https://purengom.com/2011/08/11/macbook-pro-%ec%9d%b8%eb%8f%84-%ea%b7%b8%eb%9f%ac%eb%82%98-%ec%96%b4%ec%b2%98%ea%b5%ac%eb%8b%88-%ec%97%86%ea%b2%8c%eb%8f%84/