• Journal of the Korea Society for Simulation
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• v.19 no.3
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• pp.127-135
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• 2010

Modern marine navigation requires officers on the bridge to monitor a torrent of data on both the insides and outsides of the ship from numerous useful devices. But despite these tools, navigators can still find it difficult to make a safe decision for two reasons: one is that too much data if provided too quickly tends to cause fatigue and overwhelm the officer, and the other is that any inconsistency across data from several different types of devices can lead to confusion. Indeed, the fact remains that the many marine accidents can be attributed to human error, and hence there is a strong need for decision-support tools for marine navigation. One technique of providing decision support is through the use of simulation to evaluate or predict system dynamics over time using an accurate model. This paper, as a simulation method for risk prediction for a navigation safety information system of ship, suggests a navigation prediction simulation system using various knowledge bases and discrete event simulation methodology, and supports the validity of the system through the examples of components in a restricted navigation situation scenario.

• Journal of the Society of Naval Architects of Korea
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• v.45 no.6
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• pp.656-668
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• 2008

When it comes to design and acquire underwater vehicles such as a submarine and a torpedo according to the process of SBA(Simulation Based Acquisition)/SBD(Simulation Based Design), it is necessary to predict the performance of interest precisely and to perform the test over and over again using the M&S(Modeling and Simulation) of the engineering and the engagement level. In this paper, we research the DEVS(Discrete Event System Specification) and DTSS(Discrete Time System Specification) formalism based standard model architecture for the underwater vehicle which can support both the heterogeneous level of the M&S(Engineering/Engagement) and the different system of the M&S(Discrete Event System and Discrete Time System). To validate this standard modeling architecture, we apply it to the submarine normal diving simulation.

• Journal of the Korea Society for Simulation
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• v.19 no.3
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• pp.27-35
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• 2010

War-games using C4I systems have been used to improve the command ability of commanders and the fighting power of combat forces. During a war-game simulation, a commander makes a plan for the movement of a combat force and issues orders to the combat force according to the plan. If it is possible to minimize damages from the artillery of enemy forces and take the advantage position where is effective for attack/defense, we can hold a dominant position of the battlefield. Therefore, this papers proposes a genetic algorithm-based optimal path searching method. The proposed method creates an optimal path of a combat force by taking into consideration dangerous conditions of the battlefield in which the combat force is. This paper also shows the process of creating an optimal path by using a discrete event specification modeling and simulation method.

• Journal of the Korea Society for Simulation
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• v.22 no.1
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• pp.21-30
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• 2013

A hybrid system is a combination of sub systems which have different types of state and time: a typical example is a combination of discrete event and continuous systems. A HDEVS(Hybrid DEVS) formalism was proposed for modeling and analyzing a hybrid system. The HDEVS formalism allows modelers to construct a hierarchical and modular model based on the mathematical set theory. Because the HDEVS formalism was applied to the distributed and interoperated simulators, modelers should make several heterogenous models dividing a target system. Hence, this paper proposes an extended hybrid coupled model of HDEVS formalism and an integrated hybrid modeling methodology in contrast to the existing simulation framework on interoperable simulators. By applying the proposed modeling method, a target system can be translated to a hybrid model in a similar form as the target system. This paper also contains a simulation engine design for the proposed modeling methodlogy and a case study which simulates water tank control systems.

• Journal of Computational Design and Engineering
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• v.1 no.3
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• pp.213-222
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• 2014

This paper reviews and identifies issues in the application of virtual commissioning technology for automated manufacturing systems. While the real commissioning of a manufacturing system involves a real plant system and a real controller, the virtual commissioning deals with a virtual plant model and a real controller. The expected benefits of virtual commissioning are the reduction of debugging and correction efforts during the subsequent real commissioning stage. However, it requires a virtual plant model and hence still requires significant amount time and efforts. Two main issues are identified, the physical model construction of a virtual device, and the logical model construction of a virtual device. This paper reviews the current literature related to the two issues and proposes future research directions to achieve the full utilization of virtual commissioning technology.

• Journal of the Korean Operations Research and Management Science Society
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• v.16 no.2
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• pp.128-147
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• 1991

We propose a dynamic incidence matrix (DIM) for reflecting states and time conditions of a timed Petri net (TPN) explicitly. Since a DIM consists of a conventional incidence matrix, two time-related vectors and two state-related vectors, we can get the advantages inherent in the conventional incidence matrix of describing a static structure of a system as well as another advantage of expressing time dependent state transitions. We introduce an algorithm providing the DIM with a state transition mechanism. Because the algorithm is, in fact, an algorithmic model for discrete event simulation of TPN models, we provide a theoretical basis of model transformation of a TPN model into a DEVS(Discrete Event system Specification) model. By executing the algorithm we can carry out performance analysis of computer communication protocols which are represented TPN models.

