• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2019.05a
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• pp.579-581
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• 2019

In this paper, dispersion-managed optimal link configuration with the growth/decay distribution of accumlative dispersion as the fiber span is increased, in which optical phase conjugator placed at midway, is proposed. It is confirmed that if net residual dispersion set to be -15 ps/nm or 15 ps/nm in the proposed optical link configuration, the best compensation of the distorted wavelength division multiplexed channels will be obtained.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.03a
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• pp.700-710
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• 2008

A Bubble size distribution model has been developed for the numerical simulation of cryogenic high-speed cavitating flow of the turbo-pumps in the liquid fuel rocket engine. The new model is based on the previous one proposed by the authors, in which the bubble number density was solved as a function of bubble size at each grid point of the calculation domain by means of Eulerian framework with respect to the bubble size coordinate. In the previous model, the growth/decay of bubbles due to pressure difference between bubble and liquid was solved exactly based on Rayleigh-Plesset equation. However, the unsteady heat transfer between liquid and bubble, which controls the evaporation/condensation rate, was approximated by a theoretical solution of unsteady heat conduction under a constant temperature difference. In the present study, the unsteady temperature field in the liquid around a bubble is also solved exactly in order to establish an accurate and efficient numerical simulation code for cavitating flows. The growth/decay of a single bubble and growth of bubbles with nucleation were successfully simulated by the proposed model.

• Korean Journal of Microbiology
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• v.6 no.3
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• pp.92-92
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• 1968

1) The aim of present investigation is to elucidate the relation of the balance of the production and decomposition of the fir litter. in Kwangnung plantation stands. 2) The decay constant, K, of litters was 0. 185 for the fir stand at Kwangnung. 3) The mode for the accumulation of organic carbon ($C_a$) is $c_a$= $610(1-e^{-0.185t})$), and for the decay of organic carbon (C) C = $610(1-e^{-0.185t})$. 4) The time required for the decay of half of the accumulated organic carbon in the fir stand is 3. 74 years and for 99% of elimination 27.02 years. 5) The litters of Abies holophylla killed by heat and washed with alcohol-benzol, with hot water, or with both alcohol-benzol and hot water were incubated after inoculated with suspension of firwood soil. Plate counts were made of fungi and bacteria from time to time. 6) Removal of the alcohol-benzol soluble substance stimulates at the beginning of the decay the growth of fungi and also of bacteria. 7) Removal of the water soluble fraction is detrimental to the growth of fungi in particular. 8) The distribution of soil microbial population is higher in both F and H horizon of the fir plantation soil in Kwangnung. However, the number of soil microorganisms decreases with the depth in forest soil.

• Korean Journal of Microbiology
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• v.6 no.3
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• pp.93-99
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• 1968

1) The aim of present investigation is to elucidate the relation of the balance of the production and decomposition of the fir litter. in Kwangnung plantation stands. 2) The decay constant, K, of litters was 0. 185 for the fir stand at Kwangnung. 3) The mode for the accumulation of organic carbon ($C_a$) is $c_a$= $610(1-e^{-0.185t})$), and for the decay of organic carbon (C) C = $610(1-e^{-0.185t})$. 4) The time required for the decay of half of the accumulated organic carbon in the fir stand is 3. 74 years and for 99% of elimination 27.02 years. 5) The litters of Abies holophylla killed by heat and washed with alcohol-benzol, with hot water, or with both alcohol-benzol and hot water were incubated after inoculated with suspension of firwood soil. Plate counts were made of fungi and bacteria from time to time. 6) Removal of the alcohol-benzol soluble substance stimulates at the beginning of the decay the growth of fungi and also of bacteria. 7) Removal of the water soluble fraction is detrimental to the growth of fungi in particular. 8) The distribution of soil microbial population is higher in both F and H horizon of the fir plantation soil in Kwangnung. However, the number of soil microorganisms decreases with the depth in forest soil.

• 전기의세계
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• v.17 no.2
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• pp.16-26
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• 1968

Cds is possible to add excess donors and to compensate partially using other group metals as acceptors. The impurities can ble incorporated either during crysta growth or by diffusion into a bulkcrystal. The addition of rimpurities leads also to the production of vacancies in a manner depending on the atmosphere surrounding the crystal during growth, during the diffusion process or using bulk. Cds of the mentioned above affects spectral sensitivity, speed of response, the variation on photocurrent, electron life time, and decay of photoconductivity with temperature and with intensity of illumination. In the work to be deseribed, these properties have been studied between liquid nitrogen and room temperature. In addition, the electron trap distribution has been correlated with speed of response, variation of photocurrent with temperature in various atmosphere. Four major trapping levels have been observed, and their identification with impurity and vacancy levels is discussed. And also the effects of lattice imperfections on the photoconductive properties CdS were investigated in detail.

• 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.

