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  • 1
    Online Resource
    Online Resource
    Wissenschaftliche Verlagsgesellschaft mbH ; 2016
    In:  Acta Acustica united with Acustica Vol. 102, No. 3 ( 2016-05-01), p. 423-427
    In: Acta Acustica united with Acustica, Wissenschaftliche Verlagsgesellschaft mbH, Vol. 102, No. 3 ( 2016-05-01), p. 423-427
    Type of Medium: Online Resource
    ISSN: 1610-1928
    Language: English
    Publisher: Wissenschaftliche Verlagsgesellschaft mbH
    Publication Date: 2016
    detail.hit.zdb_id: 119-3
    detail.hit.zdb_id: 2078656-6
    SSG: 7,11
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  • 2
    Online Resource
    Online Resource
    IOP Publishing ; 2011
    In:  Journal of Micromechanics and Microengineering Vol. 21, No. 8 ( 2011-08-01), p. 085015-
    In: Journal of Micromechanics and Microengineering, IOP Publishing, Vol. 21, No. 8 ( 2011-08-01), p. 085015-
    Type of Medium: Online Resource
    ISSN: 0960-1317 , 1361-6439
    RVK:
    Language: Unknown
    Publisher: IOP Publishing
    Publication Date: 2011
    detail.hit.zdb_id: 1480280-6
    detail.hit.zdb_id: 1069644-1
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  • 3
    Online Resource
    Online Resource
    The Korean Institute of Electrical Engineers ; 2017
    In:  The Transactions of The Korean Institute of Electrical Engineers Vol. 66, No. 4 ( 2017-04-01), p. 629-635
    In: The Transactions of The Korean Institute of Electrical Engineers, The Korean Institute of Electrical Engineers, Vol. 66, No. 4 ( 2017-04-01), p. 629-635
    Type of Medium: Online Resource
    ISSN: 1975-8359
    Uniform Title: 소나 시스템 설계를 위한 FFR 트랜스듀서 어레이의 등가회로 모델링
    Language: English
    Publisher: The Korean Institute of Electrical Engineers
    Publication Date: 2017
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  • 4
    Online Resource
    Online Resource
    Springer Science and Business Media LLC ; 2011
    In:  Experimental and Molecular Medicine Vol. 43, No. 6 ( 2011), p. 367-
    In: Experimental and Molecular Medicine, Springer Science and Business Media LLC, Vol. 43, No. 6 ( 2011), p. 367-
    Type of Medium: Online Resource
    ISSN: 1226-3613
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2011
    detail.hit.zdb_id: 2084833-X
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  • 5
    Online Resource
    Online Resource
    Acoustical Society of America (ASA) ; 2008
    In:  The Journal of the Acoustical Society of America Vol. 123, No. 5_Supplement ( 2008-05-01), p. 3649-3649
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 123, No. 5_Supplement ( 2008-05-01), p. 3649-3649
    Abstract: A new type of highly directional ultrasonic transducer is designed and tested as an ultrasonic range sensor by using the parametric acoustic arrays. To get intensive primary waves, a modified stepped plate transducer is proposed. Gallego-juarez et al.(1978) first proposed stepped plate transducer for high power radiation at one frequency. The steps with the height of half-wavelength of sound in air compensate discrete phase difference on the vibrating plate. However, two collimated beams are required for the parametric acoustic array. The position and height of the steps are modified to compensate the flexural vibration for two frequencies in this transducer. The transducer diameter is 50mm. The optimal primary frequencies are designed as 80kHz and 120kHz to generate difference frequency of 40kHz efficiently. The proposed transducer has the HPBW of 5° that is much higher directivity than general ultrasonic range sensor(Generally 20° on same size). The maximum SPL is 130dB at primary frequencies and 95dB at difference frequency on 75Vpk input. These experimental results show that the proposed transducer can successfully improve the spatial resolution of ultrasonic sensor. [Research is partly supported by MIC/IITA Intelligent Robot Sensor and partly supported by DAPA and ADD UD070054AD]
    Type of Medium: Online Resource
    ISSN: 0001-4966 , 1520-8524
    RVK:
    Language: English
    Publisher: Acoustical Society of America (ASA)
    Publication Date: 2008
    detail.hit.zdb_id: 1461063-2
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  • 6
    Online Resource
    Online Resource
    Acoustical Society of America (ASA) ; 2010
    In:  The Journal of the Acoustical Society of America Vol. 127, No. 6 ( 2010-06-01), p. 3494-3502
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 127, No. 6 ( 2010-06-01), p. 3494-3502
