SEOUL, Aug. 21 (Yonhap) -- South Korean stocks opened higher Thursday, helped by gains in techs and autos. The benchmark Korea Composite Stock Price Index (KOSPI) added 30.11 points, or 0.96 percent, to 3,160.2 as of 9:15 a.m. Overnight, the U.S. stock indexes ended mixed after tech heavyweights par