• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 Proceedings of the Korea Automatic Control Conference, 11th (KACC); Pohang, Korea; 24-26 Oct. 1996
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• pp.358-361
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• 1996

In this paper, we discuss decentralized optimal fault tolerant supervisory control issues on the basis of failure analysis and diagnosis from the angle of discrete event dynamic system. We address the detectability and the observability problems, and develope fault tolerant supervisory control system upon the failure analysis and diagnosis schemes. A complete min-cut is introduced and the procedure for finding the achievable or nonachievable layered optimal legal sublanguages is suggested for a preferential option among the reachable states in the controlled plant. A layered optimal supervisory control framework is proposed upon these. We extend the concept of decentralized supervisory control by considering the problem of combination of decentralized with centralized control in case pure decentralized control happens to be inadequate. We introduce the concept of locally controllable pair and present a hybrid decentralized supervisory control framework. Finally, we propose the analytical framework for a decentralized optimal fault tolerant supervisory control systems.

• 제어로봇시스템학회논문지
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• 제2권3호
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• pp.209-219
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• 1996

Fieldbus provides a real-time data communication among field devices in the process control and manufacturing automation systems. In this paper, a Petri Net model of the 1993 draft of IEC/ISA fieldbus which is proposed as an international standard of fieldbus network is developed. Based on the Petri Net model, discrete-event simulation model of IEC/ISA fieldbus network is developed. This paper evaluates the network induced delay in the data link layer of IEC/ISA fieldbus using the simulation model. In addition, an integrated discrete-event/continuous-time simulation model of fieldbus system and distributed control system is developed. This paper investigates the real-time data processing capability of IEC/ISA fieldbus and the effect of network-induced delay to the performance of control system.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.364-364
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• 2000

Timed Petri Net(TPN) is one of methods to model and to analyze Discrete Event Dynamic Systems(DEDSs) with real time values. It has two time values, earliest firing time ($\alpha$$_{i}$) and latest firing time ($\beta$$_{I}$) for the each transition. A transition of TPN is fired at arbitrary time of time interval ($\alpha$$_{I}$, $\beta$$_{i}$). Uncertainty of firing time gives difficulty to analyze and estimate a modeled system. In this paper, we proposed the Fuzzy Transition Timed Petri Net(FTTPN) with fuzzy theory to determine the optimal transition time (${\gamma}$$_{i}$). The transition firing time (${\gamma}$$_{i}$) of FTTPN is determined from fuzzy controller which is modeled with information of state transition. Each of the traffic signal controllers are modeled using the proposed method and timed petri net. And its Performance is evaluated by simulation of traffic signal controller. controller.

• 한국정보통신학회논문지
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• 제11권5호
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• pp.1029-1036
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• 2007

상태폭발문제는 이산사건 시스템 검증과정에서 피하기 어려운 문제로 알려져 있으며, 큰 시스템 해석을 어렵게 만드는 본질적인 요인이다. 본 논문에서는 이산사건 시스템의 무시간 DEVS/DEVS 명세에 대한 계층적인 설계/검증 방법을 제안하여 상태폭발문제를 회피할 수 있는 방법을 보인다. 제안한 방법은 DEVS 상위모델과 DEVS 하위 모델간의 설계/검증 과정을 계층적이면서도 반복적인 방식을 채택하여 검증에 필요한 요소 이외에는 정제 과정을 통하여 없애는 방안이다. 간단한 예제를 통하여 제안된 방법론을 소개하고 있다.

• 대한조선학회논문집
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• 제50권5호
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• pp.334-342
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• 2013

In this paper, we analyze the procedure of the design manager for the enhancement of the hull production design process by use of the simulation method. Normally, design manager assigns design jobs according to various methods and estimates the corresponding results. When the construction drawing which is the output of the detail design where a design is dealt by zones, the design manager identifies blocks and analyzes their work difficulties, and assigns jobs to design engineers who are different in capabilities. These processes including the design engineer who can be modeled with man-hours evaluation model are represented in detail as a simulation model. As the high-level modeling for the discrete-event system, we use Event Graph model. And we implemented the simulation using Simkit which is open simulation engine for the discrete-event system. We made the simulation scenario to be written by a user in the scenario generator which is separated from the simulation model, and made the simulation result to be visualized in the form of Gantt chart in a Web. In the scenario of the irregular issuance for various construction drawings which contain different numbers of blocks, we performed the Monte-Carlo simulation according to various assignment methods to find the assignment result that satisfies the mid-term schedule.

