1. Department of Electrical Engineering, Pusan National University, 2 Busandaehak-ro 63 beon-gil, Geumjeong-gu, Busan 46241, Republic of Korea
2. Department of Physics, Pukyong National University, Busan 608-737, Republic of Korea
3. Department of Physics, Bannari Amman Institute of Technology, Sathyamangalam 638401, Tamil Nadu, India