다행이다 [ dahaengida ]
We already studied the meaning of 다행 before (check here to see). 다행이다 is used when the result came out better or with no problems after the speaker had worried so much. The meaning of expression can be similar to ‘I am relieved‘ or ‘thank god‘.
너 괜찮아? 걱정 많이 했는데, 다행이다. — Are you okay? I was so worried about you. Thank god.
A) 수술이 잘 되었습니다. — The operation went well. B) 다행입니다. 감사합니다. — I am so relieved now. Thank you.