• 한국기계가공학회지
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• 제18권1호
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• pp.1-8
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• 2019

The optimal design parameters of a dynamic absorber (DA) in a machine body (that is considered as a rigid body) are discussed in this paper. The bounce and rotation motions of the rigid body have been controlled passively by a DA, which consists of a mass and a spring. The rigid body is subjected to a harmonically excited force and supported by linear springs at both ends. To define the motion of a rigid body with a DA, the equation of motion was expressed in the third-order matrix form. To define the optimal design conditions of a DA, the reduction of dynamic characteristics, represented by the amplitudes of bounce and rotation, and the transmitted powers, were evaluated and discussed. The level of reduction was found to be highly dependent on the location and spring stiffness of the DA.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2008년도 추계학술대회논문집
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• pp.414-416
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• 2008

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2009년도 춘계학술대회 논문집
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• pp.334-335
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• 2009

• 한국소음진동공학회논문집
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• 제13권10호
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• pp.760-766
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• 2003

This paper is concerned with the eddy current damper which can be used to enhance the damping of the host structure. The operating principle of the eddy current damper is first explained in detail. The dynamic interaction between the magnets and the copper plate produces eddy current thus resulting in the damping force. By attaching the eddy current damper to the host structure, the damping of the total structure can be increased so that vibrations can be suppressed. The advantage of the eddy current damper is that it doesn't require any electronic devices and power supply The effect of the eddy current damper on the global dynamic characteristics of the structure is investigated by considering the cantilever with the eddy current damper. Experimental results show that the eddy current damper is an effective device for vibration suppression.

• 한국소음진동공학회논문집
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• 제23권5호
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• pp.456-462
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• 2013

Eco-friendly material applied to building would be one of the materials which is must developed for global environmental conservation and reduction of carbon dioxide. For development of eco-friendly material, a cellulose absorber has been developed with waste paper through adjustment of various mix proportions. The developed cellulose absorber has been tested for its acoustic properties such as absorption coefficient and dynamic stiffness. The absorption coefficient was evaluated by developing six samples and using impedance tube and reverberation chamber. As a result of the evaluation, 0.64(NRC) was secured in absorption coefficient and 4.7 $MN/m^3$ was indicated in dynamic stiffness. Also, for practical use of developed absorbers as inner heartwood in drywall, comparison test of sound reduction index was performed with existing glass wool absorbers and constructed drywall of gypsum board. The results have shown 55 dB(Rw) of sound reduction index in glass-wool wall and 46 dB(Rw) in cellulose.

• 대한기계학회논문집A
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• 제28권3호
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• pp.215-221
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• 2004

Large machine and structure can not be normally treated as lumped parameter system. Such machine or structure must be broken down to individual beams or panels the motion of which must be analysed before an absorber system can be designed for each element. The absorber may be a lumped parameter system or a continuous system. One of the most common elements in a machine or structure is the cantilever, and in this paper is considered the design of a continuous parameter absorber to reduce the transverse vibrations of a beam. So this paper describes the method to obtain the accurate information about combined continuous beam system with DVA. This information is obtained from the combined system's receptance. and this paper shows the convenience and useful informations when design the dynamic vibration absorber with the combined system's receptance.

• 항공우주시스템공학회지
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• 제4권4호
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• pp.28-36
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• 2010

Current tanks have been developed to increase mobility and firepower, and its maximum range and destructive power are improved. This great change causes remained vibration of a gun barrel after firing. For this reason, people are trying to control vibration of gun barrel effectively. This thesis presents a modeling method and analysis results for gun barrel by using a thermal shroud as an absorber mass. DTS(Dynamically Tuned Shroud) is a vibration damping system using a thermal shroud as an added mass for decreasing remained vibration. The model has an advantage that the gun barrel's vibration can be decreased by dissipating a kinetic energy of thermal shroud without install an additional dynamic absorber to tip of the gun barrel. For analyzing the damping performance of the DTS, We derived an equation of motion of the barrel after setting a mathematical modeling, and found out the frequency analysis and tendency according to stiffness ratio between barrel and shroud.

• 대한조선학회논문집
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• 제32권3호
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• pp.1-18
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• 1995

중력진자식과 원심진자식의 두가지 형의 소형동흡진기를 이용한 구조물 진동의 제어시스템을 개발하였다. 개발된 본 시스템은 step 및 servo motor, 소형흡진기, metor drive unit와 제어장치로 구성되어 있으며, 구조물의 진동을 수진기로 감지하고, 이 신호를 받아 소형흡진기의 기능을 최적 제어하여 구조물의 진동을 제어한다. 제어시스템의 제어성능 검증시험을 위해 상자형 강판구조물($L{\times}W{\times}H{\times}T=800mm{\times}700mm{\times}1500mm{\times}7mm$) 중량 180kg를 제작하여 시험을 수행하였으며, 실험결과 중력진자식 흡진기는 95%의 흡진성능을, 원심진자식 흡진기는 88%의 흡진성능을 가지게 됨이 확인되었다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2004년도 추계학술대회 논문집
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• pp.375-380
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• 2004

Vibration of railway vehicle has harmful effect to dynamic performances of railway represented to stability, safety and ride comfort. Hence reduction of vibration has been discussed as an important problem and has been widely investigated. A new technology of vibration control, energy regenerative control, is introduced. Energy regenerative damper using this new vibration control converts vibration energy into other kind of energy that we can utilize. In this paper, this energy regenerative damper is applied to the dynamic absorber and vehicle suspension. And it is evaluated whether the energy regenerative railway vehicle suspension is possible.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 추계학술대회논문집
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• pp.276-281
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• 2000

As the construction of the high-rise building increases worldwide, the effort has been exerted to improve the safety and serviceability if the structure against various types of external dynamic loads such as wind load, seismic load, etc. The mass damper, defined as dynamic absorber in mechanical engineering is known one of the effective methods to control the vibration of flexible large structures. The hybrid mass damper, HMD is known as the most appropriate type of the mass dampers. In this paper, the control force was designed for HMD by numerical simulations and the performance of HMD to control the flexible vibration of the steel tower induced by sinusoidal force excitation was evaluated, also TMD was designed for a 1-DOF lumped mass model.