• KSBB Journal
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• v.11 no.5
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• pp.606-612
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• 1996

A specific ammino auid in a mixture can be crystallized inside an ion exchange column when displacer concentration is high enough to concentrate the amino acid in a pure band beyond its solubility limit. Glutamic acid formpd a discrete crystal layer in a cation exchanger column by operating displacement development mode and using a high concentration of displacer NaOH. The glutamic acid crystal formed was eluded from the column with the effluent stream and collected in a fraction collector. When 1.0 M of NaOH was used as a displacer, more than 60% of the loaded glutamic acid was recovered as crystal. The continuous crystallization and dissolution of crystal occurred, resulting in apparent movement of the crystal along the column without clogging or pressure increase. NaOH was proved a better displacer than NaCl because hydroxide ions neutralized hydrogen ions released from the resin and thus reduced the number of hydrogen ion competing with sodium ion for re-adsorption. The displacement development process coupled with crystallization provided higher concentration and recovery of glutamic acrid than conventional chromatography.

• Journal of Energy Engineering
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• v.20 no.3
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• pp.191-199
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• 2011

The char burn-out and NOx emissions from sub-bituminous coal were investigated in drop tube furnace under $O_2/N_2$ and $O_2/CO_2$ environments with different $O_2$ concentrations of 12, 21 and 31%. Results show that the char burn-out rate is faster as $O_2$ concentration increases higher and char burn-out rate under $O_2/CO_2$ decreases due to the lower oxygen diffusion into coal surface through the $CO_2$ rich boundary layer. NO concentration increases with increasing $O_2$ concentration, but declines at $O_2$ concentration of 31%. Meanwhile, NO emission indexes decreases monotonically with increasing $O_2$ concentration, which indicates that more NO reduction occurs with higher $O_2$ concentration probably due to greater HCN formation. For all conditions of $O_2$ concentration, the NO concentration under $O_2/N_2$ maintains higher than those of $O_2/CO_2$ due to presence of thermal NO.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.28 no.5
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• pp.257-264
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• 2016

In this study, experiments for measurements of entrainment rate of fluid mud were carried out using annular flume domestically for the first time. Six entrainment tests using kaolinite sediments were conducted with different initial concentrations of fluid mud. It is shown that sediment settling counteracts the otherwise buoyancy dependent entrainment of fluid mud, and that the settling effect leads to a measurably decreased entrainment rate at higher Richardson numbers in comparison with entrainment of salt water, due to additional dissipation of turbulent kinetic energy in the interfacial layer. Through the comparison with previous other studies, the overall performance of the annular flume, the experimental procedure and the test results in simulating the entrainment of fluid mud are shown to be good enough to verify.

• Korean Journal of Ecology and Environment
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• v.36 no.3 s.104
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• pp.311-321
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• 2003

We surveyed physico-chemical properties of bottom water and sediment to evaluate the influence of sediment on the eutrophication in the downstream of Nagdong River from 1998 to 2000. From May to August, DO concentration of bottom waters dropped below 5 mg $O_2/l$ and $NH_4\;^+$ and $PO_4\;^{3-}$ concentrations significantly increased in the bottom waters, resulting in the great differences between surface and bottom waters. Fluxes across water-sediment interface would be substantially active in this period. The serial orders of the water fertility or eutrophication were Joman River > Sonagdong River > Nagdong River. The organic nutrient contents of sediment increased toward the lower parts of the river system. Organic contents of the sediment would be under the influence of water pollution and exhibited a negative correlation with sediment bulk-density or particle size. The concentrations of exchangeable inorganic nutrients of sediment were greater than those of pore waters, and $PO_4\;^{3-}$, $NH_4\;^+$ and $SiO_2$ increased along the sediment depth. $PO_4\;^{3-}$ and $NO_3\;^-$ concentrations of the pore water were less than the overlying waters, while NH4+ and $SiO_2$ concentrations showed opposite trends. Exchangeable nutrients of sediment could be the repository for t]me nutrient exchange in the water-sediment interface.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.10
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• pp.4590-4599
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• 2011

The Color shift phenomenon is becoming a major degradation factor of the emitting color purity in the organic emitting diodes which is generating a plurality of colors. In this study, the basic structure of organic light emitting diode device is comprised of ITO/${\alpha}$-NPD/$Alq_3$:DCJTB[wt%]/$Alq_3$/Mg:Ag, we have carry out numerical simulation of the electric-optical characteristics in organic light emitting diode device to estimate the mechanism of color shift phenomenon. We have investigated the causes of the color shift through the change of DCJTB doping concentration ratio. As the result, we have confirmed that the changes of the recombination rate which generated by trapped electrons and holes is one of the major factors for the color shift phenomenon.

