https://purengom.com/2010/08/05/%eb%8d%b8-dell-u2311h-%eb%aa%a8%eb%8b%88%ed%84%b0-%ec%8b%9c%ec%95%bc%ea%b0%81-%ec%95%b5%ea%b8%80-%ed%85%8c%ec%8a%a4%ed%8a%b8/