• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.23 no.1
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• pp.9-16
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• 2013

This paper experimentally deals with the excitation by functional electrical stimulus(FES) and the response of electromyo-potential at the muscles of antebrachial joint in a human body. The excitation of FES, which results in the contraction of the muscles and thus the flection of the joint, shows that the flection angle of the joint is proportional to the magnitude of the stimulus current. The response of electromyo-potential measured according to the FES shows the linearly-proportional relation between the joint torque and the electromyo-potential. The results can be used for active motion of joint rehabilitation.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.29 no.1 s.232
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• pp.27-34
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• 2005

We analyze in detail axially symmetric theoretical study for the photothermal pulsed radiometry of a cylindrical model. The theoretical solutions describe the transient infrared radiation from the sample heated by short-duration pulsed heating. In the conventional transmission radiometry technique, the excitation source and the detector are on opposite sides of the sample, otherwise in the new single ended radiometry technique, the excitation source and the detector are on same sides of the sample. The analytical solution described for photothermal radiometry in this study would not need to cut or polish samples to measure the thermal diffusivity. Therefore the radial area and axial thickness of samples are not limited. The effects of excitation pulse duration and the area of heat source are discussed.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.52 no.4
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• pp.161-169
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• 2003

The applications of SRM(Switched Reluctance motor) are dramatically increasing due to a simple mechanical structure, a high efficiency and a high speed drive characteristics. Energy recovery in the regenerative region is very important when SRM is used in traction drive. This is to reduce energy loss during mechanical braking and/or to have a high efficiency drive. To control excitation voltage during motoring and regenerating voltage in the generator operation in the SRM, multi-level voltage control is effective. This paper suggests multi-level inverter which is useful for motoring and regenerative operation. The proposed method is verified through simulations and experiments.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.52 no.4
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• pp.161-161
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• 2003

The applications of SRM(Switched Reluctance motor) are dramatically increasing due to a simple mechanical structure, a high efficiency and a high speed drive characteristics. Energy recovery in the regenerative region is very important when SRM is used in traction drive. This is to reduce energy loss during mechanical braking and/or to have a high efficiency drive. To control excitation voltage during motoring and regenerating voltage in the generator operation in the SRM, multi-level voltage control is effective. This paper suggests multi-level inverter which is useful for motoring and regenerative operation. The proposed method is verified through simulations and experiments.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.26 no.6_spc
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• pp.721-728
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• 2016

The combined rotational and translational dynamic vibration absorbers (DVA) with no dampers for the beam vibration control can effectively isolate the vibration within the external excitation force region. This paper investigates the damping efficacy for the combined rotational and translational dynamic vibration absorbers to impose some robustness to the DVA system for the excitation force frequency variation. The beam is assumed to be subjected to a concentrated harmonic excitation force. The solution to the problem is found based on Galerkin method.

• Smart Structures and Systems
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• v.5 no.1
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• pp.55-68
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• 2009

In the present study, active control of a smart beam under forced vibration is analyzed. The aluminum smart beam is composed of two piezoelectric patches and strain gauge. One of the piezoelectric patches is used as controlling actuator while the other piezoelectric patch is used as vibration generating shaker. The smart beam is harmonically excited by the piezoelectric shaker at its fundamental frequency. The strain gauge is utilized to sense the vibration level. Active vibration reduction under harmonic excitation is achieved using both strain and displacement feedback control. Control actions, the finite element (FE) modeling and analyses are directly carried out by using ANSYS parametric design language (APDL). Experimental applications are performed with LabVIEW. Dynamic behavior at the tip of the beam is evaluated for the uncontrolled and controlled responses. The simulation and experimental results are compared. Good agreement is observed between simulation and experimental results under harmonic excitation.

• Smart Structures and Systems
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• v.24 no.3
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• pp.379-390
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• 2019

In this research, we propose an energy harvesting structure with a flexible blade element vibrating at its first mode to maximize the power output of the piezoelectric material. For this purpose, a piezoelectric patch was attached on the blade element used in a small-scale wind turbine, and air load was applied with a suitable angle of attack in the stall zone. The aerodynamic load created by air excitation vibrates the blade element in its first natural frequency and maximizes the voltage output of the piezoelectric patch. The variation of power outputs with respect to electrical resistance, air speed, and extra mass is experimentally investigated for various cases. An analytical model is constituted using a single-mode blade element with piezoelectric patch dynamics, and the power outputs of the obtained model are compared with experimental results.

• Steel and Composite Structures
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• v.32 no.2
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• pp.253-264
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• 2019

This paper presents the combination resonances of FG porous (FGP) cylindrical shell under two-term excitation. The effect of structural damping on the system response is also considered. With regard to classical plate theory of shells, von-$K{\acute{a}}rm{\acute{a}}n$ equation and Hook law, the relations of stress-strain is derived for shell. According to the Galerkin method, the discretized motion equation is obtained. The combination resonances are obtained by using the method of multiple scales. Four types of FGP distributions consist of uniform porosity, non-symmetric porosity soft, non-symmetric porosity stiff and symmetric porosity distribution are considered. The influence of various porosity distributions, porosity coefficients of cylindrical shell and amplitude excitations on the combination resonances for FGP cylindrical shells is investigated.

• Proceedings of the KIPE Conference
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• 2004.07a
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• pp.46-49
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• 2004

Switched Reluctance Motor(SRM) has been researched for its superior characteristics. The SRM drive system has simple mechanical and magnetic structure, and it requires simple power electronic drive circuit. It is to be compatible to wide range adjustable speed drive system because it has the same driving characteristics of DC series motor's, easy control principle and high efficiency characteristics. In this paper, 2 types of excitation strategy are researched. Conventional 1-phase excitation and 2-phase excitation method are compared and tested. Though 1-phase excitation method is robust and has high performance, 2-phase excitation method has some merit in appling power device. Some simulation and test results are foaled with some analysis.

• Proceedings of the KSME Conference
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• 2002.08a
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• pp.241-244
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• 2002

Large eddy simulation of a circular jet at the Reynolds number of 10000 is performed to investigate turbulence suppression effect with single frequency excitation at the non-dimensional frequency of 0.017. Instantaneous flow fields show that, with excitation, naturally occurring energetic vortices are suppressed through earlier saturation and breakdown of the shear layer vortices into fine grained turbulence. Due to the excitation, the Reynolds stresses are larger for the excited case near the jet and turbulence suppression begins afterward. The Reynolds normal stresses show largest suppression in the shear layer near the jet and in the centerline further downstream, while the Reynolds shear stress shows largest suppression in the shear layer at all the downstream locations.