1. National Fusion Research Institute, Gwahangno 113, Yuseong-gu, Daejeon 305-333, Korea
2. Pohang University of Science and Technology, San 31, Hyoja-dong, Nam-gu, Pohang 790-784, Korea
3. CEA, IRFM, F-13108 Saint-Paul-lez-Durance, France
4. Massachusetts Institute of Technology, Plasma Science and Fusion Center Cambridge, Massachusetts 02139, United States