You're misusing the word "racism" as many people do these days. South Korea has been actively recruiting students from the US, and is welcoming them. South Korean young people are often quite interested in US culture, and are very familiar with the music, movies, tv shows, etc. They are also very polite as a culture, and are unlikely to be openly hostile to anyone. But you will be an outsider. Don't expect to blend in. Where real racism exists, it has to do with romantic relationships and marriage. South Korean parents are not tolerant of their children getting involved with outsiders of any kind. So you can have friends, and have a nice social life, but don't expect to have the kind of casual sex that US college students have, or to be able to have a romantic relationship.