https://guide.jinbo.net/workplacesurveillance/3%ec%9e%a5-%eb%85%b8%eb%8f%99%ea%b0%90%ec%8b%9c%ec%99%80-%ea%b0%9c%ec%9d%b8%ec%a0%95%eb%b3%b4/7-%ea%b0%9c%ec%9d%b8%ec%a0%95%eb%b3%b4-%ea%b6%8c%eb%a6%ac-%ec%b9%a8%ed%95%b4%ec%97%90-%eb%8c%80%ed%95%9c-%eb%8c%80%ec%9d%91/