1. The defendant's appeal is dismissed.

2. Of the appeal costs, the part arising between the Plaintiff and the Defendant is the Defendant.

1. Basic facts

A. 1) The Plaintiff is a school juristic person established with the purpose of conducting higher education specialized in foreign languages, including establishing and operating E University. 2) The Defendant is a company engaged in guarantee insurance, credit insurance, reinsurance, other businesses permitted under the Insurance Business Act and insurance-related Acts and subordinate statutes.

3) Defendant J (Co., Ltd. before the alteration, hereinafter “Defendant Intervenor C”)

4) The Intervenor D Co., Ltd. (hereinafter referred to as the “Supplementary Intervenor D”) is a company engaged in building work, housing construction work, and civil engineering work, etc.

B. On August 17, 2016, the Plaintiff entered into a contract for extension works and remodelling works of the E University, which the Plaintiff manages with the Intervenor joining the Defendant, for the purpose of extension works of the E University and remodelling of the existing teachers (hereinafter “instant construction contract”).

(2) The provisions pertaining to this case in the contract are as follows.

Standard contract for private construction works

1. Construction name: Works to extend E University and remodel existing teachers;

3. Date of commencement: August 22, 2016: Date scheduled for completion: August 30, 2017 (Extension of Construction Works): December 15, 2017 (Construction of Existing Teachers);

5. Contract amount: Value-added tax amount of KRW 6,650,000 (including additional tax): 6,650,000 (including additional construction cost of remodelling for an existing teacher): Amount-added tax amount of KRW 574,000 (including additional construction cost of remodelling for an existing teacher): 2,111,034,747): 665,00,000;

6. Contract bond: 10% of the contract amount (payment according to the ratio of responsibility for construction works, respectively);

7. Advance payment: 10% of the contract amount (in case of issuance of securities for performance guarantee of advance payment according to the ratio of responsibility for construction works, respectively), (in case of cash payment within five days from the date of request).

8. Endd portion: once a month (as of the end of each month, cash payment before and after the end of each month) 14. Other matters 14. The ratio of construction responsibility between the Intervenor C and the Intervenor D shall be 70:0.