• 대한조선학회논문집
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• 제44권6호
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• pp.647-656
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• 2007

Simulation model of outdoor block movement of shipyard is implemented in this paper. The load of the outdoor workshops in a shipyard influences a mid-term planning and scheduling of the shipyard. Since the load analysis is expected in advance before confirming the planning and scheduling, a discrete event simulation (DES) may be a good solution. The accuracy of DES is up to the accurate modeling of Products, Processes, and Resources (PPR) included in a system. PPR in the outdoor system are clearly defined and the simulation model for the outdoor logistics is implemented by modeling the selective PPR with the help of a DES tool which is programmable by users. The simulation model is verified by comparing the results with the real shipyard data. The outputs through the simulation are discussed.

• 대한조선학회논문집
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• 제50권5호
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• pp.334-342
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• 2013

In this paper, we analyze the procedure of the design manager for the enhancement of the hull production design process by use of the simulation method. Normally, design manager assigns design jobs according to various methods and estimates the corresponding results. When the construction drawing which is the output of the detail design where a design is dealt by zones, the design manager identifies blocks and analyzes their work difficulties, and assigns jobs to design engineers who are different in capabilities. These processes including the design engineer who can be modeled with man-hours evaluation model are represented in detail as a simulation model. As the high-level modeling for the discrete-event system, we use Event Graph model. And we implemented the simulation using Simkit which is open simulation engine for the discrete-event system. We made the simulation scenario to be written by a user in the scenario generator which is separated from the simulation model, and made the simulation result to be visualized in the form of Gantt chart in a Web. In the scenario of the irregular issuance for various construction drawings which contain different numbers of blocks, we performed the Monte-Carlo simulation according to various assignment methods to find the assignment result that satisfies the mid-term schedule.

• 한국경영과학회지
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• 제20권2호
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• pp.159-178
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• 1995

Supervisory control is an approach based on formal language. it is used to model and control discrete event systems in which each discrete event process is represented as an automation. A supervisor is a generator that switches control patterns in such a way that a given discrete evenet process behaves in obedience to various constraints. A flexible manufacturing cell (FMC) is one of discrete evenet systems. Functions necessary for the operation of an FMC are characterized by operational components and informational compoments. The operational components can be modeled using the finite state machines and the informational components can be modeled using the abstract formalism which describes supporting operations of the cell controller. In this paper, we addressed function required for FMC control specification, software engineering aspects on FMC control based on supervisory control, a concept of event queue for resolving synchronization problem, and complexity reduction. Based on the mathematical model of an FMC. we synthesized the controller by integrating a supervisor for FMC with control specification that specifies event-driven operation of the cell controller. The proposed control scheme is stable mathematically so that the system always behaves on a controlled way even under the existence of uncontrollable events. Furthermore, using an event queue concept, we can solve a synchronization problem caused by the violation of instantaneity assumption of supervisory control theory in real life situation. And also, we can propotype a control software rapidly due to the modularity of the proposed control scheme.

• 한국항공우주학회지
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• 제48권2호
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• pp.159-166
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• 2020

본 연구는 복잡한 다수 무인기 시스템을 효율적으로 운용하기 위해 이산 사건 모델 기반의 다수 무인기 이종 임무 할당 기법을 제안한다. 이종 임무의 생성, 임무 할당, 무인기 출동, 임무 수행, 무인기 수리 및 정비에 이르는 무인기의 임무 시작에서 종료까지 일련의 과정을 이산 사건 모델링을 통해 수학적으로 정의하고, 이를 기반으로 주어진 임무 상황에서 필요한 최적 무인기 대수를 도출한다. 도출된 최적 무인기 대수를 적용하여 이산 사건 모델 기반의 반복 시뮬레이션을 통해 그 결과를 검증한다. 제안된 이종 임무 할당 기법으로 운용자는 제한된 무인기 자원을 효율적으로 활용하여 주어진 임무 상황에서 최적의 임무 계획을 수립할 수 있다.

