http://bigshit.tistory.com/111
http://bigshit.tistory.com/110
http://andromedarabbit.net/wp/%EC%9C%88%EB%8F%84%EC%9A%B0-%EB%AA%85%EB%A0%B9-%EC%A4%84-%EC%8A%A4%ED%81%AC%EB%A6%BD%ED%8A%B8/
http://blog.naver.com/PostView.nhn?blogId=neoxide&logNo=50185671750