SEOUL, March 31 : South Korea has sufficient helium stocks until at least June, two sources said, while the industry minister ruled out any first-half supply disruptions, allaying worries over the Iran war's impact on supplies of the gas crucial for chipmaking. Prices of helium, a by-product of natural gas processing, have risen sharply after the U.S.-Israel war on Iran disrupted such operations in Qatar, the world's largest supplier of liquified natural gas (LNG). But South Korea, home to some