1. The plaintiffs' appeal and the conjunctive claims added by this court are all dismissed.

2. Appeal;

1. The plaintiffs within the scope of the judgment of this court in the first instance trial related to the construction contract in the method of a long-term long-term contract for the construction project with the defendant on February 23, 2007, which was entered into between the defendant and the defendant on February 23, 2007. ① Additional cost claim due to the extension of the construction period (in the first instance, pursuant to Articles 23 and 26 of the General Conditions of the Construction Contract, there is a gap between the six and ten contracts, indirect cost of 16,124,870,000, and indirect cost of 7 through 10th 10th 10,000, which occurred during the contract period

(2) Pursuant to Article 19 of the Enforcement Decree of the Construction Contract Act and Article 66 of the Enforcement Decree of the same Act and Article 23(1) of the General Conditions of the Construction Contract, indirect costs of KRW 3,330,552,00 incurred during the period of the ten primary construction period and the ten primary construction period (the initial construction period and the second extension period), and indirect costs of KRW 6,048,41,00 incurred during the respective blank periods between the six primary and the ten primary construction periods due to administrative management or unjust enrichment, whichever was partly KRW 7,359,00,00 out of the total amount of KRW 6,048,41,00), ② Claim for the increase of the contract amount due to the extension of the working design service period (797,293,000), ③ Claim for the increased construction cost (179,383,084,000), ④ Claim for the reduction of the construction cost (the remainder of KRW 692,6816,1667).3

Accordingly, among the part against the judgment of the court of first instance, the part concerning the claim for indirect costs incurred during the initial construction period (470,89,000 won) and the part concerning the claim for construction cost reduced by the defendant for the management convenience facilities (692,806,619 won). Meanwhile, with respect to the above part concerning the claim for indirect costs, the plaintiffs appealed in this court.