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