1. Department of Biomedical Engineering, BK21+ Research Institute of Biomedical Engineering, College of Biomedical and Health Science, Konkuk University, Chungju, Korea
2. Department of Photonic Engineering, Chosun University, Gwangju, Korea
3. Department of Physics, Ajou University, Suwon, Korea
4. Department of Energy Systems Research, Ajou University, Suwon, Korea