Seiya Nagaoka, Islam Mohammad Raihanul, Kenji Okajima, Ryoei Ito, Ken Watanabe and Tetsu Ito 2018. EVALUATION OF ATTENUATION OF ULTRASONIC WAVE IN AIR TO MEASURE CONCRETE ROUGHNESS USING AERIAL ULTRASONIC SENSOR. GEOMATE Journal. 14, 42 (Feb. 2018), 158–163.