1. Materials and Process Simulation Center (MC 139-74), California Institute of Technology, Pasadena, California 91125
2. Center for Materials Measurement, Korea Research Institute of Standards and Science, 209 Gajeong-Ro, Yuseong-Gu, Daejeon 305-340, Republic of Korea
3. Department of Mechanical and Nuclear Engineering, Pennsylvania State University, University Park, Pennsylvania 16802
4. Division of Engineering and Applied Science, California Institute of Technology, Pasadena, California 91125