How many movies have Kim Chung-gi and Yu Chang-Guk collaborated on?

They have worked on 6 movies together! Their first movie together was Thunderhawk From Outer Space (1986) while their highest rated movie together was Thunderhawk From Outer Space 2 (1986). They have not worked together since Thunderhawk 6 - Third Generation Thunderhawk (1989). They are most known for their action films together.