https://purengom.com/2009/01/05/%ec%9d%b4%ec%96%b4%ed%8f%b0-%ec%96%b4%eb%8a%90%ec%a0%95%eb%8f%84-%ec%9d%8c%eb%9f%89%ec%9c%bc%eb%a1%9c-%eb%93%a4%ec%96%b4%ec%95%bc-%ec%b2%ad%ea%b0%81%ec%97%90-%ec%9d%b4%ec%83%81%ec%9d%b4-%ec%97%86/