• Geomechanics and Engineering
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• 제20권1호
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• pp.1-7
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• 2020

In structures excavated in rock mass, load progressively increases to a level and remains constant during the construction. Rocks display different elastic properties such as E_i and ʋ under different loading conditions and this requires to use the true values of elastic properties for the design of safe structures in rock. Also, rocks will undergo horizontal and vertical deformations depending on the amount of load applied. However, under constant loads, values of E_i and ʋ will vary in time and induce variations in the behavior of the rock mass. In some empirical equations in which deformation modulus of the rock mass is taken into consideration, elastic parameters of intact rock become functions in the equation. Hence, the use of time dependent elastic properties determined under constant loading will yield more reliable results than when only constant elastic properties are used. As well known, rock material will play an important role in the deformation mechanism since the discontinuities will be closed due to the load. In this study, E_i and ʋ values of intact rocks were investigated under different constant loads for certain rocks with high deformation capabilities. The results indicated significant time dependent variations in elastic properties under constant loading conditions. E_i value obtained from deformability test was found to be higher than the E_i value obtained from the constant loading test. This implies that when static values of elastic properties are used, the material is defined as more elastic than the rock material itself. In fact, E_i and ʋ values embedded in empirical equations are not static. Hence, this workattempts to emerge a new understanding in designing of safer structures in rock mass by numerical methods. The use of time-dependent values of E_i and ʋ under different constant loads will yield more accurate results in numerical modeling analysis.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1998년도 춘계학술대회 논문집
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• pp.183-189
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• 1998

In this paper, The load characteristics on the voltage gain and efficiency were analyzed sing an lumped constant equivalent circuit of the piezoelectric transformer. These analytical results are confirmed by experiments. Theoretical values of voltage gain were nearly constant with experimental ones. However, It was shown that theoretical values of efficiency had higher values than experimental ones.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2015년도 추계학술대회
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• pp.1045-1046
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• 2015

When using the Support Vector Machine in the online signature verification, SVM kernel function should be chosen to use non-linear SVM and the constant parameters in the kernel functions should be adjusted to appropriate values to reduce the error rate of signature verification. Non-linear SVM which is built on a strong mathematical basis shows better performance of classification with the higher discrimination power. However, choosing the kernel function and adjusting constant parameter values depend on the heuristics of the problem domain. In the signature verification, this paper deals with the problems of selecting the correct kernel function and constant parameters' values, and shows the kernel function and coefficient parameter's values with the minimum error rate. As a result of this research, we expect the average error rate to be less than 1%.

• 한국전기전자재료학회논문지
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• 제11권10호
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• pp.849-854
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• 1998

The load characteristics on the voltage gain and efficiency were analyzed using a lumped constant equivalent circuit of the piezoelectric transformer. These analytical results were confirmed by experiments. Theoretical values of voltage gain were nearly constant with experimental ones. However, It was shown that theoretical values of efficiency is higher than experimental ones.

• Bulletin of the Korean Chemical Society
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• 제9권3호
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• pp.179-182
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• 1988

A simple correlation between cross interaction constants ${\rho}_{ij}$ and bond lengths in the transition state was obtained ; it has been shown that ${\rho}_{ij}$ corresponds to force constant of activation, which in turn is related to bond length by Badger's rule involving only universal constants. A satisfactory correlation between 4-31G ab initio calculated values of bond length and force constant for C-X streching in the transition state of the methyl transfer reaction, $X^-\;+\;CH_3X\;=\;XCH_3\;+\;X^-$, indicated that Badger's rule can be extended to bonds in the transition state. Independence of ${\rho}_{ij}$ values from the variable charge transmission of reaction centers has been demonstrated with nearly constant, experimentally determined I${\rho}$XYI values, and hence similar degree of bond formation, for various $S_N2$ reactions.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 추계학술대회논문집 II
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• pp.1347-1352
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• 2001

In this study, the acoustic properties of polyester sound absorbing materials with three different bulk densities were investigated by calculating and measuring the acoustic parameters in terms of characteristic impedance, propagation constant, and absorption coefficient. For the calculations, Delany and Bazley's empirical equation was used together with the experimentally obtained specific flow resistivities under steady flow conditions. For the experimental measurements, the well-known two-thickness method was accessed. The experimentally measured values of characteristic impedance and propagation constant were generally agreed well with the corresponding calculated values. Based on the comparisons between the calculations and measurements, it was found that the magnitude of the absorption coefficient was closely related to the characteristic impedance and the real part of the propagation constant. Especially, the maximum magnitude of the absorption coefficient was depended upon the imaginary part of the propagation constant indicating the phase change of the propagation constant.

