Learn Hardcore Korean: geu namjaneun balpyohal ttaemada tteollineun neukkimi deureo. - That man gets a trembling feeling whenever he presents.

는 marks the topic: “As for that man…” It frames what follows as a general/habitual statement about him.
가 would mark him as the grammatical subject and often introduce him as new or contrastive information: 그 남자가 발표할 때마다… “It’s that man (as opposed to others) who…”
With psychological/experiential expressions like 느낌이 들다, it’s very natural to put the experiencer as the topic (그 남자는) and the feeling as the grammatical subject (느낌이).

What does -(으)ㄹ 때마다 mean, and how is it formed?

Pattern: verb/adjective stem + -(으)ㄹ 때마다 = “whenever / every time (someone) does X.”
Examples:
- 집에 올 때마다 “whenever (someone) comes home”
- 비가 올 때마다 “whenever it rains”
- 발표할 때마다 “whenever (he) presents”

Why is it 발표할 때마다 and not 발표하는 때마다?

With 때(마다) meaning “when(ever),” Korean uses the non-past attributive -(으)ㄹ 때(마다) for the general “when/whenever” sense.
발표하는 때(마다) is unidiomatic. Use:
- 발표할 때 “when (he) presents”
- 발표했을 때 “when (he) presented (that time in the past)”

Is 때마다 written together or as 때 마다?

Write it together: 때마다. The particle 마다 attaches directly to 때 with no space.

Do I need to say 발표를 하다 instead of 발표하다?

Both 발표하다 and 발표를 하다 are fine. 발표하다 is a single verb; 발표를 하다 treats 발표 as a noun object. Everyday Korean uses both without a big difference.
In your sentence, 발표할 때마다 or 발표를 할 때마다 both work.

What exactly does 떨리는 mean? How is it different from 떨리다 and 떨다?

떨리다 is an intransitive/descriptive verb: “to tremble, to be shaky; to feel nervous.” Ex: 손이 떨려요 “My hands tremble.”
떨다 can mean “to shake/tremble” (often physical) or “to shake off/lose.” It’s more action-y.
떨리는 is the attributive form of 떨리다 modifying a noun: 떨리는 느낌 = “a trembling/nervous feeling.”

Can I just say 그 남자는 발표할 때마다 떨려?

Yes. 떨려 (from 떨리다) alone means “(I/he) feel(s) nervous.” It’s shorter and very natural in speech.
Polite: 떨려요. Formal: 떨립니다.

Why use 느낌이 들다 instead of 느끼다 or 긴장하다?

느낌이 들다 = “a feeling arises/comes over (me),” sounds natural and colloquial: 떨리는 느낌이 들어요.
느끼다 takes an object and can feel more direct or formal: 긴장을 느껴요, 떨림을 느껴요 (acceptable but less common in casual talk).
긴장하다 says it plainly: 그 남자는 발표할 때마다 긴장해요 “He gets nervous whenever he presents.”

Who is doing the feeling in 느낌이 들어 if 느낌 is the subject?

Korean often uses a topic + inner subject structure:
- Topic (experiencer): 그 남자는
- Inner subject (what arises): 느낌이
- Predicate: 들어(요)
So it means “As for that man, a trembling feeling arises (in him).”

Why not 느낌이 나 instead of 느낌이 들어?

느낌이 나다 means “to give off a vibe/feeling” (something makes you feel a certain way): 옛날 느낌이 나요 “It has an old-time vibe.”
느낌이 들다 is about the experiencer: a feeling comes to/occurs in someone. For personal feelings, use 들다, not 나다.

Is the sentence too casual? How do I make it polite or formal?

Is 그 남자 natural in conversation?

그 남자 is okay if both speakers know which man you mean from prior context. Otherwise it can sound a bit distant.
Common alternatives:
- 그 사람(은) “that person”
- 저 남자(는) “that man (over there)”
- 걔(는) “that guy” (very casual; for someone your age/younger)

Can I change the word order, like 발표할 때마다 그 남자는 떨리는 느낌이 들어?

Yes. Korean word order is flexible. 발표할 때마다 그 남자는… is fine and puts a bit more focus on the time clause. The default fronting of the topic (그 남자는) is just the most common.

How do I say “whenever he has to present” instead of just “when he presents”?

What’s the difference between 때마다 and 매번?

Both can mean “every time/whenever.”
때마다 attaches to a clause: 발표할 때마다.
매번 is an adverb: 그 남자는 매번 발표할 때 떨려요.
Nuance: 때마다 ties the feeling directly to that trigger; 매번 is a general “every single time.”

Are there more natural collocations than 떨리는 느낌?

All are natural, with small nuances:
- 떨리는 느낌이 들어요 (neutral, idiomatic)
- 긴장돼요 (most direct)
- 긴장되는 느낌이 들어요 (slightly more formal)
- Very casual/short: 발표할 때마다 떨려요.