• 한국철도학회:학술대회논문집
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• 한국철도학회 2004년도 추계학술대회 논문집
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• pp.363-368
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• 2004

Maglev vehicles, which are levitated and propelled by electromagnets, often run on elevated guideways comprised of steel, aluminum and concrete. Therefore, an analysis of the dynamic interaction between the Maglev vehicle and the guideway is needed in the design of the critical speed, ride, controller design and weight reduction of the guideway. This study introduces a dynamic interaction simulation technique that applies FEM. The proposed method uses FEM to model the elevated guideway and the Maglev vehicle, which is different from conventional studies. Because the proposed method uses FEM, it is useful to calculate the deformation of the elevated guideway, the dynamic stress, and the motion of the vehicle. By applying the proposed method to an urban transit Maglev vehicle, UTM01, the dynamic response is simulated according to velocity increase and can be reviewed again. From the result of the study, we concluded that FEM simulation of the dynamic interaction between the maglev vehicle and the guideway is possible.

• 전기학회논문지
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• 제59권12호
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• pp.2157-2164
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• 2010

Microgrid is generally defined as cluster of small distributed generators, energy storages and loads. Through monitoring and coordinated control, microgrid can provide various benefits such as reduction of energy cost, peak shaving and power quality improvement. In design stage of microgrid, system dynamic simulation is necessary for optimizing of sizing and siting of DER(distributed energy resources). As number of the system components increases, simulation time will be longer. This problem can restrict optimal design. So we used simplified modeling on energy sources and average switching model on power converters to reduce simulation time. The effectiveness of this method is verified by applying to prototype microgrid system, which is consist of photovoltaic, wind power, diesel engine generators, battery energy storage system and loads installed in laboratory. Simulation by Matlab/Simulink and measurements on prototype microgrid show that the proposed method can reduce simulation time not sacrificing dynamic characteristics.

• Earthquakes and Structures
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• 제6권2호
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• pp.163-179
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• 2014

Dynamic test with scaled model of a group of intake towers was performed to study the dynamic interaction between water and towers. The test model consists of intake tower or towers, massless foundation near the towers and part of water to simulate the dynamic interaction of tower-water-foundation system. Models with a single tower and 4 towers were tested to find the different influences of the water on the tower dynamic properties, seismic responses as well as dynamic water-tower interaction. It is found that the water has little influence on the resonant frequency in the direction perpendicular to flow due to the normal force transfer role of the water in the contraction joints between towers. By the same effect of the water, maximum accelerations in the same direction on 4 towers tend to close to each other as the water level increased from low to normal level. Moreover, the acceleration responses of the single tower model are larger than the group of towers model in both directions in general. Within 30m from the surface of water, hydrodynamic pressures were quite close for a single tower and group of towers model at two water levels. For points deeper than 30m, the pressures increased about 40 to 55% for the group of towers model than the single tower model at both water levels. In respect to the pressures at different towers, two mid towers experienced higher than two side towers, the deeper, the larger the difference. And the inside hydrodynamic pressures are more dependent on ground motions than the outside.

• 한국시뮬레이션학회논문지
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• 제28권1호
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• pp.41-47
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• 2019

국방 시뮬레이션은 여러 무기체계를 실험하고 그 효용성을 평가하기 위해 활발히 사용된다. AddSIM 환경의 경우 국방 시뮬레이션에서 다루는 무기체계들을 보다 통합적인 관점에서 지원하기 위해 고안된 시뮬레이션 프레임워크로 재사용성과 확장성을 고려하여 설계되었다. AddSIM에서 사용되는 모델의 경우 기본 모델 구조에 대한 정보와 실제 무기 체계의 설계를 위해 사용되는 사용자 코드 영역에서의 검증이 통합적이며 정확한 시뮬레이션을 위해 필요하다. 따라서 본 논문에서는 AddSIM에서 사용되는 모델들에 대한 완전성을 위해 사용된 동적 검증 방법에 대해 설명한다. 사용자 코드 동적 검증 방법에 대해서는 명세 기법과 검증을 위한 알고리즘에 대해 설명한다. 또한, 검증 명세 기법 및 알고리즘을 바탕으로 구현된 동적 검증기 프로토타입에 대해 소개하며, 사례 연구에서는 AddSIM 환경에서 구현된 시뮬레이션 예제를 바탕으로 수행한 검증 결과를 분석한다.

