Yoo was also an adjunct professor of 연기학담당 at Daekyeung University in 1997. Since 2007, he has been an activist of Sunfull Movement, a non-profit organization against cyberbullying.

On December 29, 2007, Yoo landed in the news for assaulting two producers of The King and I. He was reportedly enraged because the scripts were routinely turned in late, which exhausted his wife Jeon In-hwa, an actress in the TV series. Yoo later apologized for the incident.