All appeals are dismissed.

The costs of appeal are assessed against the plaintiffs.

1. As to the ground of appeal No. 1, the lower court, on the grounds indicated in its reasoning, determined that it was a cause attributable to the Plaintiffs’ failure to take effect.

The judgment below

Examining the reasoning in light of the record, the lower court did not err by misapprehending the rules of evidence, the rules of experience and logic, or by misapprehending the legal doctrine on causes attributable to it.

2. As to the ground of appeal No. 2, according to the reasoning of the judgment below, the court below determined that the plaintiffs paid 2.5 billion won as the performance bond under the instant memorandum of Understanding shall belong to the defendant as a penalty penalty and the plaintiffs shall not claim reduction.

In this regard, the plaintiffs asserts that the above performance guarantee amount should be reduced because the amount falls under the estimated amount of damages, not the penalty for breach of contract, and the amount should be reduced unfairly.

As alleged by the plaintiffs, even if the above performance guarantee agreement is liquidated damages, considering all the circumstances revealed at the time of closing of argument in the court below, such as the plaintiffs and the defendant's position, the purpose and contents of the memorandum of understanding of this case, the scheduled amount of damages, the rate of estimated amount of total amount of damages, transaction practices at the time of closing of argument in the court below, etc., which are revealed by the records, the above amount is unreasonable since it is difficult to see that even if the whole performance guarantee belongs to the defendant, it would result in the loss of fairness by unfairly pressure against the plaintiffs, and thus, the plaintiffs

Therefore, the lower judgment did not err by misapprehending the legal doctrine on the estimate of damages, thereby affecting the conclusion of the judgment.

3. All appeals are dismissed. 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.