1. School of Electronic Engineering, College of Information Technology; Soongsil University; 551 Sangdo-Dong Dongjak-Gu Seoul 156-743 Republic of Korea
2. Department of Electrical Engineering; Soongsil University; 551 Sangdo-Dong Dongjak-Gu Seoul 156-743 Republic of Korea
3. Department of Mechanical Engineering; Soongsil University; 551 Sangdo-Dong Dongjak-Gu Seoul 156-743 Republic of Korea