[1] Samsung Adv Inst Technol, Yusong Gu, Taejon 305380, South Korea
[2] Hannam Univ, Dept Mech Engn, Taejon, South Korea
[3] Tsing Hua Univ, Dept Elect Engn, Beijing 100084, Peoples R China
[4] Huazhong Univ Sci & Technol, Dept Phys, Wuhan 430074, Peoples R China