1. Department of Physics; Kongju National University; Gongju 32588 Republic of Korea
2. Nano-Mechanical Systems Research Division; Korea Institute of Machinery and Materials (KIMM); 171 Jang-dong Yuseong-gu Daejeon 34103 Republic of Korea
3. Department of Electrical Engineering; National Polytechnic Institute of Cambodia; Phnom Penh 12400 Cambodia