• 한국소음진동공학회논문집
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• 제12권3호
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• pp.187-194
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• 2002

A seven-port impedance and admittance matrices of multilayered piezoelectric beam are derived for the analysis of piezoelectric AFM ( atomic force microscope) cantilever that is partially covered by the piezoelectric layer. The variational principle is used for deriving the extensional and flexural motional equations and the conjugate parameters. Overall impedance matrix of AFM cantilever can be obtained by combining two impedance matrices of the covered and the non-covered. she resonance and antiresonance frequencies and the effective electromechanical coupling factors are calculated using the derived matrices. The results and the three dimensional finite element solutions are compared with the experimental results in other publication.

• Journal of Electrical Engineering and Technology
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• 제13권1호
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• pp.250-255
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• 2018

This paper presents a method for minimizing standby power consumption in wireless power transfer (WPT) system via magnetic resonance coupling (MRC) that operates at 6.78 MHz. The proposed circuit controls the required capacitance according to operational condition in order to reduce standby power consumption. Based on an impedance characteristic of the class-E power amplifier, operational principles of the proposed circuit are analyzed. Moreover, to verify the effectiveness of the proposed class-E power amplifier, an 8 W prototype for WPT system is implemented. The measured input power of the proposed class-E power amplifier at standby condition is reduced from 5.81 W to 3.53 W.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1996년도 춘계학술발표회논문집(1)
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• pp.58-63
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• 1996

This paper is devoted to evaluating the accuracy of general 2D geometric transport code, HELIOS, and determining the order of merit in modeling for some important HELIOS input parameters. Benchmark test for 12 critical lattices show that HELIOS predicts criticality accurately within experimental uncertainties, showing only 250 pcm overestimation with a standard deviation of 450 pcm. The sensitivity test suggest that current coupling order, neutron group library, geometrical modeling, and resonance options must be considered carefully to obtain accurate results. Especially, current coupling order and sub-rings in fuel regions turn out to be most critical in HELIOS modeling. For MOX loaded cores, it is additionally necessary to pay attention to the resonance option and the validity of small group neutron library.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제53권5호
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• pp.309-317
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• 2004

This paper suggested the vibration characteristic improvement by variation mode of ring type ultrasonic motor. Design for the piezoelectric ceramic and elastic body of stator were calculated by the finite element method(FEM) that consider the resonance frequency, vibration mode and coupling efficiency etc. Through the result of vibration analysis from 6 order mode to 8 mode, the 7 order mode was gained very an excellent results that it was the coupling efficient, minimum power loss and bending vibration value. Here over 7 order mode, this paper was acquired that an output current for input voltage was very a large increased results. The result of vibration calculation, from thickness 0.5[mm] to 2[mm], knew the fact that the vibration displacement at 0.5[mm] is an high value too. From such result, this paper was manufactured the ultrasonic motor of outer diameter 5O[mm] , inter 22[mm] having the about 43.86[KHz] resonance frequency. We have gated that a simulation result is 42.2[KHz] and an experiment result is 43.86[KHzl The propriety of this paper was established though comparison. investigation of simulation and experiment result.

• 센서학회지
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• 제29권1호
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• pp.45-50
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• 2020

Magnetoelectric (ME) composites were designed using the PMN-PZT single crystal and Ni foils; the properties and magnetic-field sensitivities of ME composites with different piezoelectric vibration modes (i.e., 31, 32, and 36 modes that depend on the crystal orientation of the single crystal) were compared. In the off-resonance condition, the ME coupling properties of the ME composites with the 32 and 36 piezoelectric vibration modes were better than those of the ME composites with the 31 piezoelectric vibration mode. However, in the resonance condition, the ME coupling properties of the ME composites were almost similar, irrespective of the piezoelectric vibration mode. Additionally, in the off-resonance condition (at 1 kHz), the magnetic-field sensitivity of the ME composites with the 36 piezoelectric vibration mode was up to 2 nT and those of the ME composites with the 31 and 32 piezoelectric vibration modes were up to 5 nT. These magnetic-field sensitivities are similar to those offered by conventional high-sensitivity magnetic-field sensors; the potential of the proposed sensor to replace costly and bulky high-sensitivity magnetic field sensors is significant.

