eopdeiteureul hago nanikka hyudaeponi hwolssin ppallajyeosseoyo.

하고 나니까 means something like after doing it, I found that... or once I did it, ... happened / I realized ....

It is built from:

• 하다 = to do
• -고 나다 = to finish doing something
• -니까 = because / when / after, often giving a reason or a discovered result

So 업데이트를 하고 나니까 does not just mean after updating in a neutral time-order sense. It often suggests that the speaker noticed the result after completing the action.

In this sentence, the feeling is: After I updated it, I noticed that the phone had become much faster.

Both are possible.

• 업데이트를 하고
• 업데이트하고

Because 업데이트 is a noun borrowed from English, Korean often combines it with 하다 to make a verb-like expression:

• 업데이트를 하다 = to do an update / to update

In everyday speech, Korean frequently shortens this kind of structure:

• 공부를 하다 → 공부하다
• 업데이트를 하다 → 업데이트하다

So 업데이트를 하고 나니까 and 업데이트하고 나니까 are both natural. The version with 를 하다 can sound a little more explicit, while the shorter version is very common in casual usage.

-를 is the object marker.

In 업데이트를 하다, the noun 업데이트 is treated as the object of 하다:

• 업데이트 = update
• 업데이트를 하다 = to do an update

This pattern is extremely common in Korean, especially with:

• Sino-Korean nouns
• loanwords
• action nouns in general

So even though English says to update, Korean often expresses it structurally more like to do an update.

Both -고 나서 and -고 나니까 can refer to something happening after an action, but they are not exactly the same.

• -고 나서 = after doing
• -고 나니까 = after doing, then I realized / then it turned out that

So:

• 업데이트를 하고 나서 휴대폰이 훨씬 빨라졌어요
  = After updating, the phone became much faster.

• 업데이트를 하고 나니까 휴대폰이 훨씬 빨라졌어요
  = After updating, I found that the phone had become much faster.

The sentence with 나니까 feels a bit more like the speaker is talking about a result they noticed after the update.

Because 휴대폰 is the subject of 빨라졌어요.

The sentence is structured like this:

• 업데이트를 하고 나니까 = after updating
• 휴대폰이 = the phone (subject)
• 훨씬 빨라졌어요 = became much faster

The thing that became faster is the phone, so it takes the subject marker -이.

If you used 휴대폰을, it would sound like the phone is the object of some action, which is not what is happening here.

Both could appear in some contexts, but 휴대폰이 is very natural here because it presents the phone as the thing that showed this change.

• 휴대폰이 훨씬 빨라졌어요 focuses on the phone itself as the subject that became faster.
• 휴대폰은 훨씬 빨라졌어요 would sound more like as for the phone, it became much faster, often with a contrast or topic feeling.

Using -이/가 here fits the idea of reporting a noticed result: The phone became much faster.

훨씬 means much, far, or a lot in a comparative sense.

So:

• 빠르다 = to be fast
• 더 빠르다 = to be faster
• 훨씬 빠르다 = to be much faster / far faster

In this sentence, 훨씬 strengthens the comparison. It tells you the speed improvement is not small.

Examples:

• 오늘이 어제보다 훨씬 추워요. = Today is much colder than yesterday.
• 이게 훨씬 좋아요. = This is much better.

빨라졌어요 comes from 빨라지다, which means to become fast.

So:

• 빠르다 = to be fast
• 빨라지다 = to become fast / to get faster
• 빨라졌어요 = became fast / got faster

This is important because the sentence is describing a change in condition after the update. The phone was one way before, and then it became faster.

If you said 휴대폰이 훨씬 빨라요, it would mean the phone is much faster, but it would not highlight the change as clearly.

This is due to Korean adjective and verb formation.

• Base adjective: 빠르다 = to be fast
• Change-of-state form: 빨라지다 = to become fast

The form 빨라지다 is made by taking the adjective stem and adding -아지다 / -어지다, which often means to become.

Then:

• 빨라지다 → past polite form → 빨라졌어요

So the full idea is: it became faster.

This -아/어지다 pattern is very useful:

• 커지다 = become big
• 작아지다 = become small
• 좋아지다 = become good / get better
• 느려지다 = become slow / get slower

Yes, that is the natural implication.

The sentence suggests a sequence and a result:

1. the speaker updated the phone
2. afterward, the phone was much faster

With 하고 나니까, it sounds like the speaker is talking about a result they observed after doing the update. It strongly suggests that the update is the reason, or at least that the speaker sees the two as connected.

However, grammatically it is more like after I updated it, it turned out to be much faster than a strict scientific claim of causation.

빨라졌어요 is in the polite informal style, often called 해요체.

This is one of the most common styles in everyday Korean. It is polite enough for:

• strangers
• coworkers
• casual conversation
• many normal social situations

The plain/non-polite version would be:

• 빨라졌어

A more formal style would be:

• 빨라졌습니다

So this sentence sounds natural in ordinary polite conversation.

Yes, often it can.

• 휴대폰 literally means mobile phone / cell phone
• 스마트폰 specifically means smartphone

In modern everyday use, people often use both, depending on context. Since software updates are especially associated with smartphones, 스마트폰이 훨씬 빨라졌어요 would also sound very natural.

But 휴대폰 is still perfectly normal here and can easily refer to a smartphone in casual speech.

Yes, that is grammatically correct.

• 업데이트한 후에 = after updating
• 업데이트를 하고 나서 = after doing the update
• 업데이트를 하고 나니까 = after updating, I found that...

These are similar, but the nuance is slightly different:

• 한 후에 sounds a bit more neutral or formal.
• 하고 나서 is very common and natural for sequence.
• 하고 나니까 adds the feeling of discovering or noticing the result afterward.

So your version works, but the original sentence has a slightly stronger result noticed afterward feeling.

Korean often leaves out possessive words like my, your, or his/her when the meaning is obvious from context.

In English, you would usually say my phone. In Korean, if it is already clear that the speaker means their own phone, just saying 휴대폰 is enough.

So:

• 휴대폰이 훨씬 빨라졌어요 naturally means my phone got much faster if that is obvious from the situation.

This kind of omission is very common in Korean and is one of the things English speakers often need time to get used to.