1. Dept. of Photogrammetry, Univ. of Bonn, Nussallee 15, 53115 Bonn, Germany; formerly, School of Civil and Environmental Engineering, College of Engineering, Yonsei Univ., 134 Shinchondong, Seodaemungu, Seoul 120-749, Korea.
2. Korea Institute of Construction Technology, 283 Goyangdae-ro, Ilsanseo-gu, Goyang-si, Gyeonggi-do 411-712, Korea; formerly, School of Civil and Environmental Engineering, College of Engineering, Yonsei Univ., 134 Shinchondong, Seodaemungu, Seoul 120-749, Korea.
3. School of Civil and Environmental Engineering, College of Engineering, Yonsei Univ., 134 Shinchondong, Seodaemungu, Seoul 120-749, Korea.
4. School of Civil and Environmental Engineering, College of Engineering, Yonsei Univ., 134 Shinchondong, Seodaemungu, Seoul 120-749, Korea (corresponding author).