They are both about Thai girls who are kidnapped by Hong Kong Mafia because of their father's mistakes. Both girls are rather feisty as well.
The New World is probably one of the best Korean gangster films I've seen so far and I've seen a ton of them so if you watched Gangnam 1970 and liked it watch The New World.
Again it is done by the same writer and director. There are casinos but also lots of explosions and exotic locations like Jeju, Africa and Las Vegas. Also starring Ji Sung.
It was done by the same writer and director as Triangle. It is a really good story with Lee Byung Hun and Ji Sung and it is all about the world of casinos.