1. Department of Electronic Materials Devices and Equipment Engineering, Soonchunhyang University, 22 Soonchunhyang-Ro, Shinchang, Asan, Chungnam336-745, South Korea
2. Department of Mechanical Engineering, Soonchunhyang University, 22 Soonchunhyang-Ro, Shinchang, Asan, Chungnam336-745, South Korea