• Title, Summary, Keyword: Harmonic Frequency

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Determination of Polarization Resistance by Harmonic Current Measurements (조화 전류 측정에 의한 분극 저항 평가)

  • Kim, Jong Jip;Yu, Mi Young
    • Corrosion Science and Technology
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    • v.11 no.6
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    • pp.247-256
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    • 2012
  • Harmonic current was measured for a dummy cell with various values of resistance, and the procedure developed through the measurements was applied to the investigation of effects of the amplitude of applied frequency and applied potential on the harmonic current of a stainless steel and a carbon steel in chloride containing solutions. From the measurements of harmonic current in the dummy cell, the optimum values of applied frequency and applied potential in harmonic current measurements were found to be 1 mHz and 20 mV (or lower), respectively. Increase in harmonic current with applied frequency was observed in the case where the level of harmonic current is low as in a stainless steel. Decrease in polarization resistance was also noted in this corrosion system with either increasing applied frequency or decreasing applied potential. However, no obvious effects of applied frequency was observed on harmonic current and polarization resistance in a carbon steel in which the level of harmonic current is high.

Design of Reflector Type Frequency Doubler for Undesired Harmonic Suppression Using Harmonic Load Pull Simulation Technique

  • Jang, Jae-Woong;Kim, Yong-Hoon
    • Journal of electromagnetic engineering and science
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    • v.7 no.4
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    • pp.175-182
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    • 2007
  • In this paper, a study on the reflector type frequency doubler, to suppress the undesired harmonics, is presented. A 12 to 24 GHz reflective frequency doubler is simulated and experimented. Design procedure of the frequency doubler with reflector is provided and the frequency doubler with good spectral purity is fabricated successfully. It has harmonic suppression of the $40{\sim}50\;dBc$ in the $1^{st}$ harmonic and the $50{\sim}60\;dB$ in the $3^{rd}$ harmonic with no additional filter. And, it has conversion gain with the input power of 0 dBm over bandwidth of 500 MHz. A NEC's ne71300(N) GaAs FET is used and the nonlinear model(EEFET3) using IC-CAP program is extracted for harmonic load pull simulation. Good agreement between simulated and measured results has been achieved.

Optical Harmonic Modulation-Demodulation Techniques for High-Speed Light wave Transmission

  • Choi, Young-Kyu
    • Journal of information and communication convergence engineering
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    • v.6 no.2
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    • pp.192-197
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    • 2008
  • High-speed harmonic optical modulation-demodulation schemes are presented and a possibility of the schemes for applying to high-speed light wave transmission system is tested at microwave frequency range. An example of this concept is as follows : Light wave is modulated succeedingly through cascaded optical modulators by a sub-carrier to produce a modulated light wave at harmonic frequency which is higher than the feasible frequency of the individual modulators. For demodulation of the base-band signal, the high frequency optical sub-carrier is down-converted by the same kind of optical modulator with the same concept of harmonic modulation.

Ac Hysteresis Loop Depending on the Phase Angle of the Higher Harmonic Induction

  • derac Son;Eun Kyoung Kim
    • Journal of Magnetics
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    • v.1 no.2
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    • pp.90-93
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    • 1996
  • For the design of high efficiency electric machines, analysis of higher harmonic frequency components of the magnetic induction is necessary. We have measured ac magnetic properties of non-oriented silicon steel under harmonic frequencies ranging from $3^rd$ (180 Hz) to $9^th$(540 Hz) and harmonic amplitude components from 10% to 50% of the total amplitude ($B_max$=1.5T). From the experiment, it is found that, if the magnetic induction waveform has above $9^th$ harmonic frequency components of the magnetic induction, the core losses only depended on the harmonic amplitude component, but if harmonic frequency becomes lower than 9th harmonic frequency, the core losses depend on the phase angle and the harmonic amplitude, and phase angle should be considered in the design of electric machine.

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Microwave Incoherent Imaging of a Conducting Cylinder by Using Multi-Frequency Time-Harmonic Field : Part I - Incoherent Intensity Pattern by Using Multi-Frequency Time-Harmonic Field (다중주파수 시간좌화신호를 사용한 도체기중의 초고주파 incoherent 영상:Part I - 다중주파수 시간좌화신호를 사용한 incoherent 전력패턴)

  • 강진섭;라정웅
    • Journal of the Korean Institute of Telematics and Electronics B
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    • v.33B no.2
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    • pp.47-55
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    • 1996
  • A microwave incoherent imaging method for a conducting cyliner by using multi-frequency tiem-harmonic field is presented in this study. In this paper, an incoherent intensity pattern of th econducting cylinder is obtained by averagin gout the multi-frequency intensities of the coherent field such as the time-harmonic field scattered from this cylinder. This phenomenon is hsown numerically in scattering by a conducting circular cylinder illuminated by the time-harmonic plane wave, and is interpreted analytically by the mutual coherence functon defined as a frequency-averaged intensity of the time-harmonic fields in th frequency domain.

