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