• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 춘계학술대회논문집
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• pp.737-742
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• 2000

The paper describes a theoretical study on the flexural vibration of an elastic rectangular plate with periodically nonuniform material properties. The approximate solution of the natural frequency and mode shape has been obtained using the perturbation technique for sinusoidal modulation of the flexural rigidity and mass density. It has been shown that distributed modes exist in the plate which is a two-dimensional model of the flat panel speaker.

• Steel and Composite Structures
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• 제22권2호
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• pp.257-276
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• 2016

In this paper, a new simple higher-order shear deformation theory for bending and free vibration analysis of functionally graded (FG) plates is developed. The significant feature of this formulation is that, in addition to including a sinusoidal variation of transverse shear strains through the thickness of the plate, it deals with only three unknowns as the classical plate theory (CPT), instead of five as in the well-known first shear deformation theory (FSDT) and higher-order shear deformation theory (HSDT). A shear correction factor is, therefore, not required. Equations of motion are derived from Hamilton's principle. Analytical solutions for the bending and free vibration analysis are obtained for simply supported plates. The accuracy of the present solutions is verified by comparing the obtained results with those predicted by classical theory, first-order shear deformation theory, and higher-order shear deformation theory. Verification studies show that the proposed theory is not only accurate and simple in solving the bending and free vibration behaviours of FG plates, but also comparable with the other higher-order shear deformation theories which contain more number of unknowns.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 춘계학술대회논문집
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• pp.1212-1217
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• 2006

This study is concerned with static and sinusoidal disturbance rejection for a single periodic input disturbance with known period. In the area of active elimination of a disturbance force, the control input should have two different kinds of gains: one is to deliver a stable control and the other is a force component to cancel the external disturbance force. In this paper we employ a simple state feedback control law to make the balance beam stable and employ a linear observer to estimate the states which represent the external disturbance force components. Simulation results verify our proposed control method to reject a static and sinusoidal disturbance force.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 추계학술대회 논문집
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• pp.926-929
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• 2005

Recently, laser interferometer is widely used as a measuring system in many fields because of its high resolution and its ability to measure a board area in real-time ail at once. In conventional laser interferometer, for examples Out of plane ESPI, In plane ESPI, Shearography and Holography, it uses PZT or other components as a phase shift instrumentation to extract 3-D deformation data, vibration mode and others. However, in most cases PZT has some disadvantages, which include noli-linear errors and limited time of use. In present study, a new type of laser interferometer using a laser diode(LD) is proposed. Using Laser Diode Sinusoidal Phase Modulating(LD-SPM) interferometer, the phase modulation can be directly modulated by controlling the LD injection current thereby eliminating the need for PZT components.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1991년도 추계학술대회
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• pp.103-106
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• 1991

A three-dimensional finite element model of a ligamentous two motion segments (L4-S1) was developed to investigate its dynamic response. A number of parameters like the intradiscal pressure, forces in ligaments. and across facet joints in response to a sinusoidal axial compression force (-360 N to -440 N at 5 Hz) were predicted. The increase in the parameters varied from 12% to as high as 50% in comparison to response for a static load of 400 N. The predicted parameters also revealed a distortion and a phase shift in comparison to the applied sinusoidal signal. These changes may lead to degenerative changes seen clinically in persons exposed to a chronic vibration environment over time.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 추계학술대회논문집
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• pp.851-856
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• 2003

The study on the new measurement method of room acoustics is now in process in the ISO TC43/SC2/WG24 New standard(WD 18233) is dealing with the MLS, swept sinusoidal signal and impulse. This working group is composed of more than 20 specialists in 10 countries and the convener is professor J.H.Rindel in technical university of Denmark. The meeting of WG24 was held in the DIN, Berlin at 23rd. this september and the results was sent to the secretary of ISO TC43/SC2 for the circulation. Brief information of ISO/WD18233 and the result of this meeting is given here.

• 한국소음진동공학회논문집
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• 제14권9호
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• pp.827-836
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• 2004

In this paper, we design a robust multi-objective track-following controller that satisfies transient response specifications and diminishes the influence of sinusoidal disturbance. To this end, a robust control problem with the multiple constraints is considered. We show that a sufficient condition satisfying the robust control problem can be expressed by linear matrix inequalities. Finally, the robust track-following controller can be designed by solving an LMI optimization problem. The effectiveness of the proposed controller design method is verified though experiments.

• 한국지반공학회지:지반
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• 제11권4호
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• pp.37-48
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• 1995

본 연구에서는 수직가속도를 일으키는 진동실험을 통하여 정규진동 및 무작위 진동시의 건조 사질토에 대한 동적거동을 분석하였다. 실험결과로부터 진동가속도와 상대밀도의 관계곡선을 제안하였으며, 여러가지 상재하중하에서의 거동특성을 규명하였다. 실험에는 완전건조된 사질토를 사용하였으며, 입경별로 4개의 시료로 나누고, 현장입경상태를 재현한 시료를 더하여 총 5개의 시료를 사용하였다. 정규진동실험의 경우, 진동진폭은 0.4mm~0.6mm로 유지하고 진동주파수를 3~40Hz 범위에서 변화시키면서 가속도에 따른 시료의 상대밀도 변화를 측정하였다. 무작위진동실험의 경우, 무작위파 발생기를 이용하여 무작위진동파와 10~50Hz 범위의 정규진동파가 조합된 합성파를 발생시키고, 가속도센서로 가속도를 측정하면서 상대밀도의 변화를 측정하였다. 본 연구결과, 수직가속도만으로 사질토를 94%~99%의 상대밀도까지 다질 수 있었으며, 최대 상대 밀도를 발생시키는 수직가속도는 시료가 최소 건조 단위 중량일 때의 간극비와 최대 건조 단위 중량일 때의 간극비 차이에 비례하는 것을 알 수 있었다. 또한, 상재하중을 가하지 않은 경우가 상재하중을 가한 경우보다 시료의 상대밀도변화가 크게 나타탔으며, 상재하중이 클수록 상 대밀도의 변화가 일어나는 가속도가 커짐을 알 수 있었다.

• Structural Engineering and Mechanics
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• 제45권4호
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• pp.569-594
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• 2013

The free vibration of axially functionally graded tapered arches including shear deformation and rotatory inertia are studied through solving the governing differential equation of motion. Numerical results are presented for circular, parabolic, catenary, elliptic and sinusoidal arches with hinged-hinged, hinged-clamped and clamped-clamped end restraints. In this study Differential Quadrature element of lowest order (DQEL) or Lagrangian Interpolation technique is applied to solve the problems. Three general taper types for rectangular section are considered. The lowest four natural frequencies are calculated and compared with the published results.

• Advances in nano research
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• 제4권4호
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• pp.265-279
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• 2016

Present study interests with the longitudinal forced vibration of nanorods. The nonlocal elasticity theory of Eringen is used in modeling of nanorods. Uniform, linear and sinusoidal axial loads are considered. Dynamic displacements are obtained for nanorods with different geometrical properties, boundary conditions and nonlocal parameters. The nonlocal effect increases dynamic displacement and frequency when compared with local elasticity theory. Present results can be useful for modeling of the axial nanomotors and nanoelectromechanical systems.