• Title/Summary/Keyword: Discrete event

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Discrete Event Simulation and Its Application to Railway Maintenance Evaluation System (철도차량 유지보수 장비의 Discrete Event Simulation 기반 기초 성능평가 및 적용방안 연구)

  • Mun Hyeong-Seok;Jang Chang-Du;Ha Yun-Seok;Jo Yeong-Cheon
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2005.06a
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    • pp.331-336
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    • 2005
  • A lot of manufacturing knowledge and method have applied to increase manufacturing efficiency in industry field. DES(Discrete Event Simulation) is one of solution to deal with manufacturing problems in factory. Beginning of research, old maintenance system of KNR ( Korea National Railroad) and its technical problems are basically investigated. KNR has maintained railway vehicle with their own solution based on experience. Very advanced railway vehicles such as KTX (Korea Train Express) and TTX(Tilting Train Express) will be difficult to maintain with their old maintenance method. In order to apply knowledge of DES, maintenance field of railway must be considered. Imaginary maintenance machine are selected to variable of DES. Maintenance capability of each machine will be evaluated base on imaginary data from imaginary machine. The machine could be very expensive as well as difficult to replace. Target of research is minimization of number of machine in railway workshop. So basic knowledge of discrete event simulation is introduced. Then five essential stages of discrete event simulation are provided. Each maintenance case defined as event. Each event is discrete and simulated base on different case such as one maintenance line with one machine and one maintenance line with two machines in railway workshop. simple maintenance method, discrete event simulation, will be come out very powerful in complicate maintenance system and will be helpful to reduce maintenance cost as well as maintenance labor.

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DISCRETE EVENT SYSTEM SIMULATION APPROACH FOR AN OPERATION ANALYSIS OF A HEADEND PROCESS FACILITY

  • Lee, Hyo-Jik;Kim, Sung-Hyun;Park, Byung-Suk
    • Nuclear Engineering and Technology
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    • v.41 no.5
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    • pp.739-746
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    • 2009
  • This paper introduces facility operation modeling and simulation based primarily on a discrete event system modeling scheme. Many modern industrial facilities are so complex that their operational status cannot be estimated by simple calculations. In general, a facility can consist of many processes and transfers of material between processes that may be modeled as a discrete event system. This paper introduces the current status of studies on operation modeling and simulation for typical nuclear facilities, along with some examples. In addition, this paper provides insights about how a discrete event system can be applied to a model for a nuclear facility. A headend facility is chosen for operation modeling and the simulation, and detailed procedure is thoroughly described from modeling to an analysis of discrete event results. These kinds of modeling and simulation are very important because they can contribute to facility design and operation in terms of prediction of system behavior, quantification of facility capacity, bottleneck identification and efficient operation scheduling.

A Study on the Measurement of Spatial Density and Structural Characteristic Evaluation using Discrete Event Simulation (이산사건 시뮬레이션을 활용한 공간밀도측정 및 구조특성평가)

  • Yoon, So Hee;Kim, Gun A;Kim, Suk Tae
    • Journal of Korea Multimedia Society
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    • v.20 no.7
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    • pp.1090-1101
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    • 2017
  • This study analyzes spatial density and integration of Space Syntax and Discrete Event Simulation (DEVS) of complex system theory and analyzes spatial structure by property, type and depth. The aim of this study is to secure the validity of the theoretical application. The study evaluated the correlation between spatial density and integration by setting up eight types of analysis models. In addition, analyzed the correlation of structural characteristics and approached the application of discrete event simulation of spatial syntax theory. It is confirmed that the concept of integration of spatial syntax theory and analysis using discrete event simulation are valid as new spatial analysis methodology. Also expect that realistic and concrete predictions will be possible if discrete event simulation evolves into research for space allocation and space efficiency optimization.

