• The Journal of Engineering Geology
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• v.29 no.3
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• pp.303-314
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• 2019

Surface permeability and shallow geological structures play significant roles in shaping the groundwater recharge of shallow aquifers. Surface permeability can be characterized by two concepts, intrinsic permeability and hydraulic conductivity, with the latter obtained from previous near-surface geological investigations. Here we propose a hydraulic equation via the cross-correlation analysis of the rainfall-groundwater levels using a regression equation that is based on the cross-correlation between the grain size distribution curve for unconsolidated sediments and the rainfall-groundwater levels measured in the Gyeongju area, Korea, and discuss its application by comparing these results to field-based aquifer test results. The maximum cross-correlation equation between the hydraulic conductivity derived from Zunker's observation equation in a sandy alluvial aquifer and the rainfall-groundwater levels increases as a natural logarithmic function with high correlation coefficients (0.95). A 2.83% difference between the field-based aquifer test and root mean square error is observed when this regression equation is applied to the other observation wells. Therefore, rainfall-groundwater level monitoring data as well as aquifer test are very useful in estimating hydraulic conductivity.

• Journal of applied mathematics & informatics
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• v.26 no.3_4
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• pp.471-479
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• 2008

Let $R\;{\in}\;C^{m{\times}m}$ and $S\;{\in}\;C^{n{\times}n}$ be nontrivial unitary involutions, i.e., $R^*\;=\;R\;=\;R^{-1}\;{\neq}\;I_m$ and $S^*\;=\;S\;=\;S^{-1}\;{\neq}\;I_m$. We say that $G\;{\in}\;C^{m{\times}n}$ is a generalized reflexive matrix if RGS = G. The set of all m ${\times}$ n generalized reflexive matrices is denoted by $GRC^{m{\times}n}$. In this paper, an efficient method for the least squares solution $X\;{\in}\;GRC^{m{\times}n}$ of the matrix equation AXB = D with arbitrary coefficient matrices $A\;{\in}\;C^{p{\times}m}$, $B\;{\in}\;C^{n{\times}q}$and the right-hand side $D\;{\in}\;C^{p{\times}q}$ is developed based on the canonical correlation decomposition(CCD) and, an explicit formula for the general solution is presented.

• Proceedings of the KOSOMBE Conference
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• v.1994 no.12
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• pp.142-146
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• 1994

This paper proposes an fill-factor algorithm that determines embedding parameters which are needed in optimal attractor reconstruction. For reliability test, using this algorithm, we reconstructs the attractor of numerical chaotic data such as Duffing equation, Lorenz equation and Rossler equation whose embedding parameters are known. Also we reconstructs the attractor of experimental data and evaluates correlation dimension. Experimental data used in this paper are 38 ECG data of AHA(American Heart Association) ECG database. For numerical chaotic data, correlation dimension and Lyapunov exponent of reconstructed attractor are very close to those of attractor using original coordinate system.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.33.5-33
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• 2001

We consider here the problem of spectral estimation of multidimensional wide sense stationary (WSS) random process. A method, employing a special difference equation of correlation function, is proposed to solve the problem of multidimensional spectral estimation. In this approach, the special difference equation of correlation function is derived by modal decomposition method. Maximum likelihood estimator and Kalman filter are used to estimate the model parameters of the difference equation and the decomposed spectral residues. An algorithm is presented to estimate the multidimensional spectral density. According to the result of the simulation, these methods are feasible to estimate the spectral density of WSS process, which is realized by finite dimensional multivariable lineal system driven by white noise.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.106.2-106
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• 2001

The two typical composite operations of fuzzy relation are the max-min and the min-max composite operations. It is known that the two operations can be completely dual. This paper pays attention to the nature that these two typical operations are completely dual and investigates the correlation between the max-min composite relation equation and the min-max composite relation equation. An important scheme of correlation is in the characteristic of solution sets derived from these two fuzzy relation equations. The paper explains that one of the composite fuzzy relation equations is solvable using the solution method of the other fuzzy relation equation. The above-mentioned duality plays an important role in this solution procedure. Since it is not necessary to build the solution method separately like before, calculation efficiency can be raised. Moreover, the solution for the relation ...

