• Proceedings of the Korea Society for Simulation Conference
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• 1994.10a
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• pp.7-8
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• 1994

최근 들어 원자재, 재공품 또는 완제품을 신속하고 정확하게 공급/배분하기 위해 저장과 인출을 담당하는 Material Handling System을 이용하여 작업자의 개입요소를 줄이며, 제고관리 Computer를 이용하여 입고/출고 명령을 유효적절하게 처리하는 ASRS(Atomated Storage and Retreival System : 자동창고 시스템)가 널리 공급되고 있다. 중앙은행의 현금창고, 병원의 약품창고, 식품/화장품 회사의 배송창고, 군수물자의 군납창고에 이르기까지 물품의 저장 또는 공급의 필용성을 갖는 곳에서는 어디든지 찾아볼 수 있는 ASRS는 가깝게는 관공소나 대형빌딩의 주차장에도 이의 개념이 도입되어 사용됨을 볼 수 있다. 최근의 인금인상, 구인난등의 이유로 ASRS설치는 계속 증가할 추세에 있으나 자동 창고 시스템을 설치하기 위해서는 막대한 초기 투자가 필요하며 시스템의 설계 및 설치후 운영에 대한 연구가 반드시 필요하다. ASRS의 운영 Rule 검증, 수행능력 분석등의 목적을 갖는 연구에는 여러 접근방법이 있을 수 있으나 구성 설비와 운영 Rule의 복잡한 관계로 컴퓨터 시뮬레이션의 거의 유일한 문제해결 방법이다. ASRS의 Modeling에 관한 기존의 연구로는 수리모델 수립. 이산사건 시스템의 관점에서 event-graphy, petri-net을 이용한 modeling이 있으며 ASRS에 대한 전용 Simulator 개발등이 진행되었다. 본 연구의 대상 시스템은 2개의 Rack과 하나의 Stacker Crane 으로 구성된 Aisle과 입출고의 물류를 처리하는 순환 RGVS(Rail Guided Vehicle System), 입/출고장을 구성하는 Conveyor Net등으로 이루어진 제조-물류시스템의 일반적인 ASRS이다. 또 이 ASRS의 입/출고 방식은 전수 입/출고만을 포함하며 Blocking 방지를 위한 Capaicty 예약, 다중설비 선택등의 문제등을 고려하고 있다. 본 연구의 접근방법으로는 ASRS의 개념적인 Reference Model을 수립하고 이 Reference Model에 대한 Formal Model로 DEVS(Discrete Event System Specification)을 이용하여 시스템을 Modeling하였다. 이의 Computer Simulation을 위하여 DEVS형식론 환경에서의 Simulation Language인 DEVSim ++ⓒ를 이용하여 시스템을 구현하였다.

• Journal of the Society of Naval Architects of Korea
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• v.47 no.4
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• pp.628-645
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• 2010

To perform the engagement level simulation between the underwater vehicle model and the surface model those are constituted with various systems/ sub-systems, we implemented four different federates as a federation according to the IEEE 1516 HLA (High Level Architecture) protocol that is the international standard in the distributed simulation. Those are CFCS (Command and Fire Control System) federate, motion federate, external entities (torpedos, countermeasure and surfaceship) federate, and visualization federate that interacts with OSG (Open Scene Graph)-based visualization rendering module. In this paper, we present the detailed method about the model constitution for discrete event simulation in the distributed environment. For the sake of this purpose, we introduce the DEVS (Discrete Event System Specification)-HLA-based modeling method of the CFCS federate that reflects not only the interations between models, but also commands from user and tactics manager that is separated from the model. The CFCS federate makes decisions in various missions such as the normal diving, the barrier misision, the target motion analysis, the torpedo launch, and the torpedo evasion. In the perspective of DEVS modeling, the CFCS federate is the coupled model that has the tactical data process model, command model and fire control model as an atomic model. The message passing and time synchronization with other three federates are settled by the $m\ddot{a}k$ RTI (Runtime Infrastructure) that supports IEEE 1516. In this paper, we provides the detailed modeling method of the complicated model that has hierarchical relationship such as the CFCS system in the submarine and that satisfies both of DEVS modeling method for the discrete event simulation and HLA modeling method for the distributed simulation.

• Nuclear Engineering and Technology
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• v.21 no.3
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• pp.223-230
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• 1989

This paper describes dynamic simulation of the spent fuel storage system which is described by statistical discrete event models. It visualizes flow and queue of system over time, assesses the operational performance of the system acitivies and establishes the system components and streams. It gives information on system organization and operation policy with reference to the design. System was tested and analyzed over a number of critical parameters to establish the optimal system. Workforce schedule and resources with long processing time dominate process. A combination of two workforce shifts a day and two cooling pits gives the optimal solution of storage system. Discrete system simulation is an useful tool to get information on optimal design and operation of the storage system.

