1. The plaintiff's appeal and the claims extended by this court are all dismissed.

2. Demanding and expanding the costs of appeal.

1. Basic facts

A. On April 16, 2008, the Defendant received a contract from the Republic of Korea for construction works among C Construction Works (hereinafter “instant original works”) by setting the contract amount of KRW 157,428,526,00, and the construction period from April 21, 2008 to May 30, 2012 (hereinafter “instant contract”).

Since then, the construction period of the instant contract was finally extended by October 31, 2014 through several amendments agreements.

B. On November 24, 2008, the Plaintiff received subcontracting from the Defendant during the instant prime contractor (hereinafter “instant prime contractor”) by setting the contract amount of KRW 671,00,000,00 and the construction period from November 24, 2008 to May 30, 2012 (hereinafter “instant first subcontract”).

Since then, the first subcontract of this case was finally completed through several changes contracts, and the construction period was changed to KRW 585,43,200 until February 28, 2015, and the contract amount was changed to KRW 585,43,200.

C. On April 18, 2013, the Plaintiff received a subcontract from the Defendant during the instant prime construction (hereinafter “instant second subcontract”) by setting the contract amount of KRW 1,562,00,000, and the construction period from April 18, 2013 to October 31, 2014 (hereinafter “instant second subcontract”).

Since then, the 2nd subcontract was finally completed through a multiple changes contract, and the construction period was changed to 2,470,602,200 won by July 31, 2016, and the contract amount was changed to 2,470,602,200 won.

The Defendant filed a lawsuit against the Republic of Korea seeking payment of the indirect construction cost incurred due to the extension of the construction period of the instant contract (hereinafter “related lawsuit”) by Seoul Central District Court Decision 2014Gahap546143, and received a judgment in favor of the Republic of Korea on December 16, 2015, and the said judgment became final and conclusive around that time.

In the judgment of related lawsuit, the indirect construction cost that the plaintiff should pay to the defendant is additionally paid by the extension of the construction period of the first construction project of this case.