Preliminary Study on Assessing Delaminated Cracks in Cement Asphalt Mortar Layer of High-Speed Rail Track Using Traditional and Normalized Impact-Echo Methods. - Ying-Tzu Ke; Chia-Chi Cheng; Yung-Chiang Lin; Yi-Qing Ni; Keng-Tsang Hsu; Tai-Tung Wai (Sensors, 2020)