1. Department of Energy Science Sungkyunkwan University Suwon 16419 South Korea
2. Department of Physics Korea Advanced Institute of Science and Technology (KAIST) Daejeon 34141 South Korea
3. School of Electrical Engineering Korea Advanced Institute of Science and Technology (KAIST) Daejeon 34141 South Korea
4. Department of Physics Pusan National University Busan 46241 South Korea
5. Department of Electrical and Computer Engineering Sungkyunkwan University Suwon 16419 South Korea
6. Division of Chemical Engineering and Materials Science Graduate Program in System Health Science and Engineering Ewha Womans University Seoul 03760 South Korea