If one of the parties does not perform his obligation, the other party may fix a reasonable period and give peremptory notice demanding its performance, and may rescind the contract, if no performance is effected within such period; provided, if the obligor declares in advance his or her intention that he will not effect such performance, no peremptory notice shall be required.
Civil Act — Article 544 (Delay of performance and rescission)
민법 제544조