1. Graduate Student, School of Civil, Environmental, and Architectural Engineering, Korea Univ., Korea Anam-Dong, Seoul, Seongbuk-Gu 136-713, Korea.
2. Manager, Kunhwa Eng, Yoeksam-Dong, Seoul, Gangnam-Gu 702-22, Korea.
3. Manager, Hyundai Heavy Industries, Bangeojinsunhwan-Doro, Ulsan, Dong-Gu 682-792, Korea.
4. Professor, School of Civil, Environmental, and Architectural Engineering, Korea Univ., Anam-Dong, Seoul, Seongbuk-Gu 136-713, Korea (corresponding author).