[1] Korea Basic Sci Inst, Yusung Ku, Taejon 30533, South Korea
[2] Korea Adv Inst Sci & Technol, Taejon 305701, South Korea
[3] Pohang Univ Sci & Technol, Pohang, South Korea
[4] Korea Atom Energy Res Inst, Taejon, South Korea
[5] Samsung Adv Inst Technol, Taejon, South Korea
[6] Princeton Plasma Phys Lab, Princeton, NJ 08543 USA
[7] MIT, Cambridge, MA 02139 USA
[8] Gen Atom Co, San Diego, CA USA
[9] Seoul Natl Univ, Seoul, South Korea
[10] Korea Res Inst Stand & Sci, Taejon, South Korea