"I had never played her before, and she started very well, the first few games were long and tight," Radwanska said. "But after a few games I knew what I had to do to win the match, and I started to play more aggressive from there."
Radwanska, making her debut in Seoul tournament, will face Vera Dushevina.
Japanese veteran Kimiko Date-Krumm beat second-seeded Maria Kirilenko 6-3, 6-1 and will face Francesca Schiavone in the quarterfinals. Date-Krumm's win over the No.19-ranked Kirilenko was her 10th win over a top 20 player since coming back to the tour in 2008.
Wild-card entry Jang Su-jeong also advanced with a 1-6, 6-4, 6-1 win over qualifier Ons Jabeur. Jang will face Lara Arruabarrena in the last eight.