• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 하계종합학술대회 논문집(4)
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• pp.186-189
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• 2000

In this paper, the relation between the vibration and the sound radiated due to the piezoelectric ESWL (Extra-corporeal Shock Wave Lithotripter) is examined And the relation between the focus and the vibration of the objects is examined. The same experiments with the objects that can be breton are done and the relation between the vibration and the break efficiency of the phantom is experimentally investigated. These results show that the relativity between the power of the peak frequency and the break efficiency can be confirmed.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 추계학술대회논문초록집
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• pp.389.2-389
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• 2002

Nonlinear aeroelastic characteristics of a missile control surface are investigated in this study. The wing model has freeplay structural nonlinearity at its pitch axis. Nonlinear aerodynamic flows with unsteady shock waves are also considered in high-speed flow region. To effectively consider a freeplay structural nonlinearity, the fictitious mass method (FMM) is applied to structural vibration analysis based on finite element method (FEM). (omitted)

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1998년도 봄 학술발표회 논문집
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• pp.357-364
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• 1998

In this paper, ground vibration analysis methods for train transit on bridges are studied. Train loads acting on the piers are evaluated considering the interactions between the trains and the bridge. The 2D in-plane wave propagation method and the axisymmetric wave propagation method are used in the ground vibration analysis, and then the results of the ground vibration are compared. A modified axisymmetric method is presented, which can consider the effect of the train loadings on a series of piers as the train moves.

• 한국음향학회지
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• 제19권5호
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• pp.35-40
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• 2000

본 연구에서는 먼저 압전형 쇄석기에 의한 충격파 조사시에 발생하는 파쇄대상물의 진동과 그 때 들려오는 방사음과의 관계에 대하여 검토한다. 다음에 대상물에 있어서의 초점위치와 고유진동과의 관계에 대해서도 조사한 결과를 제시한다. 아울러 동일한 실험을 파쇄가능한 대상물에 시행하여 대상물의 진동과 그 파쇄효율과의 관계에 대해서도 실험적으로 검토한다. 그 결과, 초점위치에 따른 대상물 고유진동의 피크 주파수 파워와 파쇄효율과의 상관성을 명확히 확인할 수 있었다.

• 한국철도학회논문집
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• 제18권6호
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• pp.567-577
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• 2015

본 논문에서는 계측자료와 해석방법의 조합에 의하여 지반진동을 평가하는 방법을 제시하였다. 평가방법의 기본개념은 FRA(Federal Railway Administration)에서 발간한 진동상세평가 매뉴얼에서 제시한 방법과 유사하나 구체적 평가방법은 다양한 유형의 방진벽의 진동저감 효과를 용이하게 평가할 수 있도록 수정되었다. 터널바닥에 작용하는 하중밀도(force density)는 해당선로의 차량 및 궤도조건을 잘 고려할 수 있는 차량-궤도 상호작용해석에 의하여 산정하였다. 지반진동의 전파유동성(transfer mobility) 2차원 지반진동해석을 통하여 평가하였다. 지반진동의 2차원 해석은 각 모델간의 상대비교에 있어서는 좋은 결과를 얻을 수 있으나 절대치 평가는 어렵다. 따라서 여기서는 사전에 계측된 자료와 해석결과의 비교를 통하여 실제 지반진동 전파특성을 반영할 수 있도록 계산된 전파유동성을 보완하였다. 정립된 진동평가방법을 적용하여 실제 진동민원문제가 크게 발생하였던 도시철도 저심도 터널구간을 대상으로 9가지 유형의 방진벽의 진동저감 효과를 분석하였다.

