"It was my first tournament back. I think there are a lot of positive things to look at rather than thinking 'hey, I shot over par'."
Ko's challenger for the world number one ranking, Thailand's Ariya Jutanugarn, snared five birdies in the first 11 holes of the final round before fading to finish third, four strokes behind world number six Jang.
The tour now moves to the Honda LPGA tournament in Thailand this week, where the field will include Ko, Jutanugarn and rising Canadian star Brooke Henderson.
Korea's Olympic champion Inbee Park is set to make her debut for the season, after a long absence in 2016 recovering from a thumb injury. Park has not played on the tour since June although she battled past the injury to win the gold medal in August.