• 조명전기설비학회논문지
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• 제26권7호
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• pp.45-51
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• 2012

In this paper, the wireless power transfer system using the magnetic resonance was designed and the effect of resonant coil radius and load resistance to this system was analyzed by the circuit analysis method. As a result, the calculated transmitted-power is similar to measured one, and the coil size has a small effect to the coupling coefficients in the resonant frequency band. In addition, the fact that the calculated transmitted-power according to the source frequency is similar to measured one confirms that the circuit analysis methode in this paper is valid. The input side transmission efficiency ${\eta}_i$ including only the loss in the power transfer circuit is almost 90[%] with the large coil in the 10[cm] transfer distance, and 65[%] with the small coil in 1[cm]. The source side transmission efficiency ${\eta}_s$ is 30~40[%] at both coil when load resistance below 4.7[${\Omega}$] has been connected. Considering that the maximum ${\eta}_s$ is 50[%], this is valid in the practical applications.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 춘계학술대회 논문집 방전 플라즈마 유기절연재료 초전도 자성체연구회
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• pp.173-176
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• 2004

The piezoelectric ceramics for AE sensor piezoelectric devices are desirable to possess higher resonance vibrations. The compositions of $0.9Pb(Zr_xTi_{1-x})O_3-0.1Pb(Mn_{1/3}Nb_{1/3}Sb_{1/3})O_3$ (PZT-PMNS) in this work are selected for obtaining especially large electromechanical coupling factor, high mechanical quality factor and high Curie temperature. This ceramic has higher piezoelectric activity and higher electromechanical coupling factor, but the ceramic has lower Curie temperature. The piezoelectric and dielectric characteristics of PZT-PMNS ternary system are investigated as functions of $Ti^{2+}$, $Zi^{2+}$ mol rate. As the results, MPB(morphotropic phase boundary) in this piezoelectric ceramic is x=0.522. Resonance vibrations of PZT ceramics are investigated as ball-bearing drop test. For the use of AE sensor that driving with pre-amplifier, filter circuit after packed this ceramic and an elastic body.

• Journal of Electrical Engineering and Technology
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• 제10권1호
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• pp.331-337
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• 2015

A novel fully-printed microstrip antenna with negative first resonance and dual polarization is proposed. The radiator is printed on the 1-layer substrate instead of multilayers. The -1st resonance results from a composite right- and left-handed(CRLH) structure that has a circumferentially interlocked gap capacitively coupling a patch with a shorted-ring. This compact antenna is provided with a dual-polarization capability by creating two orthogonal linear polarizations in one body with coaxial feeds. The design is carried out by doing full-wave EM field simulation which is compared with the measurement of the fabricated antenna prototype. The measured results give the gain of 5 dBi and the efficiency of 78% at the -1st resonance mode as the center frequency of a downlink channel of the bandwidth over 20 MHz with 29 dB polarization isolation for mobile communication.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2005년도 추계종합학술대회
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• pp.127-130
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• 2005

In this paper, we investigated the change of recognition distance according to the resonance frequency of the transponder for the ISO 14443 Type A 13.56MHz RFID(Radio Frequency IDentification) system. We made thirteen transponders of the same size. The dimension of the transponder is $84.65mm{\times}53.00mm{\times}0.45mm$. We measured the resonance frequency by means of an inductive coupling. The measured resonance frequencies were between 12.9MHz and 17.3MHz. We measured the maximum distances where the transponder's USN(Unique Serial Number) was recognized and the subcarrier was observed. The measurement results show that we can obtain good performance when the Type A transponder has the resonance frequency around 14.2MHz for the given case.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 춘계학술대회논문집
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• pp.424-429
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• 2005

In this paper, the response characteristics of one to one resonance on the rectangular cantilever beam in which basic harmonic excitations are applied by nonlinear coupled differential integral equations are studied. This equations have 3-dimensional non-linearity of nonlinear inertia and nonlinear curvature. Galerkin and multi scale methods are used for theoretical approach to one to one internal resonance. Nonlinear response characteristics of 1st, 2nd, 3rd modes are measured from the experiment for basic harmonic excitation. From the experimental result, geometrical terms of nonlinearity display light spring effect and these terms play an important role in the response characteristics of low frequency modes. Dynamic behaviors in the out of plane are also studied.