Most likely those channels were from local broadcast channels that Comcast was passing on. If the local station drops the network, then there is nothing Comcast can do.
Also, I'm not sure what you mean by KOAM? KOAM is a broadcast channel in Kansas.
This link lists all of the stations in the Seattle/Tacoma area. The affiliations are listed, too (not sure how up to date.) No obvious Korean networks that I can see.
You could move here to Chicago. Lots of Korean networks, many of which are passed on by Comcast.
According to the Xfinity site (https://www.xfinity.com/learn/digital-cable-tv/international/korean) there are many Korean TV channels offered by Comcast. The KOAM is an add on which we pay $14,99 additional each month. But according to the site there seems to be other korean tv channels. Is this true for those in Seattle area? Are you able to view other Korean TV channels if you get a higher preferred package, not an add-on? According to the link, other Korean channels include KTN, tvK, TVK pop, WKTV, Mnet, & MYXTV.