The present invention is provided to form a trench in a semiconductor device, wherein by performing an ion implanting process to an area of a semiconductor substrate in which the trench would be formed to cause lattice defects in the area before forming the trench, an etching speed of the area is increased in subsequent trench forming processes. The gate electrode may control a magnetization state of the channel in order to selectively transmit the electrons injected from the source to the channel. The resulting transistor is a transistor in which single electron flow controls operation of the transistor. The estimator is configured to estimate whether generated water is frozen in the fuel cell stack. A modulation error in the second set of signals is calculated as a function of the characterization of the modulation error from the first set. A base station and wireless terminals change an intermittent receive period and the preamble length of data on the basis of characteristics of the multihop radio network to carry out the intermittent receiving of data.