The plaintiff's claim is dismissed.

Litigation costs shall be borne by the plaintiff.

Around January 2014, the Plaintiff completed the construction of a new apartment house in Gangdong-gu Seoul Metropolitan Government by being awarded a contract with the Defendant for the construction cost of KRW 510 million, and thereafter, the said additional construction was completed by being awarded a contract with the Defendant for the construction cost of KRW 4.35 million, and the said additional construction was paid only KRW 477 million out of the construction cost, and the fact that the Plaintiff agreed to reduce the construction cost of KRW 1.7 million out of the construction cost is not disputed between the parties.

Therefore, the Defendant is obligated to pay to the Plaintiff the remainder of the construction cost of KRW 3,565 million (=total construction cost of KRW 51,4350,000 - KRW 477,000 already received - the reduced construction cost of KRW 1.7 million) and damages for delay.

As to the defendant's defense, the defendant's defense is proved to have fully repaid the payment of the unpaid construction cost, the defendant can be acknowledged to have paid the above payment of the construction cost to the plaintiff on January 26, 2016. Thus, since the above payment of the construction cost to the plaintiff on January 26, 2016 is all extinguished due to the defendant's repayment, the above defense is with merit.

Thus, the plaintiff's claim is dismissed as it is without merit.