Abstract: Provided are a method and system for payment when a network is blocked. A method of providing a remittance service performed by a first device, the method including requesting a financial institution system to issue a block key layer for at least a portion of an amount of money retained by a user of the first device, receiving the block key layer from the financial institution system in response to the request, receiving, from a second device, remittance request data for an amount of remittance, obtaining, from the received block key layer, a block key layer corresponding to the amount of remittance, and transmitting, to the second device, a file for the block key layer corresponding to the amount of remittance.

Abstract: An optical imaging system includes: a first lens having refractive power, a second lens having refractive power, a third lens having refractive power, a fourth lens having refractive power, and a fifth lens having refractive power. Here, the first lens, the third lens, and the fifth lens may have refractive indices of about 1.6 or more, and an entire field of view of the optical imaging system may be about 120° or more.

Abstract: A cleaning device for a substrate transfer device comprises a traveling unit configured to travel along a rail having first and second areas, a rail unit including the rail and a rail structure disposed on the rail, and a rinsing unit including a suction part disposed on the rail and that rotates about a suction nozzle. When the rinsing unit is placed in contact with the rail structure, the suction part rotates about the suction nozzle.