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2004.10a
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• pp.369-374
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• 2004

Web-based analysis programs for reliability assessment of machine tools were developed in this study. First, the reliability data analysis program was developed to search for failure rate using failure data and reliability test data of mechanical part. Second, failure mode analysis was developed through performance tests like circular movement test vibration test for machine tools. This analysis program shows correlation between failure mode and performance test result. Third, tool life was predicted by correlation between flank wear and cutting time, using the extended Taylor tool life equation in turning data and the equivalently converted equation in order to apply ball endmill data to Taylor tool life equation in milling data. All the information related to input and result data can be stored in theses programs.

• Bulletin of the Korean Chemical Society
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• v.31 no.11
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• pp.3366-3370
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• 2010

The specific rates of solvolysis of t-butyl fluoroformate (1) have been measured at $40.0^{\circ}C$ in 21 pure and binary solvents. These give a satisfactory correlation over the full range of solvents when the extended Grunwald-Winstein equation, with incorporation of the solvent nucleophilicity and the solvent ionizing power, is applied. The actual values are very similar to those obtained in earlier studies of the solvolyses of isopropyl chloroformate and ethyl chlorothioformate in the more ionizing and least nucleophilic solvents, which are believed to proceed by an ionization pathway. The small negative values for the entropies of activation are consistent with the ionization nature of the proposed rate-determining step. These observations are also compared with those previously reported for the corresponding primary and secondary alkyl haloformate esters.

• Bulletin of the Korean Chemical Society
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• v.30 no.2
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• pp.378-382
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• 2009

Rates of solvolyses of benzhydryl chloride ($Ph_2$CHCl, 1) and benzhydryl bromide ($Ph_2$CHBr, 2) in ethanol, methanol, and aqueous binary mixtures incorporating ethanol, methanol, 2,2,2-trifluoroethanol (TFE) and acetone are reported. Solvolyses were also carried out in TFE-ethanol mixtures. Application of the extended Grunwald-Winstein equation led to l value of 1.19 (1), 1.29 (2) and m value of 1.00 (1), 0.77 (2), correlation coefficient of 0.965 (1) and 0.970 (2). Sensitivities (l = 1.19 (1), 1.29 (2) and m = 1.00 (1), 0.77 (2)) were similar to those obtained for several previously studied solvolyses, in which an $S_N$2 pathway is proposed for the solvolyses of benzhydryl halides ($Ph_2$CHX, X = Cl or Br).

• Journal of the Korea institute for structural maintenance and inspection
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• v.1 no.1
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• pp.97-105
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• 1997

The major object of this study is to analyze and investigate experimentally the experimenal equation for the estimate of compressive strength of concrete. The results are as follows. The relation between maturity scaled logarithm and compressive strength of concrete can be expressed in liner equation which show an good correlation. And combined method using rebound number, pulse velocity and water cement ratio also show an excellent correlation. The equation by combined method is same as the conclusions.

• Journal of Environmental Health Sciences
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• v.7 no.1
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• pp.9-20
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• 1981

This study was performed to determine the correlationship between temperature and overall removals of BOD, SS and to demonstrate the effect of temperature on treatment performance. These data for a period from February 1, 1977 to January 31, 1980 were obtained from the Cheong-Gye Cheon Sewage Treatment plant. The results of correlation and stepwise multiple regression analysis were as follows. 1) Secondary effluent BOD and SS showed negative correlationship with water temperature, with correlation coefficient of -0.1710, and -0.1654 respectively. 2) Correlation coefficient of BOD, SS removal rate and water temperature were 0.1823 and 0.0429 respectively. 3) Regresion equation for estimate of BOD removal rate was as follows $\widehat{Y}_1$ (BOD removal rate)=63.9994+0.5442X(water temperature). And BOD removal rate showed non significant change according to the water temperature. 4) Regression equation for estimate of SS removal rate was as follows $\widehat{Y}_2$ (SS removal rate)=61.6881+0.1514X(Water temperature). And SS removal rate showed non significant change according to the water temperature. 5) According to the Stepwise Multiple Regression analysis, water temperature ranked second order in the BOD removal rate estimation and the equation was as follows $\widehat{Y}_1$ (BOD removal rate)=69.7398+0.2665 $X_1$ (Primary effluent BOD)+0.3562 $X_2$ (Water temperature)-0.0122 $X_3(Flow)+4413.271X_4$ (Organic Loading).