• Journal of the Mineralogical Society of Korea
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• v.7 no.1
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• pp.14-24
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• 1994

The Sungsan clay deposits have been formed by the hydrothermal alteration of volcanic and volcanoclastic rocks of the Hwangsan Formation of Cretaceous age. Claystones are mainly composed of dickite, alunite, illitic minerals and tosudite. The mineralogical properties of clay minerals have been studied using X-ray diffraction analysis, electron microscopy, electron microprobe analysis, and infrared absorption analysis. The physicochemical condition for the clay deposits also have been studied by the activity diagrams and mineral assemblages. Dickite, the dominant mineral in clay deposits, occurs generally as massive aggregates. It shows book-structure of well-defined hexagonal plates. Chemistry of dickite agrees with its ideal formula. Peak depth ratios in infrared absorption spectra were used for discrimination between pure and mixture of kaolin minerals. Five hydrothermal alteration zones are divided according to the mineral assemblages. From center to margin, alunite, dickite, illite and albite zones are discernible. Quartz zone occurs as small lenticular form in dickite zone. The formation of dickite and illite zones are promoted by decreasing $a_{k^+}$. An increase in $a_{H_{2}SO_{4}}$ or $a_{K_{2}SO_{4}}$ is required for the formation of alunite zone. Estimated temperature of formation ranges 110-270 $^{\circ}C$

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.11
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• pp.376-385
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• 2019

This study was undertaken is to isolate brewing yeast suitable for rice beer fermentation from the traditional Nuruk, and to identify the brewing ability of the isolated yeast. After 6 months of research, four brewing yeast isolated from traditional Nuruk showed a normal fermentation pattern in terms of physicochemical data (pH, brix, alcohol content) and higher vitality, as compared to commercial brewing yeast. The concentrations of higher alcohol and ester, that impart the aroma to beer, were 78.4 to 106.5 ppm and 15.1 to 29.3 ppm, respectively. In particular, S. cerevisiae (KCCM 90313) bestowed significantly higher contents of higher alcohol and ester concentrations than rice beer prepared from commercial yeast. We conclude that the four variants of yeast isolated from traditional Nuruk are potentially suitable for manufacturing rice beer. Especially, the S. cevisiae (KCCM 90313) yeast shows excellent yeast activity and aroma production, thereby displaying potential application for manufacturing rice beer in the future.

• Ocean and Polar Research
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• v.30 no.4
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• pp.379-399
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• 2008

Spatial-temporal variations in physiochemical water qualities (temperature, salinity, DO, SPM, POC and nutrients) of surface and bottom waters were investigated along the mid-western coastal area (Taean Peninsula to Gomso Bay) of Korea. Spatial distribution patterns of temperature and salinity were mostly controlled by the physical mixing process of freshwater from Geum River and/or Gyunggi Bay with nearby coastal water. A strong tidal front is formed off Taean Peninsula during spring and summer. Seasonal variations in nutrient concentrations, lower in spring and summer and higher in fall and winter, are primarily regulated by magnitude of phytoplankton occurrence rather than freshwater loadings into the bay. Based on seasonal and spatial variability of physicochemical parameters, water quality of the study area can be divided into four water masses; Gyunggi Bay-influenced Water Mass (GBWM), Geum River-influenced Water Mass (GRWM), Yellow Sea Bottom Cold Water Mass (YSBCWM) and Cheonsu Bay Water Mass (CBWM). Water quality of the GBWM (Taean Peninsula coastal area), which has relatively low salinity and high concentrations of nutrients, is strongly controlled by the Gyunggi Bay coastal water, which is under influence of the Han River freshwater. In this water mass, the mixed layer is always developed by strong tidal mixing. As a result, a tidal front is formed along the offshore boundary of the mixed layer. Such tidal fronts probably play an important role in the distribution of phytoplankton communities, SPM and nutrients. The GRWM, with low salinity and high nutrients, especially during the flood summer season, is closely related to physiochemical properties of the Geum River. During the flood season, nutrient-enriched Geum River water mass extends up to 60 km away from the river mouth, potentially causing serious environmental problems such as eutrophication and unusual and/or noxious algal blooms. Offshore (<$30{\sim}40m$ in water depth) of the study area, YSBCWM coupled with a strong thermocline can be identified in spring-summer periods, exhibiting abundant nutrients in association with low temperature and limited biological activity. During spring and summer, a tidal front is formed in a transition zone between the coastal water mass and bottom cold water mass in the Yellow Sea, resulting in intensified upwelling and thereby supplying abundant nutrients to the GBWM and GRWM. Such cold bottom water mass and tidal front formation seems to play an important role in controlling water quality and further regulating physical ecosystem processes along mid-western Korean coastal area.

