cheongsogireul dollyeossdeoni bangi hwolssin kkaekkeushaejyeosseo.

돌리다 literally means to turn, spin, or run something, but in Korean it is also commonly used for operating certain machines or appliances.

So 청소기를 돌리다 means:

• to run the vacuum cleaner
• to vacuum

It does not mean you are physically spinning the vacuum cleaner around. It is just a natural Korean expression for using it.

Similar expressions:

• 세탁기를 돌리다 = to run the washing machine
• 건조기를 돌리다 = to run the dryer

So in this sentence, 청소기를 돌렸더니 means after I vacuumed or when I ran the vacuum cleaner.

The particle 를 marks the direct object of the verb.

In 청소기를 돌리다:

• 청소기 = vacuum cleaner
• 를 = object marker
• 돌리다 = to run/operate

So the vacuum cleaner is the thing being operated, which is why it takes 를.

Breakdown:

• 청소기 = vacuum cleaner
• 청소기를 = the vacuum cleaner
• 돌렸더니 = after running it / when I ran it

Here, -었더니 connects two events and shows that:

1. the first action happened first, and
2. the speaker then observed or discovered the result.

So 청소기를 돌렸더니 방이 훨씬 깨끗해졌어 has the feeling of:

• I vacuumed, and then I found that the room had become much cleaner
• After vacuuming, the room became much cleaner
• I vacuumed, and as a result, the room got much cleaner

A key nuance of -았/었더니 is that it often includes the speaker’s realization or observed outcome, not just a plain cause-and-effect statement.

They can all connect two clauses, but the nuance is different.

• -아서/어서

  • often gives a neutral sequence or cause
  • 청소기를 돌려서 방이 깨끗해졌어 = I vacuumed, so the room became clean

• -(으)니까

  • often means because or when I did X, I found...
  • can sound a bit more explanatory or reasoning-based

• -았/었더니

  • strongly suggests after doing X, I saw/discovered that Y happened
  • often feels more experiential or observational

So 돌렸더니 fits well because the speaker is talking about a result they noticed after vacuuming.

Because 깨끗해지다 means to become clean, and the room is the thing that undergoes that change of state.

Breakdown:

• 방이 = the room (subject)
• 깨끗해지다 = to become clean

So the room is not the object of an action here. It is the subject that changes.

Compare:

• 방을 청소했어 = I cleaned the room
  
  • 방을 is the object
• 방이 깨끗해졌어 = the room became clean
  
  • 방이 is the subject

That is why 이/가 is used.

훨씬 means much, far, or by a lot when comparing a difference.

So:

• 훨씬 깨끗해졌어 = became much cleaner

It strengthens the comparison. The sentence is not just saying the room got cleaner, but that it got noticeably cleaner.

Examples:

• 훨씬 좋아졌어 = It got much better.
• 훨씬 빨라 = It’s much faster.

It is made up of several parts:

• 깨끗하다 = to be clean
• 깨끗해지다 = to become clean
• 깨끗해졌어 = became clean

More exactly:

1. 깨끗하다 is the adjective base
2. -아/어지다 is added to mean to become
3. past tense -었-
4. informal ending -어

So:

• 깨끗하다 → 깨끗해지다 → 깨끗해졌어

This is a very common pattern:

• 조용하다 → 조용해지다 = to become quiet
• 따뜻하다 → 따뜻해지다 = to become warm
• 예뻐지다 = to become pretty

The ending -어 in 깨끗해졌어 is a casual, informal speech ending.

This means the speaker is talking:

• to a friend
• to someone younger
• in a relaxed conversation

More formal versions would be:

• 청소기를 돌렸더니 방이 훨씬 깨끗해졌어요.
  polite
• 청소기를 돌렸더니 방이 훨씬 깨끗해졌습니다.
  formal

So the original sentence sounds natural in everyday casual speech.

Usually yes, but not always in a strict scientific cause sense. It often means:

• I did X
• then I saw/found that Y happened

In this sentence, it is very natural to understand that vacuuming led to the room becoming cleaner. So there is both:

• sequence: vacuuming happened first
• result: the room became cleaner
• observation: the speaker noticed that result

That combination is exactly why -었더니 works so well here.

Yes. In natural English, both are good ways to understand it.

But if you want the nuance of the Korean more precisely, -었더니 leans a little more toward:

• After I vacuumed, I found that the room was much cleaner
• I vacuumed, and it turned out the room got much cleaner

So the Korean has slightly more of a noticed result feeling than a simple plain sequence.

Not exactly.

• 청소하다 = to clean
• 청소기를 돌리다 = to run the vacuum cleaner / to vacuum

So 청소하다 is broader. It could include:

• sweeping
• wiping
• organizing
• vacuuming

But 청소기를 돌리다 specifically refers to using a vacuum cleaner.

That is why this sentence feels more specific and vivid than just saying:

• 청소했더니 방이 훨씬 깨끗해졌어
  After I cleaned, the room became much cleaner.