• 한국전기전자재료학회논문지
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• 제24권1호
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• pp.22-26
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• 2011

On this paper, a circular unimorph-type piezoelectric transducer was proposed and studied. The transducer was fabricated by attaching a circular-shaped PZT ceramic to a circular plate of brass and output characteristics of the fabricated transducer were then analyzed and measured by changing driving points where the mechanical vibrations were applied. Two conditions depending on the location of vibration were respectively defined as a center forced model and an edge forced model. The resonance frequency and output voltage of the models were simulated by using ANSYS, a FEM(finite element method) program. Based on the results of the analyses, the vibration experiment was conducted and the output characteristics then measured through measurement equipment. As a result, the maximum output characteristics of two models were respectively generated at each resonance frequency and the resonance frequency of the center forced model was lower than the edge forced model.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1986년도 한국자동제어학술회의논문집; 한국과학기술대학, 충남; 17-18 Oct. 1986
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• pp.149-152
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• 1986

Vibration characteristics of harmonic drives and cyclo drives are reviewed. Both of two have two resonance frequencies inherently. Especially, the amplitudes of cyclo drives are over 1.0g. The test of the robot also shows large amplitude of vibration in the speed which is coincide with the resonance frequencies of reducers.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2004년도 하계종합학술대회 논문집(2)
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• pp.477-480
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• 2004

We studied the characteristics of impedance and electromechanical coupling coefficient in ZnO and AIN thin films by using resonance frequency spectrum method. The response peak of impedance decreased with the decrease of thickness of piezoelectrics, the number of mode of response peak increased with the increase of substrate thickness. An error of $k_{t}^{2}$ estimated from input $k_{t}^{2}$ increased as the thickness of piezoelectrics decreased and the thickness of substrate increased. Also, the error was increased in case of a large acoustic impedance of substrate. It was found that the composite resonator operating in optimized condition could be designed through the resonance frequency spectrum analysis of composited resonator consisted of piezoelectric thin film and substrate.

• 전자공학회논문지A
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• 제28A권12호
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• pp.19-23
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• 1991

A method for suppressing unwanted resonance modes by attaching an electromagnetic wave absorber onto a metal case was studied to prevent performance deterioration of electronic devices. The electromagnetic wave absorber fabricated for this study had an attenuation characteristics above 20dB in the frequency band from 450MHz, 1150MHz. A rectangular cavity resonator whose resonance frequencies of TE$_{101}$, TE$_{102}$ modes were 900MHz, 1250MHz, respectively, was made to measure attenuation for the electromagnetic wave absorber-metal assembly. The result showed that the resonance mode for high attenuation was sensitive to the location of electromagnetic wave absorber, and the attenuation characteristics above 20dB could be obtained when electromagnetic wave absorber was properly positioned.

• 센서학회지
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• 제25권4호
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• pp.243-246
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• 2016

The characteristics of a bimetallic surface plasmon resonance (SPR) chip were investigated to detect a tumor biomarker, carcinoembryonic antigen (CEA). The linewidth and the tangential slope of the reflectance curve of the bimetallic SPR chip was compared with those of the reflectance curve of a conventional gold (Au) SPR chip. The changes in reflectance in response to the variation in CEA in the critical concentration range were analyzed at an angle where the tangential slope of the reflectance curve was maximum. From linear regression analysis, the sensitivity of the bimetallic SPR chip with respect to the CEA in critical concentration was obtained.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 춘계학술대회논문집
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• pp.865-868
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• 2005

A Helmholtz resonator is one of noise control elements widely used in many practical applications. The resonator has very high absorption at resonance frequency but the frequency bandwidth is very small. Therefore many kinds of additional resistive screens have been applied to the resonator's neck in order to increase the bandwidth. This paper discusses the absorptive characteristics of a Helmholtz resonator damped by a flexible porous screen in form of wire mesh. First, various experimental results are introduced and studied. Secondly, the effect of the resistive screen is theoretically predicted. It is shown that the distance between the screen and aperture affects on the resonance frequency as well as the absorption of the system.

• 전기학회논문지
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• 제56권1호
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• pp.156-160
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• 2007

Surface plasmon resonance(SPR) has been widely studied for biological and chemical sensing applications. The present study conducts numerical simulation for the single and bimetallic layer SPR configurations by using the multiple beam interference matrix(MBIM) method to investigate the influence of wave interference and complex refractive indices of materials on optical characteristics such as reflectance and optical phase shift which are used for sensing. First, calculated reflectances are compared with experimental data for validation. In addition, in the single film structures this study finds out the appropriate film thicknesses with minimum reflectance for cases of gold film and silver film. For a bimetallic silver-gold film structure, in particular, the bimetallic film thicknesses that has the minimum reflectance are found 36 nm for silver and 5 nm for gold. From the results, the use of phase shift would be useful compared to reflectance in determining the SPR configuration because the phase shift becomes more sensitive than reflectance.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 하계학술대회 논문집
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• pp.680-683
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• 2001

The output characteristics of step-down piezoelectric transformer is changed by a structure of layers. In this paper, we simulated output characteristics of multi-layer piezoelectric transformers with variation of output layers. Also, fabricated piezoelectric transformers were compared with simulated data. From simulated piezoelectric transformers, the output voltage decreased with increasing number of layers. From these results, piezoelectric transformers were made and the output electrical power of the transformers was measured at resonance frequency and at other frequency. The electrical power of transformers was measured on each transformer's resonance mode. However, measured value of 12-layed transformer's output power was smaller than that of 6-layered transformer's one. It is supposed that internal capacitance and reactance of the piezoelectric transformer's were effected in this result. Therefore we need to connect other road resistance and capacitance in output circuit, in order to increase electrical power of transformers.

• Journal of information and communication convergence engineering
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• 제6권1호
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• pp.34-37
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• 2008

Effects of the addition of Cr adhesion layer to $W/SiO_2$ multilayer Bragg reflectors on the resonance characteristics of film bulk acoustic wave resonator (FBAR) devices are presented. Main resonance peaks could be significantly shifted to higher frequency, mainly due to the addition of Cr adhesion layer to multilayer Bragg reflectors and control of the bottom electrode thickness as well. The FBAR devices with the Cr adhesion layer in Bragg reflectors could result in much more improved resonance characteristics at about 3 GHz in terms of return loss and Q-factor.

• 대한전자공학회논문지TC
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• 제48권7호
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• pp.28-34
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• 2011

영차 공진과 반파장 공진을 이용한 이중 모드 Inductor loaded 패치 안테나의 방사 특성을 연구하였다. 반파장 공진 모드에서 수평방향으로의 방사 이득을 최소화시키는 동시에 전방 방사 이득을 향상시켜 영차 공진 모드 방사 패턴과의 격리도를 향상시켰다. 이중 모드 inductor loaded 패치 안테나 기판의 유전상수가 작을수록, 안테나의 동작 주파수 대역이 높을수록 두 모드 간의 공진 주파수 간격이 증가함을 확인하였다.