• Journal of Korea Water Resources Association
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• v.56 no.12
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• pp.919-928
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• 2023

Rainfall characteristics in Korea are concentrated during the summer flood season. In particular, when a large amount of turbid water flows into the dam due to the increasing trend of concentrated rainfall due to abnormal rainfall and abnormal weather conditions, prolonged turbid water phenomenon occurs due to the overturning phenomenon. Much research is being conducted on turbid water prediction to solve these problems. To predict turbid water, turbid water data from the upstream inflow is required, but spatial and temporal data resolution is currently insufficient. To improve temporal resolution, the development of the Turbidity-SS conversion equation is necessary, and to improve spatial resolution, multi-item water quality measurement instrument (YSI), Laser In-Situ Scattering and Transmissometry (LISST), and hyperspectral sensors are needed. Sensor-based measurement can improve the spatial resolution of turbid water by measuring line and surface unit data. In addition, in the case of LISST-200X, it is possible to collect data on particle size, etc., so it can be used in the Turbidity-SS conversion equation for fraction (Clay: Silt: Sand). In addition, among recent remote sensing methods, the spatial distribution of turbid water can be presented when using UAVs with higher spatial and temporal resolutions than other payloads and hyperspectral sensors with high spectral and radiometric resolutions. Therefore, in this study, the Turbidity-SS conversion equation was calculated according to the fraction through laboratory analysis using LISST-200X and YSI-EXO, and sensor-based field measurements including UAV (Matrice 600) and hyperspectral sensor (microHSI 410 SHARK) were used. Through this, the spatial distribution of turbidity and suspended sediment concentration, and the turbidity calculated using the Turbidity-SS conversion equation based on the measured suspended sediment concentration, was presented. Through this, we attempted to review the applicability of the Turbidity-SS conversion equation and understand the current status of turbid water occurrence.

• The Korean Journal of Pharmacology
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• v.26 no.2
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• pp.209-217
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• 1990

Intramolecular excimer formation with 1,3-di(1-pyrenyl)propane (Py-3-Py) and fluorescence polarization with 1,6-diphenyl-1,3,5-hexatriene (DPH) were used to evaluate the effects of barbiturates on the bulk fluidity of the model membranes of phosphatidylethanolamine fraction of synaptosomal plasma membrane vesicles (SPMVPE) isolated from bovine cerebral cortex. In the SPMVPE, barbiturates decreased the excimer to monomer fluorescence intensity ratio (I'/I) of Py-3-Py and increased the fluorescence polarization (P), anisotropy (r), limiting anisotropy $(r_{8})$, order parameter (S) and rotational relaxation time $({\bar{P}})$ of DPH in a dose-dependent manner. The relative potencies of barbiturates to order the SPMVPE were in the order: pentobarbital > hexobarbital > amobarbital > phenobarbital. Hence, it is concluded that barbiturates have ordering effects on the SPMVPE. And the membrane-ordering potencies of barbiturates appear to be correlated with the potencies for enhancement of GABA-stimulated chloride influx and with the anesthetic effects of barbiturates.

• Journal of the Korean Electrochemical Society
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• v.8 no.4
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• pp.155-161
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• 2005

In this paper, commercial CFD program FLUENT v5.3 is used for simulation of MCFC stack. Besides using conservation equations included in FLUENT by default, mass change, mole fraction change and heat added or removed due to electrochemical reactions and water gas shift reaction are considered by adding several equations using user defined function. The stacks calculated are 6 and 25 kW class coflow stack which are composed of 20 and 40 unit cells respectively. Simulation results showed that pressure drop took place in the direction of gas flow, and the pressure drop of cathode side is more larger than that of anode side. And the velocity of cathode gas decreased along with the gas flow direction, but the velocity of anode gas increased because of the mass and volume changes by the chemical reactions in each electrodes. Simulated temperature profile of the stack tended to increase along with the gas flow direction and it showed similar results with the experimental data. Water gas shift reaction was endothermic at the gas inlet side but it was exothermic at the outlet side of electrode respectively. Therefore water gas shift reaction played a role in increasing temperature difference between inlet and outlet side of stack. This results suggests that the simulation of large scale commercial stacks need to consider water gas shift reaction.

