[1] Korean Testing Certificat Inst, Reliabil & Semicond Convergence Ctr, Gunpo 15809, South Korea
[2] Tech Univ Korea, Grad Sch, Elect Engn, Shihung 15073, South Korea
[3] SUNKWANG LTI, Res & Dev, Seoul 06230, South Korea
[4] Tech Univ Korea, Dept Energy & Elect Engn, Shihung 15073, South Korea