1. Department of Environmental Engineering, Daejeon University, Yongun-dong 96-3, Dong-gu, Daejeon, Korea
2. Department of Civil and Environmental Engineering, Korea Advanced Institute of Science and Technology, Guseong-dong 373-1, Yuseong-gu, Daejeon, Korea
3. Philadelphia Water Department, 1500 E. Hunting Park Avenue, Philadelphia, PA 19124, USA