1. School of Electrical EngineeringKorea Advanced Institute of Science and Technology (KAIST) 291 Daehak‐ro, Yuseong‐gu Daejeon 34141 Republic of Korea
2. School of Electrical and Computer EngineeringPurdue University West Lafayette IN 47907 USA
3. Department of Electronic EngineeringWearable Convergence ElectronicsKyung Hee University 1732 Deogyeong‐daero, Giheung‐gu Yongin 17104 Republic of Korea
4. Powder & Ceramics DivisionKorea Institute of Materials Science (KIMS) 797, Changwondaero Changwon 51508 Republic of Korea