South Korea's Samsung Electronics Co launched an upgraded version of its Galaxy tablet in its lucrative home market on Wednesday, seeking to stem the runaway success of Apple Inc's iPad. The Galaxy Tab 10.1, the sequel of the 7-inch Tab introduced in October, is the latest push by the company to challenge the iPad. Apple's iPad sold 14 million units in the first half of this year, compared with analysts' sales estimates of about 7.5 million for the Tab for 2011, the iPad's biggest competitor. -Photos by agencies