1. Division of Materials Science Engineering, Hanyang University, 17 Haengdang-dong, Seongdong-gu, Seoul 133-791, Republic of Korea, Departments of Civil and Environmental Engineering and Mechanical Engineering, Northwestern University, Evanston, Illinois 60208, and Department of Materials Science and Engineering, Department of Mechanical Science and Engineering, Department of Physics, Beckman Institute, Frederick-Seitz Materials Research Laboratory, University of Illinois at Urbana−Champaign, Illinois 61801