Of the part of the lower judgment against the Plaintiff, 10,505,700 won and its related amount shall be 6% per annum from November 26, 2013 to December 23, 2015.

The grounds of appeal are examined.

1. The lower court acknowledged the following facts in full view of the admitted evidence.

① On May 22, 2013, the Plaintiff received the instant construction contract amounting to KRW 71,500,000 (valueing to KRW 65,00,000, value-added tax KRW 65,500,000) from the Defendant for the construction period from May 7, 2013 to July 30, 2013; and the Plaintiff supplied materials (e.g., reinforcement block and tideland) and supplies and supplies aggregate to the Defendant for the supply of equipment, earth and sand, and aggregate; and when there occurs a cause for a increase or decrease in the construction volume, the Plaintiff settled the instant construction at the time of completion by applying the contractual unit price.

② The supply value of the instant construction contract is KRW 65,00,000, calculated by multiplying the estimated construction quantity by 125,000,000 won (40,000,000 won per 40,000,000,000 per square meter per 1 square kilometer (40,000,000,000 per 1 square kilometer) on the estimated construction quantity by the total contractual unit price per 5,25,00 square meter per 1 square kilometer (525 square meter x 125,00).

③ Since there exists a difference between the actual topography and the design map of the instant construction site, the Plaintiff had an additional construction work in accordance with the actual topographical features. As a result, the volume of reinforced earth block and tideland supplied by the Plaintiff to the Defendant is 905 square meters, respectively, and the actual construction area of the reinforced earth retaining wall constructed by the Plaintiff is 703.3 square meters, and the construction price already paid to the Plaintiff is 50,000,000 won.

In accordance with such factual relations, the lower court determined as follows: (a) the Defendant already paid to the Plaintiff KRW 105,057,00 [the amount calculated as KRW 5,000,000, which deducted KRW 76,925,000 [the unit price of materials per 1 kilometer 45,000,000 (the unit price of KRW 45,000,000 per metres per 1 kilometer)]; (b) the construction cost of KRW 28,132,000 (7.3 square meter x 40,000,000 for one square meter) and the amount calculated as KRW 55,00,005,00 for the remainder after deducting KRW 10,000 for the original copy of the instant payment order; and (c) the existence or scope of the Defendant’s obligation to perform from November 16, 2013, the following day of the service of the original copy of the instant payment order.