1. A method of classifying an input pattern, the method comprising: enabling an artificial neural network to learn based on learning input data received by an input layer of the artificial neural network and learning output data outputted by an output layer of the artificial neural network; determining classification of an input pattern received by the input layer according to an output value obtained from the output layer, the obtained output value being based on the input pattern; determining a result value of the determined classification; setting, in response to the determining of the result value, the result value to the output layer so as to form data of the learning output data, and the input pattern to the input layer; updating, in response to the result value being set to the output layer, connection intensities of connection lines of the artificial neural network using the result value set to the output layer when the input pattern is input to the input layer; and determining updated classification of the input pattern according to an updated output value obtained from an output layer of the updated artificial neural network, the obtained updated output value being based on the input pattern and the updated connection intensities of the connection lines of the artificial neural network, wherein the result value is a representative value of the determined classification comprising an interval of output values corresponding to the input pattern and including the output value.