“…Ultrasound has various reception characteristics depending on the density and acoustic impedance of the measurement medium, and, on the basis of these characteristics, it is widely used in communication devices, medical devices, actuators, transducers, precision sensors, nondestructive testing (NDT), and measuring devices (Vellekoop, 1998;Choi et al, 2020). In addition, it has been used in structural health monitoring (SHM) systems (Guo et al, 2020), liquid level monitoring systems (Gao et al, 2020), early crack detection of structural systems (Chakraborty et al, 2019), and gas leak location detection systems (Wang et al, 2018).…”