Xin Ge Sr., School of Energy, Materials and Chemical Engineering, Korea University of Technology and Education, Cheonan 330-708, Republic of, Korea University of Technology and Education, Cheonan, South Korea and Ur Ryong Cho, professor, School of Energy, Materials and Applied Chemical Engineering, Korea University of Technology and Education, School of Energy, Materials and Applied Chemical Engineering, Korea University of Technology and Education, Republic of Korea, Cheonan, South Korea