• Journal of Applied Biological Chemistry
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• v.55 no.4
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• pp.217-220
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• 2012

The fruits of Acanthopanax sessiliflorus Seeman (Araliaceae) were extracted with 70% aqueous ethanol at room temperature. The concentrated extract was partitioned with ethyl acetate (EtOAc), n-butyl alcohol, and $H_2O$, successively. From the EtOAc fraction, two compounds were isolated through the repeated silica gel, octadecyl silica gel, and Sephadex LH-20 column chromatographies. According to the results of physicochemical and spectroscopic data including NMR, mass spectrometry, and infrared spectroscopy, the chemical structures of the compounds were determined as 3,5-dihydroxycinnamic acid (1) and protocatechuic acid (2). Compound 1 was isolated from the fruits of A. sessiliflirus Seeman for the first time. And the compounds were evaluated for the radical scavenging the antioxidant capacity using 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid)diammonium salt, 1,1-diphenyl-2-picrylhydrazy, and oxygen radical absorbance capacity assay.

• Journal of the Korean Applied Science and Technology
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• v.34 no.3
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• pp.555-561
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• 2017

This study was conducted to investigate the several physicochemical extraction characteristics and the antioxidant activities of ethanol extract from Rhus javanica bark. The contents of soluble solid and sugar in extract was measured to 73.5 mg/100g dry basis and $17.8^{\circ}Brix$, respectively. The contents of total aromatics, total flavonoids and total phenolic compounds was measured to 0.508 in absorbance, 49.88 mg/100g and 296.6 mg/100g, respectively. The reducing power of extract was about 27.5 % of ascorbic acid with the same soluble solid contents of the extract. But the ferric reducing antioxidant power and the DPPH radical scavenging ability of extract were measured to equivalent to those of ascorbic acid. The metal ion chelating ability of the extract was 81.58 % whereas that of ascorbic acid was 74.73 %. The nitrite scavenging ability of the extract was measured to 51.76 % at pH 2. And the antioxidative effect of the extract on soybean oil was observed with Rancimat test.

• Journal of the Korean Applied Science and Technology
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• v.34 no.3
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• pp.504-514
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• 2017

This study was carried out to investigate the emulsifying properties of concentrated red ginseng extract (CRGE). First, we determined the interfacial tension of CRGE at the oil-water interface. Second, oil-in-water emulsions were prepared with CRGE and then their physicochemical properties such as fat globule size, zeta-potential, dispersion stability, and microscopic characteristics were determined. It was found that interfacial tension gradually decreased with increasing CRGE concentration, indicative of some surface activity. In emulsions, fat globule size was decreased as CRGE concentration increased, showing a critical value ($d_{43}$ ≒ $0.39{\mu}m$) at ${\geq}3.5wt%$ of CRGE. In addition, pH and NaCl also influenced on fat globule sizes; they were increased in acidic conditions ($pH{\leq}3$) or in higher NaCl concentration (${\geq}0.4M$) and these results were interpreted in view of the change in zeta potentials. The dispersion stability by separation analyzer ($LUMiFuge^{(R)}$) showed that it was more stable in emulsions with higher CRGE concentration (i.e., ${\geq}3.5wt%$). In conclusion, CRGE was surface-active and it could be used as an emulsifier in preparation of food emulsions.

• Journal of Korean Society for Atmospheric Environment
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• v.27 no.3
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• pp.313-325
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• 2011

From October 2009 to June 2010, major greenhouse gases (GHG: $N_2O$, $CH_4$, $CO_2$) soil emission were measured from upland cabbage field at Kunsan ($35^{\circ}$56'23"N, $126^{\circ}$43'14"E), Korea by using closed static chamber method. The measurements were conducted mostly from 10:00 to 18:00LST during field experiment days (total 28 days). After analyzing GHG concentrations inside of flux chamber by using a GC equipped with a methanizer (Varian CP3800), the GHG fluxes were calculated from a linear regression of the changes in the concentrations with time. Soil parameters (e.g. soil moisture, temperature, pH, organic C, soil N) were also measured at the sampling site. The average soil pH and soil moisture were ~pH $5.42{\pm}0.03$ and $70.0{\pm}1.8$ %WFPS (water filled pore space), respectively. The ranges of GHG flux during the experimental period were $0.08\sim8.40\;mg/m^2{\cdot}hr$ for $N_2O$, $-92.96\sim139.38mg/m^2{\cdot}hr$ for $CO_2$, and $-0.09\sim0.05mg/m^2{\cdot}hr$ for $CH_4$, respectively. It revealed that monthly means of $CO_2$ and $CH_4$ flux during October (fall) were positive and significantly higher than those (negative value) during January (winter) when subsoil have low temperature and relatively high moisture due to snow during the winter measurement period. Soil mean temperature and moisture during these months were $17.5{\pm}1.2^{\circ}C$, $45.7{\pm}8.2$%WFPS for October; and $1.4{\pm}1.3^{\circ}C$, $89.9{\pm}8.8$ %WFPS for January. It may indicate that soil temperature and moisture have significant role in determining whether the $CO_2$ and $CH_4$ emission or uptake take place. Low temperature and high moisture above a certain optimum level during winter could weaken microbial activity and the gas diffusion in soil matrix, and then make soil GHG emission to the atmosphere decrease. Other soil parameters were also discussed with respect to GHG emissions. Both positive and negative gas fluxes in $CH_4$ and $CO_2$ were observed during these measurements, but not for $N_2O$. It is likely that $CH_4$ and $CO_2$ gases emanated from soil surface or up taken by the soil depending on other factors such as background concentrations and physicochemical soil conditions.

