• Title/Summary/Keyword: Lorentz Model

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Analysis of patterned ITO layer of PDP thin films using spectroscopic ellipsometry (분광타원법을 이용한 PDP용 ITO 박막의 패턴 분석)

  • 윤희삼;김상열
    • Korean Journal of Optics and Photonics
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    • v.14 no.3
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    • pp.272-278
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    • 2003
  • We studied patterned ITO layers of PDP thin films on glass substrates using spectroscopic ellipsometry. The optical property of ITO is expressed with the optical model based on two Lorentz oscillators. The effect of patterned ITO is calculated by taking the weighted average of reflectance in proportion to ITO coverage. The relative coverage of ITO is determined by using the model analysis of spectroellipsometric data. The difference of ITO coverage obtained by the best-fit model analysis of ellipsometric spectra to the expected one is critically examined and suggestions are made to minimize the observed discrepancy.

A Study of Lorentz-Meutzner's Two Evaporator Refrigeration System Using Alternative Refrigerant Mixtures (대체혼합냉매를 사용하는 Lorentz-Meutzner의 이중 증발기 냉동 시스템의 성능에 관한 연구)

  • Park, Y.M.
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.4 no.2
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    • pp.123-136
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    • 1992
  • A preliminary thermodynamic design model of two-evaporator refrigerator/freezer system is constructed. This system is based on Lorentz-Meutzner cycle using refrigerant mixtures. This model screens alternative refrigerant (R32, R125, R143a, R22, R134a, R152a, R124, R142b, R123) mixtures to select the best performance-giving refrigerant mixtures and its composition for the system. Also, it estimates the effects of cooling temperatures of intercoolers, evaporator's area ratio, cooling load ratio on the performance of the system. The COP of the system ranges from 1.4 to 1.6, which is superior to that of the single evaporator system charged with R12 by 13% to 29%. Among 15 mixtures, R22/R123, R143a/R123, R32/R142b, and R32/R124 (in the order of high COP) are most recommendable. For the case of R22/R123, R22 mass fraction more than 0.5(Load Ratio=1.0) or 0.7(Load Ratio=0.33) is recomended in order to replace R12 without reduction in volumetric capacity when keeping the compressor as the same one. COP has the highest value with X(R22)=0.7 and 0.8, respectively. For the case of R143a/R123, in the similar manner, mass fraction of R143a is more than 0.5 or 0.6 while best performance occurs at X(R143a)=0.8. Higher temperature intercooler is more important for the performance of the system than lower temperature intercooler. The area ratio of evaporators is roughly proportional to load ratio of the evaporators.

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ANALYSES OF ANNULAR LINEAR INDUCTION PUMP CHARACTERISTICS USING A TIME-HARMONIC FINITE DIFFERENCE ANALYSIS

  • Seong, Seung-Hwan;Kim, Seong-O
    • Nuclear Engineering and Technology
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    • v.40 no.3
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    • pp.213-224
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    • 2008
  • The pumping of coolant in a liquid metal fast reactor may be performed with an annular linear induction electro-magnetic (EM) pump. Linear induction pumps use a traveling magnetic field wave created by poly-phase currents, and the induced currents and their associated magnetic field generate a Lorentz force, whose effect can be the pumping of the liquid metal. The flow behaviors in the pump are very complex, including a time-varying Lorentz force and pressure pulsation, because an induction EM pump has time-varying magnetic fields and the induced convective currents that originate from the flow of the liquid metal. These phenomena lead to an instability problem in the pump arising from the changes of the generated Lorentz forces along the pump's geometry. Therefore, a magneto-hydro-dynamics (MHD) analysis is required for the design and operation of a linear induction EM pump. We have developed a time-harmonic 2-dimensional axisymmetry MHD analysis method based on the Maxwell equations. This paper describes the analysis and numerical method for obtaining solutions for some MHD parameters in an induction EM pump. Experimental test results obtained from an induction EM pump of CLIP-150 at the STC "Sintez," D.V. Efremov Institute of Electro-physical Apparatus in St. Petersburg were used to validate the method. In addition, we investigated some characteristics of a linear induction EM pump, such as the effect of the convective current and the double supply frequency (DSF) pressure pulsation. This simple model overestimated the convective eddy current generated from the sodium flow in the pump channel; however, it had a similar tendency for the measured data of the pump performance through a comparison with the experimental data. Considering its simplicity, it could be a base model for designing an EM pump and for evaluating the MHD flow in an EM pump.

Spectroscopic Ellipsometry Measurement and Modeling of Hydrogenated Amorphous Silicon (수소화된 비정질 실리콘의 타원편광분광분석 측정 및 모델링)

  • Kim, Ka-Hyun
    • Journal of the Korean Solar Energy Society
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    • v.39 no.1
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    • pp.11-19
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    • 2019
  • Spectroscopic ellipsometry is a powerful tool for analyzing optical properties of material. Ellipsometry measurement results is usually given by change of polarization state of probe light, so the measured result should be properly treated and transformed to meaningful parameters by transformation and modeling of the measurement result. In case of hydrogenated amorphous silicon, Tauc-Lorentz dispersion is usually used to model the measured ellipsometry spectrum. In this paper, modeling of spectroscopic ellipsometry result of hydrogenated amorphous silicon using Tauc-Lorentz dispersion is discussed.

