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