Building C on the Cheonggyecheon map has a bunch of through-hole parts shops and distributors. Asekakorea.co.kr is printed on the building but it’s not a valid address.
This shop counter has examples to test, and you can buy the bulk bags stocked on the shelves.
Shops are counters or small glass offices. Things are stacked everywhere. It’s not busy, they don’t seem to do a lot of retail, but don’t turn it down either.
More bulk parts. Samples are displayed in a case.
Case of connector wire bundles.
Parts and experimenters’ kits available here.
A wall of parts available by the bag.
A window display of bulk capacitors, resistors and inductors.
The entrance to building C.
It is in Korean… But here is the website for your “building C” http://www.iasea.co.kr/
Thanks James! I added it to the Cheonggyecheon wiki.