• Journal of the Korean Institute of Telematics and Electronics
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• v.27 no.11
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• pp.49-54
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• 1990

In this paper, a simple model is presented for the gate-voltage dependence of the parasitic resistance in MOSFETs with the lightly-doped drain (LDD) structure. At the LDD region located under the gate electrode, an accumulation layer is formed due to the gate voltage. The parasitic resistance of the source side LDD in the channel is treated as a parallel combination of the resistance of the accumulation layer and that of the bulk LDD, which is approximated as a spreading resistance from the end of the channel inversion layer to the ${n^+}$/LDD junction boundary. Also the effects of doping gradients at the junction are discussed. As result of the model, the LDD resistance decreases with increasing the gate voltage at the linear regime, and increase quasi-linearly with the gate voltage at the saturation regime, considering th velocity saturation both in the channel and in the LDD region. The results are in good agreement with experimental data reported by others.

• Applied Chemistry for Engineering
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• v.7 no.3
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• pp.518-529
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• 1996

To develope chemical heat pump using available energy sources such as solar heat and many kinds of waste thermal energy we have studied the enhancement effect of inserted fins in cylindical packed bed reactor. Two dimensionnal(radial and circumferential) partial differential eqaetions, concerning heat and masstransfer in CaO packed bad, are solved numerically to describe the characteristics of the reaction of fins inserted reactor and heat transfer. The results obtained by numerical analysis about two dimensional profiles of temperature and conversion in the reactant in the packed bed and exothermic heat amount released from the reactor are follows; -. The insertion of fins in reactor can redue the reaction completion time by half. -. The rate of thermochemical reaction depends of the temperature and concentration and it is also governed by the boundary conditions and heat transfer rate in the particle packed bed.

• Korean Journal of Heritage: History & Science
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• v.45 no.2
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• pp.100-113
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• 2012

The tombstone of Yi Chungmugong in the Joseon Dynasty located Namhae, Gyeongnam is consisted of sandstone. The Bisin and Bijwa of the tombstone have narrow range of magnetic value less than $0.2({\times}10^{-3}SI\;unit)$ and the Isu covered pigment on surface also has same magnetic susceptibility range. Therefore, the composition of all tombstone have similar lithological characteristics. The side of the tombstone appeared fine-grained sandstone to coarse-grained graywacke boundary clearly and back of tombstone observed lamination. Especially deterioration type is concentrated in front and back of the tombstone blistering (8.2% of back), scaling (10.2% of back), granular disintegration (28.1% of back) and discoloration (53.5% of front). Results of contaminants analysis, the front of the Bisin separated in 3 type of surface - granular disintegration-scaling. Among this area, surface detected Ca, S and Cl in high density, but these contaminants elements have more lower detect density from surface to granular disintegration. By contrast, on scaling area, these components are almost not detected, but Fe, K consisted of rock forming elements are detected. It is necessary to conservation and treatment of Yi Chungmugong tombstone in continuously, and salt cleaning on surface also needed. So through activity of conservation and restoration, epigraph preserved for their worth.

• Journal of the Korean earth science society
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• v.35 no.1
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• pp.1-18
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• 2014

The purpose of this study was to analyze the sensitivity of meteorological fields and the variation of concentration of particulate matters (PMs) due to aerosol schemes and dust options within the WRF-Chem model to estimate Asian dusts affected on 29 May 2008 in the Korean peninsula. The anthropogenic emissions within the model were adopted by the $0.5^{\circ}{\pm}0.5^{\circ}$ RETRO of the global emissions, and the photolysis option was by Fast-J photolysis. Also, three scenarios such as the RADM2 chemical mechanism and MADE/SORGAM aerosol, the MOSAIC 8 section aerosol, and the GOCART dust erosion were simulated for calculating Asian dust emissions. As a result, the scenario of the RADM2 chemical mechanism & MADE/SORGAM aerosol depicted higher concentration than the others' in both Asian dusts and the background concentration of PMs. By comparing of the daily mean of PM10 measured at each air quality monitoring site in Seoul with the scenario results, the correlation coefficient was 0.67, and the root mean square error was $44{\mu}gm^{-3}$. In addition, the air temperature, the wind speed, the planetary boundary layer height, and the outgoing long-wave radiation were simulated under conditions of no chemical option with these three scenarios within the WRF or WRF-Chem model. Both the spatial distributions of the PBL height and the wind speed of u component among the meteorological factors were similar to those of the Asia dusts in range of 1,800-3,000 m and $2-16ms^{-1}$, respectively. And, it was shown that both scenarios of the RADM2 chemical mechanism and MADE/SORGAM aerosol and the GOCART dust erosion were interacted on-line between meteorological factors and Asian dusts or aerosols within the model because the outgoing long-wave radiation was changed to lower than the others.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.11
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• pp.1050-1059
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• 2005

Heat and $SF_6$ gas dispersions over a complex terrain were investigated using wind tunnel. The wind speed, temperature and concentration profiles were measured for the 1/1000 scale complicated terrain model in an Eiffel type boundary layer wind tunnel with test section of 2.5m in height and 4.5m in width. The scale model was mounted on the top of a plate which can rotate with respect to the approaching wind. Dispersion processes from a continuous emission source driven by various wind direction were investigated, including plume climbing over the steep up-slope of the mountain and down-spreading toward the lower level of the valley. Extensive dispersion experiment data (wind speeds and concentration profiles) were provided for verification and validation of dispersion models. Under the identical flow and emission conditions, the independently measured profiles of the temperature and $SF_6$ concentration showed an excellent agreement which ensured the credibility of the results.