• 대한기계학회:학술대회논문집
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• 대한기계학회 2002년도 학술대회지
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• pp.99-102
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• 2002

The present study describes a numerical analysis for simulation of the sloshing of flows with free-surface which contained in a rectangular tank The SOLA-VOF (Volume of fluid) method uses a fixed mesh for calculating the motion of flow and the free-surface. This Eulerian approach enables the VOF method to use only a small amount of computer memory for simulating sloshing problems with complicated free-surface contours. The VOF function, representing the volume fraction of a cell occupied by the fluid, is calculated for each cells, which gives the locating of the free-surface filling any some fraction of cells with fluid. Using SOLA-VOF method, the study describes visualization about simulation of the sloshing of flows and damping effect by baffle. Translation and pitching motion of the forms have been investigated The time-dependent changes of free-surface height are used for visualization subject to several conditions such as fluid height horizontal acceleration, sinusoidal motion, and viscosity. The free-surface heights were used for comparing wall-force, which is caused by sloshing of flows. Baffle was Installed to reduce the force on the wall by sloshing of flows. Damping effects was extensively expressed under the conditions such as baffle shape and position.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제6권1호
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• pp.64-69
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• 2006

Due to the inherent nonlinear nature of Electro-rheological (ER) fluid dampers, one of the challenging aspects for utilizing these devices to achieve high system performance is the development of accurate models and control algorithms that can take advantage of their unique characteristics. In this paper, the nonlinear damping force model is made to identify the properties of the ER damper using higher order spectrum. The higher order spectral analysis is used to investigate the nonlinear frequency coupling phenomena with the damping force signal according to the sinusoidal excitation of the damper. Also, this paper presents an inverse model of the ER damper, i.e., the model can predict the required voltage so that the ER damper can produce the desired force for the requirement of vibration control of vehicle suspension systems. The inverse model is constructed by using a multi-layer perceptron neural network. A quarter-car suspension model is considered in this paper for analysis and simulation. Simulation results show that the proposed inverse model of ER damper can obtain control voltage of ER damper for required damping force.

• 한국해양공학회지
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• 제20권2호
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• pp.22-28
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• 2006

The motion and wave drift forces of floating BBDB (backward-bent duct buoy) wave energy absorbers in regular waves are calculated, taking account of the oscillating surface-pressure due to the pressure drop in the air chamber above the oscillating water column, within the scope of the linear wave theory. A series of model tests has been conducted in order to order to verify the motion and time mean wave drift force reponses in regular waves at the ocean engineering basin, MOERI/KORDI. The pneumatic damping through an orifice-type duct for the BBDB wave energy device are deducted from experimental research. Numerical simulation for motion and drift force responses of the BBDB wave energy device, considering pneumatic damping coefficients, has been carried out, and the results are compared with those of model tests.

• Earthquakes and Structures
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• 제13권1호
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• pp.51-58
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• 2017

Passive dynamic vibration absorbers (DVAs) are often used to suppress the excessive vibration of a large structure due to their simple construction and low maintenance cost compared to other vibration control techniques. A new type of passive DVA consists of two pendulums connected with spring and dashpot element is investigated. This research evaluated the performance of the DVA in reducing the vibration response of a two degree of freedom shear structure. A model for the two DOF vibration system with the absorber is developed. The nominal absorber parameters are calculated using a Genetic Algorithm(GA) procedure. A parametric study is performed to evaluate the effect of each absorber parameter on performance. The simulation results show that the optimum condition for the absorber frequencies and damping ratios is mainly affected by pendulum length, mass, and the damping coefficient of the pendulum's hinge joint. An experimental model validates the theoretical results. The simulation and experimental results show that the proposed technique is able be used as an effective alternative solution for reducing the vibration response of a multi degree of freedom vibration system.

• Smart Structures and Systems
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• 제29권3호
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• pp.457-473
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• 2022

A high-frequency vibration control method is proposed in this paper for Pumped Storage Power Plants (PSPPs) using Eddy Current Tuned Mass Damper (EC-TMD), based on which a new type of EC-TMD device is designed. The eddy current damper parameters are optimized by numerical simulation. On this basis, physical simulation model tests are conducted to compare and study the effect of structural performance with and without damping, different control strategies, and different arrangement positions of TMD. The test results show that EC-TMD can effectively reduce the control effect under high-frequency vibration of the plant structure, and after the additional damping device forms EC-TMD, the energy dissipation is further realized due to the intervention of eddy current damping, and the control effect is subsequently improved. The Multi-Tuned Mass Damper (MTMD) control strategy broadens the tuning band to improve the robustness of the system, and the vibration advantage is more obvious. Also, some suggestions are made for the placement of the dampers to promote their application.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
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• pp.633-635
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• 1997

In this paper we present a scheme of adaptive backstepping controller for nonlinear system. Backstepping approach has recently been adopted as a design tool for nonlinear control and especially backstepping with modular design used to seperately design controller and identifier. In the modular design the nonlinear damping term is contained in controller for input-to-state stability (ISS). We compare the ISS controller, which used in general case, with the weak-ISS controller that attenuates the effect of nonlinear damping term and prove their advantages and disadvantages by simulation.

• 한국자기공명학회논문지
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• 제3권2호
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• pp.71-83
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• 1999

The dynamics of the dipolar demagnetizing field is investigated by numerical simulation. The effects of radiation damping, molecular diffusion, and relaxation processes on the dipolar demagnetizing field are examined in terms of the modulation pattern of the z-magnetization and the signal intensity variation. Simulations for multi-components suggest applications for sensitivity enhancement in favorable conditions.

• Steel and Composite Structures
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• 제37권6호
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• pp.695-709
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• 2020

The buckling properties of a single-layered graphene sheet (SLGS) are examined using nonlocal integral first shear deformation theory (FSDT) by incorporating the influence of visco-Pasternak's medium. This model contains only four variables, which is even less than the conventional FSDT. The visco-Pasternak's medium is introduced by considering the damping influence to the conventional foundation model which modeled by the linear Winkler's coefficient and Pasternak's (shear) foundation coefficient. The nanoplate under consideration is subjected to compressive in- plane edge loads per unit length. The impacts of many parameters such as scale parameter, aspect ratio, the visco-Pasternak's coefficients, damping parameter, and mode numbers on the stability investigation of the SLGSs are examined in detail. The obtained results are compared with the corresponding available in the literature.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2000년도 추계학술대회논문집
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• pp.177-184
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• 2000

This study is to choose the most proper model for AGV throughout simulation of behavior of suspension to reduce trial and error because there is no AGV treating heavy weight at harbor loading and unloading at home. Therefore, we estimate the vibration modes of the various suspensions applied to AGV, which is over 75 ton included the weight of two containers using the Matlab in the case of G and 5G, one of the simulation programs.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.1126-1131
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• 2007

This paper presents unified chassis control (UCC) to improve the vehicle lateral stability. The unified chassis control implies combined control of active front steering (AFS), electronic stability control (ESC) and continuous damping control (CDC). A direct yaw moment controller based on a 2-D bicycle model is designed by using sliding mode control law. A direct roll moment controller based on a 2-D roll model is designed. The computed direct yaw moment and the direct roll moment are generated by AFS, ESP and CDC control modules respectively. A control authority of the AFS and the ESC is determined by tire slip angle. Computer simulation is conducted to evaluate the proposed integrated chassis controller by using the Matlab, simulink and the validated vehicle simulator. From the simulation results, it is shown that the proposed unified chassis control can provide with improved performance over the modular chassis control.