According to a 2008 ranking by the Organization for Economic Co-operation and Development, South Koreans work more hours a year than other OECD members. South Koreans work, on average, 2357 hours a year, compared to the USA at 1797 hours a year.
Things in Korea are changing though. Just a few years ago, the government changed the 6-day work week to the typical 5-day work week. Prior to that, Korea was the only country in the OECD that worked on Saturdays. It hasn't changed completely, though; I know my school has classes every other Saturday (which gladly I am not a part of!).
Korea also has more public holidays than I'm used to in Canada, but these too are slowly changing. After changing to a shorter work week, the government drops more and more holidays every year. It seems as though the government doesn't feel workers need a day off to celebrate Consitution Day or Arbor Day anymore.
In addition to losing public holidays every year (hey, I like to celebrate things), I'm thoroughly disappointed when national holidays fall on the weekends. In Canada, national holidays are "moved" to a weekday if they fall on a weekend, ensuring ourselves a long weekend. But in Korea, the holiday is the holiday--so if Foundation Day lands on a Sunday, well then enjoy your Sunday with the family but see you at work on Monday!
I can't believe that Koreans are the hardest workers, though. They may work longer, but work harder? Don't think so. It's a daily occurance to see teachers asleep at their desks, or shopping online, or gone off to our "nap room" (complete with couches and sleeping mats) for a deep sleep. As long as you're at work, it's good; you don't actually have to be working, it seems. I'm the only teacher I know that writes out a lesson plan---in fact, I was once told to stop making lesson plans!
I think it's more to do with status. Instead of "Mr." or "Ms", people are identified by job titles. Hi, I'm Melanie Teacher. So having a good job is more important than anything else. If your job is your identity, it makes more sense that you're there---a lot.
Read the article from CBC here: World's hardest-working countries