https://blog.gongquiz.com/2021/10/12/%ec%8b%a0%ed%98%b8%ec%9d%98-%ec%9c%a0%eb%ac%b4-on-off-yes-no-1-0-%eb%93%b1%ea%b3%bc-%ea%b0%99%ec%9d%80-%ec%8b%a0%ed%98%b8%eb%a5%bc-%ec%9d%b4%ec%9a%a9%ed%95%98%eb%8a%94-%ec%a0%9c%ec%96%b4%ea%b3%84/