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