• Explosives and Blasting
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• v.34 no.2
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• pp.1-9
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• 2016

In this study, the field tests were performed on V-cut, PLHBM 1 hole, PLHBM 2 hole in gneiss area in order to compare the effects of the vibration decay of a tunnel cut-hole according to the number of PLHBM holes with scaled distance. Based on the prediction equation of blasting vibration from the result of the tests, the decay rate of vibration were confirmed 21.8~61.1% using PLHBM 1 hole, 35.7~79.3% using PLHBM 2 hole for scaled distance within $10{\sim}100m/kg^{1/2}$ on the basis of V-cut PPV. As the scaled distance was increased, the effect of vibration decay was decreased. The effect of vibration decay of cut-hole for intial PLHBM 1~2 hole was significantly high.

• Korean Journal of Medicinal Crop Science
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• v.26 no.4
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• pp.291-295
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• 2018

Background: The use of Rehmannia glutinosa of the family Scrophulariaceae, in traditional medicine is well known. This study was conducted to elucidate the effect of air curing of the seed rhizome of R. glutinosa on its storability and yield. Methods and Results: The root of the R. glutinosa cultivar (Dagang) was harvested in at the end of November. The seed rhizomes were air cured for one to seven days. They were subsequently wrapped with newspaper and further stored in a plastic container at $1^{\circ}C$. It was observed that the weight loss and decay rates were significantly lower in the air cured seeds than in the untreated ones. Moreover, the decay rate of the control was approximately 50%, 120 days after storage. However. the decay rate of all the air cured treatment groups was less than 1%. Additionally, air curing led to an increase in the germination rate of the seeds and the root yield when compared with the untreated groups. Taken together, the ideal treatment period for air curing was found to be 3 days. Under these conditions, the germination rate and yield were 88.7% and 2,185 ㎏/10a, respectively. Conclusions: This study successfully demonstrated that the air curing of seed rhizomes can lead to a considerable increase in the storability and yield of R. glutinosa.

• The Korean Journal of Ecology
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• v.10 no.3
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• pp.109-118
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• 1987

The production and decomposition rates of litters were studied in three mountains, Mt. Halla, Mt. So-back and Mt. Tae-back. The amounts of N, P, K, Ca and Na in the soils were measured and the relationships between the mineral nutrients and decay rates were reserched, The annual litter production was the most as $1, 077.3g/m^2$ and the least as $248.0g/m^2$ in a stand of Quercus acutissima at 820m of the Mt. So-back and at 1, 350m of the Mt. So-back among the study sites, respectively. The decay rates of litter was the highest as k=0.448 and the lowest as k=0.082 in a stand of Q. acutissima at 820m of the Mt. So-back and at 1, 450m of the Mt. Tae-back at 1, 450m of the Mt. Tae-back among the study sites. The higher altitude was, the slower the decay rates were. The annual contents of mineral nutrient and their amounts inputted into the forest soil were proportional to the decay rate of organic metters.

• Journal of Technologic Dentistry
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• v.42 no.2
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• pp.163-171
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• 2020

Purpose: The purpose of this study is the tooth decay ratio of the children and adolescents in four rural areas of Kyrgyzstan. Methods: Oral examinations were conducted 2,677 children and adolescents in Nizhniy chuy, Bokonbayevo, Chon Tash and Arashan from March 2017 to November 2019. It was investigated decayed tooth ratio(DT), decay permanent tooth ratio(DPT) and missing permanent tooth ratio(DMT) according to ages and areas by direct observation of the oral cavity. Results: In all areas, the rate of all children and adolescents aged 6 to 14 had very high DT of more than 94 percent overall. Furthermore, it was showed that high DPT rates above 78% on average and DMT over 8 years old in Chon Tash and Arashan. Conclusion: These results are higher than the average of DT, DPT and DMT in OECD countries. In order to promote oral health of children and adolescents, increased interest in oral health and policy measures at the Kyrgyzstan government level are considered urgent.

• Bulletin of the Korean Chemical Society
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• v.31 no.4
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• pp.959-964
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• 2010

In this work, equilibrium molecular dynamics (MD) simulations in a microcanonical ensemble are performed to evaluate the friction coefficient of a Brownian particle (BP) in a Lennard-Jones (LJ) solvent. The friction coefficients are determined from the time dependent friction coefficients and the momentum autocorrelation functions of the BP with its infinite mass at various ratios of LJ size parameters of the BP and solvent, ${\sigma}_B/{\sigma}_s$. The determination of the friction coefficients from the decay rates of the momentum autocorrelation functions and from the slopes of the time dependent friction coefficients is difficult due to the fast decay rates of the correlation functions in the momentum-conserved MD simulation and due to the scaling of the slope as 1/N (N: the number of the solvent particle), respectively. On the other hand, the friction coefficient can be determined correctly from the time dependent friction coefficient by measuring the extrapolation of its long time decay to t=0 and also from the decay rate of the momentum autocorrelation function, which is obtained by time integration of the time dependent friction coefficient. It is found that while the friction coefficient increases quadratically with the ratio of ${\sigma}_B/{\sigma}_s$ for all ${\sigma}_B$, for a given ${\sigma}_s$ the friction coefficient increases linearly with ${\sigma}_B$.

