https://purengom.com/2011/09/01/%ed%88%ac%eb%8b%88%eb%b2%84%ec%8a%a4%ea%b0%80-hd%eb%a1%9c-%ec%8a%a4%ec%b9%b4%ec%9d%b4%eb%9d%bc%ec%9d%b4%ed%94%84%ec%97%90-%ec%a7%84%ec%9e%85-%ea%b7%b8%eb%a6%ac%ea%b3%a0-%eb%84%88%ec%97%90%ea%b2%8c/