INCHEON, May 17, 2014 (AFP) - The South Korean pair are nine under around the 6,622-metre (7,241-yard) Ocean Course, two ahead of overnight leader Lee Tae-hee, who could only card a 73, and Lee Kyoung-hoon, who shot a 69.
Australian David Bransdon scored a 69 to leave him in fifth place at six-under par.
Fellow Australian Jason Scrivener roared up the board to share sixth by matching the day's best of 67, while star draw K.J. Choi is still in the running at four under.
With 10 career victories to his name, Kim Kyung-Tae is one of the most successful players in the field, but has been winless since 2012 and spent the winter remodelling his swing in a bid to recapture his touch.
"I have been coaching myself for the past three years but this year I took some outside advice and it is starting to pay off," the 27-year-old said.
Kim's only blemish on a card boasting seven birdies was at the 15th, when an errant drive led to a double bogey.
"Actually my tee shots were a bit erratic all day," he said. "I hope to fix that tomorrow."
Kim Seung-Hyuk, 28, is still looking for his first win since turning professional in 2005, but said he was feeling calm and collected.
"I don't know why, but I just lacked a bit of confidence with the putter yesterday," he said. "Today was much better and tomorrow I hope to be aggressive on the front nine and see how it goes."
Leading second-round scores (South Korea unless stated):
207 - Kim Seung-Hyuk 66-74-67, Kim Kyung-Tae 70-70-67.
209 - Lee Kyoung-Hoon 70-70-69, Lee Tae-Hee 68-68-73.
210 - David Bransdon (AUS) 71-70-69.
211 - Jason Scrivener (AUS) 72-72-67, Jang Dong-Kyu 75-66-70.
212 - Choi Joon-Woo 71-72-69, Park Il-Hwan 73-70-69, K.J. Choi 75-67-70, Park Sang-Hyun 72-67-73.