international student job rules korea study in Korea student visa instability Korea international student immigration review Korea student work permit Korea international student administrative risk Korea student visa document mistake Korea D-4 work permission student attendance Korea part-time work Korea student visa korea attendance work rules international student korea immigration student visa korea attendance rules part-time work Korea international students D-2 visa Korea student visa Korea student visa korea rules international student korea immigration attendance korea university change immigration Korea international student visa rejection Korea hikorea d10 student visa attendance rules Korea Korean university visa d-10 visa korea student part time work korea visa international student visa korea problems international student Korea student visa pattern issues Korea international student attendance Korea student visa after graduation job seeking visa korea D-2 part-time job student visa transfer Korea