• Current Optics and Photonics
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• v.2 no.6
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• pp.589-594
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• 2018

We have investigated the dimensional nature of center-of-mass exciton confinement states in a CdMnTe/CdTe/CdMnTe heterostructure, where the CdTe well is too wide (144 nm) to confine both electrons and holes but able to confine whole excitons in the center-of-mass coordinate. Fine multiple photoluminescence spectra with a few meV separation were observed at 6 K. From the thickness dependence of the transition rate, they were attributed to even numbered center-of-mass exciton confinement states (N = 2, 4, 6, ${\cdots}$, 18). Dimensionality of the center-of-mass exciton confinement states was also investigated in terms of temperature dependence of radiative decay time. At low temperatures (${\leq}12K$), we found that the ground state excitons are likely localized possibly due to the barrier interface fluctuation, resulting in a constant decay time (~350 ps). With increased temperature (${\geq}12K$), localized excitons are thermally released, giving rise to a linear temperature dependence of radiative decay time as an evidence of two-dimensional nature.

• Journal of Korean Society of Environmental Engineers
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• v.32 no.11
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• pp.1038-1045
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• 2010

In this study, the anaerobic ultimate biodegradability and multiple decay rate of organic matter were evaluated according to various salt concentrations in seafood processing wastewater. The evaluation was also performed with various types of anaerobic bacteria and S/I (substrate/inoculum) ratios. After the S/I ratio was fixed at 0.9, the ultimate biodegradability values of the anaerobic digested sludge and granular sludge were became 72.0% and 92.0%, respectively. The multiple decay rate coefficients ($k_1$) coefficients of the anaerobic digested sludge and granular sludge were $0.0478{\sim}0.1252\;day^{-1}$ and $0.0667{\sim}0.1709\;day^{-1}$, respectively. The optimum S/I ratio of the seafood wastewater, which was determined based on the ultimate anaerobic biodegradability and gas production, was 0.9. The organic matter removal rate never became less than 85.0% under a 3,000 mg/L chloride concentration. The multiple decay rate coefficients ($k_1$) were $0.1603{\sim}0.1709\;day^{-1}$ under $3,000\;mgCl^-/L$, and $0.0492{\sim}0.0760\;day^{-1}$ in more than $6,000\;mgCl^-/L$. The multiple decay rate coefficients ($k_2$) were $0.0183{\sim}0.0348\;day^{-1}$ under $6,000\;mgCl^-/L$, and $0.0154\;day^{-1}$ at $9,000\;mgCl^-/L$. With increasing chloride concentrations, the reaction rate ($k_1$, $k_2$) and ratio of the rapidly degraded organic matter ($S_1$) decreased.

• Journal of ILASS-Korea
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• v.3 no.3
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• pp.14-22
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• 1998

The growth by steam condensation of an hygroscopic aerosol is investigated using the condensation rate model which has been derived from the mass and heat transfer equations. The present model accounts for both the solute and Kelvin effects. When the hygroscopicity is considered, condensation can occur on hygroscopic seed particles even under subsaturated steam conditions. This study focuses on the effect of hygroscopicity on the evolution of the particle size distribution and decay of the total aerosol concentration. It is found that hygroscopicity causes the particle size distribution to rapidly move upward even in a very short time, resulting in substantially higher decay of the total aerosol concentration than the case without considering hygroscopicity.

• East Asian mathematical journal
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• v.32 no.3
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• pp.399-412
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• 2016

In this paper, we study the viscoelastic Kirchhoff type equation with the following nonlinear source and time-varying delay $$u_{tt}-M(x,t,{\parallel}{\nabla}u(t){\parallel}^2){\Delta}u+{\int_{0}^{t}}h(t-{\tau})div[a(x){\nabla}u({\tau})]d{\tau}\\+{\parallel}u{\parallel}^{\gamma}u+{\mu}_1u_t(x,t)+{\mu}_2u_t(x,t-s(t))=0.$$ Under the smallness condition with respect to Kirchhoff coefficient and the relaxation function and other assumptions, we prove the uniform decay rate of the Kirchhoff type energy.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.11a
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• pp.309-314
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• 1996

Feasibility study has been accomplished to evaluate the effectiveness of the in-vessel core debris cooling through lower cavity flooding using two dimensional finite difference scheme. The volume of cerium pool and decay power rate generated in corium pool were evaluated as important parameters to the temperature distribution on the reactor vessel lower head through previous works. In this study, the corium volume based on the System 80＋ core structure and time dependent decay power rate are considered for feasibility evaluation. In addition, preliminary plans for the in-vessel core debris cooling through lower cavity flooding as severe accident management strategy, i.e. flooding timing, method and capacity, are suggested based on the result of the numerical study, international tendency related to in-vessel core debris cooling through lower cavity flooding.