• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.73-73
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• 2000

Assembly is usually performed by one robot and fixtures. This type of assembly system has Low flexibility in terms of variety of parts and part-presentation that the system can handle. This paper addresses assembly without fixtures using two-manipulator robot. An active method using force feedback is proposed for the peg-in-hole assembly in highly uncertain environment. Assembly states are described by extended contact relations. Qualitative templates for events are easily derived from the token vector of the Petrinet model. The states are recognized through identification of the events using two 6-d.o.f force/moment sensors. The proposed method is verified and evaluated through experiments with round peg- in-hole assembly.

• 한국시뮬레이션학회논문지
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• 제13권3호
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• pp.11-20
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• 2004

The major objective of this paper is to perform modeling of cyber attack and defense using vulnerability metrics. To do this, we have attempted command level modeling for realizing an approach of functional level proposed by Nong Ye, and we have defined vulnerability metrics that are able to apply to DEVS(Discrete Event System Specification) and performed modeling of cyber attack and defense using this. Our approach is to show the difference from others in that (i) it is able to analyze behaviors of systems being emerged by interaction between functional elements of network components, (ii) it is able to analyze vulnerability in quantitative manner, and (iii) it is able to establish defense suitably by using the analyzed vulnerability. We examine an example of vulnerability analysis on the cyber attack and defense through case study.

• 한국시뮬레이션학회:학술대회논문집
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• 한국시뮬레이션학회 2001년도 춘계 학술대회 논문집
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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.

• 한국시뮬레이션학회:학술대회논문집
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• 한국시뮬레이션학회 1999년도 추계학술대회 논문집
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• pp.217-217
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• 1999

The main objective of this study is to simulate the design and operational policies of the assembly shop of an automotive plant for planning purposes and to find possible improvements. The simulation study was used to answer the following questions: How does the sequence affect the daily throughput\ulcorner What are the bottlenecks to the assembly lines in a given scenario\ulcorner A Simulation model was developed in accordance with the objective of this study. The model incorporates detailed workstation logic to accurately model downtime results through the use of a pull cord system. It is written with SIMAN. The discrete event feature of SIMAN does not adequately model the conveyor systems of the asembly shop. As a result, a few subroutines were added to the SIMAN modeling structures to mimic the operations of the assembly shop. Use of the model uncovered attractive improvement opportunities, such as a tremendous gain in annual volume if four additional spaces were added to a between-line buffer.

• 한국항공운항학회지
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• 제4권1호
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• pp.7-24
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• 1996

A methodology has been developed for predicting aircraft reliability incorporating both C.C.F.s(Common-Cause Failures), and phased missions. Failure behaviour of an aircraft, or it's systems are predicted. Both independent failures, and C.C.F.s, are modelled by the Markov process, and simulated using Monte Carlo sampling with the robust variance reduction method. Prediction of safety and reliability is made through discrete-event simulation of aircraft operations. A case study is described for investigating the safety and reliability of the propulsion system of two-, three- and four-engined aircraft. This is particularly important for the design of ETOPS(Extended Range of Two-Engined Aircraft Operations) and results are presented for the cases with, and without the effect of C.C.F.s.

• 한국군사과학기술학회지
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• 제10권3호
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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.

• 한국정밀공학회지
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• 제11권4호
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• pp.126-137
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• 1994

Performance management of computer networks is intended to improve a given network performance in order for more efficient information exchange between subsystems of an integrated large-scale system. Importance of perfomance management is growing as many functions of the large- scale system depend on the quality of communication services provided by the network. The role of performance management is to manipulate the adjustable protocol parameters on line so that the network can adapt itself to a dynamic environment. This can be divided into two subtasks : performance evaluation to find how changes in protocol parameters affect the network performance and decision making to determine the magnitude and direction of parameter adjustment. This paper is the first part of the two papers focusing on conceptual design, development, and evaluation of performance management for token bus networks. This paper specifically deals with the task of performance evaluation which utilizes the principle of perturbation analysis of discrete event dynamic systems. The developed algorithm can estimate the network performance under a perturbed protocol parameter setting from observations of the network operations under a nominal parameter setting.

• 한국시뮬레이션학회논문지
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• 제11권1호
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• pp.11-22
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• 2002

In this paper, a RAID system is modeled and simulated by using the DEVS formalism. The RAID system interacts with a host system by using the high-speed Fibre channel protocol and stores data in an array of IDE disks. The DAVS 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 MCU unit. The primary-PCI unit interfaces with the host system and I/O data caches. The secondary-PCI unit includes disks. The MCU unit controls overall system. The control algorithm of MCU and PCI transactions are analyzed and modeled, From the analysis of simulation events, we can conclude that the proposed model satisfies given requirements.

• 한국시뮬레이션학회논문지
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• 제8권3호
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• pp.91-103
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• 1999

This paper proposes an algorithm which reduces transportation cost while goods are delivered in time in a logistics system. The logistics system assumed in this paper is the system in which multiple cars moves various goods from spatially distributed warehouses to stores. For reducing transportation cost, the car assignment algorithm which allocates goods to minimal cars employs the BF method; routing of each car is modelled as the TSP and is solved by using the genetic algorithm. For evaluating the proposed algorithm, the logistics system is modelled and simulated by using the DEVS formalism. The DEVS formalism specifies discrete event systems in a hierarchical, modular manner. During simulation, each car is modelled as a message and traverses warehouse and stores. When a car arrives at a warehouse or a store, predetermined amount of goods are loaded or unloaded. The arrival time and departure time of cars are analyzed and eventually whether goods are delivered in the desired time bound is verified.

• 한국멀티미디어학회논문지
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• 제25권6호
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• pp.793-806
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• 2022

As the IMO introduced MASS (Maritime Autonomous Surface Ships), ISO(International Organization for Standardization) announced ISO 19847 of a maritime data sharing standard for collecting and remotely managing data of ship systems. Previous literature evaluated the risk using HAZOP for ISO 19847 and proved that risk assessment is useful through experiments. However, redundancy of ISO 19847 ship data server which is one of the risk reduction method suggested in previous literature, was designed but couldn't tested due to the limitations of the conditions. So, in this study, to prove the usefulness of the ship data server redundancy of ISO 19847 which was not tested in previous literature. It based on the design of previous literature, and the network of ship data servers was modeled using the SES/DEVS format and simulated using the DEVS# open source library.