Improvement of Korean translation

[benesys03]

Nebulous ID : 1182150

[ghost]

Please provide a reason for these changes and explain with proof why the previous texts were incorrect, as it says on Tips topic:

"Adding comments to your PR that explains why subtle changes were made can help. If you are revising something that is already translated, an explanation is required."

[benesys03]

1. Fixed a spacing error that went against spelling regulations:

   참여하고있는 -> 참여하고 있는
   
   이 것을 -> 이것을
   

2. Modifying vague words:

   수량 지정(designate) -> 수량 입력(input)
   
   In most cases, the word '입력' is used rather than the word '지정' in situations 
   where the plasma quantity needs to be entered.
   

[ghost]

Thanks for your time, @benesys03. ^^
Approved the changes, can merge into main as soon as possible.