• Proceedings of the KIEE Conference
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• 1991.07a
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• pp.611-614
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• 1991

In variable speed driving system of three phase induction motor controlled by an inverter, because of the switching of semiconductor devices in inverter, an appreciable amount of harmonic components of voltage waveform can cause the motor to generate losses, torque ripple, acoustic noise and oscillation of semiconductor devices. In this paper a new PAM type PWM inverter using IGBT is described. The output waveforms in the proposed PAM type PWM inverter are investigated both theoretiically and experimentally. The line-voltage waveform is composed of fundamental component and the sidebands of carrier frequency. The lower order harmonics are not included in the output wave form. As each inverter arm does not operate during two-thirds period, the heats, generated in the devices are reduced. That is, the size of the inverter system can he minimized because of the reduction in the heat dissipating equipment.

• The Transactions of the Korean Institute of Power Electronics
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• v.6 no.3
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• pp.223-230
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• 2001

This power proposes a new sensorless drive system for the trapezoidal brushless DC motor generally requiring mechanical position or speed sensor. For this an indirect rotor position sensing method from the back emf waveform of non-conducting phase is explained. Back emf waveform of non-conducting is obtained from analysing terminal voltage created by making Y-connection. And an experiment is implemented with a driving system which use 87c196mc microcontroller having a peripheral associated with 3-phase signals and inverter composed of Power MOSFET. The experimental results show the validity and practicality of the proposed sensorless drive.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.3
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• pp.47-53
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• 2017

There is a difficulty in preventing drunken driving by enforcing alcohol control on the sea due to the environment of Marine transportation rather than roads. In the previous study, we proposed the algorithm, that was developed to identify the voices changed according to be drunk. Using the developed algorithm, it became possible to know the possibility of drinking by long distance ship operators and crew members. In that method drinking can be measured in real time, no matter how far the distance is, if the interception is through a voice that can be transmitted over a distance, rather than a short distance. When communicating voice using the VTS wireless devices, clipping occurs when that environment is uneven, and the rate of judgment of the possibility of drinking may be lowered. Therefore, in this paper, we proposed an enhanced method to compensate the signal in order to reduce the error rate of the possibility of drinking due to distortion of the speech signal.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.39 no.6
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• pp.27-33
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• 2002

This paper proposes a method to drive an AC plasma display panel(PDP) with a significantly improved contrast ratio. In the proposed method, during the first sub-field of one frame, all PDP cells are reset by the ramp waveform, and during the other sub-fields, only the cells turned on in the previous sub-field are reset. No light is emitted during the reset period of every sub-field except the first sub-field. For a 10-bit picture, the luminance of the dark level for the proposed method is 10 times lower than that for the conventional method, in which the ramp waveform for the reset is used in every sub-field. Accordingly, the contrast ratio for the proposed method is 10 times higher than that for the conventional method. For the 10-bit picture, the measured contrast ratio was about 3080:1 for the proposed method and about 285:1 for the conventional method, resulting in 10.8 times increase in the contrast ratio. This result shows that the proposed method can realize an image with high contrast ratio.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.1
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• pp.135-139
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• 2015

The address discharge time lags are investigated in each subfield time in AC plasma display panel and a modified driving waveform is proposed to reduce the address discharge time lag by applying different additional scan voltage under no misfiring discharge production. The weak plasma discharge in AC PDP is generated by applying high positive-going ramp waveform to the scan electrode during the first reset period and that induce the production of the priming particle and wall charge. Because the wall charge becomes the wall voltage in a cell, the wall plus external address voltage produce the address discharge. However, as the wall charge in a cell is gradually disappeared as time passed, the address discharge time in the subfield time for 1 TV frame is lagged. In the first subfield time, the address discharge is faster produced than the other subfield time because the wall charge are much remained by the high positive-going ramp voltage during the reset period in the first subfield time. Meanwhile, from the second to last subfield, the address discharge production time is gradually delayed due to the dissipation of the wall charge in a cell. In this study, the address discharge time lags are measured in each subfield time and the total address discharge time lags are shortened by applying the different additional scan voltage during the address period in each the subfield time.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.2
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• pp.147-151
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• 2011

