I would be unhappy too what with this forehead flicking, yelling and hair pulling by teachers... and the occasional whack with a stick. It probably doesn't help that they have to learn from horrible English textbooks.
I don't know, my kids actually seem pretty happy in spite of all this.
I'm not sure that you can measure happiness in that way. I would agree with an article called "Korean children are overworked and miss out on how fun being a kid is," but that's a long headline.
(Also there are so many kinds of happiness--the immediate happiness, the 'daily grind' type of routine, stable happiness, and the kind of happiness you get from reflecting upon your life and your experiences. There is self-worth, accomplishment, etc., you get the idea. I think Korea seems to focus on the latter happiness and denies immediate gratification. I say this because, from what I have observed, their school/personal lives are not always immediately gratifying, but they seem to bond to and cherish memories and people from a distance. I think it's almost like a kind of 'acquired' happiness/respect/care, if that's possible. That's why I don't think it's fair to compare Korean happiness to Spanish or Irish or American or any other type of 'happiness.' Sorry to derail the discussion a bit, but studies like this [such as Seattle being the most 'fun' city in the US] kind of bother me.)