The Korea-wide tourist information line is 1330, operated by the Korea Tourism Organization. It runs 24 hours a day and has staff available in English, Japanese, and Korean. They can help with train and bus routes, opening hours of sights, restaurant recommendations, and general travel queries.
When calling from a mobile phone, you need to prefix the area code. In Seoul, dial 02-1330; in Busan, 051-1330, and so on.