A. On May 21, 2015, the Defendant was awarded a contract to C for the construction of the F building (including additional taxes) on the land of Kimhae-si D and E (hereinafter “instant new construction”) for the construction cost of KRW 16 billion in the construction cost, and around that time, the Defendant performed the said construction by setting the site manager G.

B. On July 28, 2015, the Defendant issued a subcontract (hereinafter referred to as the “instant subcontract”) to the Plaintiff on July 28, 2015, setting the period from July 28, 2015 to July 31, 2016 of the construction cost of the electric utility, telecommunications, fire-fighting, and facility works (hereinafter referred to as “instant electric light facility works”) as KRW 2.53 billion (including surtax) and the construction period from July 28, 2015 to July 31, 2016.

C. On July 31, 2016, the Defendant entered into an agreement with the Plaintiff on the change of construction contract between July 31, 2016 and October 31, 2016, under which the expiration date of the construction period was changed from July 31, 2016 to October 31, 2016.

From July 2016 to August 2016, the Plaintiff completed the installation of excellent pipes, the installation of excellent pipes, the installation of excellent pipes, and the installation of drainage pumps pipes (hereinafter referred to as “instant excellent pipes installation”) during the instant new construction works, and completed the instant electric facilities around October 2016.

E. As between June 15, 2016 and December 15, 2016, the Defendant paid the Plaintiff the construction cost of KRW 2.53 billion of the instant subcontract, but did not pay the construction cost for the instant outstanding pipelines installation works.

[Reasons for Recognition] Unsatisfy Facts, Gap evidence Nos. 1, 2, and 3 (including virtual numbers), the court's entrustment of appraisal to appraiser H, the purport of the whole pleadings

2. Determination as to the cause of action

A. On or around July 2016, the Plaintiff asserted that the Plaintiff should pay KRW 67,793,352 to the Plaintiff since he/she received a subcontract for the instant excellent pipelines installation works from G, a director at the site of the instant new construction works, and completed the said construction works around August 2016.