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Effects of Distributed Load on the Dynamic Response of the Reinforced Concrete Slabs (분포하중이 철근 콘크리트 슬래브의 동적 거동에 미치는 영향)

  • Oh, Kyung-Yoon;Cho, Jin-Goo;Choi, Soo-Myung;Hong, Chong-Hyun
    • Journal of The Korean Society of Agricultural Engineers
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    • v.50 no.2
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    • pp.19-26
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    • 2008
  • This study has been carried out to investigate the dynamic characteristics of RC slabs. For this purpose, the 20-node solid element has been used to discretize the RC slabs into two parts of concrete and rebar. The material non-linearity considering elasto-visco plastic model and the smeared crack model have been adopted in the finite element formulation. The applied load can handle step load, load intensity of harmonic load, area of distributed load and frequency. The frequency of harmonic load has an significant effect on dynamic behaviour in terms of displacement. As the frequency is increased, the effect of load amplitude is more serious. Especially, if the frequency of harmonic load exceeds 30 Hz, it is noted that the displacement by harmonic load is greater than that by step load. In case of harmonic load, the damping effect shows no certain tendency with respect to frequency of load. In details, the damping is effective when the frequency of harmonic load is 2 Hz, but there is no consistent tendency according to damping ratio. The dynamic response when the frequency of harmonic load is 3 Hz shows same result for undamped case as well as for damped case with 5% damping ratio. It is also noted that we can get the largest deflection for damped case with 1% damping ratio. However, there is not any damping effect when the frequency of harmonic load is greater than 4 Hz.

A High Performance Harmonic Mixer Using a plastic packaged device

  • Kim, Jae-Hyun;Go, Min-Ho;Park, Hyo-Dal;Shin, Hyun-Sik
    • The Journal of the Korea institute of electronic communication sciences
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    • v.2 no.1
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    • pp.1-9
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    • 2007
  • In this paper, a third-order harmonic mixer is designed using frequency multiplier theory for the Ka-band. The gate bias voltage is selected by frequency multiplier theory to maximize the third-order harmonic element ofthe fundamental LO frequency in the proposed mixer. The designed mixer has a gate mixer structure composed of a gate terminal input for the fundamental local signal ($f_{LO}$), RF signal (${RF}$) and a drain terminal output for the harmonic frequency ($3f_{LO}-f_{RF}$) respectively. The Ka-band harmonic mixer is designed and fabricated using a commercial GaAs MESFET device with a plastic package. The proposed mixer will provide a solution for the problems found in the high cost, complex circuitry in a conventional Ka-band mixer. The 33.5 GHz harmonic mixer has a -10 dB conversion gain by pumping 11.5 GHz LO with a +5 dBm level.

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Injection Locked Synchronization Characteristics of a Millimeter Wave Second Harmonic Oscillator (밀리미터파 대역 제2고조파 출력 발진기의 주입동기 특성)

  • Choi, Young-Kyu
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.62 no.12
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    • pp.1700-1705
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    • 2013
  • A second harmonic millimeter wave oscillator utilizing sub-harmonic injection-synchronization is presented. A 8.7GHz oscillator with MES-FET is designed, and is driven as a harmonic output oscillator at 17.4GHz by means of sub-harmonic injection-synchronization. The oscillator operates as a multiplier as well as a oscillator in this scheme. Adopting this method, a high sable, high frequency millimeter wave source is obtainable even though self-oscillating frequency of an oscillator is relatively low. The range of injection-synchronization is about 26MHz, and is proportional to the input sub-harmonic power. The spectrum analysis of the 2nd harmonic output frequency shows remarkably decreased the phase noise level.

Method Based on Sparse Signal Decomposition for Harmonic and Inter-harmonic Analysis of Power System

  • Chen, Lei;Zheng, Dezhong;Chen, Shuang;Han, Baoru
    • Journal of Electrical Engineering and Technology
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    • v.12 no.2
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    • pp.559-568
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    • 2017
  • Harmonic/inter-harmonic detection and analysis is an important issue in power system signal processing. This paper proposes a fast algorithm based on matching pursuit (MP) sparse signal decomposition, which can be employed to extract the harmonic or inter-harmonic components of a distorted electric voltage/current signal. In the MP iterations, the method extracts harmonic/inter-harmonic components in order according to the spectrum peak. The Fast Fourier Transform (FFT) and nonlinear optimization techniques are used in the decomposition to realize fast and accurate estimation of the parameters. First, the frequency estimation value corresponding to the maxim spectrum peak in the present residual is obtained, and the phase corresponding to this frequency is searched in discrete sinusoids dictionary. Then the frequency and phase estimations are taken as initial values of the unknown parameters for Nelder-Mead to acquire the optimized parameters. Finally, the duration time of the disturbance is determined by comparing the inner products, and the amplitude is achieved according to the matching expression of the harmonic or inter-harmonic. Simulations and actual signal tests are performed to illustrate the effectiveness and feasibility of the proposed method.

Effect Investigation of Resonance by Harmonic Components on Structures with Velocity Seismoprobes in a Turbine Rotor System (속도계가 부착된 구조물에서 조화성분의 공진이 미치는 영향 고찰)

  • Yang, Kyeong-Hyeon;Cho, Chul-Whan;Bae, Chun-Hee;Song, Oh-Seop
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.98-102
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    • 2005
  • Most bearing casings are designed to focus on strength and weight of themselves because rotor speed passes through the critical speed when operation begins in large plants such as power plants. And It is treated importantly the relation between rotating frequency of the rotor and the natural frequency of casings to prevent resonance. But there is some cases that it is overlooked for harmonic components above rotating frequency. So we present experimentally a case that harmonic forces may make a resonance on casing fixing probes to measure vibration in a turbine-generator system and the vibration is generated when one component of harmonic forces excites the mode that the natural frequency of a certain bearing casing is close to one of harmonics of basic rotating frequency (1x).

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