The 9,000-cbm ship is worth KRW 30bn ($27m) and comes with an option for another vessel.
The 120-metre unit will sail at 15.2 knots.
Delivery is set for the fourth quarter of 2014 from the Busan yard.
STX has booked 14 ships worth $900m in the gas carrier sector this year.
In July, Geogas exercised an option for a midsize LPG newbulding at Hyundai Mipo Dockyard.
The