The Simulation of Myocardium Conduction System using DEVCS and Discrete Time CAM (DEVCS 및 Discrete Time CAM을 이용한 심근 전도 시스템의 시뮬레이션)

  • Kim, K.N.;Nam, G.K.;Son, K.S.;Lee, Y.W.;Jun, K.R.
    • Proceedings of the KOSOMBE Conference
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    • v.1997 no.05
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    • pp.150-155
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    • 1997
  • Modelling and Simulation of the activation process for the myocardium is meaningful to understand special excitation conduction system in the heart and to study cardiac functions. In this paper, we propose two dimensional cellular automata model for the activation process of the myocardium and simulated by means of discrete time and discrete event algorithm. In the model, cells are classified into anatomically similar characteristic parts of heart; SA node, internodal tracks, AV node, His bundle, bundle branch and four layers of the ventricular muscle, each of which has a set of cells with preassigned properties, that is, activation time, refractory duration and conduction time between neighbor cell. Each cell in this model has state variables to represent the state of the cell and has some simple state transition rules to change values of state variables executed by state transition function. Simulation results are as follows. First, simulation of the normal and abnormal activation process for the myocardium has been done with discrete time and discrete event formalism. Next, we show that the simulation results of discrete time and discrete event cell space model is the same. Finally, we compare the simulation time of discrete event myocardium model with discrete time myocardium models and show that the discrete event myocardium model spends much less simulation time than discrete time myocardium model and conclude the discrete event simulation method Is excellent in the simulation time aspect if the interval deviation of event time is large.

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Hybrid Systems Modeling and Simulation - PartI: Modeling and Simulation Methodology (하이브리드 시스템 모델링 및 시뮬레이션 - 제1부: 모델링 및 시뮬레이션 방법론)

  • 임성용;김탁곤
    • Journal of the Korea Society for Simulation
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    • v.10 no.3
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    • pp.1-14
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    • 2001
  • A hybrid system is defined as a mixture of continuous systems and discrete event systems. This paper first proposes a framework for hybrid systems modeling, called Hybrid Discrete Event System Specification (HDEVS) formalism. It then presents a method for simulators interoperation in which a continuous system simulator and a discrete event simulator are executed together in a cooperative manner. The formalism can specify a hybrid system in a way that a continuos system and a discrete event system are separately modeled by their own specification formalisms with a support of well-defined interface. We call such interface an A/E converter for analog-to- event conversion and an E/A converter for event-to-analog conversion. Simulators interoperation is based on the concept of pre-simulation in which simulation time for a continuous simulator is advanced in accordance with a discrete event simulator.

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A New Approach for Multiple Object Tracking ? Discrete Event based Multiple Object Tracking (DEMOT)

  • Kim, Chi-Ho;You, Bum-Jae;Kim, Hag-Bae;Oh, Sang-Rok
    • 제어로봇시스템학회:학술대회논문집
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    • 2003.10a
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    • pp.1134-1139
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    • 2003
  • Tracking is a fundamental technique which is able to be applied to gesture recognition, visual surveillance, tangible agent and so forth. Especially, multiple object tracking has been extensively studied in recent years in order to perform many and more complicated tasks. In this paper, we propose a new approach of multiple object tracking which is based on discrete event. We call this system the DEMOT (Discrete Event based Multiple Object Tracking). This approach is based on the fact that a multiple object tracking can have just four situations - initiation, continuation, termination, and overlapping. Here, initiation, continuation, termination, and overlapping constitute a primary event set and this is based on the change of the number of extracted objects between a previous frame and a current frame. This system reduces computational costs and holds down the identity of all targets. We make experiments for this system with respect to the number of targets, each event, and processing period. We describe experimental results that show the successful multiple object tracking by using our approach.

