• Korean Journal of Computational Design and Engineering
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• v.18 no.3
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• pp.224-233
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• 2013

For the scheduling and the job assignment of the ship hull production design which is a process-based work, we suggest the simulation-based scheduling using the discrete-event-based business process simulation. First, we analyze the ship hull production design process from the perspective of a job assignment to make it into the simulation model using DEVS (Discrete Event System Specification) which is the representative modeling method for a discrete-event simulation. Based on the APIs of the open-source discrete-event simulation engine, we implement the simulation using the Groovy script. We develop the scenario generator in which the user defines detail information of the construction drawing and its member blocks, and design engineers information, and the various setting for the simulation including the job assignment strategy. We use the XML files from this scenario generator as inputs of simulation so that we can get simulation result in forms of Gantt chart without changes of the simulation model.

• Proceedings of the Korea Society for Simulation Conference
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• 2003.11a
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• pp.51-57
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• 2003

In operating distributed systems, proactive management is one of the major concerns for better quality of service and future capacity planning. In order to handle this management problem effectively, it is necessary to analyze performances of the distributed system and events generated by components in the system. This paper provides a rule-based event parsing engine for proactive management. Our event parsing engine uses object hooking-based and event-token approaches. The object hooking-based approach prepares new conditions and actions in Java classes and allows dynamically exchange them as hook objects in run time. The event-token approach allows the event parsing engine consider a proper sequence and relationship among events as an event token to trigger an action. We analyze the performance of our event parsing engine with two different implementations of rule structure; one is table-based and the other is tree-based.

• 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.

• 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.

• Journal of Korean Institute of Industrial Engineers
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• v.41 no.6
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• pp.588-598
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• 2015

In this paper, a simulation model for assessing the impact of alternative field service engineer replenishment policies is introduced. The end-to-end supply chain simulation model is created using a discrete-event and agent-based simulation model, which enables accurate description of key individual entities in the investigated supply chain, such as field service engineers. Once the model is validated with the historical data, it is used to assess the impacts of field service engineer replenishment policies for a major printing equipment manufacturing firm.In the case study, newly proposed replenishment policies for post-sale distribution supply chain are assessed for the level of service improvement to end customers.

• Proceedings of the Korea Society for Simulation Conference
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• 2003.11a
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• pp.95-103
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• 2003

Event notification service is a event-based messaging middle ware service needed for various vertical domains, such as, business applications, distributed system management, and web service integration. In this paper, we investigate the architecture of an event notification service that includes a subject-based event dissemination service and a flexible message communication service. The event dissemination service is in charge of transferring events asynchronously but speedy according to the subjects of events and their environmental knowledge. It also includes content-based message filtering. The message communication service provides a common communication infrastructure supporting variety types of messages and variety of protocols. Depending on application domains and situation, we can re-configurate the communication infrastructure in order to optimize the efficiency and usability. This paper shows the performance analysis of our event notification service with various types of message formats and protocols.

• Proceedings of the Korea Society for Simulation Conference
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• 2001.10a
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• pp.453-458
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• 2001

A mobile agent is an autonomous software agent capable of moving from one computer to another while performing its tasks. We view the agent as a discrete event system in the view of its computation and communication. This paper presents a methodology far modeling and simulation of such a mobile agent system as a discrete event system. The methodology is based on the Mobile Discrete Event System Specification (MDEVS) formalism and the associated simulation environment AgentSim which are previously developed by the authors. Within the methodology an atomic model represents dynamics of a mobile agent; a coupled model is modeled as mobile agent servers for representation of structural changes between atomic agents. Being based on the object-oriented environment the modeling methodology exploits inheritance of basic classes AtomicModel and CoupledModel provided by AgentSim.

• International Journal of Naval Architecture and Ocean Engineering
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• v.8 no.1
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• pp.83-101
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• 2016

This paper suggests an event-based scenario manager capable of creating and editing a scenario for shipbuilding process simulation based on multibody dynamics. To configure various situation in shipyards and easily connect with multibody dynamics, the proposed method has two main concepts: an Actor and an Action List. The Actor represents the anatomic unit of action in the multibody dynamics and can be connected to a specific component of the dynamics kernel such as the body and joint. The user can make a scenario up by combining the actors. The Action List contains information for arranging and executing the actors. Since the shipbuilding process is a kind of event-based sequence, all simulation models were configured using Discrete EVent System Specification (DEVS) formalism. The proposed method was applied to simulations of various operations in shipyards such as lifting and erection of a block and heavy load lifting operation using multiple cranes.

• 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.

• 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.