• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.15 no.1 s.94
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• pp.105-111
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• 2005

This paper is concerned with the active vibration control of smart structure using actuator signal made of pulse width modulation. The pulse width modulation has been used in motor control, where the amount of energy fed into the motor is controlled by the pulse width instead of applied voltage. The advantage of using the pulse width modulation is that analog signal can be replaced by the digital signal so that we can reduce system costs and power consumption. The effect of pulse width modulation on the vibration response was investigated in this study and the valid transformation rule was found. Then, the pulse width modulation was realized using a microprocessor and electronic circuit. The active vibration suppression was carried out by combining the positive position feedback controller and the pulse width modulation. The experimental result shows that we can replace an expensive amplifier with a pulse width modulation system thus reducing the system cost. The result also shows that the active vibration control can be achieved by the pulse width modulation technique.

• Journal of the Optical Society of Korea
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• v.7 no.4
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• pp.258-263
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• 2003

Simple algebraic expressions are derived to approximate the optimal input RMS pulse width and the resulting output RMS pulse width in single-mode fibers. The results are compared with the previously published methods and with numerical results by the split-step Fourier method. In addition, for a transform-limited Gaussian input pulse, it is shown that there is no optimum input pulse width to minimize the output spectrum width. Finally, with fiber nonlinearity, it is shown mathematically that there is not an optimum input pulse width to minimize the product,${\sigma}_t{\sigma}_{\omega}$, which is inversely proportional to the transmission capacity of WDM systems.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.1
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• pp.81-87
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• 2021

In this study the skin care system was designed and tested by introducing V-IPL(Variable-Intense Pulse Light) methods that allow various skin treatments. The discharge method, a new method of switching on the flash lamp sequentially according to the lesions, was used. Pulse shape control is implemented in the system using the conventional LC variable method and the switching method control method of the switching element. As a result, the pulse width could be varied up to 1[㎛] by using a microprocessor, and by turning on the flash lamp sequentially along the lesions the depth and width, the pulse shape and pulse shape could be more diverse. We could also make long pulses of up to 1~100[ms] in various pulse width. And the special differences between the existing system and the proposed system in this study are as follow. Existing system is one pulse(pulse width : 1~40ms) and proposed system is three pulse(pulse width : 1~100ms).

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.10
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• pp.872-880
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• 2017

Usually, on/off control method is a way to control the thruster. Bang-Bang Control, PWM(Pulse Width Modulator) and PWPF(Pulse Width Pulse Frequency) are widely used as a typical way. When we are designing PWPF, the incorrectly designed parameters($K_m$, ${\tau}$, $U_{on}$, $U_{off}$, $U_m$) make trouble, such as the phase lag, the wasted fuel, the reduced system life. Therefore, the effect of parameters on the system performance should be analyzed before the proper parameters are selected. In this paper, we suggest the PWPF parameters design method by performing a static analysis, and analyze the interactive effects on design parameters by performing a dynamic analysis and simulation.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.50 no.2
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• pp.72-78
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• 2001

A compact size high voltage pulse generator with nanosecond rise time has been designed and investigated experimentally. The inductance of a pulse generator can be reduced by fixing the Marx generator and pulse forming network components into a single cylindrical unit. As a result, nanosecond rise time about $8{\sim}10[ns]$ and pulse width of several hundred [ns] can be obtained from a modified Marx pulse generator. And parametric studies showed that the rise time of the output pulse was depended little on the change of the load resistance and the charging capacitance while, the pulse width of the output pulse was depended greatly upon the change of the load resistance and the charging capacitance. The theoretical showed the possibility to design the laboratory-size pulse generator very fast rising time and a proper pulse width by minimizing stray inductance and varying resistance and capacitance.

• Journal of the Korean Institute of Telematics and Electronics
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• v.7 no.4
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• pp.6-13
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• 1970

The variable-width and double-pulse generator Here described is completely transistorized so its size is small and it is convenient to handle. The frequency ran be varied from 1 KHz to 500KHz, the pulse width from 0.4$\mu$sec to 8$\mu$sec, amplitude from 1V to 10V, and interval of double pulse from 0$\mu$sec to 12$\mu$sec. Positive and negative signal or double pulse trains can he obtained. An analysis has been carried out for each stage and the design equations are derived. The experimental results are compared with the analysis.

• The Transactions of the Korean Institute of Power Electronics
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• v.27 no.1
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• pp.56-62
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• 2022

In this paper, the effect of pulse width modulation methods on thermal loadings and power losses of single-phase five-level NPC inverters for photovoltaic systems are analyzed. The pulse width modulation methods affect the power losses of the NPC inverters and thus lead to different thermal loadings of NPC inverters. To identify the reliability-critical power device with respect to thermal stress, the thermal loadings of I- and T-type NPC inverters are analyzed by applying the unipolar pulse modulation method. Then, the effect of the discontinuous pulse width modulation method on power losses and thermal loadings of power devices of I- and T-type NPC inverters are analyzed. Finally, the operation of NPC inverters applying the discontinuous pulse modulation method is confirmed by experiments. The results show that the discontinuous pulse modulation method is able to improve the reliability of NPC inverters by reducing thermal loadings of reliability-critical power devices and it is more effective for T-type NPC inverters than I-type NPC inverters.

• Journal of Electrical Engineering and Technology
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• v.8 no.4
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• pp.773-779
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• 2013

We propose an efficient method to measure a pulse width using multiphase clock signals generated from a ring oscillator. These clocks, which have the same frequency and are evenly spaced, give multiple rising edges within a clock cycle. Thus, it is possible to measure a pulse width more accurately than with existing single clock-based methods. The proposed method is applied to a capacitive touch switch. Experimental results show that the capacitive touch switch with the proposed method gives a 118 fF resolution, which is 6.4 times higher than that of the touch switch with a single clock-based pulse width measurement method.

• Proceedings of the KIEE Conference
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• 2001.07c
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• pp.1631-1633
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• 2001

In manufacturing processes, various and suitable pulse shapes are required for the purpose of material processing and the pulseshape is regarded as a dominant factor due to the specific property of processing materials. Therefore, in this study, a variable pulse width, high duty cycle Pulse Forming Network(PFN) is constructed by time sequently. The power supply for this experiment consists of three switching circuits. The PFN elements operate at low voltage and drive the primary of HV leakage transformer. The secondary of the transformer has a full-wave rectifier, which passes the pulse energy to the load in a continuous sequence of properly phased and nested increments. We investigated laser pulse width as various delay time among three switching circuit. As a result, we tan obtain various laser pulse width from about 4ms to 10ms. The maximum laser pulse width obtained at this experiment was about 10ms at delay time of 4ms among each switching circuit.

• Proceedings of the Korean Ceranic Society Conference
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• 2000.04a
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• pp.107.1-107.1
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• 2000