https://blog.faceutil.com/2017/03/29/%eb%a6%ac%ec%96%bc%ed%85%8d-ac97-%ec%bd%94%eb%8d%b1-%ec%82%ac%ec%9a%b4%eb%93%9c-%eb%93%9c%eb%9d%bc%ec%9d%b4%eb%b2%84-%eb%8b%a4%ec%9a%b4%eb%a1%9c%eb%93%9c-realtek-ac97-audio-codecs-6-305-for-vistawin7/