1. Assistant Professor, Dept. of Civil Engineering, Keimyung Univ., 1095 Dalgubeol-daero, Dalseo-Gu, Daegu 42601, South Korea.
2. Professor, School of Civil, Environmental and Architectural Engineering, Korea Univ., Anam-ro 145, Seongbuk-gu, Seoul 02841, South Korea (corresponding author).