• Current Optics and Photonics
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• 제6권6호
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• pp.576-582
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• 2022

Plasmonic high-order harmonic generation (HHG) is used in nanoscale optical applications because it can help in realizing a compact coherent ultrashort pulse generator on the nanoscale, using plasmonic field enhancement. The plasmonic amplification of nanostructures induces nonlinear optical phenomena such as second-order harmonic generation, third-order harmonic generation, frequency mixing, and HHG. This amplification also causes damage to the structure itself. In this study, the plasmonic amplification according to the design of a metal-coated sapphire conical structure is theoretically calculated, and we analyze the effects of this optical amplification on HHG and damage to the sample.

• 전기학회논문지
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• 제58권11호
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• pp.2185-2191
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• 2009

Wind power and photovoltaic(PV) generation systems are the fastest growing sources of renewable energy. The nonlinear devices, such as power electronic converter or inverter, of wind power and PV generation systems are the source of harmonics in power systems. The harmonic-related problems can have significant detrimental effects in the power system, such as capacitor heating, data communication interference, rotating equipment heating, transformer heating, relay misoperation and switchgear failure. There is a greater need for harmonic analysis that can properly maintain the power quality. By measuring harmonics of existing wind power and PV generation systems as harmonics modeling, the studies were made to see the harmonic impact of grid-connected wind power and PV generation systems.

• 비파괴검사학회지
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• 제33권3호
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• pp.257-263
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• 2013

Acoustic nonlinearity of surface waves is an effective method to evaluate the micro damage on the surface of materials. In this method, the $A_1$ (magnitude of the fundamental wave) and $A_2$ (magnitude of the second-order harmonic wave) are measured for evaluation of acoustic nonlinearity. However, if there is another source of second-order harmonic wave other than the material itself, the linear relationship between $A_1{^2}$ and $A_2$ will not be guaranteed. Therefore, the second-order harmonic generation by another source should be fully suppressed. In this paper, we investigated the initial second-order harmonic generation in narrowband surface waves by multi-line laser beams. The spatial profile of laser beam was considered in the cases of Gaussian and square-like. The temporal profile was assumed to be Gaussian. In case of Gaussian spatial profile, the generation of the initial second-order harmonic wave was inevitable. However, when the spatial profile was square-like, the generation of the initial second-order harmonic wave was able to be fully suppressed at specific duty ratio. These results mean that the multi-line laser beams of square-like profile with a proper duty ratio are useful to evaluate the acoustic nonlinearity of the generated surface waves.

• 전기학회논문지
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• 제62권5호
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• pp.604-611
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• 2013

This paper presents an second harmonic elimination method based on the impedance variation scheme. Through the power quality analysis from the nonlinear loads connected on the power system, the second harmonic problems have been analyzed with a case study analysis and the experiments. In the paper, the second Harmonic generation was simulated with a single phase SCR rectifier and the analytical model is proposed for the second harmonic generation. A novel impedance variation scheme is proposed and analyzed to eliminate the second harmonic. The experiment has been performed on the 60(MVA) industry manufacturing plant. The experimental result demonstrates the proposed impedance variation scheme successfully operate on the 60(MVA) industry manufacturing plant.

• Journal of international Conference on Electrical Machines and Systems
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• 제2권3호
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• pp.254-259
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• 2013

We examined the generation of harmonic voltage by a synchronous machine adding d-axis and q-axis harmonic field windings in order to reduce the harmonics in a power line. We derived the expressions of the armature voltage in the case of supplying the currents with the frequency nf to the d-axis and q-axis harmonic field windings. We constructed the synchronous machine adding the harmonic windings. In this paper, the expressions and the experimental results on the generation of harmonic voltages by the synchronous machine are presented.

• Journal of international Conference on Electrical Machines and Systems
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• 제3권2호
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• pp.132-138
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• 2014

We investigated the harmonic voltages generated by a synchronous machine adding d-axis and q-axis harmonic field windings to reduce the harmonics in a power line. First, electronic circuits such as a frequency multiplier, band-pass filter, and phase shifter were newly designed and made to carry out the experiment. Next, an experimental circuit, for which an AC voltage of frequency 6f synchronized to the power line voltage of frequency f could be obtained, was constructed to examine the generation of harmonic voltage in more detail. Finally, an experiment involving the generation of harmonic voltage was performed using an experimental synchronous generator with harmonic windings in the d-axis and q-axis. In this paper, the power spectrum and the waveforms of the harmonic voltages in the armature winding are presented. Moreover, the values calculated from theoretical expressions of harmonic voltages in armature winding are compared with the values obtained by the experiment.

• 한국광학회:학술대회논문집
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• 한국광학회 1989년도 제4회 파동 및 레이저 학술발표회 4th Conference on Waves and lasers 논문집 - 한국광학회
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• pp.250-254
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• 1989

Second-harmonic generation at a silver-electrolyte (0.1 M KCL + H2O) interface was enhanced by surface roughness. The intensity of the second-harmonic radiation was shown to be sensitive enough to detect molecular monolayers adsorbed on a silver surface.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.199.1-199.1
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• 2014

In nonlinear optics, the properties of nonlinear optical responses such as polarization and nonlinear analysis of the nonlinear surfaces were investigated using the jellium model by optical second harmonic generation. The nonlinear response of the Al metal surfaces were calculated using TDLDA. Band structure, lattice constant and bulk modulus of the Al metal were investigated. Effective potential and electron density were compared by changing different.

• 한국광학회:학술대회논문집
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• 한국광학회 2009년도 동계학술발표회 논문집
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• pp.361-362
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• 2009

High-order harmonics from gaseous atoms driven by an intense femtosecond laser pulse can form an attosecond pulse train. By selecting suitable harmonic generation conditions, the harmonic spectrum can be broad enough to form sub-hundred attoseconds. One serious limitation, however, comes from the inherent attosecond chirp originating from the harmonic generation process. We have proposed to compensate for the positive attosecond chirp by making use of negative group delay dispersion of a metallic x-ray filter or a gaseous medium. We generated 240-as pulses from neon and compressed them to 60 as after propagating through argon, close to the transform-limited duration of 47 as.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.225-227
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• 2002

In this paper, novel concept of a photovoltaic(PV) power generation system adding the function of active filter(AF) is proposed. Even PV power generation system can be treated to a harmonics source for the power distribution system, it is necessary that the function of AF system in grid connected PV power generation system. Active Filters intended for harmonic solutions are expending their functions from harmonic compensation of nonlinear loads into harmonic isolation between utilities and consumer, and harmonic damping throughout power distribution system. So, the PV system combined the function of AF system can be usefully applied in power distribution system. Here, the control strategy of PV-AF system is introduced.