Here are a few things to consider:
* Is it a name of foreign origin? If so, it might be spelled phonetically in Korean.
* Is it a Korean word with a different romanization? Perhaps it's spelled differently in other romanization systems.
To help you find the Korean spelling, I need more information.
Please tell me:
* What language is HYOEL from?
* What does HYOEL mean?
* How is it pronounced?
Once I have more information, I can help you find the correct Korean spelling.