https://blog.faceutil.com/2017/03/19/subresync%eb%a5%bc-%ec%9e%90%eb%a7%89%ed%8c%8c%ec%9d%bc-%ed%98%95%ec%8b%9d%ea%b0%84-%eb%b3%80%ed%99%98%ed%88%b4-%ec%a4%91%ec%97%90-%ec%b5%9c%ea%b3%a0%eb%9d%bc-%ec%83%9d%ea%b0%81%ed%95%a9%eb%8b%88/