Park shot a three-under 69 and joined Germany's Yannik Paul (68) at eight under overall at Jack Nicklaus Golf Club.
"I want to prove that Korean players can have a chance to win on the (European) tour," Park said.
"I think other players feel the same and that is why a lot of Korean players are playing well at the moment."
Australasian tour Order of Merit winner David Micheluzzi is three shots off the pace in a tie for 10th.
The winner of the WA PGA Championship, TPS Sydney and NSW Open in his home summer, the 26-year-old Victorian is five under after his round-two 70.
Antoine Rozner started the second round with a four-stroke lead after an opening 63 but couldn't follow that up, shooting 74 — including a triple-bogey seven at the par-4 ninth after going out of bounds. He dropped into a share of third place with fellow Frenchman Mike Lorenzo-Vera (65), one shot behind the leaders.
"It's never easy to come back after such a low score as yesterday, but I felt pretty good," Rozner said.
"And to be honest, after seven holes, I was hitting some amazing shots and it didn't turn out the way I wanted to."
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