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Submarine Diving and Surfacing Simulation Using Discrete Event and Dynamic-based Discrete Time Combined Modeling Architecture (이산 사건 및 역학 기반 이산 시간 혼합형 모델링에 의한 잠수함의 잠항 부상 시뮬레이션)

  • Cha, Ju-Hwan;Roh, Myung-Il;Lee, Kyu-Yeul
    • Journal of the Society of Naval Architects of Korea
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    • v.47 no.2
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    • pp.248-257
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    • 2010
  • In this study, a discrete event and dynamic-based discrete time combined simulation modeling architecture, which can be used to calculate equations of motions among discrete events, is developed. This is composed of a command model, which is in charge of discrete event simulation, a numerical integration model, which finds motions by numerically integrating equations of motions, and an external force and control force model, which calculates the force and transmits it to the equations. Using this architecture, we can develop dynamic-based simulation by simply connecting and combining models, and handle simultaneously discrete event and discrete time simulation. To verify the efficiency of the architecture, it is applied to the submarine diving and surfacing simulation.

Introduction of Discrete Event Simulation and Its Application to Railway Maintenance System (Discrete Event Simulation의 차량 유지보수체계의 적용을 통한 유지보수 효율향상 연구)

  • Mun Hyung Suk;Jang Chang Doo;Ha Yun Sok;Cho Young Chun
    • Proceedings of the KSR Conference
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    • 2005.05a
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    • pp.48-57
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    • 2005
  • A lot of manufacturing knowledge and method have applied to increase manufacturing efficiency in industry field. DES(Discrete Event Simulation) is one of solution to deal with manufacturing problems in factory. Beginning of research, old maintenance system of KNR ( Korea National Railroad) and its technical problems are basically investigated. KNR has maintained railway vehicle with their own solution based on experience. Very advanced railway vehicles such as KTX (Korea Train Express) and TTX(Tilting Train Express) will be difficult to maintain with their old maintenance method. In order to apply knowledge of DES, maintenance field of railway must be considered. Imaginary maintenance machine are selected to variable of DES. Maintenance capability of each machine will be evaluated base on imaginary data from imaginary machine. The machine could be very expensive as well as difficult to replace. Target of research is minimization of number of machine in railway workshop. So basic knowledge of discrete event simulation is introduced. Then five essential stages of discrete event simulation are provided. Each maintenance case defined as event. Each event is discrete and simulated base on different case such as one maintenance line with one machine and one maintenance line with two machines in railway workshop. simple maintenance method, discrete event simulation, will be come out very powerful in complicate maintenance system and will be helpful to reduce maintenance cost as well as maintenance labor.

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Fault-tolerant robust supervisor for timed discrete event systems

  • Park, Seong-Jin;Li, Jong-Tae
    • 제어로봇시스템학회:학술대회논문집
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    • 1997.10a
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    • pp.411-413
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    • 1997
  • This paper presents the problem of fault-tolerant robust supervisory control of timed discrete event systems (DESs). First the concept of faults is quantitatively defined in timed DESs and fault tolerable event sequences are presented as a desired legal language. Given a timed DES with model uncertainty, the conditions for the existence of a supervisor which always guarantees fault tolerable event sequences embedded in the system are derived.

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Traffic Flow Analysis Methodology Using the Discrete Event Modeling and Simulation (이산 사건 모델링 및 시뮬레이션을 이용한 교통 흐름 분석 방법론)

  • 이자옥;지승도
    • Journal of Korean Society of Transportation
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    • v.14 no.1
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    • pp.101-116
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    • 1996
  • Increased attention has been paid in recent years to the need of traffic management for alleviating urban traffic congestion. This paper presents a discrete event modeling and simulation framework for analyzing the traffic flow. Traffic simulation models can be classified as being either microscopic and macroscopic models. The discrete event modeling and simulation technique can be basically employed to describe the macroscopic traffic simulation model. To do this, we have employed the System Entity Structure/Model Base (SES/MB) framework which integrates the dynamic-based formalism of simulation with the symbolic formalism of AI. The SES/MB framework supports to hierarchical, modular discrete event modeling and simulation environment. We also adopt the Symbolic DEVS (Discrete Event System Specification) to developed the automated analysis methodology for generating optimal signal light policy. Several simulation tests will demonstrates the techniques.

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