i gaein samusireun bangeumi jaldwaeyo.

This private office is well soundproofed.

Breakdown of i gaein samusireun bangeumi jaldwaeyo.

• 이: this
• 되다: to work
• 개인 사무실: the private office
• 방음: the soundproofing

Questions & Answers about i gaein samusireun bangeumi jaldwaeyo.

What is the literal structure of 이 개인 사무실은 방음이 잘돼요?

A very literal breakdown is:

• 이 = this
• 개인 사무실은 = as for this private office
• 방음이 = the soundproofing
• 잘돼요 = is done well / works well

So the sentence is structured more like:

As for this private office, the soundproofing is good / works well.

That is a very natural Korean way to express the idea.

Why are there both 은 and 이 in this sentence? Does it have two subjects?

Not exactly. It is better to think of this as topic + subject.

• 이 개인 사무실은: the topic of the sentence
• 방음이: the subject of the predicate 잘돼요

So Korean is saying:

As for this private office, the soundproofing is good.

English usually packs this into one subject, but Korean often separates the bigger topic from the thing being described.

What does 개인 사무실 mean here, and is 개인 an adjective?

개인 사무실 means private office or individual office.

Here, 개인 is originally a noun meaning individual or private person, but Korean often uses nouns directly in front of other nouns to modify them. So:

• 개인
  • 사무실
• literally something like individual/private office

This is very common in Korean. It is not an adjective in the same way English adjectives work, but it functions like a modifier here.