The South Korean international completed a season-long loan move from Swansea on Saturday but wasn't eligible to play as the Black Cats were defeated at Crystal Palace.
"It's obvious that he has quality, physical presence and he's young," Di Canio told safc.com.
"The fact that he played for a few years already in British football made me happy that he decided to sign for us.
"He played lots of games for Swansea - a good team who play good football.
"He's a player who can build up from the back in the way I want; he plays tactical balls and has a long range of delivery with precision."
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