jihacheol ipgu ap bunsilmulsenteo-e nae bunsilmuri deureowassneunji mureobwasseoyo.

Korean often stacks nouns together to make one long noun phrase.

• 지하철 = subway
• 입구 = entrance
• 앞 = front/in front
• 분실물센터 = lost-and-found center

So 지하철 입구 앞 분실물센터 means the lost-and-found center in front of the subway entrance.

A more fully expanded version would be:

• 지하철 입구 앞에 있는 분실물센터

In everyday Korean, 에 있는 is often omitted when the relationship is already clear.

앞 is a noun meaning front or the area in front of something.

So:

• 입구 앞 = in front of the entrance

In this sentence, 입구 앞 works like a location phrase that describes 분실물센터.

Compare:

• 입구 앞에 있어요 = It is in front of the entrance.
• 입구 앞 카페 = the cafe in front of the entrance

Your sentence uses the second kind of pattern.

Because the sentence is talking about asking at/to the lost-and-found center as a place or institution, not necessarily one specific person.

• 분실물센터에 물어봤어요 = I asked at the lost-and-found center.
• 직원에게 물어봤어요 = I asked the staff member.

Both are possible, but they focus differently:

• 에 → the place/office
• 에게 → the person

So this sentence sounds natural if the speaker means they contacted or asked the lost-and-found office.

분실물 is a common noun meaning a lost item or lost property.

It is often used in places like:

• stations
• airports
• schools
• offices

So 내 분실물 means my lost item.

Even though it literally has the idea of lost property, in normal English translation it is often best rendered as:

• my lost item
• the thing I lost

이 is the subject particle.

Here, 내 분실물이 들어왔는지 is an embedded clause meaning something like:

• whether my lost item had come in
• whether my lost item had been turned in

Inside that clause, 내 분실물 is the subject, so it takes 이.

A rough breakdown:

• 내 분실물 = my lost item
• 내 분실물이 들어왔는지 = whether my lost item came in / was turned in

Yes, literally 들어오다 means to come in / come inside. But in this context, it has a very natural institutional meaning:

• 분실물이 들어오다 = a lost item has been turned in / has arrived at the lost-and-found

So 내 분실물이 들어왔는지 means:

• whether my lost item had been turned in
• whether my lost item had arrived at the lost-and-found

This is a very natural Korean way to say it.

-는지 / -은지 / -ㄴ지 is used to mark an indirect question, often translated as whether, if, or who/what/where... in embedded questions.

Here:

• 들어왔는지 = whether it came in / whether it had been turned in

This is the thing being asked about.

So:

• 내 분실물이 들어왔는지 물어봤어요 = I asked whether my lost item had been turned in.

This pattern is very common with verbs like:

• 알다 = know
• 모르다 = not know
• 물어보다 = ask
• 확인하다 = check

물어보다 is a very common verb meaning to ask or to inquire.

Even though it looks like 묻다 + 보다, in many cases it functions as a standard verb meaning ask/inquire, not necessarily try asking.

So:

• 물었어요 = asked
• 물어봤어요 = asked / inquired

In everyday speech, 물어봤어요 is extremely common and natural.

It can sometimes carry a slightly softer or more conversational feeling, like I checked by asking, but in many contexts it is simply the normal way to say asked.

Because the speaker is asking whether the item had already arrived at the lost-and-found by that time.

• 들어오다 = come in
• 들어왔다 = came in / has come in
• 들어왔는지 = whether it came in / whether it has come in

Using the past form makes sense because the speaker wants to know if the event had already happened.

In English, this is often translated as:

• whether it had been turned in
• whether it had come in yet

내 is the plain form of my. 제 is the humble/polite form.

So:

• 내 분실물 = my lost item
• 제 분실물 = my lost item (more polite)

Because the sentence ends in -어요, some learners expect 제. But Korean often mixes a polite sentence ending with 내 in casual everyday speech, especially in conversation.

If you want a more consistently polite version, you could say:

• 제 분실물이 들어왔는지 물어봤어요.

Yes. Korean often compresses information, but you can expand it for clarity.

For example:

• 지하철 입구 앞에 있는 분실물센터에 제 분실물이 들어왔는지 물어봤어요.

This version makes the structure easier to see:

• 지하철 입구 앞에 있는 = which is in front of the subway entrance
• 분실물센터에 = at/to the lost-and-found center
• 제 분실물이 들어왔는지 = whether my lost item had been turned in
• 물어봤어요 = I asked

The original sentence is natural, but this expanded version can be easier for learners to parse.

Yes, but the nuance changes.

• 들어왔는지 = whether it has been turned in / whether it has come into the center
• 있는지 = whether it is there

So:

• 내 분실물이 들어왔는지 물어봤어요
  = I asked whether my lost item had been turned in.

• 내 분실물이 있는지 물어봤어요
  = I asked whether my lost item was there.

The first focuses on whether the item has arrived at the lost-and-found system. The second focuses more on its current presence there. Both are possible, but 들어왔는지 is especially natural in a lost-and-found context.