ティーウェイ航空、福岡〜清州線を開設 11月26日から1日1往復
T Way Air inaugurates the new air route between Fukuoka and Cheongju from November 26 one service for each direction per day
https://www.traicy.com/posts/20231102282498/
Cheongju International Airport is convenient for going to southern part of Seoul and Daejeon. But, the nearest train station just has bi-hourly service during daytime.
So, there should be frequent train service at least to Osong Station, where KTX trains are available.