1. All of the plaintiffs' claims are dismissed.

2. The costs of lawsuit are assessed against the plaintiffs.

1. Details of disposition;

A. The Plaintiffs are construction technology service providers providing comprehensive supervision services.

2) The Plaintiffs were awarded a contract with the Defendant for construction management services, including vicarious performance of supervisory authority on construction phase for C Apartment Construction (hereinafter “the instant apartment construction,” and “the instant construction”). (b) The Board of Audit and Inspection conducted an audit on the operation of the noise reduction system between floors of the Plaintiff Co., Ltd. (1) from November 14, 2016 to July 20, 2019; 66.1% of the Plaintiff Co., Ltd.; 33.9% of the Plaintiff Co., Ltd.). (1) The Board of Audit and Inspection conducted an audit on the operation of the noise reduction system between floors of the Board of Audit and Inspection from September 3, 2018 to January 18, 2019.

2) The result of the Board of Audit and Inspection’s measurement of noise between floors for the total 191 households of apartment units scheduled to move in at the completion stage showed that the 184 generation was lower than the actual performance grade which was approved in advance, and that the 114 generation among them was below the minimum performance standard.

3) As a result of the inspection conducted by the Board of Audit and Inspection of the noise-preventive performance of the sample generation prior to the execution on the 89 site where the sample generation was located in the 115 construction sites conducted by the Defendant, it was confirmed that the noise performance was measured after the 31 construction sites including the instant construction sites, which did not measure the performance of the sample generation noise or 2 to 382 days after the commencement of the construction works.

4) As a result of examining the appropriateness of quality of buffer materials from among the production companies that supplied buffer materials to the third-tier three companies in the order of construction among the production companies that supplied buffer materials to the Defendant 42 sites, Article 33 of the criteria for recognition and management of the structure blocking the impact of the floor soundproof of apartment houses (amended by Presidential Decree No. 2019-622, Nov. 8, 2019; hereinafter “instant notification”).