"my friend want to use usa IP Address he try to connect from Korea."
He does realize this is going to add 800-1000ms right? Not to mention the throughput bottleneck. That pretty much is game over lag for any real time game. Why does your friend need to seem like he has another IP? Game ban? If so, they would be better off using a proxy closer to home. No need to send the traffic all the way to the other side of earth. Even light can't go that fast. XD