1. a Polymer/Bio-Composites Research Lab, Department of Polymer Science and Engineering, Kumoh National Institute of Technology, Gumi, Gyungbuk 730-701, Korea
2. b Polymer/Bio-Composites Research Lab, Department of Polymer Science and Engineering, Kumoh National Institute of Technology, Gumi, Gyungbuk 730-701, Korea
3. c Korea Research Institute of Chemical Technology, Daejeon 305-343, Korea
4. d Program in Environmental Materials Science, Seoul National University, Seoul 151-921, Korea