1. All of the plaintiffs' claims are dismissed.

2. The costs of lawsuit are assessed against the plaintiffs.

1. Basic facts

A. On March 13, 2017, Plaintiff A and the Defendant entered into a contract on March 10, 2017 with respect to the construction of a newly built multi-household E (hereinafter referred to as “instant one”) in Yongsan-gu, Yongsan-gu, Yongsan-gu, Seoul (hereinafter referred to as “instant one”) with the content of KRW 528,50,000 of the contract amount on August 30, 2017 as of August 30, 2017 (excluding value-added tax) and KRW 3/1,000 of the liquidated completion date, and on May 8, 2017, the remainder was the same as the date of commencement, and the date of completion was revised as of September 30, 2017 (hereinafter referred to as “instant one contract”).

Plaintiff

On September 27, 2017, A and the Defendant entered into a contract by changing the completion date of the instant one contract to December 31, 2017. On December 28, 2017, the contract was concluded by changing the completion date of the instant one contract to March 31, 2018, and each of the provisions of the original contract which did not enter into an amendment agreement is still effective.

B. On March 13, 2017, Plaintiff B and the Defendant entered into a contract on March 10, 2017, with respect to the construction of a newly built multi-household housing (hereinafter “instant two contracts”) with the E-type housing (hereinafter “instant two contracts”) on the date of commencement; August 30, 2017, the date of completion scheduled; and KRW 1,176,000,000 of the contract amount on August 30, 2017; and KRW 3/1,000 of the liquidated damages for delay (hereinafter “instant two contracts”).

Plaintiff

B and the Defendant entered into a contract on August 16, 2017 by changing the completion date of the instant two contracts to November 15, 2017. On November 13, 2017, the two contracts entered into a contract by changing the completion date of the instant two contracts to March 31, 2018, and each of the provisions of the original contract which did not enter into an amendment agreement remains effective.

C. The terms and conditions of the standard contract for private construction works of each of the instant contracts are as follows.

Article 1 (General Provisions) A contractor (hereinafter referred to as "A") and contractor (hereinafter referred to as "B") shall cooperate with each other on an equal footing.