3-1. Neural network

Neural network is human′s neurons imitating using mathematical model. Neural network basically has three layers i.e. (1)input layer (2)hidden layer (3)output layer as shown below. This construction is called Three-layer structure. There are models in which the hidden layer is composed of two or more layers, and　the figure below shows a neural network model with a 4-layer structure with 2 hidden layers.

Fig 1 : 4-layer structure

Neural network converts some input signal to pass through neural network model. At the end of the output, there is a supervisor where we already give the ideal output beforehand as shown below.

Fig 2 : Neural network system model