Keirin is a bicycle race on a special track ( velodrome ), where the winner is determined by ranking. This sport, which began in Japan in 1948, was introduced as a legal form of gambling to raise funds for urban reconstruction after World War II. Betting is done in a similar way to horse racing, and it is very popular as a combination of sports and gambling.

In Korea, keirin was officially introduced in 1994 and is operated as a nationally authorized gambling jointly managed by the Korea Sports Promotion Foundation and local governments. The profits generated through keirin are used for public interest projects such as the National Sports Promotion Fund, Youth Development Fund, and Culture and Arts Promotion Fund, thereby promoting development throughout society.

https://www.nfl-news.org/kr/race-bet/