Do we need to add 에 to this sentence?

Question

I saw this example online where "Sam went to Korea last year in October during the autumn season" was translated to "샘 은 작년 10월 가을에 한국에 갔다". May I ask if we need to add a '에' after 작년 10월? Why or why not? Thank you!

Answer 1

"샘은 작년 10월에 한국에 갔다." "샘은 작년 가을에 한국에 갔다."

Both sentences are just natural. and the using "-에" means "in", "on", "at". But if you repeat to use, it sounds like unnatural.

"샘은 작년 10월에 가을에 한국에 갔다."

We might don't use like this in English.

"Same has been in Korea **in** Autumn **in** last year October.

And you can replace "-에" into "-중" or "-중에"

샘은 작년 10월 중에 가을에 한국에 갔다.

At the same time. You can use this.

샘은 작년 10월에, 가을에 한국에 갔다.
Sam has been in Korea in October last year (which is) fall.

If you add "," mark it's natural, and none of weird.

Answer 2

~에 used with 갔다/왔다.

• It is okay to remove ~에 when it clearly tells where; what place you went to.
• But if ~에 is about the time when that action was done, it cannot be ommitted.

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For example:

1. 가을에 한국에 갔다. -> Nice

• I went to Korea in Autumn. written in the most canonical form.

2. 가을에 한국 갔다. -> OK

• This is still a correct sentence. But it's spoken in an extremely casual tone.

3. 가을 한국에 갔다. -> Wrong

• This doesn't make sense because it means that the person went to a place called 가을 한국 rather than he went to Korea in Autumn.

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Also there's a similar question answered by 국립국어원.