1. The plaintiffs' appeal is dismissed.

2. The costs of appeal are assessed against the Plaintiffs.

Purport of claim and appeal

The first instance court.

1. The reasons for the court's explanation concerning this case are as stated in the reasoning of the judgment of the first instance, except that the court's explanation is as stated in the main sentence of Article 420 of the Civil Procedure Act, since it is the same as stated in the reasoning of the judgment of the first instance, with the exception that "No. 29, 2015" in Part 5 from the third page of the judgment of the first instance to "No. 29, 2014" and "No. 10, Mar. 14, 2016" until March 14, 2016.

2. Thus, the plaintiffs' claims against the defendant based on the letter of confirmation prepared on August 11, 2014 between the plaintiffs and the defendant shall not exceed the amount calculated by the agreement of 375,757,904 won and the rate of 24% per annum from March 18, 2016 to the date of full payment. Thus, the plaintiffs' claims shall be accepted within the scope of the above recognition as reasonable, and the remainder shall be dismissed as it is without merit. Since the judgment of the court of first instance is justified, it shall be dismissed as it is so decided as per Disposition.