geu gisareul sseun gijaga radio inteobyuedo nawasseo.

They are different words:

• 기사 = article / news story
• 기자 = reporter / journalist

They are related in meaning, which is why they often appear together, but they are not different forms of the same word.

In this sentence:

• 그 기사 = that article
• 기자 = the reporter / journalist

So 그 기사를 쓴 기자 means the reporter who wrote that article.

그 is a demonstrative meaning that.

So:

• 그 기사 = that article
• 이 기사 = this article
• 저 기사 = that article over there

Here, 그 points to an article that is already known from context, similar to English that article.

-를 is the object marker.

• 기사 ends in a vowel, so it takes -를
• 기사를 = article + object marker

In this sentence, the article is the thing being written:

• 그 기사를 쓴 = (someone) wrote that article

So 기사 is the object of 쓰다 (to write).

쓴 comes from 쓰다 (to write) and is the noun-modifying form.

So:

• 쓰다 = to write
• 쓴 = written / that wrote

In this sentence, 쓴 modifies 기자:

• 그 기사를 쓴 기자
• literally: the reporter who wrote that article

This is how Korean makes relative clauses: the clause comes before the noun it describes.

Yes, this is a form learners often notice.

For action verbs, the past noun-modifying form is often made with -ㄴ / -은. With 쓰다, the ㅡ drops before the ending:

• 쓰다
• stem: 쓰-
• drop ㅡ
• add -ㄴ
• result: 쓴

So 쓴 기자 = the reporter who wrote

This same kind of change happens with many ㅡ verbs.

Korean puts the describing clause before the noun.

English:

• the reporter who wrote that article

Korean:

• that article wrote reporter
• more naturally broken down: [그 기사를 쓴] 기자

So the structure is:

• 그 기사 = that article
• -를 = object marker
• 쓴 = wrote / who wrote
• 기자 = reporter

Altogether:

• 그 기사를 쓴 기자 = the reporter who wrote that article

This is one of the most important differences between Korean and English sentence structure.

-가 is the subject marker.

Here, the full subject of the main sentence is:

• 그 기사를 쓴 기자가
• the reporter who wrote that article
  • subject marker

That whole phrase is the subject of 나왔어.

So the sentence structure is basically:

• [The reporter who wrote that article]
  • appeared / came out
    • also on a radio interview

The -를 marks the object inside the describing clause, and the -가 marks the subject of the main clause.

에도 is 에 + 도.

• 에 can mark a place, target, or context such as on / in / at
• 도 means also, too, or sometimes even

So 라디오 인터뷰에도 means something like:

• also on a radio interview
• also in a radio interview
• sometimes even in a radio interview, depending on context

The important nuance is that the reporter appeared there in addition to something else already mentioned or understood.

Yes, 나오다 literally means to come out / to appear, but in Korean it is also very commonly used for appearing in media.

For example, someone can:

• TV에 나오다 = appear on TV
• 신문에 나오다 = appear in the newspaper
• 인터뷰에 나오다 = appear in an interview

So 라디오 인터뷰에도 나왔어 means the person appeared on / was featured in a radio interview too.

This is a very natural Korean usage.

나왔어 is the casual/informal polite level? Actually, it is plain casual speech (반말), not the polite -요 style.

Compare:

• 나왔어 = casual
• 나왔어요 = polite
• 나왔다 = plain written / neutral declarative style

So the sentence is in a casual tone, probably used with a friend, someone younger, or in relaxed conversation.

Yes.

• 라디오 = radio
• 인터뷰 = interview

Both are loanwords commonly used in Korean. Korean often combines loanwords naturally like this.

So 라디오 인터뷰 is a normal way to say radio interview.

You may also notice that particles attach directly to the whole phrase:

• 라디오 인터뷰에
• 라디오 인터뷰에도

Korean word order is somewhat flexible, but this version is the most straightforward and natural.

Basic structure here:

• 그 기사를 쓴 기자가 = subject
• 라디오 인터뷰에도 = additional location/context
• 나왔어 = verb

Because Korean puts the verb at the end, 나왔어 stays last. Some other elements can move for emphasis, but the original sentence is the neutral, natural order.

For example, moving 라디오 인터뷰에도 earlier could emphasize it more, but the standard version is the one you have.

A few very useful patterns appear here:

1. Noun-modifying clause

   • 그 기사를 쓴 기자
   • the reporter who wrote that article

2. Object marker

   • 기사를
   • the article is what was written

3. Subject marker

   • 기자가
   • the reporter is the subject of the main verb

4. 에 + 도

   • 인터뷰에도
   • also in/on the interview

5. Media appearance with 나오다

   • 인터뷰에 나오다
   • to appear in/on an interview

So this one sentence is a great example of how Korean packs a lot of information before the final verb.