• Journal of Educational Research in Mathematics
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• v.27 no.3
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• pp.537-555
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• 2017

This paper compared and contrasted Korean and Singaporean textbooks in order to explore the direction and possibility of teaching the big ideas related to the addition and subtraction of fractions with different denominators proposed by Lee & Pang (2016a). Firstly, we examined the teaching sequences related to the addition of fractions with different denominators in a series of elementary mathematics textbooks of Korea and Singapore. We then analyzed what types of representations are used and how the representations are presented for the big ideas related to the addition of fractions with different denominators. The results of the analysis showed that the contents related to fraction addition are addressed more gradually and systematically in Singaporean textbooks compared to Korean counterparts. The graphical representations appeared in the Singaporean textbooks provide specific implications for teaching the big ideas of the addition of fractions with different denominators. Based on such implications, we expect that the big ideas related to the addition of fractions with different denominators will be addressed explicitly and systematically in Korean textbooks.

• International Journal of Highway Engineering
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• v.13 no.2
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• pp.187-193
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• 2011

The stormwater runoff from road or expressway is known as one of important nonpoint pollution sources. To reduce the pollutants discharge from road or expressway, many best management practices(BMPs) have been applied and planned. Among the BMPs, road sweeping can be effective way to prevent pollutant washoff to environment. This study is performed to evaluate the characteristics of particles collected from the road by sweeping car. Size distribution and pollutant concentration of particles were analyzed. Based on the pollutant concentration and the specification of road such as length, width, and unit for pollutant generation, total amount of pollutant to be removed by road sweeping was estimated. Most of sediments collected by road sweeping was classified into sandy soil and fraction of fine grained soil was low. Although the concentrations of pollutants such as heavy metals in road sediments did not exceed the soil contamination criteria, washout of pollutants during sweeping work by spraying water might cause leaching of pollutants contained in sediments and thus resulted in low pollutant concentrations. Reduced amounts of pollutant by road sweeping showed 31.4% TSS reduction for ${\bigcirc}{\bigcirc}$ region and 7.7% TSS for ${\triangle}{\triangle}$ region. Other pollutants showed low reduction rate, because of their leaching by water spraying. Results from this study indicate that detailed and well-planned investigation for the road sweeping is necessary for the accurate estimation of pollutant reduction from road or expressway.

• Journal of Preventive Medicine and Public Health
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• v.23 no.1 s.29
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• pp.43-56
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• 1990

To evaluate the difference of concentration and mutagenicity of organic pollutants between residential and traffic area of Seoul, air samples were collected in Bulkwang (residential) and Shinchon (traffic) area. Samples were analyzed to measure the concentration of extractable organic matters (EOM) and their subfractions and mutagenicities were tested using Salmonella typhimurium TA 98. The concentrations of polycyclic aromatic hydrocarbons (PAHs) were also measured by gas-chromatography and compared between two areas. The results were as follows ; 1. While the concentration of total suspended particulate (TSP) in residential area was below the environmental standard in annual average, the concentration in traffic area was above the standard and was up to its maximum $256{\mu}g/m^3$ in November. The difference of TSP concentrations in both areas of each month was statistically significant (P<0.05). 2. The concentration of fine particle in traffic area was significantly higher compare to that in residential area and showed statistically significant monthly difference in both areas (P<0.05). The proportion of concentration of fine particle to TSP was 55-68%. 3. Mean concentrations of EOM in residential and traffic areas were $4.3{\mu}g/m^3\;and\;5.3{\mu}g/m^3$ respectively. The proportion of amount of EOM from fine particle to EOM from TSP was 70-88%. 4. While the percentage of polar neutral organic compounds (POCN) of fine particle in Bulkwang's sample was higher compare to Shinchon's sample, the percentage of aliphatic compounds of fine particle in Shinchon's sample was higher compare to Bulkwang's sample. The percentages of PAH fraction were as low as 6-10% in both areas. 5. The mutagenic activity of nit concentration of organic matters extracted from fine particle was higher compare to that of coarse particle and was increased when metabolically activated with S9. Mutagenicities with metabolic activation calculated by unit air volume were significantly different between residential and traffic area, $17\;revertants/m^3$\;and\;22\;revertants/m^3$ respectively. 6. The concentrations of benzo(a)pyrene in fine particle of traffic and residential areas were $3.10ng/m^3\;and\;2.02ng/m^3$ respectively. Sixteen PAHs were higher in samples of traffic area compare to residential area and also concentrations of PAHs in fine particle were higher compare to coarse particle.

