1. Ph.D. Candidate, Dept. of Architecture and Architectural Engineering, Seoul National Univ., 599, Gwanak-ro, Gwanak-gu, Seoul 151-744, South Korea (corresponding author).
2. Professor, Dept. of Architecture and Architectural Engineering, Seoul National Univ., 599, Gwanak-ro, Gwanak-gu, Seoul 151-744, South Korea.
3. Senior Researcher, Research Institute of Industrial Science and Technology, 180-1, Songdo-dong, Yeonsu-gu, Incheon 406-840, South Korea.