https://blog.gongquiz.com/2022/02/08/hf%ec%9d%98-%eb%81%93%eb%8a%94%ec%a0%90%ec%9d%b4-hcl%ec%9d%98-%eb%81%93%eb%8a%94%ec%a0%90-%eb%b3%b4%eb%8b%a4-%eb%86%92%ec%9d%80-%ec%9d%b4%ec%9c%a0%ec%99%80-%ea%b0%80%ec%9e%a5-%ea%b4%80%ea%b3%84/