Ms.Starkey, you need to check first for the Consular Jurisdiction of Chinese embassy and consulates from information above. If you live in Seoul now, you are required to submit your visa application through a travel agency from Seoul that designated by the Chinese embassy (the list you will get from their official website, in Korean version). Visa fee is USD140, you have to pay extra service fee to the agency. With required documents well prepared, visa processing from the embassy is 4 working days. For your trip to China, you can read Beijing Tour(https://www.travelchinaguide.com/package/beijing.htm) as a reference.