• Journal of the Korea Society for Simulation
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• v.20 no.3
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• pp.89-100
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• 2011

The MAGLEV (Magnetically Levitated Vehicle) system, which is under commercialization as a new transportation system in Korea, is operated by means of unmanned automatic control system. Therefore the plan of train operation should be carefully established and validated in advance. In general, when making the train operation plan, the statistically predicted traffic data is used. However, traffic wave can occur when real train service is operated, and the demand-driven simulation technology is required to review train operation plans and service qualities considering traffic wave. This paper presents a method and model to simulate the MAGLEV's operation considering continuous demand changes. For this purpose, we employed the discrete event model which is suitable for modeling the behavior of railway passenger transportation, and modeled the system hierarchically using DEVS (Discrete Event System Specification) formalism. In addition, through the implementation and experiment using DEVSim++ simulation environment, we tested the feasibility of the proposed model and it is also verified that our demand-driven simulation technology could be used for the prior review of the train operation plans and strategies.

• Journal of the Korea Institute of Military Science and Technology
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• v.10 no.3
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• pp.90-99
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• 2007

The DEVS formalism has the well-defined relationship between its model and simulator. However, it does not define the connection between its model and experimental frame needed when a simulator's implemented with it. So, in most DEVS based simulators, the modules of the two parts are tangled, so that changing and reusing them is not easy. This paper proposes a method to improve the changeability of the experimental frame and the reusability of the model by modularizing the two parts using the AOP technology. I applied the new method to a real project, and the result shows that it improves the two qualities effectively than before.

• Journal of Engineering Education Research
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• v.16 no.5
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• pp.18-23
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• 2013

A curriculum is a measure of how high level of knowledge is educated to students affiliated to university institutions, and is used as an indicator evaluating usefulness of the university institutions. For this reason, Designing and assessing curricula is a critical to high education institutions. However, in the case of development and quality assessment of a curriculum with a traditional way, finding a right curriculum which a designer intends is a time consuming and error-prone process. Therefore, in order to improve these problems, we propose the curriculum design engine using SES (System Entity Structure) / DEVS (Discrete Event System Specification) Framework in this paper. The SES describes all possible combination of curricula for students. The DEVS framework provides a simulation environment for models created from the SES by the students. The proposed engine will show appropriate curricula for students after a simulator appropriately filters students' requirement, according to conditions.

• Journal of the Korea Society for Simulation
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• v.15 no.3
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• pp.1-9
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• 2006

As an effective solution to resolve complex computing problems and to handle geographically dispersed data sets, grid computing has been noticed. Grid computing separates an application to several parts and executes on heterogeneous computing platforms simultaneously. The most important problem in grid computing environments is to manage grid resources and to schedule grid resources. This paper proposes a grid transaction network model that is applicable for resource management and scheduling in grid computing environment and presents a grid resource bidding algorithm for grid users and grid resource providers. Using DEVSJAVA modeling and simulation, this paper evaluates usefulness and efficiency of the proposed model.

• Proceedings of the Korea Society for Simulation Conference
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• 2002.05a
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• pp.53-59
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• 2002

본 연구는 이산 사건 시스템 형식론(DEVS: Discrete Event System Specification)을 이용한 가상전장 모델링 및 시뮬레이션 방법론을 제안한다. 기존 군체계에 관련된 모델링 기술은 물리적 모델링, 비쥬얼 모델링, 또는 개념적 모델링 등 개별 기능중심의 단편적 플랫폼 모델링에 그치고 있으며, 무기체계 분석 시뮬레이션도 개별 단위체 중심으로 평가되어져서, 다양하고 종합적인 그리고 상호운영성과 재사용성 등을 고려한 통합 모델링 및 시뮬레이션 환경을 제공하지 못하는 단점을 갖는다. 따라서 본 논문에서는 개별 전투병력에서부터 첨단 무기체계에 이르는 다양한 전장 요소들을 계층 구조적으로 통합함으로써 전장에서 발생될 수 있는 개별 전투병력의 미시적 행동 특성뿐 아니라 분대/중대/대대/사단급 단위의 거시적 전략/전술에 대한 묘사까지도 가능한 가상전장 모델링 및 시뮬레이션 환경을 제안한다. 제안된 방법론은 분대 단위의 가상전장 환경에 대한 사례연구를 통해 검증하였으며, 향후 연구로는 대단위 가상전장에 대한 묘사를 위한 HLA 분산 시뮬레이션 기술의 적용에 대한 연구가 필요할 것이다.

