• Journal of the Korea Society for Simulation
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• v.26 no.4
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• pp.51-61
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• 2017

Hadoop platform is a representative storing and managing platform for big data. Hadoop consists of distributed computing system called MapReduce and distributed file system called HDFS. It is important to analyse the effectiveness according to the change of cluster constructions and several parameters. However, since it is hard to construct thousands of clusters and analyse the constructed system, simulation method is required to analyse the system. This paper proposes Hadoop simulator based on DEVS formalism which provides hierarchical and modular modeling. Hadoop simulator provides a retargetable experimental environment that is possible to change of various parameters, algorithms and models. It is also possible to design input models reflecting the characteristics of Hadoop applications. To maximize the user's convenience, the user interface, real-time model viewer, and input scenario editor are also provided. In this paper, we validate Hadoop Simulator through the comparison with the Hadoop execution results and perform various experiments.

• Journal of the Korea Society for Simulation
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• v.21 no.2
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• pp.31-39
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• 2012

Simulation Framework is a basic software tool used to develop simulation applications. This paper describes the development of a discrete event simulation framework based on DEVS(Discrete EVent System Specification) formalism, using MATLAB language which is widely used in technical computing and engineering disciplines. The newly developed framework utilizing MATLAB object oriented programming combines the convenience of MATLAB language and the sophisticated architecture of the DEVS formalism. Hence, it supports the productivity, flexibility, extensibility that are required for the simulation application software development of the weapon systems engagement. Moreover, it promises a simulation application the increased the computation speed proportional to the number of CPU of a multi-core processor, providing the batch simulation functionality based on MATLAB parallel computing technology.

• Journal of the Korea Society for Simulation
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• v.20 no.1
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• pp.87-96
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• 2011

DEVS(Discrete Event Systems Specification) is a set theoretic formalism developed for specifying discrete event system. For execution of DEVS, we need an execution environment, which consists of simulation engine and models interpreted by the simulation engine. Common existing environments use hierarchical scheduling algorithm for DEVS execution. This hierarchical scheduling is a proper algorithm for DEVS execution because of hierarchical and modular characteristics. But this algorithm has overheads owing to message passing and time management. To overcome these overheads, we apply event-oriented simulation to DEVS execution and we remove hierarchical overheads. In eventoriented simulation, the scheduling of model execution is performed by events and event list. We propose three event-oriented execution environments for DEVS and experiment about the performance of our proposed environments in comparison with the existing execution environment using the hierarchical scheduling. The experimental results show our environments works better than existing environment using the hierarchical scheduling.

• Journal of the Korea Society for Simulation
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• v.6 no.1
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• pp.1-13
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• 1997

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.

• Proceedings of the KOSOMBE Conference
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• v.1995 no.05
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• pp.87-91
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• 1995

Combined models, specified by two or more modeling formalisms, can represent a wide variety of complex systems. This paper describes a methodology for the development of combined models in two model types of discrete events and continuous process. The methodology is based on transformation of continuous state space into discrete one to homomorphically represent dynamics of continuous processes in discrete events. As an example, a combined model of human heart is developed which Incorporates conventional differential equation formalism with Zeigler's DEVS(Discrete Event Specification System) [4]formalism.

• Proceedings of the Korea Society for Simulation Conference
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• 2001.05a
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• pp.77-81
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• 2001

In this paper, a RAID system is modeled and simulated by using the DEVS formalism. The RA[D system interacts with a host system by using the high-speed Fibre channel protocol and stores input data in an array of IDE disks. The DEVS formalism specifies discrete event systems in a hierarchical, modular manner. The RAID system model is composed of three units: primary-PCI unit, secondary-PCI unit and CPU unit. The primary-PCI unit interfaces with the host system and caches I/O data. The secondary-PCI unit includes disks. The CPU unit controls overall system. The control algorithm of CPU and PCI transactions are analyzed and modeled. From an analysis of simulation events, we can conclude that the proposed model satisfies given requirements.

• 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.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.12B
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• pp.1435-1443
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• 2009

In this paper, an energy harvesting sensor network system is modeled and simulated by using the DEVS (Discrete Event System Specification) formalism. The system is composed of a sink (master) node, which is battery or mains powered, and a set of sensor (slave) nodes, each of which harvests ambient energy and converts it into electrical energy. For simulation, (i) the behavior of energy harvesting and storing circuits of the slave node is partitioned into a set of piecewise continuous segments and then each segment is represented as a discrete state; (ii) the interaction among the master node and components of the slave node is investigated preciously; and (iii) the investigated result is modeled and simulated by using the DEVS formalism.

• Journal of KIISE:Computer Systems and Theory
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• v.30 no.7_8
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• pp.370-380
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• 2003

A large RAID system may consist of several PCI bus segments since a PCI bus segment can connect only a limited number of disks. In this paver, PCI bus transactions in a RAID system are classified in terms of the initiator and the target of the transaction. Also, the data transfer time of each transaction type is analyzed. By using the analysis results, read and write performance of two RAID system configurations are formulated. From simulation of the RAID system using the DEVS formalism, performance of the configurations are evaluated and compared with the analytical results while changing various system parameters.

• Journal of the Korea Society for Simulation
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• v.27 no.2
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• pp.61-69
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• 2018

As the technology of information and communication has developed over recent years, an embedded system is applied in multiple industries and becomes more complicated. For this reason, embedded system development cost and time are also increased. For decreasing the cost and time, this paper suggests requirement evaluation method for concurrent development of an embedded system based on Discrete Event System(DEVS) Formalism. This paper proposes a method of describing the requirements specification in the form of DEVS atomic model. Also, the paper proposes the evaluator model that compares evaluation target system and the requirements model that is an implementation of requirement specification and proposes the evaluation method using them. In addition, we propose a method to utilize the requirement model created for requirements evaluation in the concurrent development process of the embedded system. As the case study, this paper proceeds requirement evaluation of Kinect depth data processing system.