https://purengom.com/2007/04/10/hdtv-%ec%85%8b%ed%86%b1%eb%b0%95%ec%8a%a4%eb%a5%bc-%ea%b5%ac%ed%95%98%ea%b8%b0-%ed%9e%98%eb%93%a4%ec%96%b4%ec%a1%8c%eb%8b%a4/