Sang Hun Kim helped over 100 people flee North Korea
BBC Radio 4's Crossing Continents was broadcast on
Thursday, 24 April, 2003 at 1100 BST.
It is the invisible exodus.
Tens of thousands of people have risked everything to flee North Korea, some making it all the way to the south.
Christopher Gunness investigates what happens when they get there.
And he talks to some of the dedicated activists who have established the secret channels of escape.
The programme will be repeated on Monday, 28 April, 2003 at 2030 BST on BBC Radio 4.
Reporter: Christopher Gunness
Producer: David Edmonds
Editor: Hugh Levinson