The following did not work for me:
sudo mv /usr/share/fonts/truetype/unfonts-core/UnDotum.ttf /usr/share/fonts/truetype/unfonts-core/UnDotum.ttf.backup
Hoewever I successfully solved this issue with sudo apt-get remove fonts-unfonts-core and can still write in Korean (but didn't reboot yet).
The following did not work for me: fonts/truetype/ unfonts- core/UnDotum. ttf /usr/share/ fonts/truetype/ unfonts- core/UnDotum. ttf.backup
sudo mv /usr/share/
Hoewever I successfully solved this issue with sudo apt-get remove fonts-unfonts-core and can still write in Korean (but didn't reboot yet).