A. 1) The Defendant is a company engaged in the business of issuing, selling, and managing credit cards, pre-paid cards, debit cards, and debit cards. 2) The Plaintiffs are those who used or used credit cards, etc. after concluding a contract with the Defendant for the use and financial transaction with the Defendant.

B. The concept of the card accident analysis system and the introduction card accident analysis system (hereinafter “FDS”) are introduced by all domestic credit card companies as a system to detect abnormal transactions or fraudulent use due to the theft, loss, forgery, etc. of credit cards.

According to the above FDS, when it is discovered that a large amount of card use information and customer information were used based on the past accident transaction and that there were abnormal types of transaction according to statistical techniques based on the results, it is possible to take measures such as refusing to grant credit card approval if it is discovered that there was abnormal type of transaction according to an accident pattern analyzed in the course of using credit cards.

C. The Defendant’s disclosure of customer information 1) concluded a contract with A Co., Ltd. (hereinafter “A”) on January 30, 2013, setting the contract amount of KRW 227,419,500, and KRW 7 months from the date of the delivery deadline as the need for the FDS was raised after the introduction of FDS for the first time in around 2008.

B) The development personnel of A, including B, a general manager of the said project, were put into the Defendant from February 2, 2013 to August 2013, 2013, and started FDS development work. ① From February 2013 to March 2013, it is necessary to consult with the Defendant’s credit management division and business requirements, and thus, work at the Defendant’s headquarters located within the jurisdiction of Jongno-gu Seoul Metropolitan Government, and ② from March 2013 to August 2013, 2013, work at the Defendant’s salt-based computer center located within the Gangseo-gu Seoul Metropolitan Government.