https://blog.faceutil.com/2022/10/06/%ec%b0%b8%ec%8c%a4%ec%8a%a4%ec%bf%a8-%eb%ac%b4%eb%a3%8c-ppt-%ed%85%9c%ed%94%8c%eb%a6%bf-%eb%82%98%eb%88%94-%e3%8e%83/