https://blog.faceutil.com/2017/10/11/swf%ed%8c%8c%ec%9d%bc-%eb%8b%a4%ec%9a%b4%eb%a1%9c%eb%93%9c-%ed%94%84%eb%a1%9c%ea%b7%b8%eb%9e%a8-%e2%85%a9/