This is an interesting report about the route that many of the North Korea escapees take to get away through South East Asia (from the BBC).
Jung Ae, a slightly built woman with a badly damaged leg, described crossing the Tumen river to China in March this year. The freezing water came up to her neck and nearly swept her away.
She had to break through ice on the other side with her bare arms. She had been driven to escape by exhaustion and hopelessness, she told me.
Her family were suspected of disloyalty, and she had to endure hard labour on state farms to survive, sapping her will to live. She wept as she described leaving her young son behind with relatives, but said she had no hope of providing for him in North Korea.