why the communism, dead in most of the world, is live in Asia?

Communism is a good idea to people who have been super oppressed for a long time. Good idea but about as pratical as monkey with a gun. Eventually all communism turns into capitalism.

Because there is another kind of communism, because Chinese people are huge.

COMMUNISM IS ALIVE IN THE USA. DO YOU REALIZE HOW MANY POOR PEOPLE ARE IN THIS COUNTRY? THIS EXCLUDES THE ONES WHO REFUSE TO WORK FOR PERSONAL REASONS (we know the lazy ones are the worst).
THE STATE OF NJ IS A PRIME EXAMPLE OF CORRUPTION IN ALL FACETS....

I don't know about Vietnam.

In North Korea, the situation there is quite horrible but dissent is virtually impossible. You can think of the North Korean regime as the most effective dictatorship that ever came into being.

As for China, it's not really communist anymore but "capitalist yet dictatorial". It's a game of sticks and carrots there: most people are willing to submit to the so-called Communist Party in return for economic growth (and no, they don't realise that democracy can fuel growth too). Yes, there's dissent and discontent, but most surveys conducted by international organisations show that a large majority of Chinese are happy with the way things are.

Communism collapsed in Eastern Europe largely because...
1. The people were fed up with their lives and government.
2. Western influence was very strong and pervasive. Democracy eventually won the "war of minds".

China doesn't fulfil condition 1. North Korea doesn't fulfil condition 2.

And those countries are doing really well, right? North Korea can't feed its people and has to resort to its one and only resource...weapons proliferation. China... Tiennamen Square and the government's paranoia over its people having access to cell phones and the internet (why is that?). Vietnam, Laos, Cambodia are among the poorest nations in the world. So, it lives, but barely.