Not really many more punk noise venues, as the noise scene is still kind of developing and mostly through the sound art end I think, even now much more better than 2 years ag0.
I recommend checking anywhere Human Infrastructure, Dayoon Lee or Hanjo Lee (who has run the most longest running experimental group Bulgasari for 20 years) and I believe Swiss origin Ian-John Hutchinson are playing and trying to keep up.
Probably more to the sound art end (Dayoon is doing harsh noise though, quite hands on and rare approach there, Ian uses many sort of lofi-self-built and interesting junk instruments too), if the impro is also ok, then guitarists Joong Won, vocalist Eunsil No, Dactophone player Joyul, Passing Josh, Deja, and their friends are also good leads. Jena Jang is also South Korean noise artist, but now mostly living and touring Europe. I also come and play maybe once a year or so.
I just found out in April 19th there will be a Noise No Seoul festival, so you might want to check what that is all about.
