immigration overstay decision Korea korea mobile internet korea tourism guide k-eta korea Korea tax refund tourist exit procedures Korea night transportation Korea hospital visit tourist Korea korea connectivity korea entry requirements 공항 환급 방법 VAT refund Korea 한국 세금 환급 tourist overstay Korea consequences tourist medical emergency Korea late night bus Korea korea sim card korea travel tips overstay exit risk Korea travel to korea esim korea overstay clearance Korea Myeongdong tax kiosk Tax refund in Korea tourist exit record Korea visa free korea 외국인 택스 리펀 taxi at night Korea missed last subway Korea 서울 쇼핑 환급