• Bulletin of the Korean Chemical Society
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• 제27권5호
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• pp.718-724
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• 2006

The heterogeneous association behaviour of various concentration binary mixtures of mono alkyl ethers of ethylene glycol with ethyl alcohol were investigated by dielectric measurement in benzene solutions over the entire concentration range at 25 ${^{\circ}C}$. The values of static dielectric constant $\epsilon_0$ of the mixtures were measured at 1 MHz using a four terminal dielectric liquid test fixture and precision LCR meter. The high frequency limiting dielectric constant $\epsilon_\infty$ values were determined by measurement of refractive index $n_D$ ($\epsilon_\infty\;=\;n_D\;^2$). The measured values of $\epsilon_0$ and $\epsilon_\infty$ were used to evaluate the values of excess dielectric constant $\epsilon^E$, effective Kirkwood correlation factor $g^{eff}$ and corrective correlation factor $g_f$ of the binary polar mixtures to obtain qualitative and quantitative information about the H-bond complex formation. The non-linear behaviour of the observed $\epsilon_0$ values of the polar molecules and their mixtures in benzene solvent confirms the variation in the associated structures with change in polar mixture constituents concentration and also by dilution in non-polar solvents. Appearance of the maximum in $\epsilon^E$ values at different concentration of the polar mixtures suggest the formation of stable adduct complex, which depends on the molecular size of the mono alkyl ethers of ethylene glycol. Further, the observed $\epsilon^E$ < 0 also confirms the heterogeneous H-bond complex formation reduces the effective number of dipoles in these polar binary mixtures. In benzene solutions these polar molecules shows the maximum reduce in effective number of dipoles at 50 percent dilutions. But ethyl alcohol rich binary polar mixtures in benzene solvent show the maximum reduce in effective number of dipoles in benzene rich solutions.

• 한국정보통신학회논문지
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• 제10권12호
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• pp.2157-2165
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• 2006

항등 비트율 서비스를 위한 대표적인 이용자 트래픽 통제 알고리즘인 GCRA에 있어서 네트워크의 과부하와 전송 도중 불가피하게 발생하는 전송지연 변동에 따른 이용자 트래픽의 과도한 손실을 방지하기 위해서는 적절한 전송 지연변동 허용치의 설정이 매우 중요하다. 본 논문에서는 항등 비트율의 소스 트래픽에 대한 GCRA 순응검사에서 지연변동 허용치의 범 위에 따른 GCRA의 성능을 여러 측면에서 분석하고 적절한 지연변동 허용치 설정을 위한 가이드라인을 제시한다.

• 대한화학회지
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• 제57권2호
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• pp.279-288
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• 2013

이 연구에서는 1945년 교수요목기부터 2009 개정 교육과정까지 개발된 화학 교과서에서 강산의 이온화도와 이온화 상수 값이 어떻게 제시되었는지 분석하였다. 또한 설문지를 통해 화학 교사들에게 수용액에서 강산의 세기를 비교하도록 하였다. 그리고 이온화도와 이온화상수 값이 호환되지 않는 이유에 대한 교사들의 인식을 알아보았다. 연구 대상은 화학 교사 46명이었다. 연구 결과, 교사들은 교과서에 제시된 이온화 상수 값과 이온화도를 근거로 수용액에서 강산의 세기를 구분하였으며, 교과서에 제시된 이온화 상수 값이 이온화도와 서로 호환되지 않는 문제를 생각하지 못하거나, 문제로 인식하는 경우에도 그에 대한 해결을 하지 못하고 실험 오차나 측정 오차로 생각하였다.

• Current Optics and Photonics
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• 제1권6호
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• pp.637-641
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• 2017

We present dielectric constant measurements of thin films using THz metamaterials fabricated on a quartz substrate. The resonance shifts of the metamaterials exhibit saturation behavior with increasing film thickness. The saturation frequency shift varies with the real part of the dielectric constant, from which the numerical expression for the particular metamaterial design was extracted. We first performed finite-difference time-domain simulations to find an explicit relationship between the saturated frequency shift and the dielectric constant of a thin film, which was confirmed by the experimental results from conventional techniques. In particular, the quartz substrate enables us to determine their values more accurately, because of its low substrate index. As a result, we extracted the dielectric constants of various films whose values have not been addressed previously without precise control of the film thickness.