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