• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 1996년도 춘계학술대회논문집; 부산수산대학교, 10 May 1996
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• pp.370-375
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• 1996

부분구조합성법의 하나인 구분모드합성법을 이용하여, 비선형 진동해석을 행하는 새로운 방법을 제안하였다. 제안하는 방법은 비선형 운동방정식에 섭동법을 이용하여 미소변동량에 관하여 정리한 각 차수의 운동방정식에 구분모드합성법을 적용하였다. 여기서 1차의 운동방정식의 외력항은 0차의 변위로 표현하는 것에 의해 각차의 운동방정식을 풀었다. 또한, 제안한 방법을 이용하여 문형구조모델의 비선형 강제진동 시각역응답을 구하고, 그 계산결과에 관해서 검토했다. 그 결과, 본 해석방법을 특히 감쇠가 없는 경우에 있어서 비선형이 실현되고 있는 것이 확인되었다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 추계학술대회 논문집
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• pp.388-392
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• 1995

The Electronic Speckle Pattern Interferometry(ESPI) has been applied to many technical problems such as deformation and displacement measurement, strain visualization and surface roughness monitoring. Composite materials have various complicated characteristics depending on the ply materials,ply orientations,ply stacking sequences and boundary conditions. Therefore, it is difficult to analyze composite material. For efficient use of composit materials in engineering applications, the dynamic behavior such as, natural frequencies and modal patterns should be identified. This studying presents FEM results for the free vibration of symmetrically laminated composite as [30/-30/90] $_{s}$. The natural frequencies of laminated composite rectangular plates having the boundary condition(:2-edge clamped) are experimentally obtained. In order to demonstrate the validity of the experiment,FEM analysis using ANSYS was performed and natural frequencies experimentally obtained is compared with calculated by FEM analysis. The results obtained from both experiment and FEM analysis show a good agreement.t.

• 한국전기전자재료학회논문지
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• 제20권5호
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• pp.425-429
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• 2007

A linear ultrasonic motor was designed by a combination of the longitudinal and bending mode. linear ultrasonic motors are based on an elliptical motion on the surface of elastic body, such as bar or plates. The corresponding eigen-mode of one resonance frequency can be excited twice at the same time with a phase shift of 90 degrees in space and time. That is excite symmetric and anti-symmetric modes. Then it determines the thrust and speed of the motor. Linear ultrasonic motors are investigated experimentally in according to be fabricated a general classification to motor structure and material characteristic. There was the first to simulate as use of finite element analysis ANSYS 9.0. The AL-T2W8-ARM14-LEG18-ANGLE80 motor has a maxim efficiency 18 % under the speed 0.14 m/s, thrust 345 gf and preload 280 gf, operating frequency is 57.6 kHz.

• 한국소음진동공학회논문집
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• 제23권5호
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• pp.472-478
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• 2013

This paper presents optimal design procedures of mount based on a magnetorheological(MR) fluid to isolate the vibration in heavy diesel engine system. At first, frequency response and force-displacement transmissibility methods are used to get required damping force that is necessary for effective vibration isolation. From this result, a new type of high damping force engine mount is proposed and the governing equation of Bingham plastic behavior of MR fluid in flow path is mathematically derived under cylindrical coordinates. Finally, parametric design optimization featuring finite element is performed using ANSYS software to get the required damping force in MR mount system which can be used to reduce engine vibration. Damping force of the MR mount is then determined as an objective function in this analysis based on ANSYS. Furthermore, Magnetic analysis is then applied in this process.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 하계학술대회 논문집
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• pp.847-851
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• 2000

In this study, contour-vibration-mode Pb($Ni_{1/2}$,$W_{1/2}$)$O_3$-Pb(Zr,Ti)$O_3$ piezoelectric transformers for driving a 28W(T5) fluorescent lamp were fabricated to the modified filter structure with ring and dot electrodes which has been developed for application in 455kHz AM radios. The piezoelectric transformers were fabricated to the size of $31.5$\times$31.5$\times$2.5$mm^3$ with the variations of ring/dot electrode area ratio. Driving of piezoelectric transformer was carried out with input region for the ring electrode and output region for the dot electrode. The electrical properties and characteristic temperature rises caused by the vibration were measured at various load resistances. A 28 W fluorescent lamp, T5, was successfully driven by the fabricated transformer. The transformer with ring/dot electrode area ratio of 1.83 exhibited the best properties in terms of output power, efficiency and characteristic temperature rise, 30.95 W, 97.57% and8.3$^{\circ}C$ respectively.