    Abstract: An ultrasonic radiator is developed to generate a difference frequency sound from two frequencies of ultrasound in air with a parametric array. A design method is proposed for an ultrasonic radiator capable of generating highly directive, high-amplitude ultrasonic sound beams at two different frequencies in air based on a modification of the stepped-plate ultrasonic radiator. The stepped-plate ultrasonic radiator was introduced by Gallego-Juarez et al. [Ultrasonics 16, 267–271 (1978)] in their previous study and can effectively generate highly directive, large-amplitude ultrasonic sounds in air, but only at a single frequency. Because parametric array sources must be able to generate sounds at more than one frequency, a design modification is crucial to the application of a stepped-plate ultrasonic radiator as a parametric array source in air. The aforementioned method was employed to design a parametric radiator for use in air. A prototype of this design was constructed and tested to determine whether it could successfully generate a difference frequency sound with a parametric array. The results confirmed that the proposed single small-area transducer was suitable as a parametric radiator in air.
    Type of Medium: Online Resource
    ISSN: 0001-4966 , 1520-8524
    RVK:
    Language: English
    Publisher: Acoustical Society of America (ASA)
    Publication Date: 2010
    detail.hit.zdb_id: 1461063-2
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  • 7
    Online Resource
    Online Resource
    Acoustical Society of America (ASA) ; 2017
    In:  The Journal of the Acoustical Society of America Vol. 142, No. 4_Supplement ( 2017-10-01), p. 2509-2509
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 142, No. 4_Supplement ( 2017-10-01), p. 2509-2509
    Abstract: The free-flooded ring (FFR) transducer is the well-known low-frequency sound sources in underwater because its operating frequency bandwidth is broad and relatively small size. Previous researches were preformed to predict the characteristics of FFR transducers using ECM which is a type of LPM because ECM is widely used to understand its characteristics in transducer design process. However, it is hardly to predict the characteristics of an FFR transducer because the acoustic field is generated from its top and bottom openings, connected by the inner fluid, as well as the cylindrical ring surface. Here, the authors investigated an ECM of an FFR transducer consisting of three parts: the piezoelectric ring, the cylindrical cavity, and the radiation load. In addition, an LPM which can consider mutual radiation loads was proposed to improve the accuracy of the model. The proposed models were verified using commercial finite element method (COMSOL Multiphysics). It was confirmed that LPM could predict characteristics of FFR transducer more accurately than ECM. [Work supported by NRF 2016R1E1A2A02945515).]
    Type of Medium: Online Resource
    ISSN: 0001-4966 , 1520-8524
    RVK:
    Language: English
    Publisher: Acoustical Society of America (ASA)
    Publication Date: 2017
    detail.hit.zdb_id: 1461063-2
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  • 8
    Online Resource
    Online Resource
    Acoustical Society of America (ASA) ; 2013
    In:  The Journal of the Acoustical Society of America Vol. 134, No. 5_Supplement ( 2013-11-01), p. 4122-4122
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 134, No. 5_Supplement ( 2013-11-01), p. 4122-4122
    Abstract: A parametric array is a nonlinear conversion process that can generate a highly directional sound beam with a small aperture. Since parametric sound generation requires high-intensity ultrasound for nonlinear interaction, efficient sound generation is an important issue in the practical use of parametric loudspeakers. In this study, a piezoelectric micromachined ultrasonic transducer array was investigated in order to generate directional audible sound with a parametric array. A piezoelectric micromachined ultrasonic transducer, with a micron-thick radiating plate, was verified to generate ultrasound with high-efficiency in air. Two types of unit transducers with different resonance frequencies (f1 = 100 kHz, and f2 = 110 kHz) were arranged in the transducer array to extend the frequency bandwidth. The electroacoustic efficiency of the transducer was measured to 71% at its resonance frequency. The ±3dB-frequency bandwidth of the transducer array was 17 kHz. The spatial distributions of the difference frequency wave were measured and compared with the computed data in the audible frequency range. The fabricated transducer array consumed 1 W of electric power while generating a 10 kHz-difference frequency wave with sound pressure level of 80 dB.
