• Journal of Wetlands Research
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• v.20 no.2
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• pp.161-172
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• 2018

A mixed farming system that includes organic rice production and freshwater fish farming is being called into attention in Korean agricultural industry and rural areas in order to improve farm management and environmental conservation. This study was conducted to evaluate the environmental and ecological value of such mixed farming practices. Expert assessment and rapid assessment method (RAM) of wetland evaluation were employed for this study. Experts have responded that biodiversity conservation including amphibian and reptile habitat (2.39), aquatic insect habitat (2.36), Fishery habitat (2.34), vegetation diversity (2.13), avian habitat (2.05), and experience and education were the most important function of mixed farming. The wetland function evaluation conducted using modified RAM indicated that rice-fish mixed system showed improvements in most of the evaluated functions, compared to the conventional rice paddies. The overall wetland function of rice paddies in rice-fish mixed system was greatly improved as compared with the conventional rice paddies. Rice paddies are known to play an important role in biodiversity maintenance, and provide ecosystem services such as climate modulation and carbon reduction. Rice-fish mixed system of farming may not only improve various ecosystem services of rice paddies, but may increase farm income through value added fish farming, as well as promotion of social services such as education and maintenance of tradition. Additional research is needed for quantitative analysis of the values gained from the most improved wetland function when mixed farming system is actually put into practice, and to utilize the results in advertising of the organic rice, and in various sectors such as food, education and direct payment policy.

• Economic and Environmental Geology
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• v.36 no.6
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• pp.441-455
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• 2003

The most common water types are found to be Ca-$HCO_3$, Ca-Na-$HCO_3$ and Ca-Na-$HCO_3$-Cl in Gwangju groundwater. Groundwater near the Gwangju stream are characterized Ca-Cl water type, with over 50 mg/L of C1- and 400 ${\mu}$S/cm of EC. The systematic variation of $Cl^-$, $HCO_3^-$,- EC and ${\gamma}^{18}O$ values in groundwater with distance away from drainages is caused by streamwater infiltration. Stable isotope data indicate that ${\gamma}$D and ${\gamma}^{18}O$ values of groundwaters near drainages were enriched by evaporation effect, showing a equation of ${\gamma}$D=7. 1${\times}{\gamma}^{18}O$-1. ${\gamma}^{18}O$ values over -6${\textperthansand}$ are anomalous in the unconfined groundwater zones, which are influenced by the local surface water enriched in $^{18}O$ composition. Groundwater in highland shows remarkably light ${\gamma}^{18}O$ values below -8$\textperthousand$. The infiltration of streamwater is dominant in unconfined alluvium aquifer near drainages. ${\gamma}^{13}$CDIC values (-17.6∼-15.2$\textperthousand$) of groundwaters near drainages revealed that dissolved inorganic carbon (DIC) is predominantly originated from natural soil-derived $CO_2$. ${\gamma}^{15}N$ and ${\gamma}^{18}O$ values of nitrate are 0∼17.0${\textperthansand}$ and 6.6∼17.4${\textperthansand}$, respectively. Relationship between ${\gamma}^{15}N$ and ${\gamma}^{18}O$ shows a systematic isotopic fractionation caused by denitrification of 40∼60%, suggesting that the major source of groundwater nitrate originated from nitrate of soils, and mixing nitrate of soil and sewage or manure.

• Journal of the Korean Society for Marine Environment & Energy
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• v.9 no.4
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• pp.203-215
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• 2006

Field observations on the spatio-temporal distribution of organic matter of the surface sediment were carried out at 15 stations in the central parts of the South Sea of Korea from April 2002 to January 2003. The range of water temperature and salinity in bottom waters, mud content and water content of surface sediment were $8.06{\sim}23.35^{\circ}C,\;29.20{\sim}34.51\;psu,\;71.2{\sim}99.9%$ and $38.7{\sim}68.9%$, respectively. Measured parameters on the surface sediments of ignition loss (IL), chemical oxygen demand (CODs), phaeopigment, particulate organic carbon (POC) and particulate organic nitrogen (PON) also ranged in $3.9{\sim}l2.5%,\;9.60{\sim}44.05\;mgO_2/g-dry,\;1.58{\sim}29.51\;{\mu}g/g-dry,\;3.12{\sim}13.01\;mgC/g-dry$ and $0.49{\sim}2.00\;mgN/g-dry$, respectively. The spatio-temporal distribution of organic matter demonstrated higher concentrations offshore than at lesions near the coastal line. Higher concentrations occurred in the summer and spring. The results indicated that the origin of organic matter in surface sediments in the central part of the South Sea was autochthonous rather than allocthonous because the organic matter had an average C/N ratio of 6.44 (${\pm}0.51$). However, the composition of autochthonous organic matter was mainly derived from detritus rather than living phytoplankton, which was Indicated by the results of the POC/phaeopigment ratio. A principal component analysis (PCA) indicated that 73.2% of the variability in the data was described by two factors: 1) an 'environmental factor concerning the accumulation of materials (57.3%)' and 2) 'origin of organic matter and the composition by primary production (15.9%)'. The sedimentary environment in the central part of the South Sea was divided into four regions from the factor score of the PCA by the concentrations of organic matter and the composition ratio of organic matters from phytoplankton in surface sediments.

