aiga siktak moseorie meorireul buditchiji anhge josimhaesseo.

It breaks down like this:

• 아이가 = the child
• 식탁 모서리에 = on/against the corner of the table
• 머리를 = head
• 부딪치지 않게 = so that they would not bump/hit
• 조심했어 = was careful

A very literal structure is:

[the child] [their head] [on the table corner] [not bump so that] [was careful]

In natural English, Korean usually packs the prevention idea into -지 않게 조심하다, which means to be careful so that something does not happen.

Because 아이 is functioning as the subject of the clause 아이가 ... 머리를 부딪치다.

So the idea is not someone was careful with the child as a direct object. Instead, it is the child might bump their head, and the sentence is about preventing that.

That is why 가/이 is used:

• 아이가 머리를 부딪치다 = the child bumps their head

not

• 아이를 머리를 부딪치다 = ungrammatical

Korean often leaves the main subject unstated if it is obvious from context.

So in this kind of sentence, 조심했어 can have an omitted subject such as I, we, or the parent/caregiver:

• (I) was careful so that the child wouldn't bump their head...

However, depending on context, it can also sound like:

• The child was careful not to bump their head...

So the grammar allows some ambiguity, and context tells you which reading is intended.

-지 않게 means so that not..., in order not to..., or without letting... happen.

Here:

• 부딪치다 = to bump/hit
• 부딪치지 않다 = to not bump/hit
• 부딪치지 않게 = so that they do not bump/hit

When followed by 조심하다, it creates a very common pattern:

• V-지 않게 조심하다 = to be careful not to do V / to be careful so that V does not happen

So:

• 머리를 부딪치지 않게 조심했어 = was careful so that the head would not get bumped

In Korean, body parts are often treated as direct objects in expressions like this.

So:

• 머리를 부딪치다 = to bump/hit one’s head
• 팔을 다치다 is not natural, but 팔을 다치게 하다 can occur in causative contexts
• 머리를 부딪치다 is a standard, natural expression

English often uses bump your head, and Korean works similarly by making head the object:

• 머리를 = head + object marker

Here 에 marks the place or target of contact.

So 식탁 모서리에 머리를 부딪치다 means:

• to bump one’s head on/against the corner of the table

A good way to think of it is:

• 모서리 = corner/edge
• 모서리에 = at/on/against the corner

In collision expressions, 에 often points to what something hits.

모서리 can mean corner or edge, depending on context.

In this sentence, 식탁 모서리 usually means the corner of the table, especially the hard or sharp part someone might hit.

So the image is not the whole edge of the table in general, but the dangerous corner area.

Yes. Both are possible.

• 부딪치지 않게 조심했어
• 부딪치지 않도록 조심했어

Both mean roughly was careful so that they wouldn't bump their head.

The difference is small:

• -게 often feels a bit lighter and very common in speech
• -도록 can feel slightly more formal or more explicitly goal-directed

In everyday conversation, both are natural.

조심했어 is casual, plain spoken style. You would use it with close friends, family, children, or when speaking informally.

Polite version:

• 조심했어요

More plain/written style:

• 조심했다

So the same sentence could become:

• 아이가 식탁 모서리에 머리를 부딪치지 않게 조심했어요.

That is the polite everyday version.