Mind you, this was a country that was significantly poorer than Portugal not too many decades ago. It is now the country with the 7th highest median wage in the world.
How was this even possible - what makes South Korea so special for it outpace any other country in the world during this time frame? Even the Miracle at the Rhine was nothing, in its scale, compared to this.
Even today, South Korea has growth rates not unlike those of developing countries, even though it has a very developed economy.
How?
I am not capable to answer the question you pose because I do not have the literature with me right now, and I have to follow the rules of course of sourcing, but I just wanted to say that South Korea is not "unique" in Asia in its incredible growth. South Korea is one of the four nations/regions making the "Four Asian Dragons". Taiwan, Singapore, South Korea and Hong Kong are in this group because they in roughly the same period experienced tremendous economic growth. And preceding them we also saw Japan with a huge growth that shocked the world.
More of courtse can be said here, of course, but this older thread might be of interest, with credit to /u/elblanco.