• Title, Summary, Keyword: Cavity resonator

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A Helmholtz Resonator Array Panel for Low Frequency Sound Absorption (저주파수 흡음을 위한 헬름홀쯔 공명기 배열형 패널)

  • Kim, Yang-Hann;Kim, SangRyul
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.15 no.8
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    • pp.924-930
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    • 2005
  • Sound absorptive materials have good performance in high frequency range, not at low frequencies. Therefore it has been great challenge to develop a sound absorbing structure that is good at low frequency. We propose to use a Helmholtz resonator array panel for this purpose. A Helmholtz resonator is one of noise control elements widely used in many practical applications. The resonator is a simple structure composed of a rigid-walled cavity with a neck, but it has very high performance at resonance frequency. This paper discusses the sound absorption of Helmholtz resonator array panels at normal and random incidence. First, various experimental results are introduced and studied. Secondly, we theoretically predict the absorptive characteristics of the resonator away panel. The theoretical approach is based on the Fourier analysis for a periodic absorber. We believe that this method can be used to design a panel for low frequency noise control.

Application of Dielectric-loaded Cavity Resonators with HTS Endplates for Tunable High-Q Resonators and Characterization Tools for Large HTS Films (고온초전도 박막이 설치된 유전체부하 공진기의 주파수 조절 가능한 High-Q 공진기 제작 및 대면적 고온초전도 박막의 특성평가에의 응용)

  • Kwon, Hyeong-Jun;Park, Jong-Un;Kang, Hun;Hur, Jung;Lee, Sang-Young
    • 한국초전도학회:학술대회논문집
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    • v.9
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    • pp.75-82
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    • 1999
  • TE$_{01\;{\delta}}$ mode Cavity Resonators with a low loss dielectric rod and YBa$_2Cu_3O_{7-{\delta}}$ (YBCO) endplates were prepared and their microwave properties were studied at temperatures above 30 K. Both sapphire and rutile were used as the dielectrics. The TE$_{01\;{\delta}}$ mode Q$_0$ of the resonator, designed to work as a tunable resonator with variations in the gap distance (s) between the dielectric rod and the top YBCO, was more than 1000000 at s = 0 mm and at 30 K and .the resonant frequency of 19.56GHz when a sapphire rod was used for the dielectric. The TE$_2Cu_3O_{7-{\delta}}$ mode resonant frequency (f$_0$) appeared to decrease as the temperature is raised. Meanwhile, the temperature dependence of the TE$_2Cu_3O_{7-{\delta}}$ mode f$_0$ of the rutile-loaded resonator appeared different with f$_0$ increasing according to the temperature and Q$_0$ more than 300000 at 30 K and f$_0$ = 8.56 CHz. Comparisons were made between the microwave properties of the sapphire-loaded and the rutile-loaded resonators. Also, applications of the TE$_2Cu_3O_{7-{\delta}}$ mode cavity resonator for a tunable resonator with a very high Q$_0$ as · well as a characterization tool for surface resistance measurements of HTS films are described.

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Design of a Helmholtz Resonator for Noise Reduction in a Duct Considering Geometry Information: Additional Relationship Equation and Experiment (형상 정보를 고려한 덕트 소음 저감용 헬름홀츠 공명기 설계: 추가 관계식과 실험)

  • Ryu, Hokyung;Chung, Seong Jin;Lee, Jin Woo
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.38 no.4
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    • pp.459-468
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    • 2014
  • An additional relationship equation is numerically obtained to increase the accuracy of the conventional equation for obtaining the resonant frequency of a resonator. Although the conventional equation is widely used in industry because of its simplicity, it does not provide enough information on the cavity or the neck of the resonator for noise reduction in a duct. Resonator designers have difficulty implementing resonator design owing to the uncertainty in geometry presented by the well-known formula for determining the resonant frequency. To overcome this problem, this work determines an approximate equation using results of numerical calculation. To this end, shape parameters of the neck and cavity of a resonator are defined, and an equation describing the relationship between them is derived by adjusting the peak frequency in the transmission loss curve of a resonator to its resonant frequency. The application and validity of the derived equation are investigated in a numerical simulation and an acoustic experiment, respectively.

