Korea’s largest retail chain, Emart, found that slumping sales at midday were casting a shadow over its revenues and came up with a clever way to attract lunch-time shoppers. At its 38 locations throughout Seoul, Emart installed three-dimensional QR codes on outdoor pillars located to catch the sun. Like a sundial, the shadows on the QR code moved as the sun changed position, and passersby were alerted that they could only read the QR code’s message between 12 noon and 1 pm. Consumers who scanned the code were directed to the Emart online store where they received $12 coupons for products that would be delivered to their homes. Thousands of consumers claimed Emart vouchers, and sales increased by 25% during the lunch hour.