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Decoherence in a two-qubit system caused by interaction with its environment is an interesting problem to study for quantum communication. We present noise models for the two-qubit states by using Kraus operators for each noisy channel; especially bit ip, bit-phase ip, phase ip, phase damping, amplitude damping, and depolarizing channels. By analyzing the possible quantum information changes of the six noisy channels, we use quantum entropy to discuss variations of their delity and mixedness. In addition, in order to compare the degree of entanglement between the initial and the output, we investigate the concurrence.