Jamal Mohamad, F. A.; Anita Ahmad; Ruzairi Abdul Rahim; Sallehuddin Ibrahim; Juliza Jamaludin; Noorhazirah Sunar. The Identification of Optimal Frequency for Ultrasonic Transducers in Concrete-Defect Detection Using COMSOL® Simulator. Elektrika 2025, 24, 104-110.