How does a chinese person living in Dalian China make application for visa to South Korea?

My Chinese friend who is living in Dalian, China wants to take short break and come across to visit me in Seoul, South Korea. The purpose being a short visit / social meeting to spend time with together, do some shopping and sight seeing with me while I am on business trip in Korea - just for a long weekend or a 'one week' round trip. What are the visa requirements, where does she make the application apply and how long does it normally take?