The South Krean international made his first start in 9 months in the 1-0 home win against Birmingham on New Years Day having been sidelined with a knee injury.
"It is nice to be back," he told MUTV.
"I played for 75 minutes, so that will give me confidence.
"My knee feels 100 per cent and after the game I felt no reaction, so I am not afraid of getting injured again.
"I am very impressed with the reception I got from the fans.
"I have been away from the pitch for nine months, so for them to remember me is fantastic."