1. All of the plaintiffs' claims are dismissed.

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

Basic Facts

The plaintiffs are stock companies engaged in construction business, such as engineering work business, building work business, etc., and the defendant is a mutual cooperative organization between constructors established pursuant to Article 54 of the Framework Act on the Construction Industry. Pursuant to Article 56 (1) of the same Act, members are corporations engaged in various kinds of guarantees, such as bid guarantees, contract guarantees, advance payment guarantees, and fund loans, etc. necessary for them

On December 31, 2013, the Plaintiffs entered into a contract for construction works between the Plaintiffs and the Daejeon Local Government Procurement Service (hereinafter referred to as the “instant contract for construction works”) with respect to the construction of E office buildings located within the Daejeon Local Government Procurement Service and Sejong Special Self-Governing City (hereinafter referred to as the “instant construction works”), the contract for construction works (hereinafter referred to as the “instant contract for construction works”) as stipulated in the ordering office E, contract amount, KRW 8,171,932,90 (including value-added tax) and the construction period from January 7, 2014 to June 30, 2015.

In the construction contract of this case, the ratio of joint supply and demand of the plaintiffs is 52% by the plaintiff A Co., Ltd. (hereinafter referred to as "Co., Ltd." in the plaintiffs' names), 10% by the plaintiff D, 12% by the plaintiff C, and 26% by the plaintiff B.

On March 25, 2014, the Plaintiffs entered into a subcontract agreement for reinforced concrete construction works between the Plaintiffs and volcanic construction (hereinafter referred to as “culic construction”) with regard to the contract price of KRW 1,376,100,000 (including value-added tax, advance payment of KRW 148,76,009) for the instant subcontracted construction works (hereinafter referred to as “instant subcontracted construction”) and the subcontract agreement between March 25, 2014 and October 15, 2014 (hereinafter referred to as “instant subcontract agreement”).

Of the instant subcontract agreements, the parts related to the instant case are as follows.

Article 1 (Basic Principles) (1) The prime contractor A, D, C, B (hereinafter referred to as "A") and the subcontractor's volcanic construction (hereinafter referred to as "B") shall cooperate on an equal footing and faithfully in good faith.