We want to fly from Shanghai to Busan on our way home to the US. We are thinking of taking a taxi or bus from PUS to Gyeongju. Is 2 or 3 days about the right amount of time for exploring Gyeongju? We then plan to take the KTX from Gyeongju to Seoul, maybe another day in Seoul or somewhere around Seoul, before flying home. How often does the KTX run from Gyeongju to Seoul and at what times of the day? We are looking for ideas, but can not spend too much time after having been on a 3o day holiday in China.