• Title/Summary/Keyword: Acoustic Resonance

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A Study on the Development of an Electronic Ballast for 70W Ceramic Discharge Metal Halide Lamps (70W 세라믹 방전관 메탈할라이드 램프용 전자식 안정기 개발에 관한 연구)

  • 김일권;길경석;이성근;김진모
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2002.05a
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    • pp.301-304
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    • 2002
  • This paper describes a design and fabrication of an electronic ballast for 70[W]ceramic discharge metal halide lamps. The proposed ballast is composed of a rectifier, an active PFC, a half-bridge inverter, a LC resonant circuit and a controller. The design also includes a specially designed time circuit which provides reignition of the lamp. Running frequency of the ballast is set at 45[KHz]to avoid acoustic-resonance and flicker. from the test results, input power factor and efficiency of the ballast were estimated 91[%] and 97.7[%], respectively.

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Development of an Electronic Ballast for 70W Ceramic Discharge Metal Halide Lamps with Step Down Converter (강압형 컨버터를 이용한 70W CDM 램프용 전자식 안정기의 개발)

  • 김일권;길경석;김진모
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2002.11a
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    • pp.435-439
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    • 2002
  • This paper describes a design and fabrication of an electronic ballast for 70[W] ceramic discharge metal halide lamps. The proposed ballast is composed of a rectifier, an active power factor correction circuit (PFC), a half-bridge inverter, a LC resonant circuit and a microprocessor. The developed ballast also includes a specially designed time circuit which provides reignition of lamps. Running frequency of the ballast is set at 40[kHz] to avoid acoustic-resonance and flickering. From the experimental results, input power factor and efficiency of the ballast are estimated 99.8[%] and 93.1[%)] respectively.

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The Effect on Acoustic Band Characteristics of ZnO Piezoelectric Transducer according to Thickness of Counter Electrode Layers (하부전극층의 두께가 ZnO 압전변환기의 음향대역특성에 미치는 영향)

  • Park, Gi-Yub;Lee, Jong-Deok;Park, Soon-Tae
    • Journal of the Institute of Electronics Engineers of Korea TE
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    • v.37 no.1
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    • pp.18-26
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    • 2000
  • In this paper, piezoelectric transducer was theoretically analyzed to fabricate high frequency piezoelectric transducer with broadband characteristics. Piezoelectric transducer have been fabricated with 3.825${\mu}m$ ZnO film on Pt/Sapphire(0001), and its appilicability of transducer was confirmed with analyzing theoretical and experimental frequency characteristic. The resonance frequency was detected at the frequency of 827.47MHz corresponding to the half-wavelength frequency of ZnO thin film. Insertion loss was almost -50dB. The minimum insertion loss agrees with simulation analysis.

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Characteristics of detecting arc of AE sensor for using PZT ceramics (PZT 세라믹을 이용한 AE센서의 아크 검출 특성)

  • Yoo, J.S.;Kwon, O.D.;Yun, Y.J.;Kang, S.H.;Lim, K.J.
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2004.07a
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    • pp.515-518
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    • 2004
  • The Piezoelectric ceramics for AE(Acoustic Emission) sensor are desired large electromechanical coupling factor, high mechanical quality factor and good characteristic resonance frequency. In this study, the empirical formula of specimens is used $0.9Pb(Zr_xTi_{1-x})O_3-0.1Pb(Mn_{1/3}Nb_{1/3}Sb_{1/3})O_3$ (PZT-PMNS). The piezoelectric and dielectric characteristic are investigated by sintering temperature and value of x as functions of $Ti^{2+},\;Zi^{2+}$ mol rate. MPB(morphotropic Phase boundary) is defined in the x=0.522. Because it is appeared to the best piezoelectric and dielectric characteristic in the x=0.522, it can be application by AE sensor. PZT-PMNS ceramics without pre-amplifier and filter are tested for detecting of arc signal. The detection characteristic is evaluated wave form, frequency distribution.

