The Kornaire was a Cardassian warship that was in service with the Cardassian military in the mid-24th century.
Dukat's first assignment as a freshly-minted glinn was to the Kornaire. One of his tasks was to clean out a compartment where three men had gone through an explosive decompression.
In 2374, he would tell Benjamin Sisko that "I didn't sleep for a week after that." (DS9: "Waltz")