Chang Beom Choi

DEVSim++Toolset for Defense Modeling and Simulation and Interoperation

Discrete Event Systems Specification (DEVS) formalism supports the specification of discrete event models in a hierarchical and modular manner. Efforts have been made to develop the simulation environments for the modeling and simulation (M&S) of systems using DEVS formalism, particularly in defense M&S domains. This paper introduces the DEVSim++ toolset and its applications. The Object-Analysis Index (OAI) matrix is a tabular form of objects and analysis indices for requirements analysis. DEVSim++ is a realization of DEVS formalism in C++ for M&S. VeriTool is a DEVS model verification tool. DEVSimHLA is a library to support High-level Architecture (HLA) in DEVSim++. Other tools, including KComLib, FOM2CPPClass, and KHLAAdaptor, are used to develop a smart adaptor that allows for the interoperation of simulators of any kind. PlugSim is a distributed simulation framework using plug-in methods. These tools are utilized in every stage of the M&S development process, as well as in every application of the M&S missions to the military domain. Accordingly, the applications implemented by the toolset are used in the training, analytic, and acquisition missions of the Republic of Korea military branches. We expect the DEVS applications to become more prolific as M&S demands grow, and our toolset is already proven as complete and efficient in the domain of defense M&S.

DEVS-based combat modeling for engagement-level simulation

This paper presents a modeling method to demonstrate engagement-level military simulation which includes few combat objects, or entities. To this end, the paper, on the basis of the discrete event system specification (DEVS) formalism, centers on two ideas: (1) a combat entity’s model structure at the composition level; and (2) behavioral delineation of the entity’s elementary component. In detail, we classify the combat entity model into platform and weapon models and create six groups of the model categorized by two dimensions: three activities and two abstractions. And the elementary component in the group interprets an engagement scenario as a flow of executable tasks, which are expressed by DEVS semantics. The stated structures and semantics provide intuitive appeal, reducing the effort required to read and understand the model’s behavior. From the combat experiments, we can gain interesting experimental results regarding engagement situations employing underwater weapons and their tactical operations. Finally, we expect that this work will serve an immediate application suited to various engagement situations.

Battle Experiments of Naval Air Defense with Discrete Event System-based Mission-level Modeling and Simulations:

The modern naval air defense of a fleet is a critical task dictating the equipment, the operation, and the management of the fleet. Military modelers consider that an improved weapon system in naval air defense (i.e. the AEGIS system) is the most critical enabler of defense at the engagement level. However, at the mission execution level, naval air defense is a cooperative endeavor of humans and weapon systems. The weapon system and the command and control (C2) structure of a fleet engage in the situation through human reporting-in and commands, as well as weapon deployments. Hence, this paper models the combination of the human and the weapon systems in naval air defense by covering the C2 hierarchy of the fleet, as well as the weapon systems of warships. After developing this mission-level model, we perform battle experiments with varying parameters in the human and weapon aspects. These battle experiments inform us of the impact of the changes in the human and the weapon systems. For example, the speed of incoming missiles is a critical parameter for a fleet’s survival; yet the decision-making speed is another outstanding parameter, which illustrates that there is more to improve than the weapon system when considering the mission level. This modeling and these experiments provide an example, suggesting a method of combining the human C2 and the weapon systems at the mission level in the military domain.The modern naval air defense of a fleet is a critical task dictating the equipment, the operation, and the management of the fleet. Military modelers consider that an improved weapon system in naval air defense (i.e. the AEGIS system) is the most critical enabler of defense at the engagement level. However, at the mission execution level, naval air defense is a cooperative endeavor of humans and weapon systems. The weapon system and the command and control (C2) structure of a fleet engage in the situation through human reporting-in and commands, as well as weapon deployments. Hence, this paper models the combination of the human and the weapon systems in naval air defense by covering the C2 hierarchy of the fleet, as well as the weapon systems of warships. After developing this mission-level model, we perform battle experiments with varying parameters in the human and weapon aspects. These battle experiments inform us of the impact of the changes in the human and the weapon systems. For example, the speed of incoming missiles is a critical parameter for a fleets survival; yet the decision-making speed is another outstanding parameter, which illustrates that there is more to improve than the weapon system when considering the mission level. This modeling and these experiments provide an example, suggesting a method of combining the human C2 and the weapon systems at the mission level in the military domain.

DEXSim: an experimental environment for distributed execution of replicated simulators using a concept of single simulation multiple scenarios

This paper presents an efficient and scalable experimental environment for distributed execution of replicated simulators. By taking a performance-centered approach, the proposed technique makes the best use of distributed hardware resources for faster data collection. Accordingly, the primary contribution of this work is to describe how the environment improves scalability and utilizes distributed hardware resources efficiently. To do this, we suggest a new concept of single simulation multiple scenarios and propose a distributed execution simulation framework regarding the following three aspects: (1) layered architecture model design; (2) protocol definitions interacting with them; and (3) framework implementation. The proposed model architecture and protocol definitions guarantee a straightforward structural scalability and an efficient load-balanced utilization between hardware resources. Moreover, the framework operates simulation execution automatically without users’ extra work. In order to prove the efficiency of the proposed framework, we performed three extensive experiments with different models, that is, different systems. The experimental results show that simulation performance increases proportionally with the number of hardware resources, minimizing the overhead of the proposed framework’s utilization.

