1. Institute of Nuclear Engineering and Science; National Tsing Hua University; No. 101, Section 2, Kuang-Fu Road Hsinchu Taiwan 30013 R. O. C.
2. Department of Material Science and Engineering; National Tsing Hua University; Hsinchu Taiwan 30013 R. O. C.
3. Department of Material Science and Engineering; National Chiao Tung University; Hsinchu Taiwan 30013 R. O. C.
4. Department of Engineering and System Science; National Tsing Hua University; Hsinchu Taiwan 30013 R. O. C.