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