https://blog.faceutil.com/2020/07/17/%ec%bd%94%eb%a0%88%ec%9d%bc%ed%86%a1-korailtalk-v4-1-7-%ea%b5%ac%eb%b2%84%ec%a0%84-%ec%9d%b4%ec%a0%84-%eb%b2%84%ec%a0%84-%e3%89%b8/