• Title/Summary/Keyword: Acoustic Resonators

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An Empirical Acoustic Impedance Model for the Design of Acoustic Resonator with Extended Neck at a High Pressure Environment (높은 음압에서의 내부 확장관형 음향 공명기의 설계를 위한 실험적 음향 임피던스 모델)

  • Park, Soon-Hong;Seo, Sang-Hyun
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.22 no.12
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    • pp.1199-1205
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    • 2012
  • An empirical acoustic impedance model of acoustic resonators with extended neck at a high sound pressure environment is proposed. The acoustic resonator with extended neck into its cavity is appropriate for the launcher fairing application because the length of neck does not increase the total height of the resonator. This enables one to design slim and light acoustic resonators for launch vehicles. The suggested acoustic impedance model considers the incident pressure and geometric variables(the neck length, the perforation ratio and the hole diameter) in terms of non-dimensional variables. Several acoustic resonators with extended neck are manufactured and their wall impedances are measured according to the pre-defined incident pressure levels. Effects of non-dimensional variables on the non-linear acoustic impedance are investigated so that a simple non-linear impedance model for the launcher fairing application can be proposed. It is demonstrated that the estimated acoustic resistance and acoustic length correction show reasonable agreement with the measured ones within the range of design parameters for launcher fairings.

Numerical Analysis of Acoustic Characteristics in Gas Turbine Combustor with Spatial Non-homogeneity

  • Sohn, Chae-Hoon;Cho, Han-Chang
    • Journal of Mechanical Science and Technology
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    • v.18 no.8
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    • pp.1461-1469
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    • 2004
  • Acoustic characteristics in an industrial gas-turbine combustor are numerically investigated by a linear acoustic analysis. Spatially non-homogeneous temperature field in the combustor is considered in the numerical calculation and the characteristics are analyzed in view of acoustic instability. Acoustic analyses are conducted in the combustors without and with acoustic resonator, which is one of the acoustic-damping devices or combustion stabilization devices. It has been reported that severe pressure fluctuation frequently occurs in the adopted combustor, and the measured signal of pressure oscillation is compared with the acoustic-pressure response from the numerical calculation. The numerical results are in good agreement with the measurement data. In this regard. the phenomenon of pressure fluctuation in the combustor could be caused by acoustic instability. From the numerical results for the combustor with present acoustic resonators installed, the acoustic effects of the resonators are analyzed in the viewpoints of both the frequency tuning and the damping capacity. It is found that the resonators with present specifications are not optimized and thus, the improved specification or design is required.

Characteristics of film bulk acoustic resonators(FBAR) filters design with varying configuration of resonator (다양한 공진기 형태에 따른 압전박막필터 설계 및 특성)

  • Jong, Jung-Youn;Kim, Yong-Chun;Kwon, Sang-Jik;Kim, Kyung-Hwan;Yoon, Seok-Jin;Choi, Hyung-Wook
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2003.11a
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    • pp.275-278
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    • 2003
  • The aim of the study is to scrutinize the relationship between the area of resonance and center frequency with varying thickness by analyzing the characteristics of 2-port resonator. This was done through ideal design using Leach model equivalent model modified Mason model equivalent circuit for the application of bandpass filter high-frequency band with resonator Moreover, through the design of ladder-type BPF, we were able to observe changes in bandwidth, resonation, out-of-band rejection depending on the number and area of resonator.

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Thin Film Bulk Acoustic Resonators(FBAR) filters design Air-gap type using piezoelectric thin film (압전박막을 이용한 air-gap type FBAR 필터설계)

  • Jong, Jung-Youn;Kim, Yong-Chun;Kim, Sang-Jong;Kim, Kyung-Hwan;Yoon, Seok-Jin;Choi, Hyung-Wook
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2003.07b
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    • pp.838-841
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    • 2003
  • The aim of the study is to scrutinize the relationship between the area of resonance and insertion loss by analyzing the characteristics of 2-port resonator. This was done through designing an air-gap type Film Bulk Acoustic Resonator (FBAR) by using CAD model for the application of bandpass filter of high-frequency band with piezoelectric thin film. Moreover, through the design of ladder-type BPF, we were able to observe changes in bandwidth, resonation, out-of-band rejection depending on the number and area of resonator.

