Under the Visa Waiver Program, Korean citizens can enter the United States without a visa and stay for 90 days. However, anyone who intends to stay in the United States for more than 90 days for family visits, study abroad, employment, business, or any other reason, must obtain a U.S. visa that allows that period of stay. The following are the types of visas that allow you to legally stay in the United States for a certain period of time.
EN 
KO