of simulation replication to several simulation service providers. The development of parallel and distributed simulation using web services will help solve efficiently large-scale problems and also guarantee interoperability among heterogeneous networked systems.

• 한국정보과학회논문지:시스템및이론
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• 제27권6호
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• pp.599-607
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• 2000

본 논문에서는 유한페트리넷의 도달가능성에 대한 효율적인 분석방법을 제안한다. 일반적으로 도달가능성 분석은 유한페트리넷의 동적 성질에 관한 연구에 있어서 가장 근본이 되는 분석중의 하나이다. 그러나 일반적인 유한페트리넷의 경우, 도달가능성 분석은 분석시간과 요구되는 메모리 양의 측면에서 지수승의 복잡도를 요구하게 되며 많은 경우 상태공간폭발 문제를 야기할 수 있다. 이에 본 논문에서는 유한페트리넷의 분석을 위한 중간모델인 언폴딩(unfolding)상에서 장소(place)간의 구조관계 분석을 통하여 시간 및 메모리의 측면에서 효율적으로 도달가능성 분석을 수행하는 방법을 제안한다. 제안된 방법은 구조적 제약 없이 모든 종류의 유한페트리넷에 적용 가능하다.

• 한국콘텐츠학회논문지
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• 제6권11호
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• pp.258-265
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• 2006

DEVS 형식론은 이산사건 시스템의 구조를 계층적으로 나타낼 수 있기 때문에 복잡한 시스템을 모델링 하기에 적합하며, 가독성이 좋기 때문에 유지 보수에 유리한 장점이 있다. 반면에, 계층적인 모델의 구조는 시뮬레이션 실행 시에 빈번한 메시지 전달을 야기 시켜 시뮬레이션 속도가 저하되는 단점이 있다. 본 논문에서는 계층적인 DEVS 모델들을 하나로 합성하여 빈번한 메시지 전달을 방지하고 시뮬레이션 실행 속도를 개선할 수 있는 모델 합성법을 제안한다. 제안한 방법은 시뮬레이터 실행코드를 생성하기 이전에 구성 모델들 간의 메시지 전달 관계를 해석하여 실행시간에는 모델 해석과정을 생략하도록 하는 기법으로 기존의 모델 수평화 기법보다 훨씬 뛰어난 속도 향상 결과를 보인다. 제안한 방법의 효용성을 보이기 위해 실험을 통하여 시뮬레이션 속도가 18배 정도 개선될 수 있음을 보인다.

• 한국시뮬레이션학회논문지
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• 제12권4호
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• pp.25-40
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• 2003

With the growing usage of the networks, the world-wide Internet has become the main means to exchange data and carry out transactions. It has also become the main means to attack hosts. To solve the security problems which occur in the network such as Internet, we import software products of network security elements like an IDS (Intrusion Detection System) and a firewall. In this paper, we have designed and constructed the general simulation environment of network security model composed of multiple IDSes and a firewall which coordinate by CNP (Contract Net Protocol) for the effective detection of the intrusion. The CNP, the methodology for efficient integration of computer systems on heterogeneous environment such as distributed systems, is essentially a collection of agents, which cooperate to resolve a problem. Command console in the CNP is a manager who controls the execution of agents or a contractee, who performs intrusion detection. In the network security model, each model of simulation environment is hierarchically designed by DEVS(Discrete Event system Specification) formalism. The purpose of this simulation is that the application of rete pattern-matching algorithm speeds up the inference cycle phases of the intrusion detection expert system and we evaluate the characteristics and performance of CNP architecture with rete pattern-matching algorithm.

• 한국산학기술학회:학술대회논문집
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• 한국산학기술학회 2003년도 Proceeding
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• pp.197-206
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• 2003

With the growing usage of the networks, the world-wide Internet has become the main means to exchange data and carry out transactions. It has also become the main means to attack hosts. To solve the security problems which occur in the network such as Internet, we import software products of network security elements like an IDS (Intrusion Detection System) and a firewall. In this paper, we have designed and constructed the General Simulation Environment of Network Security model composed of multiple IDSes and a firewall which coordinate by CNP (Contract Net Protocol) for the effective detection of the intrusion. The CNP, the methodology for efficient integration of computer systems on heterogeneous environment such as distributed systems, is essentially a collection of agents, which cooperate to resolve a problem. Command console in the CNP is a manager who controls tie execution of agents or a contractee, who performs intrusion detection. In the Network Security model, each model of simulation environment is hierarchically designed by DEVS (Discrete EVent system Specification) formalism. The purpose of this simulation is to evaluate the characteristics and performance of CNP architecture with rete pattern matching algorithm and the application of rete pattern matching algorithm for the speeding up the inference cycle phases of the intrusion detection expert system.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제5권1호
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• pp.83-104
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• 2011

Mobile grid is a combination of grid computing and mobile computing to build grid systems in a wireless mobile environment. The development of network technology is assisting in realizing mobile grid. Mobile grid based on established grid infrastructures needs effective resource management and reliable job scheduling because mobile grid utilizes not only static grid resources but also dynamic grid resources with mobility. However, mobile devices are considered as unavailable resources in traditional grids. Mobile resources should be integrated into existing grid sites. Therefore, this paper presents a mobile grid middleware interconnecting existing grid infrastructures with mobile resources and a mobile service agent installed on the mobile resources. This paper also proposes a mobile resource reliability-based job scheduling model in order to overcome the unreliability of wireless mobile devices and guarantee stable and reliable job processing. In the proposed job scheduling model, the mobile service agent calculates the mobile resource reliability of each resource by using diverse reliability metrics and predicts it. The mobile grid middleware allocated jobs to mobile resources by predicted mobile resource reliability. We implemented a simulation model that simplifies various functions of the proposed job scheduling model by using the DEVS (Discrete Event System Specification) which is the formalism for modeling and analyzing a general system. We also conducted diverse experiments for performance evaluation. Experimental results demonstrate that the proposed model can assist in improving the performance of mobile grid in comparison with existing job scheduling models.

• 한국정보통신학회논문지
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• 제23권9호
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• pp.1038-1048
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• 2019

최근, 선박의 항해 안전을 지원하기 위한 다양한 시스템이 개발되고 있다. 이러한 시스템의 유용성을 검증하기 위해서는 실제 선박에 탑재하여 운용해보는 것이 가장 이상적이나 현실적으로는 많은 어려움이 존재한다. 그 대안으로 모델링 및 시뮬레이션(M&S) 기법을 적용한 유용성 검증 방법이 요구된다. 현실과 가장 가까운 선박 조종 시뮬레이터(FMSS)는 구축비용이 수억에서 수십억에 달하는 등 매우 고가이고, 운용을 위한 전문 인력이 필요하다는 한계가 존재한다. 이러한 이유로, 본 논문에서는 이산사건 시스템 명세(DEVS) 형식론 기반의 선박 항해 모델링 및 시뮬레이션을 통한 항해 안전 지원 시스템을 검증하기 위한 방법을 제안한다. 그 첫 단계로 SES/MB 프레임워크를 기반으로 항해 시뮬레이션 아키텍처를 설계하고, DEVS 형식론을 기반으로 선박 핵심 장비 및 항해사 에이전트를 모델링하는 것에 관한 내용을 기술한다. 이러한 내용을 바탕으로 선박 항해 시뮬레이션 시스템을 구현하고, 다양한 시나리오를 통해 충돌회피 시뮬레이션 등과 같은 항해 안전 지원 요소의 효과도 평가가 가능할 것으로 판단된다.