1. The Defendant (Counterclaim Plaintiff) paid KRW 10,000,000 to the Plaintiff (Counterclaim Defendant) and its payment from May 2, 2017 to the date of full payment.

1. Fact-finding;

A. On February 18, 2015, the Plaintiff (representative C) sent to the Defendant (representative D) an e-mail with the following contents as to the production and supply of the exhaustter restoration device (a device restoring the performance of a multi-person type of ship).

(1) The timing for sending an estimate for the production of the RS2-30A (hereinafter referred to as "Type 1 product") 100 and RS2-600A (hereinafter referred to as "Class 2 product") 50 and modeling expenses. (2) The production plan: the production plan: the production of Class 1 product in March, the production of Class 2 product in May, and the production of Class 2 product in May.

B. On February 25, 2015, the Defendant: (a) written a written estimate stating “The supply price of KRW 1,517,475 won in KRW 75,873,750 of the supply price of KRW 75,873,750 of the new modeling cost; and KRW 20,750,000 of the new modeling cost (excluding value-added tax); and (b) written the Plaintiff on February 25, 2015, the modeling cost is required to confirm the circuit in advance if the volume is sound; and (c) the modeling cost is required to confirm the circuit in the remarks column. If there is no problem after the Dongjak test, it will be said that the order will proceed later.”

Accordingly, on February 28, 2015, the Plaintiff sent a reply that “for the 100 portion as confirmed again, it confirmed the ordering and the modeling of a new product during the second week of March, and (after consultation about additional costs incurred, the additional payment plan will be completed) the modeling of a new product has been completed, and after the confirmation of performance inspection, the Plaintiff sent a reply that “after consultation about the 50 portion, as confirmed again, the order will be ordered immediately.”

C. After that, around June 2015, the Plaintiff, along with the payment of KRW 20 million to the Defendant of the “ Modeling” cost of Type 2 product, remitted the total of KRW 6 million on September 1, 2015, and KRW 10 million on September 2, 2015, and KRW 4 million on September 2, 2015. The Defendant manufactured the prototype of Type 2 product (hereinafter “the instant prototype”) and delivered it to the Plaintiff on July 2015, but thereafter, the order for Type 2 product was issued.