A. (1) On June 27, 2012, the Plaintiff concluded a contract and a subcontract (1) with the construction period fixed at KRW 5,954,00,000 from June 27, 2012 to February 26, 2014 (hereinafter “instant contract”). The Plaintiff received a contract (hereinafter “instant contract”) by setting the construction period as the contract amount of KRW 5,954,000 from June 27, 2012 to February 26, 2014.

(2) After that, on November 30, 2012, the Plaintiff awarded a contract to the Defendant for the construction of reinforced concrete (hereinafter “instant construction”) as KRW 2,192,30,000 (including value-added tax) during the construction period from November 30, 2012 to October 31, 2013.

(hereinafter “instant subcontract”). (b)

(1) On March 25, 2013, the Defendant sent to the Plaintiff a public notice stating that “The instant construction project requires the increase of the contract amount (250,000,000 won) as the conditions of the site were different from the expected items at the time of the initial estimate,” and that “the Plaintiff shall demand the waiver of the contract if the increase is not possible.”

(2) On March 26, 2013, the following day, the Plaintiff and the Defendant agreed to increase the contract amount (hereinafter “instant increase agreement”). The Defendant drafted to the Plaintiff a letter stating that “In addition to KRW 250,000,000, the Defendant agreed to increase the contract amount at the Defendant’s request during the instant construction, the Plaintiff shall not claim any additional amount under any pretext, and that no civil or criminal objection shall be brought to the Plaintiff (hereinafter “instant letter”).

(3) On July 30, 2013, the Plaintiff is an amendment contract under which the contract amount of the instant construction project is changed from KRW 2,192,30,00 to KRW 2,467,30,000 (including value added tax, increased to KRW 275,00,000), reflecting the foregoing agreement with the Defendant (hereinafter “instant amendment contract”).