• Nuclear Engineering and Technology
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• v.56 no.9
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• pp.3483-3490
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• 2024

The initial size distribution and morphological parameters of sodium aerosols are critical in evaluating the accidental suspended aerosol behaviour in Sodium-cooled Fast Reactor (SFR) containment. Mass-based measurements were more familiar in characterizing the sodium aerosols. Real-time number size distribution measurements are carried out in this study. The sensitivity analysis of sodium aerosol effective density (ρ_e) in deriving the actual number size distributions from the measured Aerodynamic Particle Size Distributions (APSD) and predicting suspended aerosol dynamics is presented. Tests are conducted in a 1 m³ chamber at 47 ± 3% RH for different initial mass concentrations (M₀) of 0.1, 1, and 2.9 g/m³. The initial APSDs measured just after the generation completions are observed to be polydisperse with the count median aerodynamic diameter (CMAD) < 1 ㎛. The literature reported ρ_e values of sodium aerosols, 2.27, 1.362, and 0.61 g/cm³ are used to derive mobility equivalent PSDs from APSD in each test. The real-time number concentration decay and size growth for four different PSDs are measured and compared with the estimate using nodal method-based code to ascertain the actual parameters. The validated parameters CMD = 0.66 ㎛, σ_g = 1.96, ρ_e = 1 g/cm³ and χ = 1 are used for improved estimation of sodium aerosol dynamics in Indian SFR containment with M₀ = 4 g/m³ for severe accident scenarios.

• Journal of the Korean Wood Science and Technology
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• v.34 no.2
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• pp.68-77
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• 2006

The heartwood of cengal (Neobalanocarpus heimii) is known to have a high degree of decay resistance by virtue of its high extractive content. After 30 years in ground contact an utility pole of this tropical hardwood was found to be degraded only in the surface layers by cavity-forming soft rot fungi. The present work was undertaken 1) to characterize the degradation of cengal heartwood from the aspect of ultrastructure and chemistry and 2) to investigate the correlation between soft rot decay and its extractive microdistribution in wood tissues. The chemical analysis of cengal heartwood revealed the presence of a high amount of extractives as well as lignin. The wood contained a relatively high amount of condensed lignin and the guaiacyl units. Microscopic observations revealed that vessels, fibers and parenchyma cells (both ray and axial parenchyma) all contained extractives in their lumina, but in variable amounts. The lumina of fibers and most axial parenchyma were completely or almost completely filled with the extractives. TEM micrographs showed that cell walls were also impregnated with extractives and that pit membranes connecting parenchyma cells were well coated and impregnated with extractives. However, fungal hyphae were present in the extractive masses localized in cell lumina, and indications were that the extractives did not completely inhibit fungal growth. The extent of cell wall degradation varied with tissue types. The fibers appeared to be more susceptible to decay than vessels and parenchyma. Middle lamella was the only cell wall region which remained intact in all cell types which were severely degraded. The microscopic observations suggested a close correlation between extractive microdistribution and the pattern and extent of cell wall degradation. In addition to the toxicity to fungi, the physical constraint of the extractive material present in cengal heartwood cells is likely to have a profound effect on the growth and path of invasion of colonizing fungi, thus conferring protection to wood by restricting fungal entry into cell walls. The presence of relatively high amount of condensed lignin is also likely to be a factor in the resistance of cengal heartwood to soft rot decay.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.23 no.1
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• pp.20-26
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• 2013

Special attention in the role of convection in vapor crystal growth has been paid since some single crystals under microgravity environments less than 1 $g_0$ exhibits a diffusive-convection mode and much uniformity in front of the crystal regions than a normal gravity acceleration of 1 $g_0$. The total molar fluxes show asymmetrical patterns in interfacial distribution, which indicates the occurrence of either one single or more than one convective cell. As the gravitational level decreases form 1 $g_0$ down to $1.0{\times}10^{-4}\;g_0$, the intensity of convection, indicative of the maximum molar fluxes, is reduced significantly for ${\Delta}T=30K$ and 90 K. The total molar fluxes decay first order exponentially with the partial pressure of component B, PB (Torr) for 20 Torr ${\leq}PB{\leq}$ 300 Torr, and two gravity accelerations of $g_y=1\;g_0$ and 0.1 $g_0$.

• The Korean Journal of Ecology
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• v.9 no.1
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• pp.9-18
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• 1986

The decomposition of litters of Pinus densiflora and the growth of microbial populations in a calcareous region, Youngwal were compared with those in a noncalcareous region, Sinlim. The decay rate of litter in Pinus densiflora in Youngwal was 0.128 and that in Sinlim was 0.096. The differences in the populations of soil bacteria and total microorganisms between the two regions were signficant at the 5% level, but that of fungi and actinomycetes was not at that level. The differences in the content of calcium and pH value of soil between the two regions were significant at the 1% level. The excessive content of calcium became to increase pH value, in turn the high pH decreased the content of available phosphorus in soil. The vertical distribution of the content of available phsophorus was consistent with that of the populations of fungi and actinomycetes in Youngwal.