Korean · Pronunciation Guide
geok-jjeong-ha-da. The unreleased ㄱ tenses the following ㅈ into ㅉ, which the romanization does not show.
geokjeonghada
Four beats with a silent closure in the middle. Post-obstruent tensing fires at the seam between the two Sino-Korean elements, and it is the loudest thing in a word that is otherwise soft.
Listen: 걱정하다
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너무 걱정하지 마세요.
Neomu geokjeonghaji maseyo.
Don't worry too much.
Listen: 너무 걱정하지 마세요.
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너무 걱정하지 마세요 uses the negative command, and 걱정하지 keeps the tensing while 마세요 stays entirely soft. The contrast between the tensed ㅉ and the surrounding nasals is what gives the phrase its shape.
Saying 'geok-jeong' with a soft j misses the tensing, and the romanization gives no hint that anything should harden -- squeeze the throat. Releasing the ㄱ is the second habit, and rounding either ㅓ is the third, since both vowels in this word are flat.