1. The defendant's appeal is all dismissed.

2. Of the appeal costs, the part arising between the plaintiffs and the defendant is the defendant.

1. In the first instance trial, the Plaintiffs unilaterally rescinded the contract for the construction of the heat facilities using the heat pumps among D works, the Plaintiffs filed a claim for damages pursuant to Article 673 of the Civil Act; ② Preliminaryly, the claim for payment, such as the cost of utility, pursuant to Article 7 Section 4 of the General Conditions for Goods Contracts incorporated into the said contract. The first instance court dismissed all of the primary claims and partly accepted the conjunctive claim (the partial dismissal of the damages for delay).

Since only the defendant appealed against this issue, the subject of this Court's trial is limited to the above preliminary claim.

2. Facts of recognition;

A. The Plaintiffs entered into a contract between the Plaintiffs and the Defendant (i) constituted a joint supply and demand organization (9% of the shares of Plaintiff A Co., Ltd., and 1% of the shares of Plaintiff B Co., Ltd.) around August 2013, and the Public Procurement Service under the Defendant’s control constitutes the joint supply and demand organization (hereinafter “the supplementary intervenor”).

(2) On September 27, 2013, a contract was concluded between the Plaintiffs and the Defendant on the content that the Plaintiff would perform the installation work of the heat equipment using the heat pumps during D construction (hereinafter “instant contract”).

3) The contract prepared at the time of the instant contract and the general terms and conditions of the goods contract incorporated into the content of the instant contract (hereinafter “general terms and conditions of the goods contract”) are attached thereto.

The main contents of this case are as follows: The name of contract contracting officer of the Gangseo-gu Local Government Procurement Service: C: The term of delivery of KRW 327,721,00: the period of delivery of KRW 327,721,00: May 20, 2015: The Gangwon-do Jeong-gun (the supplementary intervenor inspection agency and the tallying agency: the method of payment of the procuring agency: the delay of performing the contract and the cancellation and termination of the contract.