• Title/Summary/Keyword: best constants

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Measurement of a refractive index and thickness of silicon-dioxide thin film on LCD glass substrate using a variable angle ellipsometry (가변 입사각 타원 해석법을 사용한 유리기판위의 이산화규소박막의 굴절율 및 두께 측정)

  • Pang, H. Y.;Kim, H. J.;Kim, S. Y.;Kim, B. I.
    • Korean Journal of Optics and Photonics
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    • v.8 no.1
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    • pp.31-36
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    • 1997
  • We measured refractive indices and thicknesses of SiO$_2$ thin films that have been plated on LCD glass substrate for the purpose of preventing the out-diffusion of sodium ions. The best experimental condition to determine refractive index and thickness of SiO$_2$ thin film by using ellipsometry is searched for, where ⅰ) the film thickness is increased uniformly by 20 $\AA$ from 0 $\AA$ to the period thickness while the angle of incidence is fixed and ⅱ) the angle of incidence is increased uniformly by 1$^{\circ}$ from 45$^{\circ}$ to 70$^{\circ}$ while the film thickness is fixed. We estimated the errors in determining the refractive index and thickness by comparing the measurement error of $\Delta$ and Ψ with the calculated one. The ellipsometric constants of SiO$_2$ thin film on LCD glass substrate are measured at several angle of incidence around the Brewster angle, which is the best angle if the experimental error of ellipsometer is not sensitive to the incident angle. Also the best fit refractive index and thickness of SiO$_2$ thin film to these ellipsometric constants measured at several angle of incidenc eas well as the best fit ones to the SE data are obtained using regressional analysis.

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Slip Movement Simulations of Major Faults Under Very Low Strength

  • Park, Moo-Choon;Han, Uk
    • Economic and Environmental Geology
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    • v.33 no.1
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    • pp.61-75
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    • 2000
  • Through modeling fault network using thin plate finite element technique in the San Andreas Fault system with slip rate over 1mm/year, as well as elevation, heat flow, earthquakes, geodetic data and crustal thickness, we compare the results with velocity boundary conditions of plate based on the NUVEL-1 plate model and the approximation of deformation in the Great Basin region. The frictional and dislocation creep constants of the crust are calculated to reproduce the observed variations in the maximum depth of seismicity which corresponds to the temperature ranging from $350^{\circ}C$ to $410^{\circ}C$. The rheologic constants are defined by the coefficient of friction on faults, and the apparent activation energy for creep in the lower crust. Two parameters above represent systematic variations in three experiments. The pattern of model indicates that the friction coefficient of major faults is 0.17~0.25. we test whether the weakness of faults is uniform or proportional to net slip. The geologic data show a good agreement when fault weakness is a trend of an additional 30% slip dependent weakening of the San Andreas. The results of study suggest that all weakening is slip dependent. The best models can be explained by the available data with RMS mismatch of as little as 3mm/year, so their predictions can be closely related with seismic hazard estimation, at least along faults where no data are available.

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Elastic properties of ion-assisted Cr films measured by brillouin light scattering (브릴루앙 산란 실험을 이용한 이온빔 보조 증착법의 Cr 박막의 탄성특성)

  • ;;;John R. Dutcher
    • Korean Journal of Optics and Photonics
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    • v.6 no.1
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    • pp.50-55
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    • 1995
  • We have performed Brillouin light scattering experiments to study the elastic properties of Cr films deposited on soda-lime glasses by using Ar-ion assisted deposition techniques. The elastic constants of the films increased as the ion-current density employed during the film deposition increases and they approached to the values of bulk Cr. The best fit values of the elastic constants of the films manufactured with ion current density of $400\muA/cm^{2}$are $c_{11}=296, c_{13}=83, c_{33}=289$, and $c_{55}=c_{44}=108(\times10^9/N/m^{2}}$ and these are 5% lower than those of bulk Cr in hexagonal symmetry. metry.

