The three South Korean men all won their heats. The top three from the men's seven heats moved on to the seimfinals.

Choi and Shim each finished first in their heats, while Kim was second in hers. The top two skaters from each of nine heats qualified for the semifinals.

Hwang is the current World Cup leader in the men's 1,500 with two gold and one silver through three competitions. Choi also has two gold and a silver in the women's 1,500m to lead all World Cup skaters.

Preliminaries and heats for the 500m for both men and women will be held later Thursday.

Heats for the men's and women's 1,000m, and the men's 5,000m relay and women's 3,000m relay are scheduled for Friday.

All the finals will take place on the weekend: the men's and women's 500m and 1,500m on Saturday, followed by the men's and women's 1,000m, women's 3,000m relay and men's 5,000m relay on Sunday.

This is the final qualifying event for the 2018 PyeongChang Winter Olympics. South Korea is guaranteed five men and five women in all races as the Olympic host, but it will only be able to send one skater each in those races.

The country will instead try to lock down maximum quota spaces on merit. In individual races, each country can have up to three skaters.

A total of 110 Olympic spots, 55 each for men and women, are up for grabs. At World Cups, individual skaters and relay teams each earn 10,000 points for gold, 8,000 for silver, 6,400 for bronze and so forth. In the 500m and 1,000m for both men and women, 32 quota spots are up for grabs. In the 1,500 for both, the maximum is 36. And eight teams apiece will compete in the men's 5,000m and women's 3,000m relays.

South Korea leads all nations with 21 Olympic short track gold medals all-time. (Yonhap)