• Journal of Korean Society for Quality Management
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• v.46 no.4
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• pp.973-982
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• 2018

Purpose: The purpose of this study is to develop an effective simulation modeling formalism for autonomous control systems, such as unmanned aerial vehicles and unmanned surface vehicles. The proposed simulation modeling formalism can be used to evaluate the quality and effectiveness of autonomous control systems. Methods: The proposed simulation modeling formalism is developed by extending the classic DEVS (Discrete Event Systems Specifications) formalism. The main advantages of the classic DEVS formalism includes its rigorous formal definition as well as its support for the specification of discrete event models in a hierarchical and modular manner. Results: Although the classic DEVS formalism has been a popular modeling tool, it has limitations in describing an autonomous control system which needs to make decisions by its own. As a result, we proposed an extended DEVS formalism which enables the effective description of internal decisions according to its conditional variables. Conclusion: The extended DEVS formalism overcomes the limitations of the classic DEVS formalism, and it can be used for the effectiveness simulation of autonomous weapon systems.

• Journal of Korean Port Research
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• v.14 no.1
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• pp.47-55
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• 2000

In order to cope with the changes of container terminal situation in these days, many simulation studies for container terminal have been accomplished. But previous simulation studies using simulation language have limitations in model representation and difficulties in modeling of large scaled container terminal system. To make these problems better, this paper addresses an object-oriented simulation of container terminal system using a DEVS formalism. The DEVS(Discrete Event System Specification) formalism, developed by Zeigler, supports specification of discrete event system in a hierarchical and modular manner. The formalism provides a mathematical basis for studying discrete event systems with better understood and sounder semantics. In a step of system modeling, a DEVS formalism aims at the exact system modeling that has a basis of semantics and utilizing the object-oriented manner can flexibly cope with the changes of system environment. In this study a model is developed and verified through the simulation of some alternatives.

• Proceedings of the Korea Society for Simulation Conference
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• 2002.05a
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• pp.253-258
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• 2002

This paper proposes a methodology for development of protocol models. The methodology attempts to employ two modeling environments in models development, NS2 and DEVSim++, which will interoperate during simulation. NS2 is a widely used network simulator in protocol research, which employs an informal modeling approach. Within the approach time and state information of protocol models are not explicitly described, thus being hard to validate model. On the other hand the DEVS formalism is a mathematical framework for modeling a discrete event system in a hierarchical, modular manner. In DEVS, model's time and state information is described explicitly, By using DEVS formalism, models can easily be validated and errors in the modeling stage can be reduced. However, the DEVS simulator, DEVSim++, supports a small amount of models library which are required to build simulation models of general communication network. Although NS2 employs an informal modeling approach and models validation is difficult, it supports abundant models library validated by experimental users. Thus, combination of DEVS models and NS2 models may be an effective solution for network modeling. Such combination requires interoperation between DEVSim++ simulator and NS2 simulator. This paper develops an environment for such interoperation. Correctness and effectiveness of the implemented interoperation environment have been validated by simulation of UDP and TCP models.

• Journal of the Korea Society for Simulation
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• v.27 no.3
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• pp.37-44
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• 2018

In applying modeling and simulation (M&S) techniques to analyze complex discrete event dynamic systems, conventionally users had to use different simulation environments depending on the user-level. To solve the inconvenience, this paper proposes an integrated development environment for M&S depending on user-level and a formalized interface to manage the model in the development environment efficiently. The interface consists of an extended DEVS formalism and model making rules. The development environment is divided into a modeling environment and a simulation environment. In the modeling environment, three modeling methods are provided for each level of the users. Users inputs several parameters to the model generated as a result of the modeling process, and experiments in various cases by using the simulation environment. The case study shows the implementation of the proposed M&S environment, and using the implemented environment, it shows the M&S process of the complex defense combat system.