• 한국시뮬레이션학회논문지
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• 제22권2호
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• pp.11-19
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• 2013

본 논문에서는 전장 환경 요소 및 플랫폼 모델 간 상호 교환 정보를 통합하여 관리하는 전투 공간 모델(Battle Space Model)을 제안한다. 전투 공간 모델은 전장의 지형 정보와 환경 요소를 저장하는 Geographic Information System(GIS) Model, 플랫폼 모델 간 상호 교환 정보에 전장 환경 요소의 영향을 고려하는 Propagator Model, 플랫폼 모델 간 상호 교환 정보를 저장하는 Logger Model, 그리고 플랫폼 모델 간의 상호 작용(encounter) 시점을 예측하고 상호 작용 시점까지 시간을 건너뛰는 Spatial Encounter Predictor(SEP) Model로 구성된다. 또한 이산 사건 및 이산 시간 혼합형 시뮬레이션 모델 구조로 구성되어 있는 플랫폼 모델과 추가 작업 없이 직접 연결하기 위해, 전투 공간 모델 또한 이산 사건 및 이산 시간 혼합형 시뮬레이션 모델 구조로 구성하였다. 본 연구에서는 전투 공간 모델을 적용하여 수중운동체 교전 시뮬레이션을 수행하였다. 이를 통해 플랫폼 모델 각자가 반영하던 전장 환경 요소를 전투 공간 모델이 일괄적으로 반영함으로써 플랫폼 모델 개발을 단순화 할 수 있었다. 또한 각 플랫폼 모델은 다른 플랫폼 모델과의 정보 교환을 고려하지 않고 전투 공간 모델과의 정보 교환만을 고려하면 되므로, 플랫폼 모델을 중립적으로 구성할 수 있었다.

• 한국CDE학회논문집
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• 제13권1호
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• pp.67-75
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• 2008

In spite of rapidly increasing interests in digital manufacturing, there still lacks of a systematic approach in manufacturing line flow analysis via modeling and simulation; currently, the parameters for designing manufacturing line are defined by being solely based on engineers experiences. The paper proposes an application of the genetic algorithm to a discrete event line simulation finding optimal set of parameters for manufacturing line balancing problem. The proposed method has been applied to two example problems-one is a simple manufacturing model and the other for shipyard industry-in order to demonstrate its validity and usefulness.

• 한국시뮬레이션학회논문지
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• 제3권1호
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• pp.75-88
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• 1994

Discrete event modeling is finding ever more application to anlysis and design of complex manufacturing, communication, computer systems, etc. This paper shows how packet network systems may be advantageously represented as DEVS (Discrete Event System Specification) models by employing System Entity structure / Model base (SES/MB) framework developed by Zeigler. DEVS models and network structure representations support a strong basis for performance analysis of packet network systems. This approach is illustated in a typical packet network example with several routing strategies.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1993년도 하계학술대회 논문집 A
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• pp.313-315
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• 1993

This paper presents the control of input/output automata. The input/output automata provides an appropriate model for discrete event systems consisting of concurrently-operating components. Ramadge and Wonham's supervisor controller can be transformed into the controllter of input/output automata. Using input/output automata, the modelling can be more realistic and concurrent discrete event systems can be controlled easily.

• 제어로봇시스템학회논문지
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• 제2권3호
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• pp.209-219
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• 1996

Fieldbus provides a real-time data communication among field devices in the process control and manufacturing automation systems. In this paper, a Petri Net model of the 1993 draft of IEC/ISA fieldbus which is proposed as an international standard of fieldbus network is developed. Based on the Petri Net model, discrete-event simulation model of IEC/ISA fieldbus network is developed. This paper evaluates the network induced delay in the data link layer of IEC/ISA fieldbus using the simulation model. In addition, an integrated discrete-event/continuous-time simulation model of fieldbus system and distributed control system is developed. This paper investigates the real-time data processing capability of IEC/ISA fieldbus and the effect of network-induced delay to the performance of control system.

• 한국컴퓨터정보학회논문지
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• 제13권7호
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• pp.281-289
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• 2008

본 연구에서는 항공 구간별 물동량을 분석하고 수요할당과 가격정책에 따른 수익 변화를 평가할 수 있는 이산 시뮬레이션 모델이 개발되었다. 개발된 시뮬레이션 모델을 우리나라와 지리적으로 가장 가까운 환발해권 지역에서 발생하는 대내외적인 항공화물에 대하여, 실제 항공사에서 운영되고 있는 운송량 수요 데이터를 기반으로 비교, 검증하였다. 그 결과 시뮬레이션 모델이 실제 수요를 예측할 수 있음을 통계적으로 제시하였으며, 향후 항공화물 수요 관리를 분석하는데 유용함을 입증하였다.