• Microbiology and Biotechnology Letters
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• v.34 no.2
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• pp.83-93
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• 2006

In heavily industrialized areas, soil sites are contaminated with high concentrations of heavy metals. These pollutants are highly accumulated to the human body through the food web and cause serious diseases. To remove heavy metals from the soil, a potential strategy is the environmental friendly and cost effective phytoremediation. For the enhancement of remediation efficiency, the symbiotic interaction between the plant and plant growth-promoting rhizobacteria (PGPR) has been attended. In this review, the interaction of the plant and PGPR in the heavy metal-contaminated soil has been reviewed. The physicochemical and biological characteristics of the rhlzosphere can influence directly or indirectly on the biomass, activity and population structure of the rhizobacteria. The root exudates are offered to the soil microbes as useful carbon sources and growth factors, so the growth and metabolism of rhizobacteria can be promoted. PGPR have many roles to lower the level of growth-inhibiting stress ethylene within the plant, and also to provide iron and phosphorus from the soil to plant, and to produce phytohormone such as indole acetic acid. The plant with PGPR can grow better in the heavy metal contaminated soil. Therefore higher efficiency of the phytoremediation will be expected by the application of the PGPR.

• Food Science and Preservation
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• v.23 no.3
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• pp.301-309
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• 2016

The objective of this study was to investigate physicochemical and antioxidant characteristics of immature flat persimmon during 7 heat treatment aging steps. The pH decreased, and hence, acidity increased with aging. Hunter L value decreased with aging. The a value rapidly increased until step 3, whereas the b value decreased. Fructose content decreased while glucose contents slightly increased during aging. Hardness, chewiness and gumminess rapidly decreased, indicating softening in texture, but it was negligible after aging step 3. Phenolic compounds including gallic acid and homogentisic acid were detected at step 3 and then gradually increased with aging. However, contents of flavonoid and tannin were much higher in step 1 sample than others. The antioxidant activities observed by DPPH, ABTS, and FRAP assay were the highest at step 1 possibly due to the higher levels of flavonoids and tannin acid in the step 1 sample.

• Journal of Environmental Health Sciences
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• v.46 no.2
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• pp.150-158
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• 2020

Objective: This study is designed to measure the concentration of DBPs (disinfection by-products) in pool water and in air and to estimate the carcinogenic potential through the evaluation of inhalation exposure. Methods: The subjects were six indoor swimming pools with many users in Gwangju. Samples of pool water and indoor air were taken every one month from August 2018 to August 2019 and analyzed for eight swimming pool standards. Three-liter air samples were collected and the VOCs were analyzed using GC/MS directly connected to thermal desorption. Results: pH was 6.8-7.5 and the concentration of free residual chlorine in pool water was 0.40-0.96 ?/ℓ. Physicochemical test items such as KMnO₄ consumption and heavy metal items such as Aluminum met existing pool hygiene standards. No VOC materials were detected except for the DBPs. The concentration of THMs in the pool water was 11.05-41.77 ㎍/L and the THMs mainly consist of Chloroform (63-97%) and BDCM (3-31%). The concentration of indoor air THMs is 13.24-32.48 ㎍/㎥ and consists of Chloroform. The results of carcinogenic assessment of chloroform in the indoor swimming pool via inhalation exposure were 2.0 to 6.4 times higher than the 'acceptable risk level' suggested by the US EPA. Conclusions: The concentration of THMs in the pool water is 11.05-41.77 ㎍/L, most of which is chloroform. In addition, the concentration of indoor air THMs is 13.24-32.48 ㎍/㎥. The result of carcinogenic assessment of chloroform was 2.0 to 6.4 times higher than the 'acceptable risk level' suggested by the US EPA.