자성 유체 역학에 의한 광자기-굴절률 통합시도

  • Kim, Myeong-Jun
    • Proceedings of the Optical Society of Korea Conference
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    • 2008.07a
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    • pp.215-216
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    • 2008
  • Electricity unified field is described based on magnetic theory. Maxwell Einstein Lorentz Equation & pair particle photon model was introduced for Photonics. Refractive index is calculated as deceleration and deflection of photon due to photo-induced surface magnetism. MEL equation was proved with magneto-jet assumption.

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Radiated Electromagnetic Field Calculation due to Arc Discharge according to Speed of High Speed Train (고속철도의 속도에 따른 아크에 의한 전자파 방사 계산)

  • Han, In-Su;Lee, Tae-Hyung;Cho, Hong-Shik;Park, Choon-Soo;Kim, Ki-Hwan
    • Proceedings of the KSR Conference
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    • 2011.05a
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    • pp.98-100
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    • 2011
  • High speed Train Systems are the energy supplied system via the pantograph through which the voltage and the current supplied by the catenary wire flow. The arc discharges generate owing to the contact loss between the catenary and the pantograph, and the electromagnetic fields radiate. There are many different phenomena between the static charges and the moving charges in view of the radiated electromagnetic fields. To calculate the electromagnetic filed about the moving charges, it is necessary to adapt Lorentz transformation. Actually, the particle which moves near the speed of light has the relativisitic phenomena. In addition, it is necessary to predict the electromagnetic field because the radiated electromagnetic field takes effect on the near electronic devices and the human beings. In this paper, we model the arc discharge into the dipole antenna model, adapt Lorentz transformation to the case that the electric railway cars move, and calculate the radiated electromagnetic field. By the calculation, we take the basis upon the electromagnetic prediction, and apply to the future research.

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Optical Study of BaSm2Ti4O12 by Vacuum Ultra Violet Spectroscopic Ellipsometry (Vacuum Ultra Violet Spectroscopic Ellipsometry를 이용한 BaSm2Ti4O12의 광 특성 연구)

  • Hwang, S.Y.;Yoon, J.J.;Jung, Y.W.;Byun, J.S.;Kim, Y.D.;Jeong, Y.H.;Nahm, S.
    • Journal of the Korean Vacuum Society
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    • v.18 no.1
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    • pp.60-65
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    • 2009
  • We performed a study on optical properties of $BaSm_2Ti_4O_{12}$ thin films by vacuum ultra violet spectroscopic ellipsometry in the $0.92{\sim}8.6\;eV$ energy range. For the analysis of the measured ellipsometric spectra, a 5-layer model was applied where optical property of the $BaSm_2Ti_4O_{12}$ layer was well represented by a Tauc-Lorentz dispersion function. Our analysis clearly showed new structure in high energy region at about 7.5 eV Consistent changes of refractive index & extinction coefficient of the $BaSm_2Ti_4O_{12}$ thin film by the growth and annealing temperatures were also confirmed.

Intelligent Digital Redesign for Uncertain Nonlinear Systems Using Power Series (Powrer Series를 이용한 불확실성을 갖는 비선형 시스템의 지능형 디지털 재설계)

  • Sung Hwa Chang;Park Jin Bae;Go Sung Hyun;Joo Young Hoon
    • Journal of the Korean Institute of Intelligent Systems
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    • v.15 no.7
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    • pp.881-886
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    • 2005
  • This paper presents intelligent digital redesign method of global approach for hybrid state space fuzzy-model-based controllers. For effectiveness and stabilization of continuous-time uncertain nonlinear systems under discrete-time controller, Takagi-Sugeno(TS) fuzzy model is used to represent tile complex system. And global approach design problems viewed as a convex optimization problem that we minimize the error of the norm bounds between nonlinearly interpolated linear operators to be matched. Also, by using the power series, we analyzed nonlinear system's uncertain parts more precisely. When a sampling period is sufficiently small, the conversion of a continuous-time structured uncertain nonlinear system to an equivalent discrete-time system have proper reason. Sufficiently conditions for the global state-matching of tile digitally controlled system are formulated in terms of linear matrix inequalities (LMIs). Finally, a TS fuzzy model for the chaotic Lorentz system is used as an example to guarantee the stability and effectiveness of the proposed method.

Heat transfer enhancement in gas tungsten arc welding using azimuthal magnetic fields generated by external current

  • Kim, Yiseul;Lee, Jaewook;Liu, Xiaolong;Lee, Boyoung;Chang, Yunlong
    • Coupled systems mechanics
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    • v.6 no.2
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    • pp.113-125
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    • 2017
  • This paper proposes the idea to enhance the heat transfer in Gas Tungsten Arc Welding (GTAW) by using the azimuthal magnetic field. The azimuthal magnetic field generated by the external currents makes the Lorentz force stronger, and consequently improves the heat transfer by the faster flow movement. The enhanced heat transfer might improve the welding performance by increasing the temperature at the workpiece. To validate the proposed idea, a two-dimensional axi-symmetric model of GTAW is built, and the multiphysics simulation of GTAW is carried out. As the analysis result, the distributions of electric current, electromagnetic fields, arc flow velocity, and temperature are investigated. Then, the proposed idea for heat transfer enhancement is validated by comparing the Lorentz force, flow velocity, and temperature distribution with and without azimuthal magnetic fields.