1. Department of Electrical and Electronic Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 120-749, Republic of Korea
2. ZeSHTech Co., Ltd., Business Incubator, Gwangju Institute of Science and Technology, 123, Cheomdangwagi-ro, Buk-gu, Gwangju 500-712, Republic of Korea
3. Department of Electronic, Seoil University, Seoildaehak-gil 22, Jungnang-gu, Seoul 131-702, Republic of Korea