In January 2011 the European Patent Office introduced a requirement under Rule 141 EPC that patent applicants should file details of any prior art cited on a foreign case from which a European patent application claimed priority under the Paris convention. This included prior art cited by KIPO on a Korean priority patent application.
The European Patent Office has recently announced that, from 1 April 2013, this will no longer be necessary for priority claims from Korean patent applications. Instead, the KIPO cited prior art will be included automatically in the EPO file.
Please note that if the EPO has already issued a request for the applicant to file prior art details then a response to the request will still be required even if the due date falls after 1 April 2013.
The relevant EPO announcement can be found here: