1. a Department of Civil and Environmental Engineering, Natural Science Campus , Sungkyunkwan University (SKKU) , 300 Cheoncheon-dong, Jangan-gu, Suwon , Gyeonggi-do , 440-746 , South Korea
2. b School of Environmental Science and Engineering , Gwangju Institute of Science and Technology (GIST) , 261 Cheomdan-gwagiro, Buk-gu , Gwangju , 500-712 , South Korea Phone:
3. c Fax: