Britain's Deputy Prime Minister Nick Clegg (L) listens as Samsung Tesco CEO Lee Seung-han explains about a virtual store at a subway station in Seoul March 26, 2012. The virtual store allows time-pressed commuters to shop on the go using their smartphones to scan barcodes alongside pictures of popular products. Clegg is in Seoul along with leaders from more than 50 countries for a March 26-27 nuclear security summit focusing on measures to protect nuclear materials and facilities and to prevent illicit trafficking. REUTERS/Bobby Yip (SOUTH KOREA - Tags: POLITICS MILITARY BUSINESS TRANSPORT SCIENCE TECHNOLOGY)