• International Journal of Naval Architecture and Ocean Engineering
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• v.9 no.4
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• pp.446-459
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• 2017

Naval ships are assigned many and varied missions. Their performance is critical for mission success, and depends on the specifications of the components. This is why performance analyses of naval ships are required at the initial design stage. Since the design and construction of naval ships take a very long time and incurs a huge cost, Modeling and Simulation (M & S) is an effective method for performance analyses. Thus in this study, a simulation core is proposed to analyze the performance of naval ships considering their specifications. This simulation core can perform the engineering level of simulations, considering the mathematical models for naval ships, such as maneuvering equations and passive sonar equations. Also, the simulation models of the simulation core follow Discrete EVent system Specification (DEVS) and Discrete Time System Specification (DTSS) formalisms, so that simulations can progress over discrete events and discrete times. In addition, applying DEVS and DTSS formalisms makes the structure of simulation models flexible and reusable. To verify the applicability of this simulation core, such a simulation core was applied to simulations for the performance analyses of a submarine in an Anti-SUrface Warfare (ASUW) mission. These simulations were composed of two scenarios. The first scenario of submarine diving carried out maneuvering performance analysis by analyzing the pitch angle variation and depth variation of the submarine over time. The second scenario of submarine detection carried out detection performance analysis by analyzing how well the sonar of the submarine resolves adjacent targets. The results of these simulations ensure that the simulation core of this study could be applied to the performance analyses of naval ships considering their specifications.

• Journal of the Korea Institute of Military Science and Technology
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• v.17 no.2
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• pp.235-247
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• 2014

Based on two dimensional model partition method proposed in Part 1, Part 2 provides detailed model specification and implementation. To mathematically delineate a model's behaviors and interactions among them, we extend the DEVS (Discrete Event Systems Specification) formalism and newly propose CE-DEVS (Combat Entity-DEVS) for an upper abstraction sub-model of a combat entity model. The proposed CE-DEVS additionally define two sets and one function to reflect essential semantics for the model's behaviors explicitly. These definitions enable us to understand and represent the model's behaviors easily since they eliminate differences of meaning between real-world expressions and model specifications. For model implementation, upper abstraction sub-models are implemented with DEVSim++, while the lower sub-models are realized using the C++ language. With the use of overall modeling techniques proposed in Part 1 and 2, we can conduct constructive simulation and assess factors about combat logics as well as battle field functions of the next-generation combat entity, minimizing additional modeling efforts. From the anti-torpedo warfare experiment, we can gain interesting experimental results regarding engagement situations employing developing weapons and their tactics. Finally, we expect that this work will serve an immediate application for various engagement warfare.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.12
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• pp.2581-2588
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• 2012

Survivability of combat system is changed by various facts in dynamic battle field. Existing survivability analysis programs for a combat system analyze statically survivability for combat system in spite of dynamic battle environment. To overcome this limitation, we propose an agent-based modeling and simulation method for dynamic survivability analysis of the combat system. To do this, we have adopted DEVS formalism, SES/MB framework and agent technology for modeling components of the combat system and crews. The proposed method has advantages of being able to analyze not only a static survivability of the combat system but also a dynamic survivability of combat system by applying responses of crews in battle field.

• ETRI Journal
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• v.37 no.1
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• pp.175-185
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• 2015

This paper presents a system-of-systems (SoS) approach to the formal modeling of a cyber-physical system (CPS) for simulation-based analysis. The approach is based on a convergence technology for modeling and simulation of a highly complex system in which SoS modeling methodology, hybrid systems modeling theory, and simulation interoperation technology are merged. The methodology maps each constituent system of a CPS to a disparate model of either continuous or discrete types. The theory employs two formalisms for modeling of the two model types with formal specification of interfaces between them. Finally, the technology adapts a simulation bus called DEVS BUS whose protocol synchronizes time and exchange messages between subsystems simulation. Benefits of the approach include reusability of simulation models and environments, and simulation-based analysis of subsystems of a CPS in an inter-relational manner.

• Journal of the Korea Society for Simulation
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• v.16 no.2
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• pp.1-8
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• 2007

Resource management in grid computing environment is essential for integration and interaction among heterogeneous resources. This paper discusses resource management methods of centralized and decentralized broker-based modeling for solving complex problems of resource management and presents design and development of the decentralized broker-based resource management modeling in grid computing environment. This model comprises a global resource broker and a local resource broker, and we derive reduction of communication and functional dispersion of Job management using a local resource broker. The simulation experiment shows the improvement of resource utilization and average response time and proves that this model improves utilization of resources and replies to user requests promptly.