1. The Defendant (Counterclaim Plaintiff) shall pay to the Plaintiff (Counterclaim Defendant) KRW 52,430,300 as well as the full payment from July 14, 2017.

The principal lawsuit and counterclaim shall be judged together.

1. Basic facts

A. C Co., Ltd. entered into a contract for construction works with the Incheon Metropolitan City Free Economic Zone Authority, and the Defendant was awarded a subcontract for the instant construction works and appurtenant works from C Co., Ltd.

B. On April 11, 2016, the Plaintiff and the Defendant refer to the construction method of piling up at the sea site of PCHOUSE among the above ancillary construction works.

On April 11, 2016, and October 30, 2016, the date of completion of construction works (hereinafter “instant construction works”) entered into a contract of KRW 1,092,00,000 for manufacturing and installation works (hereinafter “instant construction contract”).

C. The Plaintiff filed the instant lawsuit with the Plaintiff by asserting that the instant construction was implemented in accordance with the instant construction contract, and that the amount of additional costs, other than the said contract amount, was incurred.

[Ground of recognition] A without dispute, entry of evidence No. 1, purport of the whole pleadings

2. Determination as to the claim on the principal lawsuit

A. 1) Claim for additional construction cost in order to change the contents of the general legal doctrine and pay additional construction cost, there was an additional construction work that had not been the original contract in the completed construction work, and it should be presumed that there was an agreement between the contractor and the contractor (see, e.g., Supreme Court Decisions 2005Da63870, Apr. 27, 2006; 2007Da156, Nov. 30, 2007). In principle, in order to recognize the contractor’s claim for additional construction cost, there should be a separate agreement between the contractor and the contractor on the implementation of the additional construction work and the payment of additional construction cost, and the burden of proof on this case is the Plaintiff. 2) In light of the above legal principle, the Plaintiff asserted that the Defendant is liable to pay additional construction cost to the Plaintiff, as stated below, but the Defendant is obligated to pay the additional construction cost to the Plaintiff.