South Korea 's In Gee Chun won the U.S. Women 's Open Sunday at Lancaster Country Club in her first appearance in this championship .
In Gee Chun did n't do so with dumb luck .
South Korea 's In Gee Chun won the U.S. Women 's Open Sunday at Lancaster Country Club in her first appearance in this championship , but she did n't do so with dumb luck .