College student studying for 1month South Korea

My Daughter will be in Ulsan for 1 month. Her return flight from Busan to Shanghi to come home to the US has a 22 hour layover. I made a hotel reservation at the airport hotel which is a 5 min walk. Can you walk me thru what she has to do to obtain a visa for those 22 hours she will be there. I am a nervous mom and want to make sure we have everything in order.