Prof. Changdon Kee is a Professor Emeritus in the Department of Aerospace Engineering at Seoul National University (SNU), South Korea and supervises SNU GNSS Lab (SNUGL, http://gnss.snu.ac.kr). He received B.S. and M.S. degrees from Seoul National University and a Ph.D. degree from Stanford University. He served as a Technical Advisor to the Federal Aviation Administration (FAA) on the Wide Area Augmentation System (WAAS) in 1994. Prof. Kee currently serves as a Technical Advisor for Korea Civil Aviation Safety Authority (KCASA) and Ministry of Public Administration and Security (MOPAS). He also served as a President of Korean Institute of Navigation. He has more than 20 years of GNSS and flight control research experiences.