A method for manufacturing a bag for use in vacuum packaging comprises forming a first panel having a receiving feature and a second panel having an insertion feature, such that the insertion feature can be removably connected with the receiving feature, thereby forming a zipper. Where a transaction preceding the end transaction procedure includes a step that employs all the access modules in the transaction, a flush of the transaction log is performed during execution of the last step of the transaction. Each rectification circuit is composed of at least one rectifier semiconductor and the two rectification circuits are respectively connected to the contacts of the two power transmission connectors. In this way, a frequency converter is able to detect the risk of appliance disturbance or failure as a result of network disturbances before the operation is interrupted. A blocking board is secured between the first cooling portion and the second cooling portion to prevent air flowing from the first cooling portion to the second cooling portion.