Stephen Yoo is a Ph.D student in Nuclear and Radiological Engineering, George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology. He recieved B.E. and M.E. degrees in Nuclear Engineering, Kyung Hee University, Korea. His research interests are in safety and security of nuclear facilities, including analog/digital instrumentation and control (I&C) systems, safety assessment, and cybersecurity issues arousing from the digital I&C systems. His recent research covers developing a resilience strategy using machine/reinforcement learning against cyber-attacks, and developing a cyber-physical protection system for molten salt reactors (MSRs).