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