1. Graduate, KyungPook National Univ., School of Architecture and Civil Engineering, 1370, Sangyegk-Dong, Buk-Gu, DaeGu 702-701, Korea.
2. Ph.D. Candidate, School of Architecture and Civil Engineering, KyungPook National Univ., 1370, Sangyegk-Dong, Buk-Gu, DaeGu 702-701, Korea.
3. Associate Professor, School of Architecture and Civil Engineering, KyungPook National Univ., 1370, Sangyegk-Dong, Buk-Gu, DaeGu 702-701, Korea (corresponding author).