Yan-Shek Hoh was born in China. He received the Ph.D. degree in physics from Ohio State University, Columbus, in 1976.From 1976 to 1977 he was a Postdoctoral Research Associate at the Infrared Molecular Spectroscopy Laboratory, Ohio State University. Between 1977 and 1979, he was first associated with the Computer Sciences Corporation, Silver Spring, MD, to perform analysis of satellite attitude determination and then joined the Singer Company, Links Division, Silver Spring, MD, to work on nuclear power plant simulation. Since 1979 he has been with The MITRE Corporation, McLean, Va. His work includes collision avoidance analysis of air traffic control systems, design of large adaptive HF networks, and theoretical studies of terrestrial wave guide propagation in the ELF band.