The country's good day was led by fourth seed Jeon Hyeok-jin, the top ranked player left in the tournament at the Yeomju Gymnasium.

He was in fine form as he brushed aside France's fifth seed Brice Leverdez with a 21-9, 21-12 victory.

Lee Dong-keun, the 11th seed, had a trickier time of it and had to come from behind to defeat Indonesia's Panji Ahmad Maulana 16-21, 21-19, 21-11.

South Korea's semi-final contingent was completed by unseeded hope Kim Min-ki, a 21-18, 21-14 winner over Lee Chia-hao of Chinese Taipei.

He will now play Lee, while Joen will face Thailand's seventh seed Khosit Phetpradab in the semi-finals.

The Thai knocked out compatriot Kantaphon Wangcharoen today, 21-11, 21-7. 

In the women's draw there was disappointment for the hosts as top seed Sung Ji-hyun was knocked out in three.

She was beaten 27-25, 7-21, 21-12 by China's unseeded hope Wang Zhiyi.

That set up an all-Chinese last four clash with double World Junior Championships gold medallist Gao Fangjie, a 21-17, 13-21, 21-16 winner over Thailand's Pornpawee Chochuwong.

Thailand's second seed Nitchaon Jindapol, now the best ranked player left in, made the last four after defeating Chinese Taipei's Lee Chia-hsin 21-18, 21-8.

She will play South Korea's last remaining hope, fifth seed Lee Jang-mi who beat Indonesia's Gregoria Mariska Tunjung 21-15, 18-21, 21-15. 

The semi-finals at the Grand Prix Gold level tournament will be played tomorrow.