https://purengom.com/2010/08/17/%eb%a9%80%ed%8b%b0-%ed%84%b0%ec%b9%98%ec%99%80-%eb%a7%a4%ec%a7%81-%ed%8a%b8%eb%9e%99%ed%8c%a8%eb%93%9c-%ea%b7%b8%eb%a6%ac%ea%b3%a0-apple%ec%9d%98-%eb%b3%80%ed%99%94%ec%97%90-%ea%b4%80%ed%95%b4/