Mune ga Ippai ni Naru (胸がいっぱいになる - Overflowing)

Mune ga Ippai ni Naru

Yesterday, a farewell party for teachers who would retire or change their jobs at my university was held.

Since I was also one of the teachers who leave the university, my boss paid me a heartfelt compliment, then I was filled with joy.

When you are filled with emotions such as joy or grief, you can describe it as 'mune ga ippai ni naru' (胸がいっぱいになる).

'Mune' (胸) means "heart," 'ippai' (いっぱい) means "full" or "many," and 'naru' (なる) means "to be," so the literal meaning of this phrase is "one's heart is filled."

[Example] Kanasimi de mune ga ippai ni natta (悲しみで胸がいっぱいになった - "I overflowed with grief").

胸がいっぱいになる

昨日、私の大学で退職・転職する教員の送別会が行われました。

私も転職する教員の一人で、上司からとても嬉しいお言葉を頂き、喜びで心が満たされました。

このように、喜びや悲しみなどの感情で心が満たされることを、「胸がいっぱいになる」と言います。

「胸」は "heart"、「いっぱい」は "full/many"、「になる」は "to be" を意味するので、この表現の文字どおりの意味は "one's heart is filled" となります。

【例文】悲しみで胸がいっぱいになった。

• Yesterday, a farewell party for teachers who would retire or change their jobs at my university was held.
• Yesterday, a farewell party for teachers who arewould retiringe or changinge their jobs at my university was held.

  Your sentence was fine, this just seems more natural to me.

• Since I was also one of the teachers who leave the university, my boss paid me a heartfelt compliment, then I was filled with joy.
• Since I was also one of the teachers who is leavinge the university, my boss paid me a heartfelt compliment, wthichen I was filled me with joy.

勉強になりました!

• Mune ga Ippai ni Naru (胸がいっぱいになる - Overflowing)
• Mune ga Ippai ni Naru (胸がいっぱいになる - Overflowing)

  I'm not sure about "overflowing". Are you sure that it's more like 溢れる than 満ちる？

• Yesterday, a farewell party for teachers who would retire or change their jobs at my university was held.
• Yesterday, my university held a farewell party for teachers who are retiring or changing jobs at my university was held.

  1. It's more natural in English for something to do something else (instead of it just happening)
  
  So, "my university held" is more natural.
  
  However, you can also say "Yesterday, there was a party held at my university for ..." because the doer (行為者) is unimportant. (this is closer to what you wrote).
  
  2. Putting "at my university" or "was held" at the end of the sentence sounds strange here.
  
  The three main bits of information you want to express are:
  
  a) There was a party;
  b) It was held at the university; and
  c) The purpose of the party
  
  (also (d) the time, "Yesterday")
  
  It's more natural to combine (a) and (b) into one part and make (c) another part. The natural sentence structure for this is (a+b) (c). Your sentence structure starts off with a bit of (a), then goes (c) (a+b).
  
  The (a+b) (c) sentence structure also works well with your following sentence because that sentence refers back to (c), which is at the end of this sentence. The distance between mentioning (c) and referring back to it is shorter, so it's easier to understand.

• Since I was also one of the teachers who leave the university, my boss paid me a heartfelt compliment, then I was filled with joy.
• Since I was also one of the teachers leaving the university, my boss paid me a heartfelt compliment, and it filled me with joy.

  The "which" correction is good too.

• When you are filled with emotions such as joy or grief, you can describe it as 'mune ga ippai ni naru' (胸がいっぱいになる).
• This sentence is perfect! No correction needed!

• 'Mune' (胸) means "heart," 'ippai' (いっぱい) means "full" or "many," and 'naru' (なる) means "to be," so the literal meaning of this phrase is "one's heart is filled."
• 'Mune' (胸) means "heart," 'ippai' (いっぱい) can mean "full" or "many," and 'naru' (なる) means "to become," so the literal meaning of this phrase is "one's heart becomes filled."

  I changed "means" to "can mean" to show that "full" and "many" are different senses. I suppose ガラスがいっぱい、蚊がいっぱい

• [Example] Kanasimi de mune ga ippai ni natta (悲しみで胸がいっぱいになった - "I overflowed with grief").
• [Example] Kanasimi de mune ga ippai ni natta (悲しみで胸がいっぱいになった - "I became filled with grief").

  "overflowed" sounds weird in English in this case. Does 溢れる also sound strange in Japanese?