Thanks for the info. Ah, so then the satellite (or "concourse" as it's IMO rather confusingly called, as you normally expect the concourse to be outside of security, like where train and other transportation comes to the airport) ends up in the middle? That would make sense. Now the KE page on it (https://www.koreanair.com/global/en/...r_titledparsys) makes sense: take one train to "concourse" and then another one from there to the other terminal (need to switch, no one train that goes through though).

It hasn't worked for me for from Korea to Taiwan or Japan, or to Korea from Japan, with KE (where of course you don't need a visa). It just gives a useless image without any scannable code (called "check-in coupon" or something), and doesn't really check you in. I guess I'll try it again despite the very buggy KE app and see if may be now it works...in the past I've given up even trying to do OLCI with KE, knowing that it simply doesn't work. But hopefully it's improved now and does work.