The top five characters say "Hanguk Eunhaeng gwon"; this translates to "Korea Bank note" (as with other East Asian languages, the word for "bank" literally means "silver house"). Over on the left, you'll notice that the first four characters of the banknote title are repeated: "Hanguk Eunhaeng", or "Korea Bank". In context, this means "On behalf of the Bank of Korea". The red circle, and the characters inside it, are from a traditional
East Asian seal, as is used in China, Japan and Korea in the same way that signatures are used in the West. The four characters inside the circle are presumably the name of the official whose seal it is, written in "seal script".
As thai-vic said, the characters at left, repeated on the English-side as well, say "ten jeon". The numeral "ten" also is repeated twice, in the top corners.
The tiny lettering at the bottom of the Korean side of the note is the name of the printing company.
Don't say "infinitely" when you mean "very"; otherwise, you'll have no word left when you want to talk about something really infinite. - C. S. Lewis