Yang, who finished eighth at The Masters last week, embarked on a back-nine birdie blitz to close on his equally in-form but lesser known compatriot.
With Kim topping the second round leaderboard at 11-under-par after a three-under 69, Yang closed with four consecutive birdies which keyed a six-under-par 66 to earn a share of second alongside Asian number one Thongchai Jaidee and Welshman Jamie Donaldson.
Shane Lowry leads the Irish charge on 138 after a 68 yesterday, one better than Peter Lawrie who shot 67 for 139. Damien McGrane (67) and Graeme McDowell (70) are both on 140, while Paul McGinley (71) lies on 143 and Gareth Maybin 144 following a second 72.
Thongchai battled his usually reliable putter to card a two under 70, while Donaldson posted six birdies in a 68 to improve to 10-under-par overall, a shot clear of Spain’s Pablo Larrazabal (69) and Finland’s Mikko Illonen (67).
Yang was forced to scramble for par at the last to concede just one bogey on his second circuit after hitting his approach into a deep greenside pot bunker which are a feature of the links-style back nine.
While Yang saved par at his final hole of a bright but breezy second day, Kim will hope his only dropped shot of the day after misjudging the wind into the final green will not become a factor over the weekend.
The 21-year-old is looking to follow up a third place at the Luxehills Chengdu Open at the start of April and a maiden victory on the Korean Tour at the SBS Tomato Open just last week.
Donaldson, who finished sixth at the Open de Andalucia in Malaga at the end of March, raised hopes of a maiden European Tour title as last year’s SAS Masters runner-up continues to turn his game around after losing his card in 2006.
Luxehills Chengdu Open winner Liang Wenchong remained in the hunt to become only the third Chinese winner of the Volvo China Open after carding a 70 to sit alone at eight under with American Ryder Cup captain Corey Pavin (70) and Malaysian Open champion Noh Seung-yul (68) a further shot off the pace alongside Kim Dae-hyun (67) rounding out the top 10.