Hi all,

I'm not from the UK and thought that the US PhD programmes involving both 'coursework' and 'research' was common knowledge.

One of my friends knew a Korean PhD student who completed his PhD in Electrical Engineering in 2 years. There are many ingredients behind this notable achievement : excellent supervisor, good lab, great support from friends, single, lol !

Indeed many of us will be aware of the system in the US. However this is not a US forum, therefore without you being explicit about where you are referring to, you're going to create confusion.
In the UK, where the vast majority of the students on this forum are from, it is virtually unheard of for people to complete a PhD in two years. I suspect there would be major concerns raised about whether the depth of research conducted for a 2 year PhD was sufficient for a PhD to be awarded. I know some exceptional scholars... not of whom have completed there PhDs in this time frame.
Also science/humanities PhDs are likely to differ. Whereas lab work -- if everything goes 'right' --means luck might be an element in the length of one's PhD, I'd hazard a guess that this is rarely the case with arts/humanities/social sciences.