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APPROXIMATED SEPARATION FORMULA FOR THE HELMHOLTZ EQUATION

  • Lee, Ju-Hyun;Jeong, Nayoung;Kang, Sungkwon
    • Honam Mathematical Journal
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    • v.41 no.2
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    • pp.403-420
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    • 2019
  • The Helmholtz equation represents acoustic or electromagnetic scattering phenomena. The Method of Lines are known to have many advantages in simulation of forward and inverse scattering problems due to the usage of angle rays and Bessel functions. However, the method does not account for the jump phenomena on obstacle boundary and the approximation includes many high order Bessel functions. The high order Bessel functions have extreme blow-up or die-out features in resonance region obstacle boundary. Therefore, in particular, when we consider shape reconstruction problems, the method is suffered from severe instabilities due to the logical confliction and the severe singularities of high order Bessel functions. In this paper, two approximation formulas for the Helmholtz equation are introduced. The formulas are new and powerful. The derivation is based on Method of Lines, Huygen's principle, boundary jump relations, Addition Formula, and the orthogonality of the trigonometric functions. The formulas reduce the approximation dimension significantly so that only lower order Bessel functions are required. They overcome the severe instability near the obstacle boundary and reduce the computational time significantly. The convergence is exponential. The formulas adopt the scattering jump phenomena on the boundary, and separate the boundary information from the measured scattered fields. Thus, the sensitivities of the scattered fields caused by the boundary changes can be analyzed easily. Several numerical experiments are performed. The results show the superiority of the proposed formulas in accuracy, efficiency, and stability.

A Study on the Acoustic Characteristics Parameter of Resonance Cavity and Phonation in Liver Diseases (간 질환이 공명강과 발성에 미치는 음성분석학적 특징 요소 연구)

  • Lim, Soon-Yong;Lim, Sung-Su;Youn, Yong-Heum;Min, Ji-Sun;Song, Han-Sol;Kim, Bong-Hyun;Ka, Min-Kyoung;Cho, Dong-Uk
    • Proceedings of the Korea Information Processing Society Conference
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    • 2011.04a
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    • pp.1093-1096
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    • 2011
  • 현대 의료 분야는 질병의 진단과 치료뿐만 아니라 질병의 예방 및 건강증진을 위한 관리, 유지의 역할도 중요하게 대두되고 있다. 즉, 질병의 조기 발견과 진단으로 예방 및 관리를 생활화하고 건강수준을 높이는 방향을 제시하는 등 건강증진을 유도하는 계기를 증대시키고 있다. 따라서 본 논문에서는 간질환이 음성에 미치는 영향을 연구하기 위해 간 질환자를 대상으로 공명강과 발성의 변화를 측정하는 실험을 수행하였다. 이를 위해 간 질환자를 피실험자 집단으로 구성하여 간질환으로 인해 입원했을 때와 치료 후에 퇴원했을 때의 음성을 각각 수집하여 음성 분석 요소 중 제3포먼트 주파수 대역폭과 무성음 추출 패턴수를 측정하여 간 질환으로 인해 공명강과 발성에 미치는 영향을 분석하는 연구를 수행하였다.

Transmitted Noise Reduction Performance of Piezoelectric Single Panel through Piezo-damping (압전감쇠를 통한 압전단일패널의 전달 소음저감성능)

  • 이중근;김재환;김기선;이형식
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.2 no.2
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    • pp.49-56
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    • 2001
  • The possibility of a noise reduction of piezoelectric single Panels is experimentally studied. Piezoelectric single panel is basically a plate structure on which piezoelectric patch with shunt circuit is mounted. The use of piezoelectric shunt damping can reduce the transmission at resonance frequencies of the panel structure. Piezo-damping is implemented by using a newly proposed tuning method. This method is based on electrical impedance model and maximizing the dissipated energy at the shunt circuit. By measuring the electrical impedance at the piezoelectric patch bonded on a structure, an equivalent electrical model is constructed near the system resonance frequency. Resonant shunt circuit for piezoelectric shunt damping is composed of register and inductor in series, and they are determined by maximizing the dissipated energy throughout the circuit. The transmitted noise reduction performance of single Panel is tested on an acoustic tunnel. The tunnel is a tube with a square cross section and a loud speaker is mounted at one side of the tube as a sound source. Panels are mounted in the middle of the tunnel and the transmitted sound pressure across Panels is measured. By enabling the piezoelectric shunt damping noise reduction is achieved at the resonance frequencies as well. Piezoelectric single panel with piezoelectric shunt damping is a promising technology for noise reduction in a broadband frequency.

