We put 250 signs on the pavements because they will actually be seen by the pedestrians that are looking down at their smartphones," Kim says. But neither type of warning seems to have registered with locals interviewed "I'm always on my smartphone, and I've never seen the signs before," says Kim Hyun-Chul, 29. "They need to make them stand out more.Koo Sung-Hoi, 27, was also unaware of the efforts to keep him from a smartphone-related injury. "I think the signs on the pavements are too small to be noticed Koo says. South Korean smartphone users spend an average of four hours a day tweeting , chatting or playing games,with about 15 per cent showing symptoms of addiction, according to state