1. a Department of Polymer Chemistry , Faculty of Engineering Kyoto University , Kyoto, Japan
2. b Ibaraki Electrical Communication Laboratory, Nippon Telegraph and Telephone Public Corporation , Tokai-mura, Ibiaraki-ken, Japan
3. c Polymer Research Institute, University of Massachusetts , Amherst, Massachusetts
4. d Tire Materials Research Section, Tire Research and Development Department , Bridgestone Tire Co., Kodaira, Tokyo, Japan