Take your pick. Here are the choices you have on the first day of the fair at Earls Court. And of course you have to choose between Yi Mun-yol at the British Library and Yoon Tae-ho at the KCC in the evening too. Click on the graphic for a more legible version, and click on the various hyperlinks in this post for more details of the different events.
You can find more details of the green (cultural programme) events here, the blueish (professional programme) events here, and the peachy (Korean pavilion) events here.