1. All of the plaintiff's claims are dismissed.

2. The costs of lawsuit shall be borne by the Plaintiff.

1. Basic facts

A. On October 2015, the Plaintiff entered into a contract with the Defendants for the production and delivery of windows (hereinafter “instant windows”) at the construction site of Pyeongtaek-si D (hereinafter “instant supply contract”) by determining the amount of supplied goods as KRW 12,000,000 (the contract amount of KRW 2,000,000, the remainder of KRW 10,000).

B. Since then, as the window size of this case was changed from 16T page to 23T, and the door was added, 720,000 won was increased for the supply price of this case.

(420,000 additional fire doors, 300,000 won of additional fire doors).

On October 31, 2015, the Plaintiff paid the Defendants KRW 1,940,00 as down payment, and on November 10, 2015, the Plaintiff paid KRW 10,300,000 in total under the pretext of the remainder and the fire doors (=the remainder amount of KRW 10,000,000 in the door door door price of KRW 300,000).

[Ground of Recognition] Facts without dispute between the parties, Gap evidence 1 to 4, Eul evidence 1 to 4 (including each number), the purport of the whole pleadings

2. The gist of the parties’ assertion argues that the Defendants refused to supply the window of this case even if all of the supply prices of this case were paid, and thus, the Defendants asserted to the effect that the supply contract of this case should be revoked or cancelled on the grounds of the Defendants’ nonperformance of obligations, and sought payment of damages for the total amount of KRW 33,325,00 (the total amount of KRW 18,450,000 for construction cost and damages for delay) and damages for delay.

On the other hand, the defendants completed all supply of the windows of this case while during night work. The plaintiff asserts that the plaintiff did not pay 480,000 won out of the supply price of this case and did not supply the windows of this case.

3. The duty to pay the price of delivered goods of this case and the duty to supply the window of this case are simultaneously performed with each other, and the defendants are liable for delay of performance until the plaintiff provides performance with respect to the price of delivered goods of this case.