The world No 6 shrugged off a sluggish start to take the opening game in and benefited by a flurry of unforced errors from the South Korean at the later stage of the second game to win the match in 47 minutes.
The former world champion has reduced her head-to-head deficit with Sung to 8-9 after the win. She will next play world No 1 Tai Tzu-ying of Taiwan on Thursday.