1. The Defendant: 7,738,568,147 won to the Plaintiffs and 6% per annum from April 25, 2014 to June 1, 2016.

1. Basic facts

A. 1) The Defendant is a commissioned-execution-type quasi-governmental institution under Article 5(3)2 (b) of the Act on the Management of Public Institutions; and on October 12, 2004, the term “C Construction Project” with the total length of 11.304 km between Section 4 Section D Station and E Station among the “C Construction Project” as of October 12, 2004 (hereinafter “instant Construction Project”).

2) As to the construction cost (including value-added tax), the construction cost (including the amount of design) was set at KRW 290,800,000 (including value-added tax) and the construction period was set at 40 months from the date of commencement and publicly announced. 2) The Plaintiffs constituted joint supply and demand companies (representative:

(hereinafter referred to as “A” and “B” respectively. The ratio of its investment is 90%, Plaintiff B 10%, and Plaintiff B 10%.

3) On December 28, 2004, the Plaintiffs were joint contractors organized as above, and the Defendant entered into a contract for the instant construction project with respect to the instant construction project (hereinafter “instant construction contract”).

(4) The construction contract of this case was concluded. The plaintiffs performed the construction work of this case in 152,670,000,000 won for a total of 40 months from December 28, 2004 to April 27, 2008. The main contents of the general conditions (hereinafter "general conditions of this case") are as follows.

1. Terms and conditions of the construction contract shall be entered;

B. The instant construction contract and the instant construction contract are modified several times, but the instant construction contract were modified on December 10, 209. On September 25, 2013, the method of the instant construction contract was modified into a contract for continuing expenditure from a long-term continuing expenditure. On December 31, 2013, the final amendment was made until December 31, 2013, and the specific details of the amendment were as follows.

2. The details of the amendment to the instant construction contract are as indicated;

Each of the following contracts is specified as “the multiple-level contract”, and the individual modified contract is specified as “the next modified contract by the number of teas”, and the modified contract as the continuing expenditure contract is changed as “the instant continuing expenditure contract” and “the instant modified contract.”