In this paper, we present a partitioning algorithm for distributed simulation of DEVS (Discrete Event System Specification) models. To preserve concurrency inherent in models, the proposed algorithm utilizes the structural information of models. Through benchmark simulation experiments, we show that the proposed algorithm can generate good partitions.

VRML (Virtual Reality Modeling Language) is an Web-based standard for modeling 3D spaces and provides applications with 3D interactive interfaces. With its recent upgrade, it supports events, routes, scripts, and other behavior modeling constructs. This paper approaches VRML as a simulation modeling language. This approach promotes the sharing and distribution of simulation results and demonstration among distributed users as well as efficient modeling of systems through the direct mapping of 3D objects and behaviors. This paper analyzes the behavior modeling constructs of VRML, presents effective modeling alternatives through the modeling of a simple material processing system, and discusses the upgrade direction of VRML as a foundation for distributed interactive simulation system.

This study deals with an autonomous generation of simulation codes for the design of processes of c CIM system based on the concept of model transformation. We assume we have a functional model of an organization which is developed using the well-known IDEF0 methodology. Then, a modeling methodology, called PROWD(PRocess flOW Description), is suggested to develop the flow processes of the organization. To Derive simulation specifications for the transformed PROWD model, we define a module of a "unit system" for each activity of PROWD model. Then specifications for system entities and resources are derived from input/control/mechanism/output and entity flows of PROWD model. Entitiy queues are defined from the sates and events of unit systems. Finally, SIMAN model frame is generated from those specifications through a suggested algorithm. The implementability and validity of the proposed approach is tested by developing a prototype of a computer-assisted design system on the operation processes of FMS installed at SNU-ASRI (Seoul National University-Automation and Systems Research Institute).nstitute).

It is essential to construct an efficient material flow system for the successful introduction of automated manufacturing systems. Automated Guided Vehicle System (AGVS) plays a significant role more and more in modern manufacturing environments, because of the flexibility and the precision they offer. However, as the size and the complexity of systems increase, the problems of dispatching, routing and scheduling of AGVs become complicated due to their independent and asynchronous demands. In this paper, we review relevant papers, and provide a new and more efficient method for dispatching AGV, named MEVTT (Minimum Empty Vehicle Travel Time) and demonstrate its performance and efficiency using simulation.

Results from a nonequilibrium molecular dynamics (NEMD) simulation are presented for an argon liquid subject to a shear flow. The segmented molecular dynamics method and the subtraction technique used in NEMD program to reduce the thermal fluctuation noise in data are studied with different shear rates. The standard deviation in the shear stress reduced from 0.030 to 0.004 by the segmented molecular dynamics method for 50 repeated segments. On the other hand, the standard deviation of the data remained the same when the subtraction technique was applied, where as the results of shear stress by constant value in a random way.

In 3D computer graphics, fractal techniques have been applied to terrain models. Even though fractal models are convenient way to get the data of terrain models, it is not easy to gain the final results by manipulating the data of terrain model. However, by using the object oriented programming techniques, we could reduce the effort of programming job to find the final result. In this paper, a set of classes made by object oriented programming technique is presented. To show the results, the data of a terrain model were made by a fractal technique, namely, the midpoint displacement methods with square lattices of points.

For many optimization problems where some of the system components are stochastic, the objective functions cannot be represented analytically. Therefore, modeling by computer simulation is one of the most effective means of studying such complex systems. Many, if not most, simulation optimization problems have multiple aspects. Historically, multiple aspects have been combined ad hoc to form a scalar objective function, usually through a linear combination (weighted sum) of the multiple attributes, or by turning objectives into constraints. The genetic algorithm (GA), however, is readily modified to deal with multiple aspects. In this paper we propose a MAGA (Multiple Aspects-based Genetic Algorithm) as an algorithm for finding the Pareto optimal set. We demonstrate its ability to find and maintain a diverse "Pareto optimal population" on two problems.

Designing and constructing a proper simulator for real power plants requires extensive research in human engineering and computer science and integration of different fields of technologies such as system analysis, operational knowledge for nuclear plant, etc. A full scope replica type simulator for nuclear power plant is developed. The simulator has the same feature and operational functions as one in the main control room (MCR) of a reference power plant. The simulator provides the necessary training to recover or reduce damages from accidents that usually are unpredictable. This paper describes the configurations and characteristics for the simulator that is developed for Younggwang Nuclear Power Plant #3,4 which is the basic model of the Korean Nuclear Power Plant. The paper also describes technical aspects of Auto Code Generator that is used for developing the simulator. The successful development of the simulator will contribute to improve safety in operation of nuclear power plants.

For the purpose of decreasing economic loss from the traffic jam, a car route guidance system efficiently utilizing the existing roads has attracted a great deal of attention. In this paper, the search algorithm for optimal path and alternative paths, which is the main function of a car route guidance system, was presented using evolution program. Search efficiency was promoted by changing the population size of path individuals in each generation, applying the concept of age and lifetime to path individuals. Through simulation on the virtual road-traffic network consisting of 100 nodes with various turn constraints and traffic volumes, not only the optimal path with the minimal cost was obtained, avoiding turn constraints and traffic congestion, but also alternative paths with similar costs and acceptable difference was acquired, compared with optimal path.

The Off-Dock Container Yard (ODCY)s in Pusan are located at 48 different places, and it causes serious problems in the container cargo transport and inland traffic near Pusan district. Hence, the analysis and evaluation of ODCY operation is important. Therefore, this paper proposes a simulation model which evaluates the operation of ODCY. It also proposes a simulation model using an object-oriented approach which includes the system is modeled with object-class hierarchy and SIMPLE++, an object-oriented simulation software, is used to develop the model.