1. Department of Electrical Engineering; Korea University; Seoul 136-713 Republic of Korea
2. Department of Electrical Engineering; KAIST; Daejeon 305-701 Republic of Korea
3. Department of Mechanical Engineering; Hanbat National University; Daejeon 305-719 Republic of Korea
4. Electronic Materials and Module Team; Korea Institute of Ceramic Engineering and Technology; Seoul 153-801 Republic of Korea
5. Department of Physics; Korea University; Seoul 136-713 Republic of Korea