While learning a few Korean words and phrases will definitely help you in your daily life, speaking Korean is not necessary to teach English in Korea.

A lot of foreigners mistakenly relate the Korean language to Chinese, and think that Korean has thousands of characters, but this is not actually the case. Hangul (the Korean language), has only 24 characters which are made up of 14 consonants and 10 vowels. Each character block will have a combination of at least 2 of the 24 Hangul letters, which are known as Jamo. Hangul was originally created so that every Korean citizen, regardless of economical or social status would be fully literate.  It therefore takes a surprisingly short time to learn how to read and write Hangul; one could literally learn the basics on how to do so in a few hours.

If you are interested in getting the basics down, here are a few websites that will help you get started:

BYKI (Before You Know It)

Offering material that is free to download.  Also included are software bundles that are offered for a reasonable price.  The BYKI software is great for visualization as well as pronunciation, as it comes complete with flashcards with audio to go along with each word.

Mr Oh’s Learn Korean

This is a good resource for those looking to learn a few Korean catch phrases that will help with greetings, ordering food and getting around.

Omniglot

This is a great website that starts with the basics of learning the characters of the Korean alphabet.  The site describes how to read and use the Korean characters and how to combine them in order to form words.