COLUMBIA, Mo. — As American teenagers go, Sally Kim is pretty typical. She’s crazy about singer Bruno Mars and the Plain White T’s rock band, spends way too much time on Facebook and can’t wait to start college in the fall. Yet when it comes to that familiar bane of her fellow high school seniors — uncool parents — Kim has few worries. Hers are nearly 7,000 miles away in Seoul, South Korea. They sent their only child to live with relatives in Missouri a decade ago, when she was just 8.