Simplify the following text for a Grade 8 native English-speaking person.
Original: Lee Beon-Seok ( hangul : ì ë '' ì , October 20 1900 - May 11 1972 ) was Korean politician and independence activists .
Simplified: Lee Beom-seok ( 1900 â `` 1972 ) was the Korean independence activists and first prime minister of South Korea from 1948 to 1950 . For a time , he also headed the Korean Youth Corps ( ì ì ë 1\/4 ì ì ë