1. The plaintiff (Counterclaim defendant)'s appeal is dismissed.

2.A. B. A.D. on the counterclaim brought at the trial.

1. Basic facts

A. 1) On July 29, 2011, the Plaintiff entered into a contract for work, E Co., Ltd. (hereinafter “E”).

(2) On August 3, 2011, the Plaintiff entered into a contract with the Defendant to establish all broadcasting systems, including broadcasting equipment, systems, networks, and mileages (storage media) necessary for the operation of E’s general programming channels, and to receive KRW 20.5 billion (value-added tax separate) (value-added tax). (2) On August 3, 2011, the Plaintiff subcontracted the broadcast system and the part of the installation of mileage to the Defendant (including value-added tax) for the payment of KRW 12,108,821,527 (hereinafter “instant contract”).

The contents of the instant contract related to the instant case (the special terms and conditions of additional contract, hereinafter referred to as “the instant special terms and conditions”) are as shown in the attached Form.

3) On October 4, 2011, the Defendant, with the Plaintiff’s approval, demanded technical skills, such as the installation of softage, etc., for the Defendant’s Intervenor C Co., Ltd. (hereinafter “ Intervenor C”).

(4) Defendant C re-subcontracted to the Intervenor D Co., Ltd. (hereinafter referred to as the “ Intervenor D”) for the work of linking the listed mileages established around October 201.

B. 1) With respect to the construction of the instant news accident, the Plaintiff’s employees F have overall control over the construction work, and the Intervenor’s employees G, H, and Intervenor D were in charge of design and construction work. 2) On January 16, 2012, F notified the Defendant and the Intervenor of the work plan to extend the volume of the connection with the news from 102TB (TerB) to 131TB (hereinafter “instant construction work”).

3) In accordance with the above work programme, H performed the work of installing additional 29TB sets on the existing mileage at the E Data Center on January 17, 2012. 4) I was the case where “the work of linking the mileage installed additionally on the existing mileage from January 18, 2012 to 04:00”.