could [you] expand on faldage's comment about the korean characters having something to do with what goes on in mouth when making them?

Here's a better explanation than I can do: link. Basically, different parts of the composite glyphs map to manner and place of articulation (link) and other features such as aspiration. Besides Tengwar and hangul, there are some other featural alphabets (link), such as Shavian and Visible Speech.

Ceci n'est pas un seing.