1. Convergence Research Center for Solar Energy, Daegu Gyeongbuk Institute of Science & Technology, 333 Techno jungang-daero, Hyeonpung-myeon, Dalseong-gun, Daegu 711-873, Republic of Korea
2. Department
of Physics, Sogang University, 35 Baekbeom-ro,
Mapo-gu, Seoul 121-742, Republic of Korea