Skin care has become an increasingly lucrative business for cosmetic companies. That's why big names like Amazon and the Kardashians are trying to cash in. The industry's revenue is expected to grow within the next four years to more than $379 billion dollars, according to an IBISWorld report. There's one country that's been playing an outsized role in skin care's growth— South Korea. Here's a look at how South Korea is helping skin care dominate the beauty industry.