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