Pak gave up a two-stroke lead with a double-bogey at the 16th hole, but followed with a birdie and sealed her third title of the season when Han bogeyed the 18th.
In defeating one of the hottest players on the LPGA Tour, Pak moved within a victory of the best -- Annika Sorenstam -- for the tour lead. Sorenstam skipped the event.
Pak closed with an even-par 71, giving her a 72-hole total of 13-under 271, two shots better than Han and Marisa Baena of Colombia. Mi-Hyun Kim of Korea and Heather Bowie shared fourth at 274.
Three of the top-five finishers were from Korea. Han had won two of the previous four events, including last week's tournament in Dublin, Ohio.