• Korean Journal of Ecology and Environment
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• v.47 no.1
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• pp.53-61
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• 2014

The origin of particulate organic matter (POM) and food web structure were investigated in Shingu reservoir based on stable isotope analysis from pre-monsoon (July) to post-monsoon (September) 2007. According to the depth in Shingu reservoir, the $^{13}C$ and $^{15}N$ values of POM for pre-monsoon period were nonsignificant distinction, while it was significant variation after rainfall period. The ${\delta}^{13}C$ values of POM in premonsoon period ranged from -25.1‰ to -26.1‰ in whole water column, but the ${\delta}^{13}C$ values of POM in post-monsoon period showed relatively wide range between -23.2‰ and -27.5‰. The apparently lighter values (average -27.5‰) in near bottom water (7 m water depth) demonstrate that POM in high turbid water in post-monsoon period may be derived from the outside terrestrial plants (allochthonous) through heavy rainfall during the summer monsoon period. After rainfall period, $^{13}C$ and $^{15}N$ values of D. brachyurum showed -23.3‰ and 12.2‰, respectively, while B. longirostris showed -27.1% and 8.7%, respectively. It suggested that D. brachyurum mainly feed on POM in autochthonous organic matter pool, but B. longirostris mainly consumed POM in allochthonous organic matter pool after rainfall period. Carbon and nitrogen stable isotope ratios were markedly different among secondary consumers. The carp (C. carpio) and catfish (S. asotus) were in the higher trophic level and crucian carp (C. auratus) and mudfish (M. mizolepis) were in the lower trophic level. $^{13}C$ and $^{15}N$ values of Z. platypus didn't significantly changed between before and after rainfall period. But P. parva and C. auratus apparently changed the $^{13}C$ and $^{15}N$ values after rainfall period. It is suggested that P. parva and C. auratus seem to feed allochthonous food source while Z. platypus depend on autochthonous food source.

• Economic and Environmental Geology
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• v.46 no.3
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• pp.267-278
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• 2013

The East African Rift System(EARS) is known to be hosted epithermal Au-Ag deposits, and the best-known example is Main Ethiopian Rift Valley(MER) related to Quaternary bimodal volcanism. Large horst-graben system during rifting provides open space for emplacement of bimodal magmas and flow channel of geothermal fluids. In recent, large hydrothermally altered zones(Shala, Langano, and Allalobeda) and hot spring related to deeply circulating geothermal water have been increasing their importance due to new discoveries in MER and Danakil depression. The hot springs in Shala and Allalobeda occur as boiling pool and geyser on the surface, whereas some areas didn't observe them due to decreasing ground water table. The host rocks are altered to quartz, kaolinite, illite, smectite, and chlorite due to interaction with rising geothermal water. The hot springs in MER are neutral to slightly alkaline pH(7.88~8.83) and mostly classified into $HCO_3{^-}$ type geothermal water. They are strongly depleted in Au, and Ag, but show a higher Se concentration of up to 26.7 ppm. In contrast, siliceous altered rocks around hot springs are strongly enriched in Pb(up to 33 ppm, Shala), Zn(up to 313 ppm, Shala), Cu(up to 53.1 ppm, Demaegona), and Mn(up to 0.18 wt%t, Shala). In conclusion, anomalous Se in hot spring water, Pb, Zn, Cu, and Mn in siliceous altered rocks, and new discoveries in MER have been increasing potential for epithermal gold mineralization.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.35 no.5
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• pp.1039-1049
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• 2015

The inflow estimation at large multipurpose dam reservoir is carried out by considering the water balance among the discharge, the storage change during unit time interval obtained from the observed water level near dam structure and area-volume curve. This method can be ideal for level pool reservoir but include potential errors when the inflow is influenced by the water level slope due to backwater effects from upstream flood inflows and strong wind induced by typhoon. In addition, the other uncertainties arisen from the storage reduction due to sedimentation after the dam construction and water level noise due to mechanical vibration transmitted from the electric power generator. These uncertainties impedes the accurate hydraulic inflow measurement requiring exquisite hydrometric data arrangement for reservoir waterbody. In this study, the distributed hydrologic model using UBC-3P boundary setting was applied and its feasibility was evaluated. Finally, the modeling performance has been verified since the calculated determination coefficient has been in between 0.96 to 0.99 after comparing with observed peak inflow and total inflow at Namgang dam reservoir.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.6
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• pp.655-663
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• 2010

Wettability is important to enhance not only CHF but also nucleate boiling heat transfer, as shown by the results of different kinds of boiling experiments. In this regard, an excellent boiling performance (a high CHF and heat transfer performance) could be achieved in the case of pool boiling by some favorable surface modifications that can satisfy the optimized wettability condition. To determine the optimized boiling condition, we design special heaters to examine how two materials, which have different wettabilities (e.g., hydrophilic and hydrophobic materials), affect the boiling phenomena. The special heaters have hydrophobic dots on a hydrophilic surface. The contact angle of the hydrophobic surface is $120^{\circ}$ to water at the room temperature. The contact angle of the hydrophilic surface is $60^{\circ}$ at same conditions. Experiments involving micro hydrophobic dots and two types of milli hydrophobic dots are performed, and the results are compared with a reference surface.

