1. Department of Applied Physics, Faculty of Engineering, Tohoku University, Sendai, Miyagi 980-77
2. College of Engineering, Nihon University, Koriyama, Fukushima 963
3. School of Physics and Technology, Chonbuk National University, Chonju, 560-756, Korea
4. Department of Basic Science, Ishinomaki Sensyu University, Ishinomaki, Miyagi 986-60