Simplify the following text for a Grade 7 native English-speaking person.
Original: Yoo Sang-Chul ( born October 18 , 1971 ) is a retired South Korean football player who , as of 2005 was playing for Ulsan Hyundai Horang-i .
Simplified: Yoo Sang-Chul ( born 18 October 1971 ) is a former South Korean football player .