The Oxford graduate, who recently qualified as a barrister, had been transferred to the intensive therapy unit at Chelsea and Westminster from St Mary's Hospital, west London, where she was taken immediately after the crash.
Ms Hah, who lived in London, was among five victims who were seriously injured and were being treated at the hospital. The other four are in a stable condition, a spokeswoman said yesterday.
"The family is not willing to give interviews and have asked that their privacy be respected," she added. Ms Hah came to Britain with her family at the age of three from South Korea.
The accident, which happened in the morning rush- hour, occurred when a Thames train, which had just left Paddington for Bedwyn in Wiltshire, passed through a red signal at Ladbroke Grove in west London. It collided with a London-bound Great Western express from Cheltenham in Gloucestershire.
In the confusion after the crash there were fears that up to 170 people had died, but the final toll of 31 makes it Britain's worst rail crash since the Clapham disaster in 1988, when 35 people died. Paddington station was closed for more than two weeks while the wreckage of the train was cleared.Reuse content