https://purengom.com/2008/11/20/%eb%82%b4-%ec%b9%b4%eb%93%9c%eb%a1%9c-%ed%95%b4%ec%99%b8%ec%97%90%ec%84%9c-%ec%93%b0%eb%a9%b4-%ec%96%bc%eb%a7%88%eb%82%98-%ec%88%98%ec%88%98%eb%a3%8c%eb%a1%9c-%eb%82%bc%ea%b9%8c/