Backhole as an Acoustic Damper for the Swirl Injector (스월 인젝터의 음향학적 감쇄기로서의 백홀에 대한 연구)

  • 황성하;윤영빈
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • pp.153-156
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    • 2003
  • Backhole, which is one of geometric parameters in swirl coaxial injectors, is found to affect the inner flow motion and the acoustic characteristics of the swirl injector. In order to analyze the effect of the backhole as a damping device such as acoustic cavities of the combustion chamber, it was regarded as a Helmholtz or Quarter-wave resonator. As a result, it is known that the swirl coaxial injector with the backhole may produce the resonant frequency coincided with the frequency of the combustion chamber.

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Analysis of the Spherical-Rectangular Patch Microstrip Resonator (구면사각패치 마이크로스트립 공진기 해석)

  • Yang, Doo-Young;Lee, Sang-Seol
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.27 no.11
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    • pp.25-31
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    • 1990
  • We analyze the spherical-rectangular patch microstrip resonator with conformal surface by the cavity model and derive the formulas to calculate resonant frequency in the consideration of effective dielectric constant in order to minimize the errors of resonant frequency due to the fringing fields. A transmission type spherical-rectangular patch microstrip resonator operating at 3GHz, for example, is designed and fabricated on Epsilam-10 substate. Measuring data of resonant frequency and return loss are 2.985 GHz and -44.4dB respectively. Those well agreed with theoretical values.

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Analysis and Design of the Cylindrical-rectangular Patch Microstrip Resonator (원통면 사각패치 마이크로스트립 공진기 특성 해석 및 설계)

  • 이민수;이상설
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.16 no.10
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    • pp.925-933
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    • 1991
  • Caracteristics of cylindrical rectanyular patch microshtrip resonator are analyzed by cavity model. To minimize the error of resonant frequency due to fringing field, the resonant frequency is calcylated by the concept of effective dielectric constant. The transmisson type resonator operating at 3GHz is designed and manufactured. The measured data of the resonant frequency and reflection loss are 3.019Ghz and \ulcorner32.78dB respectively. These results nearly coincide with theoretical results.

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Applied of Integrated Optical Biosensor based on Combination of Photonic Crystal Micro-Cavity and Ring Resonator (광결정 공진기와 링 공진기의 공진특성 결합을 통한 바이오센서 응용)

  • Kim, Hong-Seung;Kim, Doo-Gun;Oh, Geum-Yoon;Lee, Tae-Kyeong;Choi, Young-Wan
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.60 no.4
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    • pp.817-822
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    • 2011
  • We propose a novel ring structure based on the stadium-shaped ring resonator (SSRR) with dual photonic crystal microcavity (DPCM) for biosensor and analyzed the sensing characteristics. The Q-factor of the photonic crystal microcavity (PCM) can be significantly enhanced when the PCM or DPCM has the same resonance condition as the SSRR. The simulation results show that the Q-factor of the SRR with DPCM was increased by three times in comparison with single PCM structure. We also defined a mutual interference between two PCMs. Assuming a detectable spectral resolution of 10 picometers, a refractive index resolution of $3.03\times10-5$ can be measured on the SSRR-DPCM.

A Study on the Acoustic Absorption Performance of a Helmholtz Resonator (헬름홀츠 공명기의 흡음성능에 관한 연구)

  • Song, Hwa-Young;Lee, Dong-Hoon
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.18 no.1
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    • pp.71-79
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    • 2008
  • A helmholtz resonator has been widely used for the purpose of suppressing the low frequency noises propagated from various heat and fluid machineries. However, the conventional resonator has demerits that the effective absorption bandwidth is narrow and the absorption performance is not so outstanding in the only limited configurations of neck and cavity as well. In order to overcome these problems, in this paper, a resonator with perforated neck is proposed. The absorption performances of the resonator are measured by two-microphone method and estimated by transfer matrix method. The measured values of normal absorption coefficients agree well with the estimated values. By introducing the perforated plates at the neck of a resonator, it is shown that the absorption performance have been significantly improved.

A Study on the Numerical Analysis of Reentrant Cavity Resonator by Mode Matching Method and Orthogonality (모드결합법과 모드직교성에 의한 요철형 공진기의 공진주파수 계산)

  • 이승무;홍의석
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.12 no.1
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    • pp.1-8
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    • 1987
  • In this paper, resonance frequencies of a reentrant cavity are computed by the mode matching method and the mode orthogonality. The reentrant cavity is composed of a coaxial cable and a cylindrical waveguide, so that resonance frequencies of the resonator can be varied by adjusting the length of the inner conductor of a coaxial cable. The result can be applied to numerous microwave devices such as klystron, wavemeter and resonant circuits of a amplifier and to the measurement of dielectric parameters.

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