A recurrent neural network including an input layer, a hidden layer, and an output layer, wherein the hidden layer includes hybrid memory cell units, each of the hybrid memory cell units including a first memory cells of a first type, the first memory cells being configured to remember a first cell state value fed back to each of gates to determine a degree to which each of the gates is open or closed, and configured to continue to update the first cell state value, and a second memory cells of a second type, each second memory cell of the second memory cells including a first time gate configured to control a second cell state value of the second memory cell based on phase signals of an oscillatory frequency, and a second time gate configured to control an output value of the second memory cell based on the phase signals, and each second memory cell of the second memory cells being configured to remember the second cell state value.
Please help me write a proper abstract based on the patent claims. CLAIM: 1. A recurrent neural network comprising: an input layer; a hidden layer; and an output layer, wherein the hidden layer comprises hybrid memory cell units, each of the hybrid memory cell units comprising: a first memory cells of a first type, the first memory cells being configured to remember a first cell state value fed back to each of gates to determine a degree to which each of the gates is open or closed, and configured to continue to update the first cell state value; and a second memory cells of a second type, each second memory cell of the second memory cells comprising a first time gate configured to control a second cell state value of the second memory cell based on phase signals of an oscillatory frequency, and a second time gate configured to control an output value of the second memory cell based on the phase signals, and each second memory cell of the second memory cells being configured to remember the second cell state value. 2. The recurrent neural network of claim 1, wherein each of the hybrid memory cell units is configured to fully open the first time gate and the second time gate with respect to a predetermined percentage of the first memory cells. 3. The recurrent neural network of claim 2, wherein when a ratio of a number of neuron indices to a total number of neurons included in each of the hybrid memory cell units exceeds the predetermined percentage, the first time gate and the second time gate are further configured to be fully opened and set to a first value. 4. The recurrent neural network of claim 1, wherein the hidden layer comprises remaining neurons which remain after neurons included in each of the hybrid memory cell units are randomly dropped out by a random variable drawn from a uniform distribution between “0” to “1”, and a number of the remaining neurons is determined based on a sparsity threshold. 5. The recurrent neural network of claim 4, wherein in the second memory cells comprising the remaining neurons, a value of a second parameter corresponding to a ratio of a duration of an open phase to an oscillation period of the oscillatory frequency is identical to the sparsity threshold. 6. The recurrent neural network of claim 4, wherein when the random variable is less than the sparsity threshold, the first time gate and the second time gate are further configured to be set to a first value. 7. The recurrent neural network of claim 1, wherein a periodic oscillation is applied to the second memory cells, and wherein the second memory cell has a fixed phase relationship. 8. The recurrent neural network of claim 7, wherein the periodic oscillation is generated based on a first parameter corresponding to an oscillation period of the oscillatory frequency. 9. The recurrent neural network of claim 8, wherein when a rounded value of a mod operation between a time for the second memory cells and an oscillation period of the second memory cells is zero, the first time gate and the second time gate are further configured to be opened and set to a first value, and wherein when the rounded value is not zero, the first time gate and the second time gate are further configured to be closed. 10. The recurrent neural network of claim 1, wherein when a current time exceeds a refractory end time in which a state of the first time gate and a state of the second time gate are changed from an off state or a refractory state to an on state, the first time gate and the second time gate are further configured to be opened and set to a first value. 11. The recurrent neural network of claim 10, wherein when the first time gate and the second time gate are set to the first value, the second memory cells are further configured to update the second cell state value. 12. The recurrent neural network of claim 1, wherein the recurrent neural network is configured to receive input values sampled from a continuous input signal. 13. The recurrent neural network of claim 1, wherein the first time gate is controlled based on a first oscillatory frequency and the second time gate is controlled based on a second oscillatory frequency. 14. The recurrent neural network of claim 1, wherein the recurrent neural network is further configured to receive a plurality of input values corresponding to a plurality of sampling rates, and wherein each of the phase signals comprises an open phase corresponding to a sampling rate of the plurality of sampling rates. 15. The recurrent neural network of claim 1, wherein the first time gate and the second time gate are further configured to operate based on: an open phase comprising a rising phase in which a phase signal changes from a first state to a second state, and a falling phase in which the phase signal changes from the second state to the first state; and a closed phase in which the first state of the phase signal is maintained. 16. The recurrent neural network of claim 15, wherein the first time gate is further configured to: update the second cell state value based on an input value of each of the hybrid memory cell units, in response to the phase signal being in the open phase; and maintain the second cell state value regardless of the input value in response to the phase signal being in the closed phase. 