Yes. If you have a valid KETA approval, you can enter Korea by ship instead of by air, and you do not need to submit a new KETA application simply because your mode of transportation has changed.
However, if other information you previously entered has also changed, such as your expected arrival or departure date, address in Korea, or contact information, you should update the changed details.
If you are planning a trip to Korea, enter the required information accurately and apply for KETA before departure.