• Journal of Radiation Protection and Research
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• v.40 no.4
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• pp.223-230
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• 2015

The objective of this study is to identify the radionuclide distribution in public water by carrying out the analysis of artificial radionuclides($^{134}Cs$, $^{137}Cs$, $^{239+240}Pu$), natural radionuclide($^{210}Pb$) and TOC in the lake Euiam sediment in Chuncheon, South Korea. The $^{134}Cs$ concentration in all lake sediments showed below MDA values, and the $^{137}Cs$ concentration in lake sediment were ranged from MDA to $8.79Bq{\cdot}kg^{-1}-dry$. The $^{137}Cs$ concentrations in surface sediment were reported to be 2.4 to $4.2Bq{\cdot}kg^{-1}-dry$. The lowest concentration of $^{137}Cs$ was reported at St. 4 and the highest concentration was reported at St. 3, respectively. The $^{239+240}Pu$ concentration in lake sediment were ranged from 0.049 to $0.47Bq{\cdot}kg^{-1}-dry$. The lowest concentration was reported at St. 2 and the highest concentration was reported at St. 3. The correlation(r) between the $^{239+240}Pu$ concentration and $^{137}Cs$ concentration in lake sediment presented higher values (0.54 to 0.97) and this suggests the behavior and origin of $^{137}Cs$ is identical to the $^{239+240}Pu$ in the sediment. The $^{134}Cs$ concentration below MDA value and the $^{239+240}Pu/^{137}Cs$ ratio(mean value of 0.041) indicated that the artificial radionuclides in the sediment were originated from global fallout by the atmospheric testing of nuclear weapons conducted by former USSR and U.S.A, but not from the Fukushima Daiichi NPP accident. The sedimentation rate derived from $^{210}Pb$ age-dating method at St. 2 is calculated to be $0.31{\pm}0.06cm{\cdot}y^{-1}$. This value is similar to the value ($0.41{\pm}0.05cm{\cdot}y^{-1}$) estimated from the $^{137}Cs$ maximum peak produced from early 1960's. The content of TOC in lake Euiam sediments varied from 0.20 to 13.01%. While the highest correlation between TOC and $^{137}Cs$ concentration in the sediment were found at St. 1, the others presented the low correlation.

• The korean journal of orthodontics
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• v.38 no.4
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• pp.275-282
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• 2008

Objective: The purpose of this study was to investigate the effect of using laser for ceramic bracket bonding of porcelain surfaces and to compare it with conventional treatment of porcelain surfaces. Methods: Ninety feldspathic porcelain specimens were divided into 9 groups of 10, with each group having different surface treatments performed. Surface treatment groups were orthophosphoric acid, orthophosphoric acid with silane, hydrofluoric acid, hydrofluoric acid with silane, sandblasted, sandblasted with silane, laser etched, laser etched with silane, and glazed surface served as a control group. In the laser etched groups, the specimens were irradiated with 2-watt superpulse carbon dioxide ($CO_2$) laser for 20 seconds. Ceramic brackets were bonded with light-cure composite resin and all specimens were stored in water at $37^{\circ}C$ for 24 hours. Shear bond strength was determined in megapascals (MPa) by shear test at 1 mm/minute crosshead speed and the failure pattern was assessed. For statistical analysis, one-way ANOVA and tukey test were used. Results: Statistical analysis showed significant differences between the groups. The HFA + S group showed the highest mean shear bond strength ($13.92{\pm}1.94\;MPa$). This was followed by SB + S ($10.16\;{\pm}\;1.27\;MPa$), HFA ($10.09\;{\pm}\;1.07\;MPa$), L + S ($8.25\;{\pm}\;1.24\;MPa$), L ($7.86\;{\pm}\;0.96\;MPa$), OFA + S ($7.22\;{\pm}\;1.09\;MPa$), SB ($3.41\;{\pm}\;0.37\;MPa$), OFA ($2.81\;{\pm}\;0.37\;MPa$), G ($2.46\;{\pm}\;1.36\;MPa$), Bond failure patterns of HFA and silane groups, except L + S, were cohesive modes in porcelain while adhesive failure was observed in the control group and the rest of the groups. Conclusions : A 2-watt superpulse $CO_2$ laser etching of porcelain surfaces can provide a satisfactory result for porcelain surface treatment for ceramic bracket bonding. Laser irradiation may be an alternative conditioning method for the treatment of porcelain surfaces.

