Thursday, February 25, 1999 Published at 14:08 GMT
Solitary: Tough test of survival instinct
Solitary confinement or "killing a man without his dying"
The pale, undernourished face of Woo Yong-gak, who has re-emerged in the outside world after 41 years of solitary confinement, is a testimony to immense resilience.
The first words Woo Yong-gak expressed to the cheering crowds were that he was "happy to see light."
His life in solitary confinement is almost unimaginable, even to human rights activists who work with prisoners.
Long-term prisoners in South Korean prisons were, according to activists, tortured and beaten until at least the early 1990s.
Under military rule, the torture was constant while the prisoners refused to sign away their Communist beliefs.
Deprived of human contact with other prisoners - they exercised together for half an hour each day - and starved of any ties with the outside world, the survival of the 17 prisoners is a test of psychological and physical resilience.
According to Clare McVey of Amnesty International, prisoners who have been released in recent years say that the only visitors they were allowed were Buddhist monks.
They could correspond with their families, but many of them, unlike Yong-gak, had no family to speak of.
Life inside was almost entirely spent in dark and cold cells and medical attention was scarce. Torture sometimes took the form of being locked up with a particularly sadistic prisoner.
For Helen Bamber, director of the London-based Medical Foundation for the Care of Victims of Torture, "solitary confinement is one of the harshest methods of punishment and torture.
"Keeping someone in a state of isolation, with no means of renewing their intellectual life, has been described as killing a man without his dying," she said.
Ex-prisoners who have spoken to the Centre say they had to work very hard not to lose their sanity while inside. They recall overwhelming feeling of disorientation and fears of going insane.
But solitary confinement also takes a heavy physical toll. As Helen Bamber says: "The body is no longer functioning in a way that it does in normal, everyday life. They also become undernourished, often as a result of paranoia over food being contaminated."
Many prisoners have not returned to North Korea after being released, often preferring to stay together in the care of human rights organisations in Seoul.
But even after their release, they will still be subject to security checks and are, says Amnesty, not really officially supposed to see each other.
They will take added solace in the fact that as political prisoners they never succumbed to pressure to sign the oath of obedience to the National Security Law which bans the display of any pro-North Korean sentiment.
As Woo Yong-gak said: "Life in jail felt really long and slow but I have never been repentant. I endured it with strong will."