The easiest resource as an online dictionary is dic.naver.com. However, I'm getting tired of using Naver dictionary, as the examples in the Korean-English dictionary are written (of course) for Koreans. Therefore, the examples are translated using simple Korean grammar, and the focus is on a new and vibrant English grammar, to teach English usage to Koreans. Looking at those examples is therefore not fruitful for a student of Korean. The same is true, in a similar way, of trying to study Korean from a book written for Koreans to study English from.
My gist is that I wish I was getting more exposure to Korean particles used in combination with a verb (maybe this could be called "Korean co-location"). Usually, naver presents only 를+Korean verb for English of all difficulties and levels. It's just not for a student of Korean.
I sorely regret not having found a good dictionary for a student of Korean.
For example, dictionary entries that would explain like:
- X는 1이 ~~되다
- A에 이용되는 X
- X로 고정된 Y
- X를 Y로 포함하는 Z (which means Z includes X as Y)
Those things would be nice to see in the examples sections.