On a single deposit-plus deposit interaction structure, asset utilization, interest payment, and asset return all proceed safely with automated smart contracts. In addition, KLAYswap manages a separate Safety Fund related to a single deposit on its own in order to safely manage the assets and profits of a single pool depositor. The Safety Fund functions as a rainy day fund that accumulates fees collected from plus depositors who exceed certain safety standards, and in the event of contingencies in which a single pool asset utilized by Plus Deposit cannot be returned, the Safety Fund will be used to cover the shortage instead. As a result, a single depositor can safely enjoy opportunities to generate profits by minimizing the asset loss risk.