• Proceedings of the Korea Information Processing Society Conference
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• 2010.11a
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• pp.538-541
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• 2010

상황인지 시뮬레이션이란 상황자료의 수집, 추론 및 결론 도출의 과정을 실제 환경이 아닌 가상의 시뮬레이션 환경 안에서 실험해 볼 수 있는 것을 말하며, 상황인지 기술과 DEVS(Discrete Event System Specification), 페트리-넷(Petri-Net)등의 기반 기술이 사용된다. 본 논문에서는 사용자들이 보다 편리하게 상황인지 시스템을 구축하고 실제보다 적은 시간으로 구축된 시스템을 실험할 수 있는 시뮬레이션 환경을 제공할 수 있는 통합 개발 프레임워크를 개발하고자 한다. 시뮬레이션 통합 개발 프레임워크 특징으로는, 첫째 상황인지를 위한 추론 기능을 가지는 에이전트와 시뮬레이션 기능들을 플러그인 및 라이브러리로 제공할 수 있고, 둘째, 통합환경 안에서 제공되는 도구들을 사용하여 사용자들이 보다 편리하게 개발 및 실험을 할 수 있다는 장점이 있다. 따라서 본 논문에서는 상황 아키텍처를 위한 모델 표현 계층, 멀티 에이전트 시스템을 위한 연산 계층, 환경과의 상호작용을 위한 인터랙션 계층, 그리고 시뮬레이션 계층인 4-계층구조의 통합개발환경을 연구하였다.

• Proceedings of the Korea Information Processing Society Conference
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• 2007.11a
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• pp.793-796
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• 2007

RFID (Radio Frequency IDentification) 리더의 동작 영역은 리더의 감도와 전력이 도달할 수 있는 거리에 의해 제한된다. RFID Shower 는 근접한 리더로부터 전송되는 신호를 증폭하여 리더의 동작영역을 확장한다. 그러나, RFID Shower 의 동작 영역 안에 여러 리더들이 있을 경우 리더들간의 신호충돌이 발생한다. 이를 해결하기 위해 중재 알고리즘이 제안되었다. 본 논문에서는 RFID 리더들을 위한 중재 알고리즘을 DEVS 형식론에 기반하여 모델링하고 시뮬레이션 하여 성능을 측정, 비교하였다.

• Journal of the Korea Society for Simulation
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• v.17 no.2
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• pp.49-61
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• 2008

Most battleship warfare M&S systems run relatively slow and the simulation results are often unfair since the system should interact with human operators(controller and/or gamer). To deal with these problems, we have proposed the agent-based battleship warfare M&S system which interact with multiple agent systems instead of human operators. Agent-based M&S system may be able to efficiently support the analysis of effectiveness and/or the operational tactics development of given warfare by providing autonomous reasoning capabilities without the intervention of human controller. To do this, the paper propose the design concept and methodology using the advanced modeling and simulation framework as well as autonomous agent design principle. Several simulation tests performed on the battleship warfare case study on Korea Yellow sea will illustrate our techniques.

• Proceedings of the Korea Society for Simulation Conference
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• 1994.10a
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• pp.32-32
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• 1994

In this example, a message passing based multicomputer system with general interdonnedtion network is considered. After multicomputer systems are developed with morm-hole routing network, topologies of interconecting network are not major considertion for process management and resource sharing. Tehre is an independeent operating system kernel oneach node. It communicates with other kernels using message passingmechanism. Based on this architecture, the problem is how mech does performance degradation will occur in the case of processor sharing on multicomputer systems. Processor sharing between application programs is veryimprotant decision on system performance. In almost cases, application programs running on massively parallel computer systems are not so much user-interactive. Thus, the main performance index is system throughput. Each application program has various communication patterns. and the sharing of processors causes serious performance degradation in hte worst case such that one processor is shared by two processes and another processes are waiting the messages from those processes. As a result, considering this problem is improtant since it gives the reason whether the system allows processor sharingor not. Input data has many parameters in this simulation . It contains the number of threads per task , communication patterns between threads, data generation and also defects in random inupt data. Many parallel aplication programs has its specific communication patterns, and there are computation and communication phases. Therefore, this phase informatin cannot be obtained random input data. If we get trace data from some real applications. we can simulate the problem more realistic . On the other hand, simualtion results will be waseteful unless sufficient trace data with varisous communication patterns is gathered. In this project , random input data are used for simulation . Only controllable data are the number of threads of each task and mapping strategy. First, each task runs independently. After that , each task shres one and more processors with other tasks. As more processors are shared , there will be performance degradation . Form this degradation rate , we can know the overhead of processor sharing . Process scheduling policy can affects the results of simulation . For process scheduling, priority queue and FIFO queue are implemented to support round-robin scheduling and priority scheduling.