• Proceedings of the Korea Society for Simulation Conference
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• 2001.10a
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• pp.484-484
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• 2001

The sophistication of current software applications results in the increasing cost fur software development time. The component-based software development framework is proposed to overcome the difficulty and time-consuming requirements by modularity and reusability. As is the general software case, a component-based simulation framework encourages the reusability of the real system model based on the modularity of the applied simulation methodology. This paper presents a component-based simulation environment that is based on the DEVS/COM run-time infrastructure. The DEVS (Discrete Event System Specification) formalism provides a formal modeling and simulation framework for the generic dynamic systems [1] and Microsoft's COM (Component Object Model) is one of the strongest competitor fur the component standard. The reusability by the DEVS/COM simulation environment saves model development time remarkably and component technology make simulator itself to be a subparts of real application.

• Proceedings of the Korea Society for Simulation Conference
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• 2002.11a
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• pp.85-89
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• 2002

Development of distributed simulation environment must be required in order to simulate the distributed models regionally and inter-operate with running simulations individually, Simulation based on DEVS formalism is difficult to simulate the distributed models. DEVS formalism is modeling methodology. To specify model, this formalism separates behavior and structure, therefore it is able to design complex model easily. HLA is standard framework of distribute simulation environment, It is defined to facilitate the interoperability and the reusability. RTI (Run Time Infrastructure) is software that provides common service to simulation systems and implementation of the HLA Interface Specification. Method of implementation is that modules cooperating with RTI are added to simulator on DEVS simulation environment. On the DEVS simulation environment (DEVS-Obj -C) that already developed, Highest class of abstract simulator uses service that RTI provide, then This environment is able to change DEVS model into Federate and run distribute simulation that inter-operates with the RTI. Because this distributed simulation environment includes convenience of modeling that obtains through the DEVS formalism and accompanies HLA standard, this environment make it possible to simulate with_ complex systems and heterogeneous simulations

• Journal of the Korea Society for Simulation
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• v.15 no.2
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• pp.1-12
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• 2006

As the needs of intelligent systems increase, there have been diverse approaches that combine artificial intelligence (AI) and simulation in the last decade. RG-DEVS, which is the basis for this paper, embedded AI planning techniques into the simulation modeling methodology of DEVS, in order to specify dynamically a simulation model. However, a hierarchy concept, which is used for various types of problem solving systems. is not included in the planning of RG-DEVS. The hierarchy concept reduces the computational cost of planning by reducing the search space, and also makes it easy to apply the hierarchical process flow of a target system to planning. This paper proposes Hierarchical RG-DEVS (HRG-DEVS) in an attempt to insert hierarchical planning capability into RG-DEVS. For the verification of the proposed modeling methodology, HRG-DEVS is applied to model the block's world problem of ABSTRIPS, which is a classical planning problem.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 1999.10a
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• pp.35-42
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• 1999

In order to cope with the changes of container terminal situation in these days, many simulation studies for container terminal have been accomplished. But established simulation studies using simulation language have restrictions in model representation and difficulties in modeling of large scaled container terminal system. To make these problems better, in this paper addresses object-oriented simulation of container terminal system using a DEVS formalism. In a step of system modeling, using a DEVS formalism aim at the exact system modeling that has a basis of semantics and utilizing the object-oriented manner can flexibly cope with the changes of system environment. In this study a model was developed and verified through the simulation of some alternatives.

• Proceedings of the Korea Society for Simulation Conference
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• 2005.05a
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• pp.100-105
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• 2005

Development of complex discrete event simulators requires cooperation between domain experts and modeling experts who involve the development. With the cooperation the domain experts derive user requirement and modeling experts transform the requirement to a simulation model. This paper proposes a method for consistency verification of simulation model in DEVS formalism against the user requirement in UML diagrams. It also presents an automated tool, called VeriDEVS, which implements the proposed method. Inputs of VeriDEVS are three UML diagrams, namely use case, class and sequence diagrams, and DEVS Graph, all in Visio; outputs of a verification result is represented in PowerPoint files.

• Proceedings of the Korea Society for Simulation Conference
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• 2005.05a
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• pp.123-128
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• 2005

War-game modeling and simulation system have been developed and applied to virtual tactical training both inside and outside of country However, most existing models have been developed for individual purpose based on the simple platform modeling such as physical modeling, visual modeling, and conceptual modeling. Thus, those modeling and simulation system cannot support the interoperability, expensively, variety and reusability. To deal with these problems, the paper propose an integrated design methodology for the War-game systems based on the DEVS/HLA.