    Type of Medium: Online Resource
    ISSN: 0001-4966 , 1520-8524
    RVK:
    Language: English
    Publisher: Acoustical Society of America (ASA)
    Publication Date: 2013
    detail.hit.zdb_id: 1461063-2
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  • 9
    Online Resource
    Online Resource
    Acoustical Society of America (ASA) ; 2004
    In:  The Journal of the Acoustical Society of America Vol. 115, No. 5_Supplement ( 2004-05-01), p. 2526-2526
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 115, No. 5_Supplement ( 2004-05-01), p. 2526-2526
    Abstract: The mutual resistance of transducer arrays is investigated in order to design arrays with improved performance for high intensity sounds at a given frequency. This work proposes the theory that the mutual resistance is related to the loading effects of pressure waves propagated from a piston driver on the surface of another driver. Using this interpretation, the important characteristics of the mutual resistance of two piston drivers are explained and the conditions for local maxima in the mutual resistance are easily determined. On the basis of analyses of the interactions between a driver and acoustic pressure waves, we propose a method to determine the driver radius and the distance between two drivers that give maximum mutual radiation resistance. To evaluate the proposed method, the total resistance of a transducer array is calculated using the formulas for mutual and self-resistance established by Pritchard. The results of the calculations of the total resistances of arrays with many drivers show that a transducer array with drivers arranged sparsely can achieve a larger value of the radiation power per unit area as well as better radiation efficiency than an array in which the drivers are in a closely packed arrangement at a given frequency.
    Type of Medium: Online Resource
    ISSN: 0001-4966 , 1520-8524
    RVK:
    Language: English
    Publisher: Acoustical Society of America (ASA)
    Publication Date: 2004
    detail.hit.zdb_id: 1461063-2
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  • 10
    Online Resource
    Online Resource
    Acoustical Society of America (ASA) ; 2011
    In:  The Journal of the Acoustical Society of America Vol. 130, No. 4_Supplement ( 2011-10-01), p. 2464-2464
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 130, No. 4_Supplement ( 2011-10-01), p. 2464-2464
    Abstract: Micro-machined microphones are attracting attention of industry because of their benefit of size over conventional ones. Since most of micro-machined microphones are capacitive sensors, the sizes of their electrodes determine the low frequency noise level that increases with inverse of frequency (1/f). Therefore, the size of microphone itself becomes larger than one that can be fabricated. Here, we introduce a micro-machined microphone that can overcome the limit of capacitive microphones. The proposed microphone is composed of a field-effect-transistor (FET) and an electret. The difference between the conventional electret capacitive microphones and the proposed microphone may be the transduction mechanism: The change in the position of an electret causes the change in electric field on the gate of FET. Compared with capacitive transduction, the resistive channel of FET can be designed to have low sensor impedance, and subsequently have low impedance at low frequency. To make experimental specimen, FET onto membrane and electret was fabricated with conventional metal-oxide-semiconductor fabrication process and micromachining process, respectively. The FET membrane chip and the electret chip were assembled. Simple current to voltage converter was applied as a pre-amplifier. Its feasibility to apply low frequency acoustic sensor will be proved by simulation and experimental results.
    Type of Medium: Online Resource
    ISSN: 0001-4966 , 1520-8524
    RVK:
    Language: English
    Publisher: Acoustical Society of America (ASA)
    Publication Date: 2011
    detail.hit.zdb_id: 1461063-2
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