• The Korean Journal of Ecology
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• v.22 no.3
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• pp.109-117
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• 1999

Thirty two species of coastal plants (mainly halophytes) were investigated for their free amino acids and the total and water-soluble nitrogen contents in leaves. All plants except some species (e.g. Scutellaria and Linaria) contained proline, but only Ageratum. Tetragonia and Raphanus in rather high amounts, that it can be thought to serve as a cytoplasmic osmolyte. In some plant species (Euphorbia. Glehnia. Peucedanum. Raphanus and monocotyledonous Carex and Zoysia), however, hydroxyproline. (OH-Pro) rather than proline were accumulated to a considerable extent. The concentrations of total free amino acids were low in Aster tripolium, Linaria. Lysimachia. Plantago. Rumex, Vitex and especially in the members of the Chenopodiaceae and Crassulaceae. Marked differences also occurred in the nitrogen levels. Aizoaceae, Chenopodiaceae, Convolvulaceae, Cruciferae, Euphorbiaceae and Leguminosae usually showed high values of total and soluble amino nitrogen, while the opposite was true for most of the Cyperaceae, Gramineae, Lamiaceae, Plantaginaceae, Scophuriaceae, and Verbenaceae. The free amino acids in the investigated plant species contributed very little to the nitrogen content, but in plants of Euphorbia, Messerschmidia and Orostachys. their amino acid-N made up for 25∼30% of the total nitrogen. In conclusion, only a few cases did proline known as compatible solute constitute a significant proportion of the free amino acid pool in coastal plants.

• International Union of Geodesy and Geophysics Korean Journal of Geophysical Research
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• v.25 no.1
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• pp.57-81
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• 1997

Numerical prediction of nocturnal thermal high in summer of the 1995 near Taegu city located in a basin has been carried out by a non-hydrostatic numerical model over complex terrain through one-way double nesting technique in the Z following coordinate system. Under the prevailing westerly winds, vertical turbulent fluxes of momentum and heat over mountains for daytime hours are quite strong with a large magnitude of more than $120W/\textrm{m}^2$, but a small one of $5W/\textrm{m}^2$ at the surface of the basin. Convective boundary layer (CBL) is developed with a thickness of about 600m over the ground in the lee side of Mt. Hyungje, and extends to the edge of inland at the interface of land sea in the east. Sensible heat flux near the surface of the top of the mountain is $50W/\textrm{m}^2$, but its flux in the basin is almost zero. Convergence of sensible heat flux occurs from the ground surface toward the atmosphere in the lower layer, causing the layer over the mountain to be warmed up, but no convergance of the flux over the basin results from the significant mixing of air within the CBL. As horizontal transport of sensible heat flux from the top of the mountain toward over the basin results in the continuous accumulation of heat with time, enhancing air temperature at the surface of the basin, especially Taegu city to be higher than $39.3^{\circ}C$. Since latent heat fluxes are $270W/\textrm{m}^2$ near the top of the mountain and $300W/\textrm{m}^2$ along the slope of the mountain and the basin, evaporation of water vapor from the surface of the basin is much higher than one from the mountain and then, horizontal transport of latent heat flux is from the basin toward the mountain, showing relative humidity of 65 to 75% over the mountain to be much greater than 50% to 55% in the basin. At night, sensible heat fluxes have negative values of $-120W/\textrm{m}^2$ along the slope near the top of the mountain and $-50W/\textrm{m}^2$ at the surface of the basin, which indicate gain of heat from the lower atmosphere. Nighttime radiative cooling produces a shallow nocturnal surface inversion layer with a thickness of about 100m, which is much lower than common surface inversion layer, and lifts extremely heated air masses for daytime hours, namely, a warm pool of $34^{\circ}C$ to be isolated over the ground surface in the basin. As heat transfer from the warm pool in the lower atmosphere toward the ground of the basin occurs, the air near the surface of the basin does not much cool down, resulting in the persistence of high temperature at night, called nocturnal thermal high or tropical night. High relative humidity of 75% is found at the surface of the basin under the moderate wind, while slightly low relative humidity of 60% is along the eastern slope of the high mountain, due to adiabatic heating by the srong downslope wind. Air temperature near the surface of the basin with high moisture in the evening does not get lower than that during the day and the high temperature produces nocturnal warming situation.