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Broadband Transmission Noise Reduction Performance of Smart Panels Featuring Piezoelectric Shunt Damping and Passive Characteristics (압전감쇠와 수동적 특성을 갖는 압전지능패널의 광대역 전달 소음저감성능)

  • 이중근;김재환
    • The Journal of the Acoustical Society of Korea
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    • v.21 no.2
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    • pp.150-159
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    • 2002
  • The possibility of a broadband noise reduction of piezoelectric smart panels is experimentally studied. Piezoelectric smart panel is basically a plate structure on which piezoelectric patch with shunt circuits is mounted and sound absorbing material is bonded on the surface of the structure. Sound absorbing materials can absorb the sound transmitted at mid frequency region effectively while the use of piezoelectric shunt damping can reduce the transmission at resonance frequencies of the panel structure. To be able to tune the piezoelectric shunt circuit, the measured electrical impedance model is adopted. Resonant shunt circuit composed of register and inductor in stories is considered and the circuit parameters are determined based on maximizing the dissipated energy through the circuit. The transmitted noise reduction performance of smart panels is investigated using an acoustic tunnel. The tunnel is a square crosses sectional tunnel and a loud speaker is mounted at one side of the tunnel as a sound source. Panels are mounted in the middle of the tunnel and the transmitted sound pressure across the panels is measured. Noise reduction performance of a double smart panel possessing absorbing material and air gap shows a good result at mid frequency region except the first resonance frequency. By enabling the piezoelectric shunt damping, noise reduction is achieved at the resonance frequency as well. Piezoelectric smart panels incorporating passive method and piezoelectric shunt damping are a promising technology for noise reduction in a broadband frequency.

Transmission Noise Seduction Performance of Smart Panels using Piezoelectric Shunt Damping (압전감쇠를 이용한 압전지능패널의 전달 소음저감 성능)

  • 이중근
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.3 no.1
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    • pp.49-57
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    • 2002
  • The possibility of a transmission noise reduction of piezoelectric smart panels using piezoelectric shunt damping is experimentally studied. Piezoelectric smart panel is basically a plate structure on which piezoelectric patch with shunt circuits is mounted and sound absorbing materials are bonded on the surface of the structure. Sound absorbing materials can absorb the sound transmitted at mid frequency region effectively while the use of piezoelectric shunt damping can reduce the transmission at resonance frequencies of the panel structure. To be able to reduce the sound transmission at low panel resonances, piezoelectric damping using the measured electrical impedance model is adopted. Resonant shunt circuit for piezoelectric shunt damping is composed of register and inductor in series, and they are determined by maximizing the dissipated energy throughout the circuit. The transmitted noise reduction performance of smart panels is investigated using an acoustic tunnel. The tunnel is a tube with square crosses section and a loud-speaker is mounted at one side of the tube as a sound source. Panels are mounted in the middle of the tunnel and the transmitted sound pressure across panels is measured. Noise reduction performance of a smart panels possessing absorbing material and/or air gap shows a good result at mid frequency region but little effect in the resonance frequency. By enabling the piezoelectric shunt damping, noise reduction of 10dB, 8dB is achieved at the resonance frequencise as well. Piezoelectric smart panels incorporating passive method and piezoelectric shunt damping are a promising technology for noise reduction in a broadband frequency.

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The Design of Broadband Ultrasonic Transducers for Fish Species Identification - Dual Resonance Design of a Ultrasonic Transducer Using a Single Acoustic Matching Layer - (어종식별을 위한 광대역 초음파 변환기의 설계 II - 단일음향정합층을 이용한 이중공진형 변환기의 설계 -)

  • 이대재
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.34 no.1
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    • pp.74-84
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    • 1998
  • A doubly resonant ultrasonic transducer has been designed as an attempt to increase the bandwidth of underwater transducers. The dual resonance conditions were accomplished by attaching a single acoustic matching layer on the front face of a Tonpilz transducer consisted of an aluminum head, a piezoelectric ring, a brass tail and a prestress bolt. A modified Mason's model was used for the performance analysis and the design of transducers, and the constructed transducers were tested experimentally and numerically by changing the impedances and thicknesses of the head, tail and matching layers in the water tank. Two distinct resonance peaks in the transmitting voltage response(TVR) of a developed transducer were observed at 34.3 and 40.4 kHz, respectively, with the difference frequency of 6.1kHz and the center frequency of 37.2kHz. The values of TVR at these frequencies were 136.5 dB re $1\;\muPa/V$ at 34.3 kHz and 136.8 dB re $1\;\muPa/V$ at 40.4 kHz, respectively. Reasonable agreement between the experimental results and the numerical results was achieved. From this result, it is expected that the generation of the distinct resonances at any two desired frequencies can be achieved through the proper choice of the matching layer to provide the impedance transformation between the transducer and the medium.

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