A. On November 1, 2017, the Defendant received a subcontract for the manufacture and installation works of burning gas treatment facilities from C Co., Ltd. among “Building Works for Resource Circulation Facilities” of D Co., Ltd., Ltd., Ltd., “Regrified Resources Circulation Facilities”

On December 29, 2017, the Plaintiff received re-subcontracts from the Defendant for the construction work (hereinafter referred to as the “construction work in this case”) manufacturing and installing 374,00,000 won in price for an estimated quantity of 170 tons of burning gas treatment facilities (in steel structure) during the construction work (hereinafter referred to as “value-added tax separate”).

(hereinafter referred to as the “instant contract”). B.

In the special terms and conditions of the instant contract, “The volume exceeding 170 tons of the drawing volume standard ((.) - 3% shall be settled through mutual consultation,” and “the difference in the material cost shall be settled only in the case of production with the TS304 material.”

C. During the construction, the volume of the instant construction project increased from 170 tons to 18.788 tons, and the Plaintiff decided not to manufacture the virtue 15.94 tons, which was originally included in the expected volume, under the agreement with the Defendant.

The plaintiff also made some of the materials as STS304 materials, and there was a reason to settle the difference between the material cost.

The Plaintiff completed the instant construction and completed the trial run by June 2018.

Until now, the Defendant paid the Plaintiff KRW 291,080,000 (including value-added tax) as the construction cost.

[Evidence: Evidence No. 1, 2, 3, 4, 5, 6 (including paper numbers), evidence No. 1, and all purport of oral argument]

2. Assertion and determination

A. The Plaintiff’s claim content source, the Defendant, by appropriating 170 tons per ton as 2.2 million won per ton, set the construction cost as 374,00,000 won (excluding value-added tax). The volume increased by 18.78 tons per ton. As such, 41,33,600 won (excluding value-added tax) increased by 2.2 million won per ton, and 41,70,705,680 won for STS304 material cost (excluding value-added tax), and 612,790 won for STS316L material cost (excluding value-added tax), in total, 70,652,070 won (excluding value-added tax). The addition is agreed.