Candidates to become the nation's first astronaut will be trimmed to ten people by next Friday.

The Korea Aerospace Research Institute said the 30 who passed the second round will undergo a thorough physical examination and an aptitude test.

The ten candidates who make it to the third screening will be cut to two by year's end.

From early next year, the two will be trained at a Russian space center for a year but only one will be chosen to board the Russian Soyuz spacecraft in April 2008.

The initial number of applicants was some 36-thousand.