balpyo jaryoreul baegeophae dunikka jeopsogi an dwaedo geokjeongi deol dwae.

발표 자료 means presentation materials or presentation files/materials.

• 발표 = presentation
• 자료 = materials, data, resources

In this sentence, it most naturally refers to the files or materials needed for a presentation, such as slides, documents, or handouts.

를 marks 발표 자료 as the direct object of 백업하다.

So:

• 발표 자료를 백업하다 = to back up the presentation materials

This is very straightforward object marking. The thing being backed up gets 를.

It combines two parts:

• 백업해 두다 = to back something up and leave it prepared/in that state
• -니까 = because / since

So 백업해 두니까 means something like:

• because I backed it up beforehand
• since I have it backed up
• because I made a backup in advance

The important nuance comes from -아/어 두다 in 해 두다. That grammar often means doing something in advance and leaving it ready for future use.

-아/어 두다 often means:

• doing something in advance
• doing something and leaving it that way
• preparing something for a later situation

So:

• 백업하다 = to back up
• 백업해 두다 = to back it up ahead of time and have that backup available

In this sentence, that nuance matters a lot. The speaker is saying the backup was made beforehand, so if access fails later, there is less to worry about.

Here -니까 expresses the reason quite clearly: because / since.

• 백업해 두니까 = because I’ve backed it up
• 접속이 안 돼도 걱정이 덜 돼 = even if I can’t connect, I worry less

Compared with -아서/어서, -니까 often sounds a bit more explicit or speaker-centered when giving a reason. It fits well when the speaker is explaining why they feel a certain way.

So this sentence has a natural logic:

1. I backed up the presentation materials.
2. Therefore, even if connection fails, I’m less worried.

These are different ideas.

• 접속하다 = to connect / log in / access
• 접속이 안 되다 = connection doesn’t work / it’s not possible to connect

In Korean, N이/가 안 되다 is very common for saying something doesn’t work, isn’t possible, or won’t go through.

So:

• 접속을 안 하다 = not connect / choose not to connect
• 접속이 안 되다 = be unable to connect / connection fails

In this sentence, the speaker means access might fail, not that they personally decide not to connect.

-아/어도 means even if or even though.

So:

• 안 되다 = to not work / to not be possible
• 안 돼도 = even if it doesn’t work / even if I can’t connect

That creates a contrast:

• Even if access fails, I’m less worried.

It shows that the second part remains true regardless of that problem.

In 접속이 안 되다, 접속 is treated as the subject of 안 되다.

This pattern is very common in Korean:

• 예약이 안 돼요 = the reservation doesn’t work / I can’t make a reservation
• 결제가 안 돼요 = payment doesn’t go through
• 접속이 안 돼요 = connection doesn’t work / I can’t connect

So 이/가 is natural because the sentence is structured like connection is not working/possible.

It means I worry less or I’m less worried.

Breakdown:

• 걱정 = worry
• 되다 in 걱정이 되다 = to become a worry / to be worrying
• 덜 = less

So:

• 걱정이 되다 = to be worrying / to cause worry
• 걱정이 덜 되다 = to be less worrying / to cause less worry

In natural English, you would usually say:

• I’m less worried
• I don’t worry as much

Both are possible in Korean, but they are slightly different in feel.

• 걱정을 덜 해 = I worry less
• 걱정이 덜 돼 = it feels less worrying / I become less worried

The sentence uses 걱정이 되다, which is a very common expression meaning to be worrying.

So 걱정이 덜 돼 feels a little more like the speaker’s worry level naturally decreases because they prepared in advance.

덜 means less.

It is used when something happens to a smaller degree than usual or expected.

Examples:

• 덜 아파요 = It hurts less.
• 덜 바빠요 = I’m less busy.
• 걱정이 덜 돼 = I’m less worried.

So in this sentence, 덜 reduces the amount of worry; it does not mean there is no worry at all.

Yes. The final 돼 is casual/plain spoken style.

The more polite version would be:

• 발표 자료를 백업해 두니까 접속이 안 돼도 걱정이 덜 돼요.

So the original sounds natural in conversation, especially when speaking to a friend, classmate, or someone you do not need to be highly formal with.

Yes, very much so.

Because of 백업해 두다, the sentence strongly suggests preparation in advance. The speaker is saying that because the presentation materials were already backed up, a possible connection problem is less serious.

So the overall feeling is:

• I planned ahead
• I’m prepared
• even if something goes wrong, it’s manageable

That preparedness nuance is one of the key points of the sentence.