In the last two days, nearly 500 North Korean refugees have been flown from South Vietnam to South Korea. The South Korean government tried to keep this quiet, as North Korea is very sensitive about its citizens trying to flee the workers paradise. Moreover, the refugees initially flee to China, which does not want to encourage large numbers of North Koreans sneaking across the North Korean border into China. This is because it's widely believed that millions of North Koreans would flee the country if they had a chance. Increasingly, South Korean and other refugee-aid groups are providing money to help North Korean refugees get out of China, so they can then get to South Korea. China will not allow many North Korean refugees to travel directly from China to South Korea. 

North Korea is arguably the most repressive police state on the planet. But over a decade of economic decline and famine has resulted in more people fleeing the country. There are no numbers on who gets across the border into China, but the number who make it to South Korea are carefully tabulated. 

North Korean Refugees Reaching South Korea

2000 - 312
2001 - 583
2002 - 1140
2003 - 1285
2004 - 760 (Jan.-June)

It is thought that over 100,000 North Koreans have made it out of the country into China, plus some to Russia, in the past decade.