INCHEON, May 16, 2014 (AFP) - The 29-year-old is eight under around the 7,241-metre (6,622-yard) course in pursuit of his first professional victory, with Australian Ryan Haller breathing down his neck after a sizzling 66.
Former champion Park Sang-Hyun was third at five under par, while 71 players made a cut set at plus three.
"My putting has been good for two days," Lee said.
"The wind tends to be harder in the afternoon so I am not sure if I will be too aggressive on Saturday," he said.
Haller also had his putter dialled-in after a first-round 72 he insisted was better than the scorecard suggested.
"Yesterday I actually hit the ball a bit better, but I didn't make a putt," said the 39-year-old from Brisbane.
Star draw K.J. Choi and defending champion Matt Griffin, who both shot 73 on Thursday, made sure of playing the weekend after shooting 67 and 70 respectively.
"I am much happier with my putting today," Choi, a three-time winner of the tournament, said.
Leading second-round scores (South Korea unless stated):
136 - Lee Tae-Hee 68-68
138 - Ryan Haller (AUS) 72-66
139 - Park Sang-Hyun 72-67
140- Jamie Arnold (AUS) 73-67, Kim Kyung-Tae 70-70, Lee Kyoung-Hoon 70-70, Kim Seung-Hyuk 66-74