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, from the Defendant, performed construction project management services under a contract with the Defendant, including vicarious performance of supervisory authority on construction phase for apartment construction works (hereinafter “the instant apartment construction works,” and “the instant construction works”), (i) the construction project management services, including joint construction phase supervision authority, (ii) the construction project management services were outsourced (the service period from February 2, 2015 to September 1, 2018; (iii) Plaintiff A51% Co., Ltd.; and (iv) Plaintiff B49% Co., Ltd.; hereinafter “stock company”). (iv) 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 (i) the apartment construction works conducted by the Defendant, etc. 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) In addition, as a result of the inspection conducted after the Board of Audit and Inspection confirmed whether buffer materials brought into the site for 99 sites meet the quality standards, it started the construction before the issuance of this buffer material quality inspection report (58%) at the 57 construction sites including the instant construction site. In particular, 42 out of the Defendant 55 sites are buffer materials.