A. On June 24, 2015, the Plaintiff entered into a service contract with the Defendant’s Air Force 18 Air Force (hereinafter “instant service contract”) on the condition that the contract amount of the unused septic tank and removed waste disposal service was KRW 196,948,00, and the contract period was until December 10, 2015 from the same date (hereinafter “instant service contract”), and received KRW 137,863,00 as advance payment from the Defendant.

B. According to Article 4 of the Contract Special Conditions attached to the instant service contract, “The contract amount for transportation, disposal, and commercial rent shall be the sum of the amount calculated by multiplying the unit price by the quantity on the specifications of each type of wastes, and shall not be required to increase the unit price for disposal due to price increase after the contract. The cost for waste disposal services shall be determined according to the actual quantity of collection and shall be settled according to the quantity of inspection,” and according to the contract specifications, the unit price is as follows.

The applicable unit price of construction waste per unit (won) ton 1,552 ton of a mixture of construction waste 1,562 ton of a mixture of construction waste 10,101 construction waste transport ton 10,101 construction waste transport 35,782

C. Accordingly, the Plaintiff completed the construction of unused septic tanks removal and waste disposal services, and the total construction cost from which the unit price under the above contract is applied according to the actual quantity collected by the Plaintiff is KRW 176,398,000.

[Ground of recognition] Evidence Nos. 1 through 3, Evidence Nos. 1, 4, and 5, the purport of the whole pleadings

2. Determination

A. According to the above facts finding as to the cause of the claim, the Defendant is obligated to pay to the Plaintiff damages for delay at each rate of 20% per annum under the Civil Act from December 11, 2015 to October 25, 2016, which is the day following the completion date of construction for the remaining 38,526,000 won after deducting 137,863,000 won from the total construction amount of 176,389,000 won from the Plaintiff who was paid as advance payment, and from the next day to the day of full payment, 5% per annum under the Act on Special Cases concerning the Promotion, etc. of Legal Proceedings from the next day to the day of full payment.

B. The defendant's assertion and judgment 1.