• Korean Journal of Food Science and Technology
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• v.44 no.4
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• pp.401-410
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• 2012

This study examines the authenticity discrimination of the circulated honey by using stable isotope ratio methods. In the case of domestic honey, the range of ${\delta}^{13}C$ for the samples labeled as pure honey was about -27- -21‰ at the $C_3$ origin, and the range of that for artificial honey was over -19‰ at the $C_4$ origin. The range of ${\delta}^{13}C$ for all imported honey was over -27- -23‰ originating from the $C_3$ plant. According to the nectar-source, ${\delta}^2H$ and ${\delta}^{18}O$ for domestic honey were significantly different for 6 and 5 groups, respectively. However, we could not explain the detailed relationship as well as the geographical feature of ${\delta}^2H$ and ${\delta}^{18}O$. The difference for ${\delta}^2H$ and ${\delta}^{18}O$ in the wide range of latitude, such as between Australia and Canada, was more or less shown. However, it was difficult to find out the trends of ${\delta}^2H$ and ${\delta}^{18}O$ for imported honey versus the geographical information in the similar latitudinal country.

• Journal of Korean Society of Environmental Engineers
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• v.34 no.9
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• pp.590-596
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• 2012

Enhanced coagulation is best available technologies to treat NOM in water to produce clean drinking water. In this research, the comparison experiments between conventional coagulation (CC) and enhanced coagulation (EC) using 4 type coagulants i.e., ferric chloride, aluminium sulphate (alum), poly aluminium sulphate organic magnesium (PSOM) and poly aluminium chloride (PACl) were performed in terms of surrogate parameters such as dissolved organic carbon (DOC), trihalomethane formation potential (THMFP), haloacetic acid formation potential (HAAFP) and zeta potential variation in order to find out the most effective coagulant and conditions to fit Nakdong River water. When applied to EC process, the turbidity removal efficiency did not increased gradually compared to the CC process when adding coagulants. Furthermore, the removal efficiency of turbidity became decreased much more as coagulants were added increasingly whereas the removal efficiency of DOC, THMFP and HAAFP became increased by 13~18%, 9~18% and 9~18% respectively compared to the CC process. The characteristics of turbidity removal showed relatively high removal efficiency considering the pH variation in entire pH range when using $FeCl_3$ and PACl. Additionally, in case of alum and PSOM steady removal efficiency was shown between pH 5 and pH 8. In terms of DOC surrogate the coagulants including 4 type coagulants indicated high removal efficiency between pH 5 and pH 7. The removal efficiency of dissolved organic matter (DOM) in EC between less than 1 kDa and more than 10 kDa augmented by 11~21% and 16% respectively compared to the CC process. The removal efficiency of hydrophobic and hydrophilic organic matter proved to be increased by 27~38% and 11~15% respectively. In conclusion, the most effective coagulant relating to EC for Nakdong River water was proved to be $FeCl_3$ followed by PSOM, PAC and alum in order.

• Journal of Bio-Environment Control
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• v.13 no.1
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• pp.51-55
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• 2004

