1. The plaintiff's appeal and the defendant's incidental appeal are all dismissed.

2. Costs arising from an appeal and an incidental appeal shall be respectively.

1. The reasoning of this Court’s judgment cited in the judgment of the first instance is as follows, and such reasoning is the same as that of the judgment of the first instance, and thus, is acceptable in accordance with the main sentence of Article 420 of the Civil Procedure Act.

2. The part of the appellate court's decision No. 5 of the first instance court's decision as to the primary claim is as follows.

2. Judgment as to the main claim

A. The Plaintiff’s assertion 1) (1) where a user uses an authorized certificate for account transfer pursuant to Article 7(2) of the Basic Terms and Conditions, the designated device or additional security measures should be used. The Defendant did not take such additional security measures at the time of termination. The termination of the instant case does not follow the prior agreement between the addressee and the originator (Article 7(2)1 of the Framework Act on Electronic Documents and Transactions) in order to verify whether the electronic document was of the originator, and it is difficult to deem that the received electronic document was sent by a person with justifiable grounds to believe that it was based on the originator’s will (Article 7(2)2 of the same Act) and (2) even if the termination of the instant case was sent by a person with justifiable grounds to believe that the termination was based on the Plaintiff’s intent, the Defendant did not constitute an act of the originator under Article 21(1) and (2) of the Electronic Financial Transactions Act and Article 2-4, and Article 2-5 of the Telecommunications Fraud Refund Act.

Therefore, the expression of intent contained in the electronic document for the cancellation of the instant case can be seen as the Plaintiff.