Sacheon Airport is in Sacheon, but many travelers are actually heading to Jinju. Decide which city is your first real destination before choosing ground transport.
Korea Airports Corporation currently says the airport bus stop is about 10 meters to the right after exiting the passenger terminal. The taxi stand is across the crosswalk outside the terminal. The airport's public-transport page also offers a route-search option for buses, so check the current route and departure rather than relying on an old timetable.
For scale, the airport's current taxi guidance lists the Sacheon intercity bus terminal–airport trip at about 5 minutes, with the local taxi base fare starting at KRW 3,300, while the Jinju bus terminal–airport trip is listed at about 20 minutes and approximately KRW 15,000. These are estimates, not fixed fares; traffic and the exact pickup/drop-off point can change the total.
If you are connecting to a long-distance bus, confirm whether you need the Sacheon terminal or a Jinju terminal before boarding a taxi. If your flight arrives late, check the remaining bus option before walking away from the terminal, because a regional airport has fewer fallback departures than Seoul or Busan.