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Modeling of FBAR Devices with Bragg Reflectors

  • Lee, Jae-Young;Yoon, Gi-Wan;Linh, Mai
    • Journal of information and communication convergence engineering
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    • v.4 no.3
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    • pp.108-110
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    • 2006
  • Film bulk acoustic resonators for radio frequency wireless applications are presented. Various simulations and modeling were carried out. The impedance of a five-layered FBAR showed almost the same trend of the wideband characteristics as that of an ideal FBAR, but the characteristics of the higher modes appear to be much more suppressed. In addition, the wideband impedance decreased with increasing device size. The resonance characteristics depend strongly on the physical dimensions.

Thin Film Bulk Acoustic Resonators for RF Applications

  • Linh, Mai;Lee, Jae-Young;Yoon, Gi-Wan
    • Journal of information and communication convergence engineering
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    • v.4 no.3
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    • pp.111-113
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    • 2006
  • A new thin film deposition technique of piezoelectric ZnO film and its successful application for film bulk: acoustic resonator (FBAR) devices are presented. The two-step deposition used seems to be able to deposit ZnO film with a highly preferred orientation. The FBAR devices with the ZnO films show an excellent return loss of $35{\sim}50$ dB at $1.5{\sim}2$ GHz.

RF MEMS Devices for Wireless Applications

  • Park, Jae Y.;Jong U. Bu;Lee, Joong W.
    • JSTS:Journal of Semiconductor Technology and Science
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    • v.1 no.1
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    • pp.70-83
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    • 2001
  • In this paper, the recent progress of RF MEMS research for wireless/mobile communications is reviewed. The RF MEMS components reviewed in this paper include RF MEMS switches, tunable capacitors, high Q inductors, and thin film bulk acoustic resonators (TFBARs) to become core components for constructing miniaturized on chip RF transceiver with multi-band and multi-mode operation. Specific applications are also discussed for each of these components with emphasis on for miniaturization, integration, and performance enhancement of existing and future wireless transceiver developments.

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Development of a Silencer for an Acoustic Enclosure of a Large Transformer (대형 변압기의 밀폐장치용 소음기 개발)

  • Lee, Jun-Shin;Lee, Wook-Ryun;Lee, Tae-Sung
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2005.05a
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    • pp.786-789
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    • 2005
  • An acoustic total or partial enclosure is widely used to reduce the sound pressure level propagating from a noise source. However, the performance of the acoustic enclosure is decreased by its inherent limitations such as temperature rise or acoustic pressure build up inside the enclosed acoustic field. In general, a silencer is installed to overcome these limitations, for large amount of air can be exchanged through the silencers. In this reason, a parallel baffle type duct silencer with acoustic resonators is studied to reduce the transmitted noise from a transformer. In this silencer, the high frequency components of the transmitted noise over 360Hz are effectively absorbed by the parallel baffles and the other ones, 120 and 240 Hz, are reduced due to the presence of Helmholtz resonators. Large sound attenuation is achieved by applying the sound resonating barrier to the large transformers in a substation.

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Design of Acoustic Resonator Array for Low Frequency Mode Control of Launch Vehicle (위성 발사체 탑재부 저주파 음향 모드 제어를 위한 공명기 배치 설계)

  • Seo, Sang-Hyun;Park, Soon-Hong;Jang, Young-Soon;Yi, Yeong-Moo;Cho, Gwang-Rae
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2005.05a
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    • pp.521-524
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    • 2005
  • To protect a satellite and electronic equipment from the acoustic loads generated by rocket propulsion system, many launch vehicle use acoustic blanket. Most high frequency region of the acoustic loads is reduced by nose fairing skins and acoustic barrier, but low frequency region is not. In order to control low frequency acoustic mode, we designed away resonator panel which was made of composite materials. This paper shows the absorption coefficient measurement result of resonator and SPL(Sound Pressure Level) reduction by using resonators in a rectangular cavity for experiment. Proper arrangement of acoustic resonators at each mode reduce effectively SPL around the satellite through changing boundary condition.

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Frequency property of FBAR RF fitter using PZT (FBAR(Film Bulk Acoustic Resonator)의 주파수 특성에 관한 연구)

  • Yun, Chang-Jin;Jung, Yung-Hak;Kim, Eung-Kwon;Song, Jun-Tae
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2003.05c
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    • pp.57-60
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    • 2003
  • This paper describes the modeling and simulation results for film bulk acoustic resonators(FBAR). We present the frequency tuning mechanisms, analytical solutions of the wave equation and the influence of the thickness of the electrodes. The impedance for PZT based FBAR is derived utilizing proper boundary conditions and their material parameters. Ferroelectrics-based RF filter composed of FBARs are designed.

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