A. 1) The Defendant subcontracted 54,000,000 reinforced concrete construction among the construction of detached houses located in Gwangju-dong-gu, Gwangju-gu, which was ordered by D around October 2014 by the Plaintiff and completed the construction work. Meanwhile, in the process of the construction work, the Defendant further subcontracted 4,400,000 retaining wall construction from the Plaintiff and completed the construction work (hereinafter referred to as the “instant construction”).

(2) The Defendant received KRW 50,000,000 from the Plaintiff as the construction price of this case.

B. Around 2015, the Defendant filed a lawsuit against the Plaintiff seeking payment of the unpaid construction cost of KRW 13,418,600 with the Gwangju District Court Decision 2015Da64697 (hereinafter “prior lawsuit”) (hereinafter “prior lawsuit”).

(2) On February 25, 2016, the Defendant received a seizure and collection order against the Plaintiff’s deposit claim as the title of execution on the following grounds: (i) around March 14, 2016: (ii) around February 25, 2016, the Defendant collected KRW 6,796,222.

3) On March 2016, the Plaintiff filed an appeal for the subsequent suit with the Gwangju District Court 2016Na1973 as to the prior suit, and the said court rendered a judgment dismissing the Defendant’s claim on November 25, 2016, and the said judgment became final and conclusive. [The grounds for recognition] Nos. 1 and 2 evidence (if a number is available, the number is included) and the purport of the entire pleadings.

2. Determination as to the cause of action

A. The Plaintiff’s assertion 1) Inasmuch as the judgment dismissing the Defendant’s claim was final and conclusive in a prior suit, the Defendant’s KRW 6,796,222, which was collected from the Plaintiff in accordance with the prior suit, must be returned to the Plaintiff in unjust enrichment. 2) In the instant construction work executed by the Defendant, there is a defect equivalent to KRW 51,337,00 in total, including KRW 39,666,00 in relation to the omission of reinforcement steel bars, and KRW 11,671,00 in the construction of the multilateral hub.