Hi I am also thinking of taking the train from Seoul to Busan. Would like to check for those who have taken this before , is there room for 2 large luggage on the train ?
Theoretically yes but 90% all space taken up.
A few things to note
(1) try to go down early (don’t last min like me)
(2) also make sure you carry light (possible carry on luggage)
I booked first class train tickets. Seat quite huge and space is big. The space between your table to your seat is super wide until char bo will complain because if you put iPad on the table, you need to move forward and stretch before your hands can reach the iPad.
Also the luggage rack is small so if you got big luggage and you are late (ie, can’t find space on rack), you probably have to just dumped it inside the cabin floor. But I find Koreans are professionals. I seen some Koreans putting their luggage near train door and block the emergency exit. I hiong hiong stacked my luggage on top of theirs. Wife laughed as she say later don’t let them throw your luggage out of the train door. When I reached, I still see my luggage nice nice on the floor. If in China, maybe already gone
I booked Mon 12pm train ticket at 10am, still can get first class. 
