For non tourists, there's a Hana bank rechargable transportation card, which offers free transfers, when you open an account at Hana bank, your smart bank card can be charged with money to be used on buses, taxis. "Hankkumi" transportation cards are also available at manned booths within the subway stops. These cards cost 2.500 won and are rechargeable at the station or at many GS 25 locations. Unfortunately with only one subway line, which bisects the city and runs southeast from the northwest corner, only central Daejeon, old downtown Daejeon station area and a handful of sites are convenient to reach solely by subway. The subway IS now compatible with Seoul T-money passes. Hankkumi cards or tags purchased after February 2011 now contain both Hankkumi and Seoul T-money functionality.
On foot
Daejeon is mostly far too spread out to be convenient to walk between attractions. However, Expo Park, the National Science Museum, Hanbat Arboretum, Dajeon Museum of Art, Mannyeon-dong, and even Dunsan-dong although this last one is pushing it are situated close enough to one another to wander back and forth.
By bike
Daejeon has a system of public-use bikes for a nominal fee, however, in practice, the racks tend to be far and few between, mostly on the north side of town around Dunsan-dong and more often than not completely empty.