Author,Title,Journal,ISSN,Publisher,Date,Volume,Number,Page,URL,URL(DOI) Kobayashi Tsutomu and Tai Hidekazu,Measurement method of the particle concentration using converged ultrasonic impulse radiated from a piano-concave transducer with broadband width,THE JOURNAL OF THE ACOUSTICAL SOCIETY OF JAPAN,03694232,Acoustical Society of Japan,2007,63,8,434-441,https://cir.nii.ac.jp/crid/1390001206566706304,https://doi.org/10.20697/jasj.63.8_434