1. Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
2. George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, USA
3. School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, USA
4. LG Electronics, 38 Baumoe-Ro, Seocho-Gu, Seoul 06763, South Korea