By + gerund to describe how to do things (unit #8, part 2)

by + gerund (~ 함으로써 정도)

You could improve your accent by listening to language CDs.

I learn new words best by writing them on pieces of paper and sticking them on things.

The best way to learn slang is not by watching the news but by watching movies.

그냥 gerund의 경우가 단순한 명사화 라면 by + gerund 는 방법의 의미를 추가하는 것

I could be only a good friend of my dog by playing with him.

But my mom could be a god of him by feeding him.

In freaking hot summer, Many Koreans recover their vitality by eating 삼계탕 on 복날. 

Flavor of 삼계탕 can be enriched by adding various items like ginseng, garlic or something like that.