• 한국정밀공학회지
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• 제12권1호
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• pp.87-96
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• 1995

A new fungivle material named Epoxy-Granite composite is applied to the column structure of drilling center in order to investigate the advanced dynamic charateristics comparing with a conventional cast iron material. The dimensions of new column structure are adjusted to keep the same stiffness (EI value) and the manufacturing conditions are formulated based on the preceeding research experience about the development of Epoxy-Granite structural material. The two kinds of experiments are set up, one of which is for the measurement of natural mode and frequency using experimental modal analysis, and the other one is for the measurement of vibration amplitude during idling operation of a machine tool. The comparison of maximum accelerance values at each natural frequency of bending mode shows a Epoxy-Granite column have larger modal damping ratios(over 2times) than a cast iron column. The vibration amplitude of Epoxy-Granite column measrued on the bed, motor base, and top of column are also much smaller (up to 12%) than the case of cast iron column. It is therefore confirmed that a Epoxy-Granite material exhibits a good anti- vibrational propderty even if it is used under the actual operational environments of machine tool as a practical structural element.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2011년도 추계학술대회 논문집
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• pp.124-129
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• 2011

An improved NDIF method is introduced to efficiently extract eigenvalues of two-dimensional, arbitrarily shaped acoustic cavities. The NDIF method, which was developed by the authors for the eigen-mode analysis of arbitrarily shaped acoustic cavities, membranes, and plates, has the feature that it yields highly accurate eigenvalues compared with other analytical methods or numerical methods (FEM and BEM). However, the NDIF method has the weak point that the system matrix of the NDIF method depends on the frequency parameter and, as a result, a final system equation doesn't take the form of an algebra eigenvalue problem. The system matrix of the improved NDIF method developed in the paper is independent of the frequency parameter and eigenvalues can be efficiently obtained by solving a typical algebraic eigenvalue problem. Finally, the validity and accuracy of the proposed method is verified in two case studies, which indicate that eigenvalues and mode shapes obtained by the proposed method are very accurate compared to the exact method, the NDIF method or FEM(ANSYS).

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 하계학술대회 논문집 Vol.8
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• pp.292-293
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• 2007

In the study, in order to develop low temperature sintering ceramics for multilayer piezoelectric transformer, $(Pb,Ca,Sr)Ti(Mn,Sb)O_3$ ceramics were fabricated using $Na_2CO_3$, $Li_2CO_3$, $MnO_2$ and $Bi_2O_3$ as sintering aids and their dielectric and piezoelectric properties were investigated according to the amount of $Bi_2O_3$ addition. At the sintering temperature of $900^{\circ}C$, density, thickness vibration mode electromechanical coupling factor ($k_t$), thickness vibration mode mechanical quality factor ($Q_{mt}$) and dielecteic constant (${\varepsilon}_r$) showed the optimum value of $6.94[g/cm^3]$, 0.497, 3,162 and 209, respectively, for multilayer piezoelectric transformer application.

• 비파괴검사학회지
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• 제28권3호
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• pp.273-278
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• 2008

In this paper, effects of thermoelastic stress by using lock-in thermography was measured in the cantilever beam. In experiment, a circular holed plate was applied to analyze variation of transient stress under the condition of repeated cyclic loading. And the finite element modal analysis as computational work was performed. According to the surface temperature obtained from infrared thermography, the stress of the nearby hole was predicted based on thermoelastic equation. As results, each stress distributions between 2nd and 3rd vibration mode were qualitatively and quantitatively investigated, respectively. Also, dynamic stress concentration factors according to the change of vibration amplitude were estimated for the resonance frequency.

• 한국음향학회지
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• 제8권1호
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• pp.13-22
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• 1989

본 연구에서는 음역의 변화를 위해 현재 사용중인 방법 대신 피아노 현에 집중질량을 달아, 피아노 현의 진동특성 및 음색에 관해 분석하였다. 이론적 해석은, 현의 질량을 등분화 하여 다자유도계의 스프링-질량 시스템으로 변환시켜 Holzer 방법으로 해석한 불연속계와, 모우드 합 방법과 라플라스 변환방법을 이용한 연속계로 해석하였으며 실험적 해석은 업라이트 피아노의 현에 집중질량을 부착시켜 수행하였다.