• Tribology and Lubricants
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• 제16권4호
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• pp.295-301
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• 2000

The dynamic simulation of slider in hard disk drive is performed using Factored Implicit Finite Difference method. The modified Reynolds equation with Fukui and Kaneko model is employed as a governing equation. Equations of motion for the slider of three degrees of freedom are solved simultaneously with the modified Reynolds equation. The transient responses of the slider for disk step bumps and slider impulse forces are shown for various cases and are compared for the iteration algorithm and new algorithm.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 추계학술대회 논문집 학회본부 A
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• pp.425-433
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• 1999

This paper describes a simulation model and a scaled hardware model to analyze the dynamic performance of Unified Power Flow Controller, which can flexibly adjust the active and reactive power flow through the ac transmission line. The design of control system was developed using vector control method. The results of simulation and scaled hardware test show that the developed control system works accurately. And both models are very effective to analyze the dynamic performance of the Unified Power Flow Controller.

• 항공우주시스템공학회지
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• 제14권4호
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• pp.10-17
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• 2020

When an aircraft is taxiing, excitation force is applied according to the shape of the road surface. The sprung mass acceleration caused by the excitation of the road surface negatively affects the feeling of boarding. This paper addresses the verification process of the semi-active control method applied to improve the feeling of boarding. The Magneto-Rheological damper landing gear model is employed alongside the control method. It is a Oleo-Pneumatic damper filled with a fluid having the characteristics of increasing yield stress when subjected to a magnetic field. The control method involves verifying Skyhook Control Type2 developed by Skyhook control. The Sinozuka white noise model that considers runway characteristics was employed for the road surface in the simulation. The runway road surface obtained through this model has stochastic characteristics, so the dynamic characteristics were analyzed by applying Monte-Carlo simulation. A dynamic analysis was conducted by co-simulating the landing gear model made by RecurDyn and the control method designed by Simulink. Simulation results show that the Skyhook Control Type2 method has the best control effect in the low speed range compared to the passive type (without control) and skyhook control.

• Journal of Mechanical Science and Technology
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• 제19권spc1호
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• pp.265-271
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• 2005

Randomness exists in engineering. Tolerance, assemble-error, environment temperature and wear make the parameters of a mechanical system uncertain. So the behavior or response of the mechanical system is uncertain. In this paper, the uncertain parameters are treated as random variables. So if the probability distribution of a random parameter is known, the simulation of mechanical multibody dynamics can be made by Monte-Carlo method. Thus multibody dynamics simulation results can be obtained in statistics. A new concept called functional reliability is put forward in this paper, which can be defined as the probability of the dynamic parameters(such as position, orientation, velocity, acceleration etc.) of the key parts of a mechanical multibody system belong to their tolerance values. A flexible mechanical arm with random parameters is studied in this paper. The length, width, thickness and density of the flexible arm are treated as random variables and Gaussian distribution is used with given mean and variance. Computer code is developed based on the dynamic model and Monte-Carlo method to simulate the dynamic behavior of the flexible arm. At the same time the end effector's locating reliability is calculated with circular tolerance area. The theory and method presented in this paper are applicable on the dynamics modeling of general multibody systems.

• Structural Engineering and Mechanics
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• 제64권4호
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• pp.461-472
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• 2017

The dynamic tests of recycled aggregate concrete (RAC) are carried out, the rate-dependent mechanical models of RAC are proposed. The dynamic mechanical behaviors of RAC frame structure are investigated by adopting the numerical simulation method of the finite element. It is indicated that the lateral stiffness and the hysteresis loops of RAC frame structure obtained from the numerical simulation agree well with the test results, more so for the numerical simulation which is considered the strain rate effect than for the numerical simulation with strain rate excluded. The natural vibration frequency and the lateral stiffness increase with the increase of the strain rate. The dynamic model of the lateral stiffness is proposed, which is reasonably applied to describe the effect of the strain rate on the lateral stiffness of RAC frame structure. The effect of the strain rate on the structural deformation and capacity of RAC is analyzed. The analyses show that the inter-story drift decreases with the increase of the strain rate. However, with the increasing strain rate, the structural capacity increases. The dynamic models of the base shear coefficient and the overturning moment of RAC frame structure are developed. The dynamic models are important and can be used to evaluate the strength deterioration of RAC structure under dynamic loading.

• 한국경영과학회:학술대회논문집
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• 대한산업공학회/한국경영과학회 1996년도 춘계공동학술대회논문집; 공군사관학교, 청주; 26-27 Apr. 1996
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• pp.56-60
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• 1996

In most dynamic manufacturing environments today, systems and processes are constantly changing. Simulation tools are required that can accurately model the system in detail, but still be easy to use, and allow rapid model redevelopment to react quickly for system changes. An object-oriented simulation modeling environment is presented to provide flexible modeling capabilities for simulation. Also, when simulating an assembly system, a large number of factors must be considered. Because of such complexities, simulation has been used as the primary method in designing, planning and analyzing. In this paper, the dynamic manufacturing environment is discussed for the assembly system. Also, an application method of simulation tools is presented with the experimental data from the automobile manufacturing shop to improve the productivity effectively.