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