Abstract: The technology disclosed in the present specification is a method of evaluating insulation performance of a low-temperature storage tank, the method including an operation of transferring an internal electrode to a lower base material, wherein the operation includes: a first operation of measuring an amount of infrared energy of a sensor pad; a second operation of assuming a temperature of a substrate of the sensor pad as a specific value; a third operation of calculating a temperature of a first surface of the sensor pad by using the amount of the infrared energy measured from the sensor pad and the temperature of the substrate; a fourth operation of obtaining a temperature of the substrate from a transient heat conduction equation by using the temperature of the first surface as a boundary condition; a fifth operation of determining whether the obtained temperature of the substrate is equal to the assumed temperature of the substrate; and a sixth operation of, when the temperatures of the substrate are equa

Abstract: A telephone service system in an ATM private network, includes: a PSTN interface unit for performing PCM with an analog telephone signal transmitted from a channel in a PSTN, converting the modulated data into a CEPT frame before sending it to a subscriber, performing the PCM with CEPT frame data, from a subscriber, and converting the modulated data into an analog telephone signal, before forwarding it to the PSTN; a first ATM cell processing unit for converting the CEPT frame data from the PSTN interface unit into an ATM cell, converting an ATM cell from a subscriber into CEPT frame data, and sending it to the PSTN interface unit; an ATM switching unit for switching the ATM cell from the first ATM processing unit to the subscriber, and switching the ATM cell from the subscriber to the PSTN; a second ATM processing unit for converting the ATM cell from the ATM switching unit into CEPT frame data before sending it to the subscriber, and converting the CEPT frame data from the subscriber into an ATM cell before