At the Incheon Airport in Korea (ICN), flights from several airlines often arrive at nearly the same time, making it easier to get to immigration quickly. If you take a Korean airline, you will likely arrive at the main terminal. Otherwise, on arrival at ICN, you will proceed along a series of corridors and down the stairs to board a train to the main terminal (trains run every 5 minutes). The quickest way is to board at the third set of train doors from the right; you will exit on the same side you entered. When the train arrives at the main terminal, you can run upstairs to immigration, as it can be slow if the lines are long. Try the rightmost line for foreign passports, because they often open another line further to the right, so you can dash to the new line; in addition, if there is no line at the Korean citizens’ lane, agents will sometimes bring you there from the rightmost foreign lane.
After immigration, there are boards giving your luggage carousel number. Go downstairs, take a free cart (push down on the handle to move it), collect your luggage, and walk through customs and out (slightly left) into the terminal lobby. It is better not to change money at the booths; instead, use your bank card at an ATM if necessary. Along the far wall by terminal exit 9 there is a booth labeled "Airport Limousine bus." Say you are going to "Daejeon" (day-jun); the ticket will cost 23,100 won. Then walk to the left outside along the terminal until you get to bus stop 9D by exit 9. There is also a bus ticket office outside if the one inside is crowded. The bus leaves every 20–30 minutes or so. Unless you have a lot of luggage, you can bring it on the bus with you. If you hand in your luggage to be placed underneath the bus, you will get a claim ticket; show this to the driver when you exit so that he or she will retrieve your luggage for you.
The bus takes 2.5–3 hours to get to Daejeon. There will usually be a 15-minute stop at a highway rest area on the way. After the bus exits the highway through the toll gate at Daejeon, it will be only 5 minutes until your stop. The bus will go along a tree-lined street with many research institutes; KASI will be on your left. You will pass it, and then the road will curve around and come to a Y intersection. Your stop is immediately after the bus turns right at the intersection. Walk back along the bus route for 15 minutes until you reach KASI (now on your right). If you have too much luggage to walk, take the bus one stop further to the Government Complex. There you can get a taxi to take you to KASI (roughly 10 minutes, 6000 won). If you are going to your hotel downtown, take a taxi from the Government Complex stop.
If the buses sell out, or you just like trains and do not have much luggage, you can take trains from Incheon Airport to Daejeon. It takes about the same amount of time but requires more transfers. Follow the airport signs for ARex trains. You can buy a ticket all the way from the airport to Daejeon via Seoul Station (in which case they'll ticket you on a slightly later train to Daejeon to make sure you catch it), or buy a ticket to Seoul Station and then buy a ticket there to Daejeon on the very next train; it doesn't make much difference. I recommend that you use the local, not the express, ARex train to Seoul Station because it takes only 10 minutes longer but runs more frequently, so you'll probably arrive earlier (the express is more luxurious though). Seoul Station is the final stop; the local and express trains take 53 or 43 minutes and cost about 4000 or 8000 won, respectively. At Seoul Station, follow the signs upstairs to KTX, the express long-distance trains. If you already have your ticket, just go to the platform indicated; otherwise, buy your ticket after looking at the departure board to find the next train to Daejeon (any KTX heading to Busan will stop in Daejeon). The KTX takes 1 hour to reach Daejeon. At Daejeon Station, go upstairs and cross to the main area, and then go downstairs to the main exit. Follow the signs to the taxi rank. A taxi should take 20–30 minutes and cost ~11,000 won.
Taxi drivers will not recognize "KASI"; instead, say Chun-mun Yun-gu-wun. It is best to print out the KASI main web page or visitor guide so that you can show the driver the Korean characters.
Just before the Y intersection is a small booth (on the KASI side of the road) selling bus tickets. You can buy a ticket for a specific bus in advance or buy a ticket on the day of travel. The bus stop is immediately next to the booth. The bus to the airport takes 2.5–3 hours and leaves you on the departure level. United Airlines check-in is on row K.