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Growth Properties of Sputtered ZnO Thin Films Affected by Oxygen Partial Pressure Ratio (산소분압비에 따른 ZnO 박막의 성장특성)

  • Kang, Man-Il;Kim, Moon-Won;Kim, Yong-Gi;Ryu, Ji-Wook;Jang, Han-O
    • Journal of the Korean Vacuum Society
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    • v.17 no.3
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    • pp.204-210
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    • 2008
  • ZnO thin films were grown on a glass by RF sputtering system with RF power 100W and oxygen partial pressure of $0%{/sim}30%$. Elliptic constants were measured by using a phase modulated spectroscopic ellipsometer and analyzed with the Tauc-Lorentz dispersion formula and best fit method in the range of 1.5 to 3.8eV. Also, scanning electron microscope(SEM) was used for the analysis of surface crystallization condition. From elliptic constants spectra, optical constants, thickness and roughness of ZnO films were evaluated. Total thickness of ZnO films obtained by ellipsometry showed good agreement with SEM data. It was found that the grain size of the films were getting smaller with increasing oxygen partial pressure. Band-gap of ZnO films increase with the oxygen partial pressure. These findings clearly indicate that optical properties of ZnO films are strongly dependent on the oxygen partial pressure. It could be explained that increasing the oxygen partial pressure induced high crystalline imperfection in the ZnO films.

Prediction of Vapor Pressure of the Inert Gases (비활성 기체의 증기압 예측)

  • Chung, Jaygwan-G.
    • Journal of the Korean Chemical Society
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    • v.47 no.6
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    • pp.541-546
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    • 2003
  • Experimental vapor pressure measurements available in the literature for the inert gases have been rigorously analyzed and used to evaluate the constants A, B, C, D, and exponent of the following equation in the form of reduced vapor pressure and reduced temperature : $InP_r=A+{\frac{B}{T_r}+CInT_r+DT_n^r}$ According to varying exponent n all four constants have been obtained for the inert gases by the error analysis. This has provided us the best n and four constants for each of the inert gases ; Argon, krypton, xenon, helium, and neon. In order to obtain the calculated vapor pressure by the above equation, only the normal boiling point and the critical pressure and critical temperature are necessary to get the vapor pressure for an overall average deviation of 0.31 % for 406 experimental vapor pressure points consisting of five gases available in the literature. The average deviation for argon, krypton, and xenon is 0.24%, 0.09%, and 0.22%, respectively, for neon 1.31% and for helium 0.61%. These results are not unexpected in view of the significant quantum effects associated with helium and to a lesser degree with neon.

A Study on Complexation of Cu(Ⅱ) Ion with Hydrazide Schiff Base Lignads (Cu(Ⅱ) 이온과 Hydrazide Schiff Base 리간드와의 착물형성에 관한 연구)

  • Cho, Hwee Kyung;Cha, Bun Hee;Hur, Young Ae;Choi, Kyu Seong
    • Journal of the Korean Chemical Society
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    • v.39 no.4
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    • pp.281-287
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    • 1995
  • Copper(Ⅱ) complexes with N,N'-oxalylbis(salicylaldehydehydrazone), N,N'-malonylbis(salicylaldehydehydrazone) and N,N'-succinylbis(salicylaldehydehydrazone) have been prepared in 95% DMF. Their protonation and stability constants were investigated by potentiometric titration. We observed that MBSH ligand showed the largest protonation constant. The values of the protonation constants among three different ligands were increased as following order SBSH < OBSH < MBSH. However, the increasing order of stability constants was somewhat different such as Cu(Ⅱ)-SBSH < Cu(Ⅱ)-MBSH < Cu(Ⅱ)-OBSH. In addition, thermodynamic parameters, ΔH and ΔS of Cu(Ⅱ) complexes have been studied. As a result, we found the SBSH ligand produced the best stable copper (Ⅱ) complex.

