It was likely to be sourced from South America, they said.
The corn was bought in one consignment at $205.74 a tonne c&f plus a $1.25 a tonne surcharge for additional port unloading.
The seller was said to be trading house Olam for arrival in South Korea in June.
Shipment was sought for May 7-26 if sourced from the US Pacific Northwest coast, between April 17 and May 6 if sourced from the US Gulf or east Europe, between April 12 and May 1 if from South America or between April 22 and May 11 if from South Africa.
But traders said there was talk of an extra agreement that the corn may be shipped later from South America between April 28 to May 18.
South Korea's largest feedmaker Nonghyup Feed Inc (NOFI) also purchased 138,000 tonnes of corn to be sourced from worldwide origins in an international tender that closed on Tuesday.