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