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