We were analyzed the piezoelectric characteristic for electronics printing to inkjet printing system. These applications were possible use to Actuator, MEMS, FPCB, RFID, Solar cell and LCD color filter etc. Piezoelectric print head is firing from ink droplet control consideration ink viscosity properties. At this time, micro pattern for PCB metal printing was possible by droplet control of piezoelectric driving. These driving characteristics are variable voltage pulse waveform. We are used the piezoelectric analysis software of Finite Element Method (FEM), Piezoelectric design parameters are acquired from piezoelectric analysis, and measurement of piezoelectric. It designed for piezoelectric head to possible electric print pattern of inkjet printing system. For this validity we were established through in comparison with simulation and measurement. Designed piezoelectric specification obtained voltage 98V, firing frequency 10 kHz, resolution 360dpi, drop volume 20pl, nozzle number 256, and nozzle pitch 0.33 mm.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.17 no.2
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• pp.28-33
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• 2003

The piezoelectric transformer converters electrical energy into mechanical energy, It is high efficiency and small size transformer for high output voltage. The piezoelectric transformer operates the resonance frequency and the output voltage waveform is close to sine wave. Therefore, it is suitable for driving the LCD backlight in the notebook computer. In this paper, we discussed about the inverter which os driving piezoelectric transformer by generating sine wave through LC resonance after converting input DC voltage to the gate signal of FET. As the result of experiments, it was showed that the resonance frequency and voltage gain of the piezoelectric transformer was proportional to the load variation, and voltage gain was independent of the input voltage variation.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.55 no.5
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• pp.239-244
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• 2006

To drive the high-image quality plasma displays of XGA and/or full-HD, we must effectively improve the driving waveform, which get the reset period for the stabilized control of wall charges, the address period to select discharge or non-discharge, and sustain period for luminance in 1 TV-frame, and also the display quality. To accomplish them, the development of the technology for the fast address discharge is required. In this paper, the correlation between the sustain-electrode gap and address discharge characteristics for the high-speed addressing was analyzed using the measurements of dynamic voltage margins. Results showed that the narrower the gap between the sustain electrodes, the narrower the with of the scan pulse became and a dynamic margin of data voltage of 29.2 V was obtained at scan pulse width of $1.0{\mu}s\;and\;V_{ramp}$ of 240 V for driving 4-inch test penal, which the gap between sustain electrodes was $65{\mu}m$.

• Journal of international Conference on Electrical Machines and Systems
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• v.2 no.2
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• pp.190-196
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• 2013

It presents a unification of buck-boost and flyback converter for driving a cascaded H-bridge multilevel inverter with a single independent DC voltage source. Cascaded H-bridge multilevel inverter is useful to make many output voltage levels for sinusoidal waveform by combining two or more H-bridge modules. However, each H-bridge module needs an independent DC voltage source to generate multi levels in an output voltage. This topological characteristic brings a demerit of increasing the number of independent DC voltage sources when it needs to increase the number of output voltage levels. To solve this problem, we propose a converter combining a buck-boost converter with a flyback converter. The proposed converter provides independent DC voltage sources at back-end two H-bridge modules. After analyzing theoretical operation of the circuit topology, the validity of the proposed approach is verified by computer-aided simulations using PSIM and experiments.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.32 no.1
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• pp.40-46
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• 2019

To study the frequency response characteristics of alternating-current-driven organic light-emitting diodes (OLEDs), we fabricated blue-fluorescent OLEDs and analyzed their electroluminescent characteristics according to the alternating current voltage and frequency. The luminance-frequency characteristics of alternating-current-driven OLED was similar to that of a low-pass filter, and the luminance of high-voltage OLED decreased at higher frequency than low-voltage OLED. The luminance characteristics of the OLED according to the frequency is due to the capacitive reactance in the OLED, generated during the alternating current driving. The frequency response characteristics of the OLED according to the voltage is due to the decrease in internal resistance of the organic layer. In addition, the negative voltage component of the alternating current did not affect the frequency response of the OLED. Therefore, the electroluminescent characteristics of OLED with an alternating current power of 60 Hz are not influenced by the frequency.