• 대한전자공학회논문지
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• 제9권5호
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• pp.12-18
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• 1972

정현 신호 및 zero 평균 정상 정규 잡음의 협대역파 신호를 갖는 n차 반파 zero기억형 비선형 장치의 출력 SN 비 및 m차 고조파 발생의 관계를 밝혔다. 최대 출력 SN비는 소 신호 입력에서 m=n=2 이었으며 대 신호 입력에선 항시 n=2이었다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2010년도 하계학술대회 논문집
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• pp.232-233
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• 2010

This paper investigates occupational exposure to time-varying magnetic field generation in high power rectifier systems. Two different kinds of high power rectifier systems of 25kA are modeled and analyzed. The performance is compared and evaluated on the basis of exposure guidelines from ICNIRP. In order to focus on the qualitative effect of rectifier operation, the mechanical structure of current carrying conductors is simplified as infinite long bus-bar model and low frequency harmonic contents up to 65kHz are considered. Thyristor rectifier generates a significant amount of low frequency magnetic field harmonic contents both at ac and dc side of rectifier infringing the limit from ICNIRP. The multilevel rectifier-IGCT type has almost negligible field generation from ac input side and smaller harmonic contents in dc load side complying with ICNIRP guideline. This remarkable advantage of multilevel rectifier-IGCT type can lead to very simple site layout design for installation and cost-effective compliance to guideline of occupational exposure against magnetic field.

• The Korean Journal of Ceramics
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• 제6권3호
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• pp.206-208
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• 2000

0.65 mol% MgO-doped LiNbO$_3$single crystals were grown by CZ method. The obtained single crystals were colorless and transparent. Noncritically phase-matched second harmonic generation (SHG) of 532-nm radiation from 1064-nm in MgO-doped LiNbO$_3$has been investigated by using pulsed Nd:YAG laser. The phase-matching temperature was room temperature. SHG conversion efficiencies were typically achieved higher than 50% at the phase-matching temperature with no photorefractive damage in the region of fundamental power density which was used in this experiment. The thermo-birefringence coefficient and the electro-birefringence coefficient of SHG were calculated from the temperature phase-matching profile with the electric field.

• Journal of the Optical Society of Korea
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• 제10권4호
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• pp.188-195
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• 2006

Third harmonic generation microscopy is described in the frame work of the theory of harmonic generation with Gaussian focused beams inside a bulk material as well as at the vicinity of an interface. This model is then applied to characterize different types of materials in terms of electronic third-order susceptibility. Examples of bulk glasses, poled glasses, laser-induced modifications in glasses and nanoparticles in solution are given in order to give a survey of the broad application field of THG microscopy in material characterization.

• 한국광학회지
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• 제10권4호
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• pp.301-305
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• 1999

Czocharlski pulling method에 의해 성장된 새로운 광학결정 YCOB($YCa_4O(BO_3)_3$)의 파장에 따른 위상 정합 조건을 제시하였으며, Nd:YAG 레이저의 1064nm의 출력을 기본파로 하였을 때 제2조화파 발생 효율을 조사하였다. 또한 $Yb^{3+}$이온과 $Nd^{3+}$ 이온이 도핑된 YCOB의 제2조화파 발생효율을 조사하여 희토류 이온 도핑에 따른 비선형성의 변화를 조사하였다.

• 자연과학논문집
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• 제12권1호
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• pp.31-39
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• 2002

전류밀도와 에칭시간을 변화시키면서 제작된 다공질 규소 초격자의 표면에서 Nd:YAG 레이저의 제2 고조파를 발생시켰다. 이로부터 대칭구조가 바뀌고 유전율이 상승됨이 관측되었다.

• Journal of Power Electronics
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• 제19권5호
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• pp.1289-1302
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• 2019

In this paper, an optimal allocation method of a hybrid active power filter in an active distribution network is designed based on the differential evolution algorithm to resolve the harmonic generation problem when a distributed generation system is connected to the grid. A distributed generation system model in the calculation of power flow is established. An improved back/forward sweep algorithm and a decoupling algorithm are proposed for fundamental power flow and harmonic power flow. On this basis, a multi-objective optimization allocation model of the location and capacity of a hybrid filter in an active distribution network is built, and an optimal allocation scheme of the hybrid active power filter based on the differential evolution algorithm is proposed. To verify the effect of the harmonic suppression of the designed scheme, simulation analysis in an IEEE-33 nodes model and an experimental analysis on a test platform of a microgrid are adopted.

• Current Optics and Photonics
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• 제2권6호
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• pp.606-611
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• 2018

Measurement of the nonlinear optical coefficients is not an easy task since it requires complicated experimental setup and analysis. We suggest an easy way to estimate the relative nonlinear optical tensor components by direct measurement of the output powers of the second harmonic generation and spontaneous parametric down conversion experiments. The experiments were done in quasi-phase-matched type-0 as well as type-1 interactions at similar pump wavelengths in a 5% MgO-doped periodically poled $LiNbO_3$ crystal to obtain the ratio of the nonlinear optical tensor components $d_{33}/d_{31}$ in each experiment. The obtained ratios were then compared with the previously ascertained values [J. Opt. Soc. Am. B, 14, 2268-2294 (1997)].

• 한국전기전자재료학회논문지
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• 제18권1호
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• pp.81-88
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• 2005

The Langmuir monolayers of polyamic acid salts with three kinds of alkyl chains have been investigated by means of conventional $\pi$-A isotherms and second harmonic generation measurements proposed in this paper. The surface molecular density dependence of second harmonic intensity clearly shows the region of aggregation while corresponding $\pi$-A isotherm doesn't show any changes in the surface morphology at the same region. The surface morphology analysis based on the second harmonic measurement was consistent with the Brewster angle microscope measurement results.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2015년도 전력전자학술대회 논문집
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• pp.53-54
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• 2015

A new simple and effective scheme to improve power quality for a grid-connected inverter in distributed generation systems under distorted grid voltages will be presented. The proposed scheme is constructed with two controllers to regulate fundamental and harmonic components separately. In order to accomplish the proposed control scheme, the fourth order band pass filter is used to extract harmonic components from distorted gird voltages. Then, the undesired harmonic components are excellently suppressed by proportional decoupling controller. Experimental results are presented to verify the simplicity and effectiveness of proposed scheme.