Hello @juhyeon_PARK, welcome to the community!
The main issue is handling the binary data and referencing it correctly. I suggest reading the docs and using the AI on that page to ask how to do what you need:
You can also simplify the process, I don’t think having two different code nodes is the best approach..
However, I just fixed your workflow as it is, it should work now..
Please test it on your end and let me know if you run into any problems.
also, this is the openai docs for create transcription if you want to edit any parameters
https://platform.openai.com/docs/api-reference/audio/createTranscription