1. Researcher, Dept. of Architectural Engineering, Yonsei Univ., Seoul 03722, South Korea (corresponding author).
2. Assistant Professor, School of Architecture, Korea National Univ. of Transportation, Chungju, Chungcheongbuk-do 27469, South Korea.
3. Associate Professor, Graduate Institute of Ferrous Technology and Graduate School of Engineering Mastership, Pohang Univ. of Science and Technology, 77 Cheongam-Ro, Nam-Ku, Pohang 37673, South Korea.