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Evaluation of Regression Models with various Criteria and Optimization Methods for Pollutant Load Estimations (다양한 평가 지표와 최적화 기법을 통한 오염부하 산정 회귀 모형 평가)

  • Kim, Jonggun;Lim, Kyoung Jae;Park, Youn Shik
    • Proceedings of the Korea Water Resources Association Conference
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    • 2018.05a
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    • pp.448-448
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    • 2018
  • In this study, the regression models (Load ESTimator and eight-parameter model) were evaluated to estimate instantaneous pollutant loads under various criteria and optimization methods. As shown in the results, LOADEST commonly used in interpolating pollutant loads could not necessarily provide the best results with the automatic selected regression model. It is inferred that the various regression models in LOADEST need to be considered to find the best solution based on the characteristics of watersheds applied. The recently developed eight-parameter model integrated with Genetic Algorithm (GA) and Gradient Descent Method (GDM) were also compared with LOADEST indicating that the eight-parameter model performed better than LOADEST, but it showed different behaviors in calibration and validation. The eight-parameter model with GDM could reproduce the nitrogen loads properly outside of calibration period (validation). Furthermore, the accuracy and precision of model estimations were evaluated using various criteria (e.g., $R^2$ and gradient and constant of linear regression line). The results showed higher precisions with the $R^2$ values closed to 1.0 in LOADEST and better accuracy with the constants (in linear regression line) closed to 0.0 in the eight-parameter model with GDM. In hence, based on these finding we recommend that users need to evaluate the regression models under various criteria and calibration methods to provide the more accurate and precise results for pollutant load estimations.

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우주급 경통 열-흡습 설계

  • Lee, Deog-Gyu
    • Aerospace Engineering and Technology
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    • v.4 no.1
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    • pp.108-113
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    • 2005
  • Strucutral and hygrothermal analysis for a composite tube is carried out in this study, that provides critical parameters for the design of a highly dimensionally stable space telescope. Carpet plots for laminate effective engineering constants are generated and used for the best tube lay-ups with high elastic modulus and highly insensitive to thermal and moisture expansion, which is essential for maintaining optical alignment of opto-mechanical system under random force applied during a launch campaign and orbital thermal load. Despace in the longitudinal direction under hygrothermal load of the tubes constructed with the selected lay-ups is calculated for the validation of lay-up designs on the dimensionalstability. Dynamic analysis is also carried out to feature the resonant behaviour. A zig-zag triangular element accurately representing through thickness stress variations for laminated structures is developed in this study and incorporated into the structural and hygrothermal analysis.

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Density Functional Theory Calculations for Chemical Reaction Mechanisms of C4F8

  • Choe, Hui-Cheol;Song, Mi-Yeong;Yun, Jeong-Sik
    • Proceedings of the Korean Vacuum Society Conference
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    • 2015.08a
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    • pp.133-133
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    • 2015
  • Recently, it has been shown that the ${\omega}B97X-D/aVTZ$ method is strongly recommended as the best practical density functional theory(DFT) for rigorous and extensive studies of saturated or unsaturated $C_4F_8$ species because of its high performance and reliability especially for van der Waals interactions. All the feasible isomerization and dissociation paths of $C_4F_8$ molecules were investigated at this theoretical level and rate constants of their chemical reactions were computed by using variational transition-state theory for a deep insight into $C_4F_8$ reaction mechanisms. Fates and roles of C4F8 molecules and their fragments in plasma phases could be clearly explained based on our computational results.

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A Simpler Method to Estimate the Elastic Constant of Collagen-like Microfibril Using Voigt-Reuss Bounds (복합재료역학을 이용한 콜라겐 단백질 마이크로피브릴의 탄성율 예측 개선)

  • Yoon, Young-June;Bae, Cheol-Soo
    • Journal of Biomedical Engineering Research
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    • v.31 no.3
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    • pp.194-198
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    • 2010
  • The effective Young’s modulus of a microfibril surrounded by water may be simply calculated by using the upper (Voigt) and lower (Reuss) bounds, which is one way to estimate the Young’s modulus in composite materials. The Steered Molecular Dynamics (SMD) has been used for estimating the Young’s modulus of a microfibril surrounded by water. In this paper, the result estimated by the upper (Voigt) and lower (Reuss) bounds shows 9.2% to 21.8% discrepancy from the result estimated by SMD, but introducing “efficiency of reinforcement parameter” removes the discrepancy and shows good agreement with the result estimated by SMD. We found the best fit for the Young’s modulus against the size of the gap between microfibrils. Also the steps using these bounds are much simpler than SMD.