**About the Editors**

**Jong-Ryul Yang** received his B.S. degrees in electrical engineering and material science from Ajou University, Suwon, South Korea, in 2003 and his Ph.D. degree in electrical engineering from the Korea Advanced Institute of Science and Technology, Daejeon, South Korea, in 2009. From February 2009 to October 2011, he worked as a senior engineer in the System LSI Division, Samsung Electronics, Yongin, South Korea. From November 2011 to August 2016, he was a senior researcher in the Advanced Medical Device Research Division, Korea Electrotechnology Research Institute, Ansan, South Korea. From March 2012 to August 2016, he was an associate professor in the Department of Energy and Power Conversion Engineering, University of Science and Technology, Ansan, South Korea. Since September 2016, he has been an associate professor in the Department of Electronic Engineering, Yeungnam University, Gyeongsan, South Korea. He is a senior member of IEEE, a lifetime member of KIEES, KIEE, and IEIE, and a board member of MDPI *Sensors*. His research interests include RF/millimeter-wave/terahertz-wave circuits and systems, specifically for CMOS detector ICs, high-power millimeter-wave transmitters, sub-terahertz imaging systems, and miniaturized radar sensors.

**Seong-Tae Han** received his B.S. degree in physics education in 1999, and both his M.S. and the Ph.D. degrees in physics, in 2001 and 2005, respectively, from Seoul National University (SNU), Seoul, Korea. As a research assistant, he participated in developing ultrawide-band TWTs for electronic warfare and satellite communication at X-band. He demonstrated the first working MEMS-fabricated vacuum electronic device (a folded waveguide TWT) at Ka-band. Dr. Han was a researcher with the Research Institute of Basic Science, SNU, in 2005, where his research focused on novel vacuum electron devices employing recent innovations, such as photonic crystals and cold cathodes based on nano/MEMS technologies. In September 2005, he joined in the Plasma Science and Fusion Center, Massachusetts Institute of Technology (MIT), Cambridge, MA, as a postdoctoral research associate, where he worked on sub-THz gyrotrons for DNP/NMR research and ECH transmission lines for ITER. Since 2008, he has been a senior and principal researcher with the Korea Electrotechnology Research Institute, Korea (KERI), where he leads programs for developing high-power and high-frequency gyrotrons for active denial systems and real-time nondestructive inspection systems, respectively. His research interests cover high-power microwaves and charged particle beams, as well as their industrial applications. Currently, he serves as the director of Electrophysic Research Center with KERI and a professor with the Department of Energy and Power Conversion Engineering in the University of Science and Technology.
