S-1 Corp. on Friday reported its first-quarter net profit of 40.7 billion won (US$29.5 million), down 15.4 percent from a year earlier.Operating income for the January-March period was 48.8 billion won, down 21.9 percent from a year ago, the company said in a regulatory filing. Revenue rose 4.8 percent to 662.8 billion won.The operating profit was 18.5 percent lower than the average estimate, according to a survey by Yonhap Infomax, the financial data firm of Yonhap News Agency. The estimate of net profit was not available.Source: Yonhap News Agency