https://blog.wongcw.com/2021/08/31/%e9%9f%93%e5%9c%8b%e6%9c%80%e5%a4%a7%e5%9c%a8%e7%b7%9a%e6%94%af%e4%bb%98%e6%9c%8d%e5%8b%99%e5%95%86kakao-pay%e5%b0%87ipo%e8%a6%8f%e6%a8%a1%e5%89%8a%e6%b8%9b%e8%87%b313%e5%84%84%e7%be%8e%e5%85%83/