On 20 May 2019 KoreaPost released a stamp to commemorate the “Redefinition of the SI Base Units”. Together with the stamp release KoreaPost also released extra promotion materials showing the idea behind the international standards commemorated by this release.
Because these materials are usually shown to a Korean language audience you might not have noticed them. But here is a complete set for the release of KPC3371 “Redefinition of the SI Base Units”:
All graphics copyright KoreaPost.