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