The 19-year-old South Korean fired his second 67 at the 7,185-yard, par-71 Woo Jeong Hills Country Club and is 8 under for the tournament.
“The reason I’m at the top of the leaderboard is because I’ve only had two bogeys in two rounds, one today and one yesterday,” said Noh.
“That’s the most important part of doing well here, limiting your dropped shots and picking up birdies where you can. I’ve made a lot of up-and-downs. I’m not sure if my short game has improved or if it’s just good this week.”
Kang Sung-hoon of South Korea is second, four shots back after 11 holes of his second round, one shot ahead of New Zealand’s Danny Lee after 13 holes.
Anthony Brown of Australia is 6 back on 140, after completing a second-round 71.
“Today was a bit up and down. I was kind of hitting everywhere on the front nine, but I was much more solid on the back nine where I was 2 under,” said Brown. “I’ve been really solid for the past two days, except the first nine of my second round. I’ve just got to try to keep doing what I’ve been doing.”
First-round leader Ronald Harvey of Australia also did not complete his second round Friday because of delays in the first round caused by fog.
After a first-round 67, Harvey was 2 over after 14 holes.