I would like to get visa to go China about 1 week for my study program. Which document I should prepare for China visa application?

You can apply for a business visa to China. But be note that China visa application should be submitted to an travel agency appointed by Chinese embassy or consulate. And following documents should be prepared:
1. Invitation letter from China, eg. your inviter's company or organization;
2. Application form for China visa application;
3. One passport-sized Photo;
4. Original passport and copy of its information pages;
5. Return ticket and hotel bookings in China;
6. Student visa or ARC valid for more than 6 months in South Korea.
Fee for a single entry visa is won 35,000. Additional service fee for travel agencys may differ in cases. So, contact them for details. Anyway, if you have no invitation letter from China, you can just try to apply for a tourist visa instead.