Source: http://kcrc.or.kr/?doc=bbs/gnuboard.php&bo_table=z_interchange&wr_id=114 https://kcrc.or.kr/data/file/recent/%EB%AF%BC%EC%A1%B1%ED%99%94%ED%95%B4_68%ED%98%B8_2014_7_8%EC%9B%94%ED%98%B8.pdf