• Korean Chemical Engineering Research
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• v.45 no.4
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• pp.400-409
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• 2007

Morphology of methane/propane clathrate hydrate crystal was investigated under different undercooling conditions. After the water pressurized with compound guest gas was fully saturated by agitation, medium within the vessel was rapidly undercooled and maintained at the constant temperature while the visual observations using microscope revealed detailed features of subsequent crystal nucleation, migration, growth and interference occurring within liquid pool. The growth of hydrate was always initiated with film formations at the bounding surface between bulk gas and liquid regions under all tested experimental conditions. Then a number of small crystals ascended, some of which settled beneath the hydrate film. When undercooling was relatively small, some of the settled crystals slowly grew into faceted columns. As the undercooling increased, the downward growth of crystals underneath the hydrate film became dendritic and occurred with greater rate and with finer arm spacing. The shapes of the floating crystals within liquid pool were diverse and included octahedron and triangular or hexagonal platelet. When the undercooling was small, the octahedral crystals were found dominant. As the undercooling increased, the shape of the floating crystals also became dendritic. The detailed growth characteristics of floating crystals are reported focused on the influences caused by undercooling and memory effect.

• Korean Journal of Food Science and Technology
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• v.22 no.7
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• pp.828-832
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• 1990

Pileus and stipe extracts of shiitake mushroom were prepared with various ethanol concentration by different extraction time at $60^{\circ}C$. Yields, total reducing sugars, free amino acids and nucleotides in ultrafiltrated extracts were analyzed. Yields were higher in hot water extracts but there was no difference depending on changes of extraction time. Total reducing sugar contents got higher by hot water extraction than by solvent extraction. In hot water extracts of the pileus and stipe, reducing sugar content were in the range of $416.18{\sim}488.18\;mg%\;and\;435.37{\sim}452.12\;mg%$, respectively. Threonine+serine, glutamic acid, lysine and arginine were dominent in the free amino acids pool of raw material. The contents of free amino acids in hot water extracts of pileus and stipe were about 528.46mg% in 2 hr and 221.01 mg% in 3 hr. The proportion of bitter amino acids in extracts to total free amino acid contents was in the range of $16{\sim}29%,\;35{\sim}37%$ in pileus and stipe extracts, respectively. Nucleotides contents were higher in pileus than in the stipe. When the 25% ethanol solution was used for extraction solvent, nucleotides contents in pileus and stipe extracts was high.

• Journal of Environmental Science International
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• v.4 no.4
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• pp.357-365
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• 1995

The use of chlorinated water in swimming pools produces elevated chloroform levels in the water and air of the pools which can cause chloroform body burden of swimming individuals. Present study confirmed the chloroform body burdens from a 40-min swimming and evaluated the decay of chloroform breath concentration after the cessation of a 60-min swimming. Air and water concentrations were measured in the pools. The water and air chloroform concentrations ranged from 18.1 to 25.3 ${mu}g/l$ and from 30.9 to 60.7 ${\mu}g/m3$ for the confirmation study, respectively. The breath level after 40-min swimming was about 64 to 266 folds higher than the corresponding background breath. The breath concentration after the 40-min swimming ranged from 10.5 to 21.3 ${\mu}g/m3$, while that prior to the corresponding swimming ranged from 0.07 to 0.19 ${\mu}g/m3$. In addition, the post-exposure breath level varied with the subjects who swam in the pool on the same visiting day. Breath concentration increased gradually during 60-min swimming, then decreased rapidly within 5 minutes after the cessation of exposure, after that, decreased slowly, and finally approached to a background breath level at 1-2 hr after exposure.

• KSBB Journal
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• v.15 no.6
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• pp.664-669
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• 2000

Micellar aggregates are known to be useful for the selective isolation of biologically active materials such as amino acids, proteins, and enzymes from crude mixtures sparsely dispersed in water. In this study, the effects of pH, salt type and its concentration on the solubilization of $\alpha$-chymotrypsin into the organic micellar phase, which consisted of AOT (sodium 야(2-ethylhexy)sulfosuccinate) and iso-octane, were comprehensively examined. It was found that maximum extraction efficiency was attained at a pH below the isoelectric point of $\alpha$-chymotrypsin; at pH=5.0 for NaCl and KCl, and at pH=7.0 for $CaCl_2$and $MgCl_2$. In order to avoid complications stemming from the precipitationof protein at low pH interfaces, the protein concentrations in the organic and aqueous phases were directly measured. The size of the micelle water pool was estimated by measuring the molar ratio of the surfactant to the water, W(sub)o. The resulting values of W(sub)o were nearly constant at 30 and 19 for NaCl and KCl, respectively, and were independent of pH. The addition of 1:2 salts like $MgCl_2$and $CaCl_2$ led to much lower, but a constant value of, W(sub)o than the 1:1 salts.