1. Of the judgment of the court of first instance, the part against the Plaintiff, which ordered additional payment as follows.

1. Basic facts

A. 1) Defendant B entered into a contract with the Plaintiff to manufacture and supply a large-scale trade classification machine (a facility that automatically classifys mail for each page after verifying information, such as the postal number, etc. of mail) used by the post office, and which was concluded between the Plaintiff and the Plaintiff on September 5, 2012 and January 24, 2013, one of the large-scale trade classification machines under the contract concluded between the Plaintiff and the Plaintiff (hereinafter “instant No. 1”).

(2) Defendant B, other than the instant one, installed in the C mail concentration office and completed the trial operation on May 31, 2016. (2) In addition, Defendant B opened the C mail concentration office on December 1, 2014 and September 17, 2015 pursuant to the contract (a total of contract amounts of KRW 2.45 billion) concluded on December 27, 2016, with two large-scale trade classification units (hereinafter “instant units”). In addition, Defendant B opened the trial operation on January 2, 2017.

3) Under the goods contract between the Plaintiff and the Defendant B, the Defendant B bears the obligation to guarantee the performance of each of the instant facilities until the passing of the trial operation of each of the instant facilities, and submits to the Plaintiff a security or a letter of guarantee, etc. the performance bond for the trial operation performance within the scope of 15% of the contract amount to guarantee the performance (Article 6 of the additional special condition under the condition of the trial operation condition). The obligation to repair the defects within the warranty period of two years from the date of completion of the trial operation of each of the instant facilities, and the obligation to pay the warranty bond equivalent to 5/100 of the contract amount as a guarantee, etc. to guarantee the defect repair (Articles 18 and 19 of the condition of the goods purchase contract)

Defendant B, which entered into a guarantee insurance contract between the Defendants, shall compensate the Plaintiff’s damage caused by the Defendant B’s nonperformance of the performance guarantee obligation as part of paying the performance guarantee and the performance warranty bond for the instant period of No. 2.