https://rein.kr/posts/2008-05-19-%EB%85%BC%EB%AC%B8-%EC%9D%BD%EA%B8%B0-cs-%ED%98%B9%EC%9D%80-p2p-%EA%B5%AC%EC%A1%B0%EC%97%90%EC%84%9C-%EC%B9%98%ED%8C%85%EC%9D%84-%EB%A7%89%EB%8A%94-%EB%8F%99%EA%B8%B0%ED%99%94-%EB%B0%A9%EB%B2%95/