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