1. Department of Chemical Engineering, Sunchon National University, Sunchon, Cheon Nam 540-742, Korea, Department of Chemistry and Biochemistry, The University of Oklahoma, Norman, Oklahoma 73019, Department of Chemical Engineering, Yonsei University, Seoul 1202-749, Korea, and Department of Materials Science and Engineering, Kwangju Institute of Science and Technology (K-JIST), Kwangju 500-712, Korea