• The Transactions of the Korean Institute of Electrical Engineers B
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• v.51 no.11
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• pp.601-611
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• 2002

As resent trends in structural construction have been to build taller and larger structures than any time in the past, they have had high flexibility and low damping that can cause large vibration response under severe environmental loading such as earthquakes, winds, and mechanical excitations. The damper with mass and sqring is one aproach to safeguarding the structure against excessive vibrations. In this paper, a large capacity hybrid-type linear motor damper(LMD) was designed and fabricated for the application to the vibration control of a large building structure model. It has been designed to be able to move the damper mass, 1,500 kg up to ${\pm}250mm$ strokes at the first mode natural frequency of the building structure model, ${\pm}0.51Hz$. Linear motor is consisted of the fixed coil and the movable NdFeB permanent magnets field part. The PM field part composed magnet modules and iron yoke, is the damper mass itself, 1500kg. LMD therefore has a simplified structure and requires a few elements in the driving system, being compared with a rotary motor damper and a hydraulic damper. However, the manufacture of large PM linear actuator is difficult because of the limit of PM size and the attraction and repulsion at the assembly of PM. Therefore, large damper system is manufactured and tested for dynamic characteristics and frequency response.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.280-285
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• 2000

With recent development of technology of high stiffness material and the structural design, the construction of high rise structures such as tall building, tower has increased. The more flexible and slender structure is vulnerable to the internal and external dynamic loads induced by earthquake, wind and traffic load. There have been great effort and many researches to minimize the influence of dynamic loads on the structure. The traditional and stable method, the application of the passive damper, is not able to comply with various dynamic loads, while the mass damper which active control technology is integrated can effectively comply with load types. Therefore, the application of active control of huge structures with AMD(Active mass damper) or HMD(Hybrid Mass damper) is increasing. Up to now, most of actuators are servomotor and hydraulic actuator. But it is known that the electromagnetic actuator applies non contacting control force, which makes the control system easier with no characteristic change depending on time. In this paper, Hybrid mass damper with electromagnetic actuator was designed and applied to building scaled structure. The performance of designed HMD tested by shake table test is included.

• Journal of the Korean Ceramic Society
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• v.40 no.3
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• pp.286-292
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• 2003

In this study, new shock absorbing system was proposed using silica gel particles according to the nano-technology. For the design and real application of the proposed damper, an experimental investigations are carried out using colloidal damper, which is statically loaded. The porous matrix is composed from silica gel(labyrinth architecture), coated by organo-silicones substances, in order to achieve a hydrophobic surface. Water is considered as associated lyophobic liquid. Reversible colloidal damper static test rig and the measuring technique of the static hysteresis were described. Iufluence of the water volume and particle diameters upon the reversible colloidal damper hysteresis was investigated. Also, influence of the relaxation time on the hysteresis of the damper was investigated. As a result, the proposed new shock absorbing damper is proved as an effective one, which can be replaced for the conventional hydraulic damper.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.619-624
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• 2004

This paper applies the fuzzy logic controller to a semiactive seat suspension system in order to obtain the better ride comfort in constraint of specific rattle space. The seat suspension system used for this research is a scissors-type one with the MR (Magnetic Rheological) fluid damper. Since a seat suspension system with a driver can not be exactly modeled, it is effective to control with the fuzzy logic controller. The rule was carefully tuned to effectively reduce the vibration transmitted to a driver. The on-road ride was realized on a hydraulic excitor and the result shows that the fuzzy controller has reduced the vibration of a seat suspension system compared to the continuous skyhook controller.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2005.11a
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• pp.224-228
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• 2005

Dynamic control tests for Backhole as a dynamic damper were performed. For the forced oscillation generated by pressure drop in the feed line and internal wave analysis of swirl injector, hydrodynamic pulsator and 1D visualization model injector was produced, respectively We focus on effect of Backhole as a dynamic damper instead of a acoustic one. So, the breakup length and film thickness of liquid sheet on the steady state and the forced oscillation state have been measured and compared.

• Journal of Power System Engineering
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• v.4 no.1
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• pp.51-59
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• 2000

Active suspension systems have been using for improving ride quality and stability for vehicles. An active suspension system is composed of a hydraulic pump, pressure control valves, hydraulic dampers, vehicle body, tires and other components. In this study, the mathematical model for the active suspension system based on the quarter car concept is derived, and a program for analysing the dynamic behaviour of the suspension system is developed. The computed results by the developed program are compared with the experimental results for confirming the reliability and usefulness of the developed program.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.45 no.4
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• pp.582-589
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• 1996

In this paper, an adaptive control problem of a hydraulic actuator for vehicle active suspension controller is divided into two parts: the inner loop controller and the outer loop controller. Inner loop controller, which is a nonlinear adaptive controller, is designed to control the force generated by the nonlinear hydraulic actuator acting under the effects of Coulomb friction. For simplicity of designing a nonlinear controller, the spool valve dynamics of a hydraulic actuator is reduced using a singular perturbation technique. The estimation error signal used to an indirect parameter adaptation is calculated without a regressor filtering. The absolute velocity of a sprung mass will be damped down by its negatively proportional term(sky-hook damper) adopted as an outer loop controller. Simulation results are presented to show the importance of controlling the actuator force and the validity of the proposed adaptive controller. (author). refs., figs. tab.

• International Journal of Automotive Technology
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• v.8 no.5
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• pp.615-622
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• 2007

In this study, a Coupled Computational Fluid Dynamics(CFD) and Finite Element Analysis(FEA) method are used to predict and evaluate the performance of an automotive shock absorber. Averaged Navier-Stokes equations are solved by the SIMPLE method and the RNG $k-\varepsilon$ is used to model turbulence. CFD analysis is carried out for different intake valve deflections and piston velocities. The force exerted on the valve in each valve deflection is obtained. The valve deflection-force relationship is investigated by the FEA method. The force exerted on the valve in each piston velocity is obtained with a combination of CFD and FEA results. Numerical results are compared with the experimental data and have shown agreement. Dependence of valve deflection as a function of piston velocity is investigated. Effects of hydraulic oil temperature change on valve behavior are also studied.

• The Journal of the Acoustical Society of Korea
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• v.40 no.1
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• pp.64-72
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• 2021

This paper carried out the optimal design of Tuned Mass Damper (TMD) to attenuate the vibrational energy of pipeline subjected to fluid movement. Under the uncertainty of the vibration source and the specification of a pipeline system, an adaptive approach to design TMD is suggested. A surrogate pipeline system model was designed using MATLAB, and the optimal design method was developed based on the surrogate pipe model. The developed optimization method was validated using Finite Element (FE) model in ANSYS Workbench. And the TMD was designed to account for measurement error and installed on the industrial pipeline system. It showed that the pipeline vibrational amplitude was reduced by 95 % after installing the TMD.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.04a
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• pp.238-239
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• 2014