CDC (Center for Disease Control,US) as long as you have been treated correctly, asymptomatic with negative CXR (chest x-ray, current with in the last 6 months) together with the certification from your health care provider, then you are ok. If you came from Asia, chances are, you were vaccinated with BCG in the past. This would always show positive for TB skin test. I do not know how is the law in Korea about this. email the Korean Embassy whatever country you are.