• The Transactions of the Korean Institute of Electrical Engineers P
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• v.62 no.1
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• pp.1-5
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• 2013

The aim of this study is to research maximum harvesting energy by the optimal input wave condition. The voltage characteristics of the PZT bimorph were investigated in terms of the sine wave, triangle wave and square wave according to frequency range 0~70Hz. It was found that the square wave compared with a triangular wave or square wave was showed the higher output energy. PZT bimorph was mechanically vibrated by solenoid coil experiments, which revealed two voltage peak mode according to frequency. Maximum voltage at second vibration frequency 28Hz demonstrated that the generated DC voltage was proportional to the tip displacement of the bimorph and the phase difference between the input frequency and bimorph vibration frequency was 90 degree. It was expected that optimized design to harvest a much higher energy level from lower frequency vibrations.

• Journal of the Korean Institute of Telematics and Electronics
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• v.15 no.1
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• pp.23-26
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• 1978

The circuit which generates full-wave is designed throught only simple formula, and full wave is used for square-wave of which duty ratio is variable but period constant.

• Proceedings of the KIPE Conference
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• 2000.07a
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• pp.133-136
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• 2000

Current Source Inverter(CSI) operated in square wave mode is more efficient than the PWM CSI because of increased cost greater complexity of control algorithm, and substantial switching losses EMI. But the square wave output current of CSI rich in low order harmonics produce motor torque ripples. Therefore in this paper describes the active power filters for square wave current compensation of current source induction motor. Also extended current synchronous detection(ECSD) as compensation algorithm is proposed. To confirm the validity o proposed system some simulation results are presented and discussed.

• Structural Engineering and Mechanics
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• v.83 no.1
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• pp.53-66
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• 2022

The main objective of the present research was investigating the effects of a floating wave barrier installed in front of an offshore jacket structure on the wave height, base shear, and overturning moment. A jacket model with the height of 4.55 m was fabricated and tested in the 402 m-long wave flume of NIMALA marine laboratory. The jacket was tested at the water depth of 4 m subjected to the random waves with a JONSWAP energy spectrum. Three input wave heights were chosen for the tests: 20 cm, 23 cm, and 28 cm. Two different cross sections with the same area were selected for the wave barrier: square and rhombus. Results showed that the average decrease in the jacket's base shear due to the presence of a floating wave barrier with square and rhombus cross section was 24.67% and 34.29%, respectively. The use of wave barriers with square and rhombus cross sections also resulted in 19.78% and 33.11% decrease in the jacket's overturning moment, respectively. Hence, it can be concluded that a floating wave barrier can significantly reduce the base shear and overturning moment in an offshore jacket structure; and a rhombus cross section is more effective than an equivalent square section.

• Proceedings of the KIEE Conference
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• 2006.10c
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• pp.585-587
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• 2006

Generally, LPF(low pass filter) circuits are used for converting square wave to average value, but these are not used necessary for average value of square wave in real time because of time constant of LPF. This paper deals with acquiring method for average value of square wave in real tine in case of frequency of output voltage is fixed, waveform of output voltage is square wave and duty of output voltage is varied like as 1 quadrant or 4 quadrant chopper.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.34D no.9
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• pp.7-14
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• 1997

A rigorous analysis method of electromagentic scattering from frequency selective surface with gridded square loop elements in case of oblique incident and arbitrary polarization is presented, which uses the roof-top subdomain basis function. The frequency response and polarization characteristics of the reflected wave and the transmitted wave for various widths of the grid and the conductor square loop, and for the various gaps between the grid and the conductor square loop, and for the various gaps between the grid and square loop is investigated. To confirm the validity of presented method, frequency selective surfaces with gridded square loop elements are fabricated with honeycomb structures, calculate dvalues for the frequency response of the reflected wave and the transmitted wave for arbitrary incident angle and polarization are compared with measured values.

• Proceedings of the KIPE Conference
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• 2005.07a
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• pp.325-328
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• 2005

EEFLs are mostly driven by sinusoidal wave driving method although EEFLs (External Electrode Fluorescent Lamps) are driven by both sinusoidal wave and square wave. The sinusoidal driving method reduces the cost and allows more power efficiency since this driving method can reduce the voltage stress of EEFL inverter switches and achieve the soft switching of the switches. And a transformer should be used in the inverter since the high voltage should be applied to the both ends of EEFL to turn on the lamp. However, the power loss mainly occurs at the transformer in the sinusoidal wave driving method. In order to remove the transformer which makes the power loss, a new method is presented. In this paper, the square wave is applied directly to the both ends of EEFL by a proposed two-stage inverter. Moreover, the luminance and power efficiency will be compared between the common sinusoidal wave driving method and square wave driving method.

• Journal of the Korean Institute of Telematics and Electronics
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• v.12 no.2
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• pp.43-46
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• 1975

In a chopper amplifier the input signal of the AC amplifier is a train of square-waves. In the rase of square-wave the operatiom of AC amplifier is much different from that of ordinary sinusoidal wave. In this paper for the purpose of contributing to the design of chopper amplifier destortions of waveforms in the amplifier were investigated. When the time constant of each stage is equal the waveform in each stave apppears as square wave whose top is exponentially decaying. And when each stave has different time constant the waveform in n-th stage is composed of n-square waves whose tops are exponentially decaying.

• The Transactions of the Korean Institute of Power Electronics
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• v.18 no.3
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• pp.225-231
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• 2013

This paper presents an improved signal processing technique in the square-wave-type voltage injection method for IPMSM sensorless drives. Since the sensorless method based on the square-wave voltage injection does not use low-pass filters to get an error signal for estimating rotor position and allows the frequency of the injected voltage signal to be high, the sensorless drive system may achieve an enhanced control bandwidth and reduced acoustic noise. However, this sensorless method still requires low-pass and band-pass filters to extract the fundamental component current and the injected frequency component current from the motor current, respectively. In this paper, these filters are replaced by simple arithmetic operations so that the time delay for estimating the rotor position can be effectively reduced to only one current sampling. Hence, the proposed technique can simplify its whole signal process for the IPMSM sensorless control using the square-wave-type voltage injection. The proposed technique is verified by the experiment on the 800W IPMSM drive system.

• Journal of Electrical Engineering and Technology
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• v.13 no.4
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• pp.1515-1527
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• 2018

This paper presents a sensorless speed control of IPMSM (Interior Permanent Magnet Synchronous Motor) using the high-frequency (HF) square wave injection method. In the proposed HF pulsating square wave injection method, injection voltage is applied into the estimated d-axis of rotor and high-frequency induced q-axis current is considered to estimate the rotor position. Conventional square wave injection methods may need complex demodulation process to find rotor position, while in the proposed method, an easy demodulation process based on the rising-falling edge of the injected voltage and carrier induced q-axis current is implemented, which needs less processing time and improves control bandwidth. Unlike some saliency-based sensorless methods, the proposed method uses maximum torque per ampere (MTPA) strategy, instead of zero d-axis command current strategy, to improve control performance. Furthermore, this paper directly uses resultant d-axis current to detect the magnet polarity and eliminates the need to add an extra pulse injection for magnet polarity detection. As experimental results show, the proposed method can quickly find initial rotor position and MTPA strategy helps to improve the control performance. The effectiveness of the proposed method and all theoretical concepts are verified by mathematical equations, simulation, and experimental tests.