• Journal of Korean Society of Transportation
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• v.12 no.3
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• pp.49-64
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• 1994

The development of a mathematical modular framework based on Petri Network theory to model a traffic network is the subject of this paper. Traffic intersections are the primitive elements of a transportation network and are characterized as event driven and asynchronous systems. Petri network have been utilized to model these discrete event systems; further analysis of their structure can reveal information relevant to the concurrency, parallelism, synchronization, and deadlock avoidance issuse. The Petri-net based model of a generic traffic junction is presented. These modular networks are effective in synchronizing their components and can be used for modeling purposes of an asynchronous large scale transportation system. The derived model is suitable for simulations on a multiprocessor computer since its program execution safety is secured. The software pseudocode for simulating a transportation network model on a multiprocessor system is presented.

• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.96.1-96
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• 2002

$\textbullet$ Abstract $\textbullet$ Introduction $\textbullet$ Building a Model for Diagnosis $\textbullet$ Modular Approach to Diagnosis $\textbullet$ Extension to a General Case $\textbullet$ Conclusion $\textbullet$ References

• Proceedings of the Korea Society for Simulation Conference
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• 1996.05a
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• pp.15-15
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• 1996

A shop floor control system (SFCS) is the central part of a CIM system used to control the activities of several pieces of manufacturing equipment (e.g., NC machines, robots, conveyors, AGVs, AS/RS). The SFCS receives orders and related process plans, and then performs selecting a specific process routing, allocating resources, scheduling the workpieces, downloading the processing instructions (e.g., RS-274 instructions for NC machines, VAL II programs for robot), monitoring the progress of activities, detecting and recovering from errors, and preparing reports on the status of the manufacturing system. Simulation has been utilized in discovering control policies used for resolving shop floor be control problems such as resource contentions, part dispatching, deadlock. The simulation model must be designed to respond to real-time data coming from a shop floor. However, to rapidly build a realtime simulation model of SFCS cannot be easily accomplished. This talk is to address an automatic program generator of discrete event simulation model for shop floor control from process plans and resource models. The program generator is capable of constructing complete discrete simulation models for multi-product and multi-stage flexible manufacturing systems.

• Journal of the Korea Society for Simulation
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• v.21 no.1
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• pp.27-34
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• 2012

Proposed in the paper is an agent based and object-oriented methodology to create a virtual logistics support system model. The proposed virtual logistics support system model consists of three types of objects: the logistics force agent model(static model), the military supplies transport manager model(function model), the military supplies state manager model(dynamic model). A logistic force agent model consists of two agent: main function agent and function agent. To improve the reusability and composability of a logistics force agent model, the function agent is designed to adapt to different logistics force agent configuration. A military supplies transport manager is agent that get information about supply route, make decisions based on decision variables, which are maintained by the military supplies state manager, and transport military supplies. A military supplies state manager is requested military supplies from logistics force agent, provide decision variables such as the capacity, order of priority. For the implementation of the proposed virtual logistics force agent model, this paper employs Discrete Event Systems Specification(DEVS) formalism.

• International Journal of Reliability and Applications
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• v.1 no.1
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• pp.65-79
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• 2000

This research considers a system which has an ultimate terminal event such as death, critical failure, bankruptcy together with a certain indicative events (temporary malfunction, special treatment, kind of defaults) that frequently occurs before the terminal event comes to the system. Some investigation of a model for the corresponding bivariate data of the system have been done with an explanation of the situation in terms of two continuous variables instead of continuous-discrete variables and some other properties. Also an analysis has been carried out to evaluate the effect of intermediate observation of occurrence of indicative event so that the result can be used for a possible suggestion of an intermediate observing schedule.

• 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 Academia-Industrial cooperation Society
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• v.13 no.8
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• pp.3319-3325
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• 2012

This paper describes the development of the TrackSim, which is a discrete event simulation tool for photolithography equipment of semiconductor industry. The TrackSim is focused on the accurate simulation model of the photolithography equipment and easy-to-use user interfaces. TrackSim provides 3D simulation environment for evaluating, validating, and scheduling the photolithography process. One of the major characteristics of TrackSim is in that it is developed based on Applied Materials' AutoMod, a discrete event simulation software broadly used in semiconductor industry. Accordingly, the photolithography model of TrackSim can be used to perform simulation connected with other simulation models built with AutoMod.