• Geomechanics and Engineering
• /
• v.20 no.1
• /
• pp.1-7
• /
• 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.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1998.06a
• /
• pp.183-189
• /
• 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.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2015.10a
• /
• pp.1045-1046
• /
• 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%.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.11 no.10
• /
• pp.849-854
• /
• 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
• /
• v.9 no.3
• /
• pp.179-182
• /
• 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.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2001.11b
• /
• pp.1347-1352
• /
• 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.

• Smart Structures and Systems
• /
• v.34 no.1
• /
• pp.25-32
• /
• 2024

As materials cure, the internal electrical flow changes, leading to variations in the dielectric constant over time. This study aims to assess the impact of voltage values extracted from time domain reflectometry (TDR) waveforms, measured during the curing of materials, on predicting the dielectric constant. The experiments are conducted over a curing period ranging from 60 to 8640 minutes, with 30 TDR trials. From the measured waveforms, values of V₀, V₁, V₂, V_f, and Δt are deduced. Additionally, curing time is included as an input variable. Groups A and B are distinguished based on the presence or absence of Δt, indicating a physical relationship between Δt and the dielectric constant. The dielectric constant is set as the output variable. The SHapley Additive exPlanations (SHAP) algorithm is applied to the compiled data. The results indicate that Δt and V₁ are the most influential input variables in both Group-A and Group-B. The study also presents the distribution of SHAP values and interacts SHAP values to infer the interrelationships among the input variables. To validate the reliability of these findings, the partial dependence (PD) algorithm is applied to estimate the marginal effects of each input variable, with outcomes closely aligning with those of the SHAP algorithm. This research suggests that understanding the contributions and proportional relationships of each input variable can aid in interpreting the relationships among various material properties.

• Bulletin of the Korean Chemical Society
• /
• v.27 no.5
• /
• pp.718-724
• /
• 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.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.10 no.12
• /
• pp.2157-2165
• /
• 2006

In implementing GCRA, well known as the representative user traffic policing algorithm for constant-bit rate service, it is essential to set proper values for delay variation tolerance in order to prevent network overload and excessive user data loss due to delay variation incurred inevitably during transmission process. In this paper, we investigate the performance of GCRA algorithm for various values of delay variation tolerance and suggest a guideline for setting proper delay variation tolerance values.

• Journal of the Korean Chemical Society
• /
• v.57 no.2
• /
• pp.279-288
• /
• 2013

In this study, we analyzed the values of ionization and ionization constants in the chemistry textbooks developed during 1945-2009 year. The chemistry teachers compared strength of strong acids in aqueous solution by questionnaire. In the questionnaire, we searched chemistry teachers' cognitions about the discordance reason of ionization constant formulation and the values in the textbooks. The subjects were 46 chemistry teachers. As results, the teachers compared the strength of strong acids in aqueous solution based on the ionization and ionization constant values in the textbooks. They didn't notice the problem of discordance of ionization constant formulation and the values in the textbooks. Even though they recognized the problem, they could not find the solution, and thought the problem arrived by experiment error or measurement error.