DEVS-based doctrine validation of fleet anti-air defense

The fleet anti-air defense system is growing increasingly complex. This complexity requires a complicated doctrine for its operators, and the doctrine needs to be analyzed under what-if scenarios. The most ideal analysis method is investigating live combat outcomes, yet such events rarely occur. Hence, we develop a discrete event-based model, perform battle experiments of fleet anti-air defense, and analyze the results. This battle experiment resulted in a better fleet formation against air threats and recommendations for weapon loads on warships.

An HLA-Based Distributed Cosimulation Framework in Mixed-Signal System-on-Chip Design

In mixed-signal system-on-chip (SoC) design, distributed cosimulation is one of the practical approaches for unifying various abstracted hardware models using different description languages. Conventional ad hoc distributed cosimulation solutions do not have formal theoretical backgrounds of simulator integration into their solutions. In this brief, we propose a general cosimulation framework based on the high-level architecture (HLA) and newly defined programming language interface for interoperation (PLI-I) as a formal simulator interface. Based on the PLI-I and HLA, we propose formal integration and interoperation procedures. To reduce integration costs, the procedures have been developed into a common library and then merged with model-dependent signal-event converter to handle differently abstracted in/out signals. During the interoperation, to resolve the different time-advance mechanisms of the digital and analog simulators, the adapter executes an advanced HLA-based synchronization based on the presimulation concepts. The case study shows the reduced design effort in integrating and validating the heterogeneous models and simulators using the proposed framework in mixed-signal SoC design.

High-Level Architecture service management for the interoperation of federations

In High-Level Architecture, federates are integrated into a federation in single Run-Time Infrastructure middleware, which handles High-Level Architecture services for interoperation. The interoperation of federations is required in order to combine systems simulated in existing federations. Unlike a single federation, the interoperation of federations provides the data security and makes it possible to interoperate federates developed in different Run-Time Infrastructures. Previous research has used a proxy method to interoperate federations without modifying the Run-Time Infrastructure. Based on the proxy method, this paper proposes a form of High-Level Architecture service management for the interoperation of federations. Federations construct a twotwo–level hierarchical federation that uses proxies to interoperate different levels and that defines the data structure for interoperation and data security. For each High-Level Architecture service protocol, we propose the algorithms of the proxy and show how the service protocol works in the two-level hierarchical federations. In addition, the proxy handles the race condition, which may occur in interoperation of federations, and describes how to solve it. The algorithms are verified theoretically, and a case study shows the practical application for the interoperation of federations.

A Scalable Modeling and Simulation Environment for Chemical Gas Emergencies

To reflect an evacuation process using a conventional agent-based approach to model human movement under chemical gas exposure, a scalable and hybrid agent-based simulation (ABS) model incorporates an interactive computational fluid dynamics (CFD) gas flow model. To embrace the hybrid ABS model, CFD model, and models for countermeasure in various domains, a scalable runtime infrastructure (RTI)-based simulation environment is also proposed. This environment provides a simulator-level interface to integrate a continuous and discrete-event simulator into the RTI by resolving data/event interaction and time synchronization among heterogeneous simulation models. The authors successfully interoperated the hybrid ABS model, interactive CFD model, control center model, and gas sensor model to evaluate the countermeasures in the proposed environment. As a case study, they applied a 3D-based virtual training engine as a standalone modeling and simulation element to show the scalability of the proposed environment.

Time management in hierarchical federation using RTI-RTI interoperation

High Level Architecture (HLA) provides interoperation of federates, and hierarchical federation was proposed to extend interoperability to the federation level. In a hierarchical federation, several federations make a hierarchical structure using proxies which represent the behavior of the federations. Time synchronization of federates is essential for interoperation and should be accomplished in hierarchical federation. Previous research studies have suggested a time synchronization algorithm based on LITS (Least Incoming Time Stamp) but a deadlock problem remains in some cases. This paper proposes time management in hierarchical federation. We propose time synchronization algorithm to solve the deadlock problem and stipulates the time states of the proxy for representing federation. A proxy model is constructed based on the proposed algorithm and the algorithm is verified to work correctly in hierarchical federation.

Extendable Simulation Framework for Virtual World Environment Based on the DEVS Formalism

A virtual world is an interactive virtual environment in which users interact with each other with computers, and can be used as a platform for virtual training activities. In order to enhance the trainee’s immersive experience, domain-specific simulation models are required for virtual world services. For this reason, we propose an extendable simulation framework for the virtual world. The simulation framework is composed of Core Simulation Framework and Virtual Level Architecture. By utilizing the Core Simulation Framework and the Virtual Level Architecture, the content creator of the virtual world can create extendable simulations for domain-specific content.