The present invention provides a method for improving the recovery of cesium-131 from barium carbonate. Utilizing the system and method disclosed herein, digital voice telephony signals received in TDM frame-based format are converted to packet-based or cell-based format for transmission on a network, and vice-versa. A loss modulus of the colored resin sheet at a temperature of the pressing is higher than a loss modulus of the first transparent resin sheet at the temperature of the pressing. A fault monitor operates on a second OS. Therefore, variable duplexing of the plurality of STM interface chips in a board is made possible.