The Korean word 순진하다 - to be naive, innocent, or pure - relates to the characters 純眞.
To get an understanding of how a word is used, sometimes I do an image search. In this case, searching for 純眞 yielded what (I think?) is pictures of Japanese whetstones:
Perhaps these whetstones are very pure, hence the link to 純眞. But is '純眞' really rarely used apart from when describing the purity of whetstones?