• 한국정보시스템학회지:정보시스템연구
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• 제27권4호
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• pp.35-70
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• 2018

Purpose Recently, 3D factory simulation technology has emeged as a powerful tool for modeling and analysis of a wide range of production systems, however, it has been not paid much attention in Korea. In this context, this paper aims to provide a comprehensive literature review on discrete event simulation softwares and introduce a promising 3D factory simulation software called FlexSim and its application domains. Design/methodology/approach In order to demonstrate worldwide popularity and technical superiority of FlexSim software, we analyzed the recent list of rankings for commercial discrete simulation softwares released by winter simulation conference and users' opinions collected from business software review site. Moreover, several main application domains are derived from a review of the previous research papers that deal with applications of FlexSim software. Findings FlexSim software recently moved up the list of major commercial simulation softwares, and technical superiorities of the software demonstrate that it is a promising tool for practical 3D factory simulation. Moreover, recent research papers suggest that FlexSim software can be used as a component of smart factory system. In this context, it is expected that FlexSim software becomes more popular in the era of industry 4.0.

• 한국항행학회논문지
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• 제24권3호
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• pp.184-191
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• 2020

항공용 SIL은 항공전자시스템의 통합 및 검증에 사용되는 통합시험환경이다. 항공용 SIL에는 여러 가지 제약으로 인해 항공기에 탑재되는 장비를 직접 연동할 수 없을 때 장비의 소프트웨어 모델이 필요하다. 지금까지 항공기 개발에 적용한 항공용 SIL의 소프트웨어 모델은 표준화된 방법 없이 일반적인 소프트웨어 개발 방법의 적용으로 재사용이 어려워 소프트웨어 모델 재사용을 위한 프레임워크의 필요성이 제기되었다. 이러한 항공용 SIL 모델의 표준화된 모델링 방법을 위해 DEVS (discrete event system specification) 형식론을 채용하였다. DEVS 형식론은 이벤트 구동(event-driven) 알고리즘이며 이는 기존의 항공용 SIL에 적용되는 절차적이고 반복적인 알고리즘과 어울려 동작하기 힘들다. 이에 본 논문에서는 항공용 SIL 모델의 특징과 기존 방식이 가지는 한계를 보완하고 모델의 재사용성을 극대화할 수 있는 이벤트 기반의 모델링 방법과 실시간 시뮬레이션 방법을 제안한다.

• 한국시뮬레이션학회논문지
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• 제20권1호
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• pp.87-96
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• 2011

DEVS는 이산 사건 시스템을 명세하는 집합론에 근거한 수학적인 틀이다. 이러한 DEVS를 통해 시스템을 시뮬레이션할 때는 명세된 DEVS로부터 구현된 모델과 시뮬레이션 엔진으로 이루어진 실행 환경이 필요하다. 시뮬레이션 엔진은 스케줄링 알고리즘을 통해 모델을 해석하고 실행하는데, 주로 DEVS의 계층적이고 모듈러한 특성을 따라 계층적인 스케줄링 방법을 사용한다. 그러나 이 방법은 계층적인 구조로 인해 시간 관리와 메시지 패싱에 있어서 오버헤드가 존재한다. 본 논문에서는 이러한 오버헤드를 해결하기 위해 이벤트 지향 시뮬레이션을 적용한다. 이벤트 지향의 시뮬레이션은 이벤트에 의해서 모델이 실행되며 이벤트 리스트에 의해 이벤트가 관리된다. 이벤트 리스트에 의해서 시간 관리가 되고 메시지 패싱이 이루어지기 때문에 계층적인 오버헤드를 줄이고 성능 향상을 이룰 수 있다. 본 논문은 이벤트 리스트를 이용한 실행 환경을 제안하고 이러한 실행 환경을 위한 모델 구현 방안에 대해 논하며, 각 실행 환경의 성능을 비교, 분석한다.

• 한국시뮬레이션학회논문지
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• 제8권3호
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• pp.1-16
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• 1999

This paper deals with a discrete simulation optimization method for designing a complex probabilistic discrete event system. The proposed algorithm in this paper searches the effective and reliable alternatives satisfying the target values of the system to be designed through a single run in a relatively short time period. It tries to estimate an autoregressive model, and construct mean and confidence interval for evaluating correctly the objective function obtained by small amount of output data. The experimental results using the proposed method are also shown.

• International Journal of Naval Architecture and Ocean Engineering
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• 제4권3호
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• pp.211-227
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• 2012

To implement a combined discrete event and discrete time simulation such as submarine diving simulation in a distributed environment, e.g., in the High Level Architecture (HLA)/Run-Time Infrastructure (RTI), a HLA interface, which can easily connect combined models with the HLA/RTI, was developed in this study. To verify the function and performance of the HLA interface, it was applied to the submarine dive scenario in a distributed environment, and the distributed simulation shows the same results as the stand-alone simulation. Finally, by adding a visualization model to the simulation and by editing this model, we can confirm that the HLA interface can provide user-friendly functions such as adding new model and editing a model.