1. As to the Plaintiff (Counterclaim Defendant) KRW 10,724,03, and KRW 9,581,121, among them, the Defendant (Counterclaim Defendant)’s KRW 10,724,03 and the Plaintiff’s KRW 9,581,121.

1. Facts of recognition;

A. On September 9, 2009, the Plaintiff and the Defendant entered into a contract for construction works (hereinafter “instant contract”) with the Defendant on the condition that the Plaintiff entered into a contract for construction works among the construction works for building sites for D ground factories (hereinafter “instant construction works”) with the contract amount of KRW 380,970,700 (including value-added tax) and the construction period from September 10, 2009 to October 31, 2009 (hereinafter “instant contract”).

B. The Defendant completed the instant construction work in accordance with the instant contract, and the Plaintiff paid KRW 47,558,720 to the Defendant the remainder of the construction cost on June 15, 2017, thereby paying the entire construction cost.

C. Although the instant construction project included a stacking construction project to prevent the occurrence of a cross-section between the site for new construction of a factory and the adjacent land (hereinafter “instant stacking construction”), the Defendant did not undertake the instant stacking construction project, and the amount equivalent to the construction cost of the instant stacking construction project out of the contract amount under the instant contract is KRW 7,876,121 (including value-added tax).

【Ground of recognition】 The fact that there has been no dispute, Gap's evidence Nos. 1, 2, 5, 8 (including branch numbers, if any; hereinafter the same shall apply), Eul's evidence Nos. 1, 3 through 7, and the purport of the whole pleadings

2. Determination on the main claim

A. According to the above facts, the Defendant is obligated to pay the Plaintiff KRW 7,876,121, which is the amount equivalent to the construction cost of the instant installation due to the performance of the obligation to return unjust enrichment.

B. The Plaintiff’s claim for return of unjust enrichment equivalent to the cost of materials, such as fume, etc., was placed on the site of the instant construction site. At the time of the instant construction contract, the Plaintiff and the Defendant, while performing the instant construction project, excluded the Plaintiff’s use of the materials owned by the Plaintiff from the construction cost.