All appeals are dismissed.

The costs of appeal are assessed against the Defendants.

The grounds of appeal are examined.

1. Examining the grounds of appeal by Defendant B in light of the relevant legal principles and records, the lower judgment that determined that Defendant B was obligated to return KRW 30 million to the Plaintiff as unjust enrichment did not err by misapprehending the facts in violation of logical and empirical rules or by misapprehending the legal doctrine on unjust enrichment.

2. Examining the grounds of appeal by Defendant C in light of the relevant legal principles and records, the lower court did not exhaust all necessary deliberations, but did not err by misapprehending the legal doctrine on the probative value of the disposal document, omitting judgment, or misapprehending the legal doctrine, without exhaust all necessary deliberations, which determined that there was insufficient proof as to the fact that there was a trade union agreement or settlement agreement

3. Therefore, all appeals are dismissed, and the costs of appeal are assessed against the losing party. It is so decided as per Disposition by the assent of all participating Justices on the bench.