Simplify the following text for a Grade 8 native English-speaking person.
Original: Chun Doo-hwan ( born 18 January , 1931 ) was a Korean military officer and the President of South Korea from 1980 to 1988 .
Simplified: Chun Doo-hwan ( born January 18 , 1931 ) was a ROK Army general and the President of South Korea from 1980 to 1988 .