Learn Hardcore Korean: banmyeon gaeksil aneseoneun heubyeonhamyeon chuga yogeumi bugwadwaeyo. - On the other hand, smoking in the room incurs an additional charge.

"반면" means "on the other hand/whereas" and sets up a contrast with something just mentioned. It sounds most natural when there is a prior statement to oppose (e.g., “The balcony is okay; on the other hand, inside the room…”). Without prior context, use something like "하지만" (“however”) or simply drop "반면."

Is there any difference between "반면" and "반면에"?

Both are natural and mean essentially the same. "반면에" can feel a touch more conversational; "반면" can feel a bit crisper or more written. You can use either here.

What does the "-에서는" in "객실 안에서는" do?

"-에서" marks the place where an action happens; adding "-는" makes that place a contrastive topic (“as for inside the room (as opposed to elsewhere)”). Without "-는" ("객실 안에서…") it’s still correct but the contrast is weaker.

Why "안에서" and not "안에"?

Use "-에서" for locations where an action occurs, and "-에" for static existence/position. Smoking is an action, so "안에서" (inside, where the action happens) is right. Compare: "방 안에 의자가 있어요" (There is a chair in the room) vs. "방 안에서 공부해요" (I study in the room).

Could I just say "객실에서는" instead of "객실 안에서는"?

Yes. "객실에서는" is natural and already implies “inside the room.” "객실 안에서는" adds extra emphasis on the interior. Formal signs also use "객실 내(에서는)" where "내" is a Sino-Korean “inside/within.”

What’s the difference between "객실" and "방"?

"객실" is a hotel/guestroom term (more formal/commercial). "방" is any “room” in general speech. In hotel policies, "객실" is preferred.

"흡연하면" vs. "담배를 피우면" — which is better?

Both mean “if (you) smoke.” "흡연하다" is more formal/technical (common in rules or signs). "담배를 피우다" is everyday casual speech. On a notice, you'd expect "흡연."

Why isn’t there an object particle after "흡연"? Should it be "흡연을 하면"?

"흡연하다" is a verb meaning “to smoke,” so no object is needed. "흡연을 하다" is possible but wordier and less common in concise notices. "흡연하면" is preferred.

What does the "-면" in "흡연하면" express exactly?

"-(으)면" is a real conditional (“if/when”). It can also express a general rule: “When/If one smokes (in that situation), …” For added politeness to the subject, you can say "흡연하시면."

Who is the subject here? There’s no “you.”

Korean often omits obvious subjects. The understood subject is “anyone/you (the guest).” If you want to make the agent explicit in an active sentence, you could say "호텔에서 추가 요금을 부과해요" (The hotel charges an extra fee).

"추가 요금" sounds like a fee. Is that the same as a fine?

Not quite.

"추가 요금" = extra charge (e.g., cleaning/penalty fee set by the property).
"벌금" = criminal fine.
"과태료" = administrative fine.
"청소비" = cleaning fee. The sentence is about an extra charge, not a legal fine.

Should it be "추가요금" or "추가 요금" (spacing)?

Both spellings are common in real-world use. Many dictionaries list "추가요금" as a single compound, but you’ll also see "추가 요금." Choose one style and be consistent.

What exactly is "부과돼요"? Why not "부과되요"?

It’s the passive verb "부과되다" (“to be imposed/levied”) in polite present: "부과돼요" (from "되어요" → contracted to "돼요"). "되요" is a common misspelling; the correct form is always "돼요."

"부과되다" vs. "부과하다" vs. "청구되다" — what’s the nuance?

"부과되다": an authority/organization imposes a fee or penalty (passive, formal).
"부과하다": active version (“to impose”).
"청구되다/청구하다": to be billed/requested for payment, often at checkout. In policy lines, "부과되다" is standard.

Is the politeness/register appropriate? How would a formal sign say it?

"-돼요" is polite but relatively casual/informal-policy tone. A formal notice would use "-습니다" and often Sino-Korean style: "단, 객실 내에서 흡연 시 추가요금이 부과됩니다."

Can I change the word order?

Yes. Korean allows flexible order. For example:

"객실 안에서(는) 흡연하면 추가 요금이 부과돼요." (original)
"흡연하면 객실 안에서(는) 추가 요금이 부과돼요." The meaning stays the same; placing the location first foregrounds the place.

If the goal is to forbid smoking, why not say "안 돼요"?

You can: "객실 안에서 흡연하시면 안 돼요" = “You must not smoke in the room.” The original sentence states a consequence (a charge) rather than a direct prohibition, which can sound less confrontational and more policy-like.

How is the whole sentence pronounced?

Approximate syllable-by-syllable: "반면 [ban-myeon] 객실 [gaek-ssil] 안에서는 [a-ne-seo-neun] 흡연하면 [heup-yeon-ha-myeon] 추가 요금이 [chu-ga yo-geum-i] 부과돼요 [bu-gwa-dwae-yo]." Note the tensification in "객실" → [객씰] and "돼요" pronounced like “dwae-yo,” not “de-yo.”