According to Visa Bulletin for Dec. 2008, the Priority Date for this preference is Jan. 01, 1998. Therefore it will possibly take much longer than a decade.
The Priority Date is the date that an immigration petition for your sister is filed. Your sister can apply the Green Card in the U.S. or the immigration Visa in Korea when your immigration petition(Form I-130) is approved and the priority date is within the established cutoff date published by the U.S. Dept. of State every month. Thanks.