Hangul syllable dyeo

The surrounding word gives it meaning.

Hangul, Korea's writing system, was created in the 15th century. Its blocks combine consonant and vowel letters: 뎌 joins ㄷ and ㅕ.

A 1908 Korean poem preserves 뎌푸른 하날, 뎌것은, and 뎌世上 (世上 means “world”).

Does 뎌 relate to 져 and 저?

Historical sources trace 뎌 to 져, then to 저.

Palatalization moves a consonant's articulation toward the palate, changing its sound.

In the Middle Korean period, 뎌 sometimes served as a third-person pronoun for someone already mentioned; modern Korean uses 그.