Recently, I encountered a new Korea word "woosoo" (우수). I asked my friend CH what this word meant. He told me it was an old word, used mostly in traditional fine literature. He wanted to know where I had seen this word. Here is where I saw it:
Turns out this means something like "rain water", and this manhole cover must be for a storm drain. Anyway, we both got a big kick out of that, finding "fine literture" on a manhole cover in the street!