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  • Comparative Studies. Non-European Languages/Literatures  (3)
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  • Comparative Studies. Non-European Languages/Literatures  (3)
RVK
  • 1
    Online Resource
    Online Resource
    Feasibility study on a highly-directional parametric array loudspeaker applicable to mobile devices
    Acoustical Society of America (ASA) ; 2017
    In:  The Journal of the Acoustical Society of America Vol. 141, No. 5_Supplement ( 2017-05-01), p. 4017-4017
    Details
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 141, No. 5_Supplement ( 2017-05-01), p. 4017-4017
    Abstract: A conventional parametric array (PA) loudspeaker has a relatively small aperture and produces a highly directional audible sound beam. Due to limitations arising from their size and power consumption, standard PA loudspeakers are not used in mobile devices. PA loudspeakers are typically larger than 25 cm and require more than 60 W. We show that piezoelectric micro-machined ultrasonic transducer (pMUT) arrays can emit highly directional ultrasonic sounds with a power efficiency of up to 80% [Je and Moon, Ultrasonics 53, 1124-1134 (2014)]. Highly directional sound beams with a frequency bandwidth of 13 kHz can be generated efficiently by pMUT arrays with two resonant frequencies [Je and Moon, JASA 173(4), 1732-1743 (2015)] . We used a signal processor, power amplifier, and pMUT array to build a loudspeaker system that is smaller than, and requires less power than, a conventional PA loudspeaker system. In our loudspeaker system, the maximum sound pressure level (SPL) is 75 dB, ± 3 dB frequency bandwidth is 12.5 kHz, and the total power consumption is 3.4 W. Hence, this loudspeaker system could potentially be used in mobile devices. [This work was supported by Samsung Research Funding Center, SRFC-IT1404-00.]
    Type of Medium: Online Resource
    ISSN: 0001-4966 , 1520-8524
    URL: Article
    DOI: 10.1121/1.4989235
    RVK:
    EQ 1000
    Language: English
    Publisher: Acoustical Society of America (ASA)
    Publication Date: 2017
    detail.hit.zdb_id: 1461063-2
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    Online Resource
  • 2
    Online Resource
    Online Resource
    Computation of bit error rate for underwater communication with and without low-salinity water in the western sea of Jeju.
    Acoustical Society of America (ASA) ; 2011
    In:  The Journal of the Acoustical Society of America Vol. 129, No. 4_Supplement ( 2011-04-01), p. 2667-2667
    Details
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 129, No. 4_Supplement ( 2011-04-01), p. 2667-2667
    Abstract: Salinity is one of variables in the empirical formula of the sound speed (SS) of seawater. Its effects on the SS are generally neglected because the average salinity is 34 psu and varies within a few psu seasonally and spatially in the ocean. Recently, low-salinity water around 25 psu flows into the western sea of Jeju Island in Korea due to the Yangtze River flood in China during summer. In this paper, it was analyzed how the low-salinity water affected the SS profile (SSP) and the underwater communication. The SSP was calculated with and without the low-salinity layer, and the communication channel was estimated by the simulated acoustic eigen-rays. The bit error rate (BER) was computed using binary phase-shift keying modulation, and the effects of the low-salinity water on the BER were investigated. The SSP was changed to a positive slope by the low-salinity layer at the sub-surface up to 20 m of depth, forming the acoustic wave guide which mostly resulted in the decrease of the BER. Consequently, this paper suggests that it is important to consider the low-salinity water near Jeju for the underwater acoustic modeling and communication. [Work supported by UD100014DD.]
    Type of Medium: Online Resource
    ISSN: 0001-4966 , 1520-8524
    URL: Article
    DOI: 10.1121/1.3588926
    RVK:
    EQ 1000
    Language: English
    Publisher: Acoustical Society of America (ASA)
    Publication Date: 2011
    detail.hit.zdb_id: 1461063-2
    Location Call Number Limitation Availability
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    Online Resource
  • 3
    Online Resource
    Online Resource
    Digital beamsteering system using acoustic transducer array.
    Acoustical Society of America (ASA) ; 2011
    In:  The Journal of the Acoustical Society of America Vol. 129, No. 4_Supplement ( 2011-04-01), p. 2675-2675
    Details
    In: The Journal of the Acoustical Society of America, Acoustical Society of America (ASA), Vol. 129, No. 4_Supplement ( 2011-04-01), p. 2675-2675
    Abstract: Acoustic signal processing can be applied to sonar, acoustic communications and multimedia applications. Especially transmitting acoustic signal to the desired direction has many applications in military and industry. In this paper, we present digital beamsteering algorithm using parametric array transducers. To generate the desired beampattern, the proposed algorithm utilizes the complex weight instead of time delay. With this complex operation, many algorithms including constant beamwidth algorithm and linear constrained beamforming algorithms can be applied to make versatile transmitting beampatterns. To verify the generated beampattern, we build acoustic beamsteering system by using commercial transducers and LABVIEW software and hardware. The system includes GUI software, which allows user to change many parameters such as number of sensors, complex weight of each sensor, type of transmit data, etc. The GUI can also be easily modified and extended to accommodate the characteristics of transducers. With the laboratory experiments, we verified the performance of the algorithm and system. The proposed algorithm and system can be used to build many application systems such as multimedia, acoustic communications, and sonar system. [Work supported by Grant No. UD100014DD.]
    Type of Medium: Online Resource
    ISSN: 0001-4966 , 1520-8524
    URL: Article
    DOI: 10.1121/1.3588963
    RVK:
    EQ 1000
    Language: English
    Publisher: Acoustical Society of America (ASA)
    Publication Date: 2011
    detail.hit.zdb_id: 1461063-2
    Location Call Number Limitation Availability
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    Online Resource
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