The most commonly used inorganic nutrient compositions such as Murashige & Skoog medium have been optimized for heterotrophic growth. Therefore, they may not be optimal for photomixotrophic and photoautotrophic growth of plantlets. In photomixotrophic micropropagation, emdium sugar level is often lowered, while light and $CO_2$ levels in vessel are raised, and chlorophyllous explants are used to facilitate photosynthetic carbon acquisition. In a factorial experiment effect of addition (+) and omission(_) of organic materials (OM, 0.5 g ${\cdot}$ $m^{-3}$ each of thiamine, nicotinic acid and pyridoxine and 100 ${\cdot}$ $m^{-3}$ myo-inositiol) combined with three sucrose levels (0, 15, and 30 kg ${\cdot}$ $m^{-3}$) was tested on the growth of potato plantlets. Each of nodal cuttings with a leaf was cultured on 0.1${\times}$$10^{-4}m^{-3}$) MS agar ( 8 kg ${\cdot}$ $m^{-3}$) medium (pH 5.80 before autoclave) in glass test tubes (100 mm${\times}$25mm) capped with a sheet of transparent film with a 6 mm diameter gas permeable filter (5.1 air exchanges ${\cdot}$$h^{-1}$). Cultures were maintained in a room for 27 days at $23^{\circ}C$, 50% RH, 350-450${\mu}mol\;{\codt}\;mol^{-1}CO_2$, 16 h ${\cdot}$ $d^{-1}$ photoperiod at 13${\mu}mol\;{\codt}\;m\;{\codt}\;s^{-1}$ PPFD provided by white cool fluorescent lamps. Growth of potato plantlet in the +OM and -OM treatments were similar, while medium pH was 0.2 scale lower in the latter. Dry weight, % dry matter, and stem diameter enhanced, while shoot to root dry weight ratio, leaf area, chlorophyll concentration per gram dry weight, and medium pH decreased with increasing initial sucrose level. Interaction between OM and sucrose levels was observed in shoot length and medium pH. Results indicate that OM can be omitted from the medium without detrimental effect while addition of sucrose was beneficial for the photomixotrophic growth of potato plantlets under raised light and $CO_2$.

• Korean Journal of Food Science and Technology
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• v.12 no.2
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• pp.97-102
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• 1980

Cladosporium fulvum, Aspergillus ochraceus, Aspergillus terreus and N-1 (unidentified species) were cultured on the artificial media containing sucrose as a carbon source at 20, 25 and $30^{\circ}C$ for 10 to 12 days. The lipids in the felts were extracted with chloroform-methanol mixture and the class composition and fatty acids of the lipid were determined. The summarized results are as follows 1. The average felts produced by each species per 100 ml of media were $3.82{\pm}0.30g$ for Cl. fulvum, $2.62{\pm}0.23g$ for Asp. ochraceus, $4.24{\pm}0.25g$ for Asp. terreus and $4.62{\pm}0.10g$ for N-1. Their crude fat contents $27.5{\pm}1.61%,\;50.47{\pm}1.00%,\;46.6{\pm}1.59%$ and 33.78 % and the fat coefficient 6.92, 8.88, 13.01 and 10.28, respectively. 2. The lipids produced by these species were mainly composed of triglyceride and the next free fatty acid in Cl. fulvum and N-1 and phospholipid Asp. ochraceus and Asp. terreus. 3. The major fatty acids of the lipids were in order of oleic, palmitic, linoleic and stearic acids in Asp. ochraceus, Asp. terreus and Cl. fulvum and linoleic, palmitic, oleic and stearic acid in N-1. The total percentage contents of these major fatty acids were over 98 % the former and over 95 % the latter. 4. The constituent fatty acids of the lipid were changed depending on the incubation temperature but hardly found a certain tendency except linoleic acid which was higher at lower temperature. 5. The total percentages of unsaturated fatty acids in the lipids were $50{\sim}60%$ and comparatively higher at lower incubation temperature.

• Korean Journal of Environment and Ecology
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• v.35 no.2
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• pp.154-163
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• 2021

This study was carried out to present the habitat distribution status and the habitat distribution prediction of Sophora koreensis, which is the Korean Endemic Plant included in the EN (Endangered) class of the IUCN Red List. The habit distribution survey of Sophora koreensis confirmed 19 habitats in Gangwon Province, including 13 habitats in Yanggu-gun, 3 habitats in Inje-gun, 2 habitats in Chuncheon-si, and 1 habitat in Hongcheon-gun. The northernmost habitat of Sophora koreensis in Korea was in Imdang-ri, Yanggu-gun; the easternmost habitat in Hangye-ri, Inje-gun; the westernmost habitat in Jinae-ri, Chuncheon-si; and the southernmost habitat in Sungdong-ri, Hongcheon-gun. The altitude of the Sophora koreensis habitats ranged from 169 to 711 m, with an average altitude of 375m. The area of the habitats was 8,000-734,000 m², with an average area of 202,789 m². Most habitats were the managed forests, such as thinning and pruning forests. The MaxEnt program analysis for the potential habitat of Sophora koreensis showed the AUC value of 0.9762. The predictive habitat distribution was Yanggu-gun, Inje-gun, Hwacheon-gun, and Chuncheon-si in Gangwon Province. The variables that influence the prediction of the habitat distribution were the annual precipitation, soil carbon content, and maximum monthly temperature. This study confirmed that habitats of Sophora koreensis were mostly found in the ridge area with rich light intensity. They can be used as basic data for the designation of protected areas of Sophora koreensis habitat.