• 한국소음진동공학회논문집
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• 제12권1호
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• pp.48-56
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• 2002

A computational work of the impulse wave which is discharged from the open end of a pipe is compared to the Lighthill\`s aeroacoustics theory. The second-order total variation diminishing(TVD) scheme is employed to solve the axisymmetric, compressible, unsteady Euler equations. The relationship between the initial compressure wave form and the resulting impulse wave is characterized in terms of the peak pressure. The overpressure, pressure gradient and wavelength of the initial compression wave are changed to investigate the influence of the initial compressure wave form on the peak pressure of impulse wave. The results obtained show that for the initial compression wave of a large wavelength and small pressure gradient the peak pressure of the impulse wave depends upon the wavelength and pressure gradient of compression wave, but for the initial compression wave of a short wavelength and large pressure gradient the peak pressure of the impulse wave is almost constant regardless of the wavelength and pressure gradient of compression wave. The peak pressure of the impulse wave is increased with an increase in the overpressure of the initial compression wave. The results from the numerical ana1ysis are well compared to the results from the aeroacoutics theory with a food agreement.

• Smart Structures and Systems
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• 제18권2호
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• pp.335-354
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• 2016

This contribution presents an extended one-dimensional theory for piezoelectric beam-type structures with non-ideal electrodes. For these types of electrodes the equipotential area condition is not satisfied. The main motivation of our research is originated from passive vibration control: when an elastic structure is covered by several piezoelectric patches that are linked via resistances and inductances, vibrational energy is efficiently dissipated if the electric network is properly designed. Assuming infinitely small piezoelectric patches that are connected by an infinite number of electrical, in particular resistive and inductive elements, one obtains the Telegrapher's equation for the voltage across the piezoelectric transducer. Embedding this outcome into the framework of Bernoulli-Euler, the final equations are coupled to the wave equations for the longitudinal motion of a bar and to the partial differential equations for the lateral motion of the beam. We present results for the wave propagation of a longitudinal bar for several types of electrode properties. The frequency spectra are computed (phase angle, wave number, wave speed), which point out the effect of resistive and inductive electrodes on wave characteristics. Our results show that electrical damping due to the resistivity of the electrodes is different from internal (=strain velocity dependent) or external (=velocity dependent) mechanical damping. Finally, results are presented, when the structure is excited by a harmonic single force, yielding that resistive-inductive electrodes are suitable candidates for passive vibration control that might be of great interest for practical applications in the future.

• 한국소음진동공학회논문집
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• 제21권3호
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• pp.227-233
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• 2011

The ultrasonic guided wave phased array using magnetostrictive patch transducers is proposed. The magnetostrictive transducer has received much attention because it is cost-effective and capable to generate ultrasonic waves with a simple configuration. However, it has not been used for ultrasonic guided wave phased array applications until now. In this paper, we propose a magnetostrictive transducer based phased array system consisting of a multi-channel function generator, power amplifiers and Lamb wave magnetostrictive transducers. To check the performance of the ultrasonic guided wave phased array, several Lamb wave focusing experiments were carried out in an aluminum plate. The results demonstrated the capability of the developed array to focus the Lamb waves at specific target points.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2008년도 춘계학술대회논문집
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• pp.852-855
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• 2008

In this paper, we proposed a new type's PZT actuator using surface acoustic wave. This actuator uses Rayleigh wave as an operational traveling wave. For the development of the actuator, each components of surface acoustic wave motor like PZT substrate, slider and IDT was studied theoretically and fabricated. For the measurement of transfer function of PZT substrate and operation of surface acoustic wave motor, network analyzer and 13.56MHz RF generator were used. Also the model which expresses the driving characteristic best was suggested and simulation was executed for the suggested model. And the future research works for improvement of SAW actuator was suggested.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 춘계학술대회논문집
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• pp.457-467
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• 2004

Wave Transmission analysis is one of methods for power transmission and reflection coefficients in coupled infinite structures. This paper focuses the wave transmission analysis of point coupled structures among semi-infinite beams and infinite thin plates considering all kinds of waves. It is supposed that the junction through the beams and plates is an identical spot and no point of contact exist except the spot. The boundary conditions are applied at the spot for continuities of 6 DOF displacements and 6 DOF force equilibriums, and then wave fields are obtained in the coupled structures. Since wave components in plate field are simplified using asymptotic expressions of Henkel functions, the displacements and forces at the plate junction can be simply expressed with magnitudes of the wave components. The wave fields according to incident waves gives the power transmission coefficients in beam/plate point coupled structures. For both coupled structures with a beam vertically and obliquely joined to a plate, power transmission analysis is performed and the analysis results are compared and examined.