17. The recurrent neural network of claim 15, wherein the second time gate is further configured to update an output value of the second memory cells, in response to the phase signal being in the open phase. 18. The recurrent neural network of claim 1, wherein each of the phase signals comprises a shaped pulse corresponding to a fraction of an oscillation period of the oscillatory frequency. 19. The recurrent neural network of claim 1, wherein the first time gate and the second time gate are further configured to be opened and closed based on at least one from among a first parameter corresponding to an oscillation period of the oscillatory frequency, a second parameter corresponding to a ratio of a duration of an open phase to the oscillation period, and a third parameter corresponding to a phase shift in the oscillatory frequency, and wherein the open phase comprises a rising phase in which a phase signal changes from a first state to a second state, and a falling phase in which the phase signal changes from the second state to the first state. 20. The recurrent neural network of claim 19, wherein the first time gate is further configured to be opened and closed based on first independent oscillations in the first time gate, and the second time gate is further configured to be opened and closed based on second independent oscillations in the second time gate, and wherein the first independent oscillations and the second independent oscillations are specified by at least one from among the oscillation period, the ratio of the duration of the open phase to the oscillation period, or the phase shift. 21. The recurrent neural network of claim 19, wherein the oscillation period, the ratio of the duration of the open phase to the oscillation period, and the phase shift are trained in advance. 22. The recurrent neural network of claim 1, wherein the hybrid memory cell units are configured to be selectively updated based on input values of hybrid memory cell units that are asynchronously sampled. 23. The recurrent neural network of claim 1, wherein each of the second memory cells further comprises: an input gate configured to determine a degree to which an input value of the second memory cell is reflected; a forget gate configured to determine a degree to which the second cell state value is forgotten; and an output gate configured to determine a degree to which the second cell state value is output, based on a determination of whether the second cell state value is to be maintained or updated, wherein the first time gate is further configured to determine, based on the phase signals, whether the second cell state value is to be maintained or updated based on the degree to which the input value is reflected and the degree to which the second cell state value is forgotten, and wherein the second time gate is further configured to determine, based on the phase signals, whether the output value is to be maintained or updated based on the degree to which the second cell state value is output. 24. The recurrent neural network of claim 23, wherein the first time gate is further configured to update the second cell state value based on the input value, and the second cell state value is controlled by a gating function of the forget gate. 25. The recurrent neural network of claim 19, wherein the first time gate and the second time gate are further configured to be opened and closed based on an oscillation parameterized by the first parameter, the second parameter, and the third parameter. 26. A hybrid memory cell unit comprising: a first memory cells configured to remember a first cell state value fed back to each of gates to determine a degree to which each of the gates is open or closed, and configured to continue to update the first cell state value; and a second memory cells, each second memory cell of the second memory cells comprising a first time gate configured to control a second cell state value of the second memory cell based on a phase signal of an oscillatory frequency, and a second time gate configured to control an output value of the second memory cell based on the phase signal, and each second memory cell of the second memory cells being configured to remember the second cell state value. 27. The hybrid memory cell unit of claim 26, wherein the hybrid memory cell unit is configured to fully open the first time gate and the second time gate with respect to a predetermined percentage of the first memory cells. 28. The hybrid memory cell unit of claim 27, wherein when a ratio of a number of neuron indices to a total number of neurons included in the hybrid memory cell unit exceeds the predetermined percentage, the first time gate and the second time gate are further configured to be fully opened and set to a first value. 29. A recurrent neural network comprising: an input layer; a hidden layer; and an output layer, wherein the hidden layer comprises hybrid memory cell units, the hybrid memory cell units comprising: a plurality of first memory cells configured to remember a first cell state value fed back to each of gates to determine a degree to which each of the gates is open or closed, and configured to continue to update the first cell state value; and a plurality of second memory cells comprising a plurality of first time gates and a plurality of second time gates, the second plurality of memory cells being configured to remember a second cell state value, wherein each second memory cell of the plurality of second memory cells comprises a respective first time gate of the plurality of first time gates, the first time gate being configured to control the second cell state value of the second memory cell based on phase signals of an oscillatory frequency, and a respective second time gate of the plurality of second time gates, the second time gate being configured to control an output value of the second memory cell based on the phase signals.