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