• Journal of Microbiology and Biotechnology
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• v.16 no.8
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• pp.1255-1261
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• 2006

An alkaliphilic bacterium, Bacillus sp. strain BK, was found to produce extracellular cellulase-free xylanolytic enzymes with xylan-binding activity. Since the pellet-bound xylanase is eluted with 2% TEA from the pellet of the culture, they contain a xylan-binding region that is stronger than the xylan-binding xylanase of the extracellular enzyme. The xylanases had a different molecular weight and xylan-binding ability. The enzyme activity of xylanase in the extracellular fraction was 6 times higher than in the pellet-bound enzyme. Among the enzymes, xylanase had the highest enzyme activity. When Bacillus sp. strain BK was grown in pH 10.5 alkaline medium containing xylan as the sole carbon source, the bacterium produced xylanase, arabinofuranosidase, acetyl esterase, and $\beta$-xylosidase with specific activities of 1.23, 0.11, 0.06, and 0.04 unit per mg of protein, respectively. However, there was no cellulase activity detected in the crude enzyme preparation. The hydrolysis of agricultural residues and kraft pulps by the xylanolytic enzymes was examined at 50$^{\circ}C$ and pH 7.0. The rate of xylan hydrolysis in com hull was higher than those of sugarcane bagasse, rice straw, com cop, rice husk, and rice bran. In contrast, the rate of xylan hydrolysis in sugarcane pulp was 2.01 and 3.52 times higher than those of eucalyptus and pine pulp, respectively. In conclusion, this enzyme can be used to hydrolyze xylan in agricultural residues and kraft pulps to breach and regenerate paper from recycled environmental resources.

• Journal of Korean Society for Atmospheric Environment
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• v.27 no.3
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• pp.303-312
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• 2011

Data on the energy usage including biomass, emissions of air pollutants ($SO_x$, $NO_x$, CO), and the air quality in North Korea are analyzed. The energy usage in North Korea has decreased in the 1990s and thus, the emission amount of air pollutants. Coal and biomass constitute a major fraction of energy sources since the 1990s. It is identified that the emission amount of air pollutants per unit energy consumption in North Korea is much higher than South Korea for the period data are available (since 1990) implying that the air pollutant emission management system in North Korea is inadequate. In particular, the amount of biomass burning for household cooking and heating is significant with the huge emissions of air pollutants such as CO and organic species both in the gas and aerosol phase. Furthermore, it is found that the existing energy usage and air pollutant emission data are not consistent in biomass burning related data.

• Journal of Chest Surgery
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• v.49 no.3
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• pp.165-170
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• 2016

Background: In elderly high-risk surgical patients, sutureless aortic valve replacement (AVR) should be an alternative to standard AVR. The potential advantages of sutureless aortic prostheses include reducing cross-clamping and cardiopulmonary bypass (CPB) time and facilitating minimally invasive surgery and complex cardiac interventions, while maintaining satisfactory hemodynamic outcomes and low rates of paravalvular leakage. The current study reports our single-center experience regarding the early outcomes of sutureless aortic valve implantation. Methods: Between October 2012 and June 2015, 65 patients scheduled for surgical valve replacement with symptomatic aortic valve disease and New York Heart Association function of class II or higher were included to this study. Perceval S (Sorin Biomedica Cardio Srl, Sallugia, Italy) and Edwards Intuity (Edwards Lifesciences, Irvine, CA, USA) valves were used. Results: The mean age of the patients was $71.15{\pm}8.60years$. Forty-four patients (67.7%) were female. The average preoperative left ventricular ejection fraction was $56.9{\pm}9.93$. The CPB time was $96.51{\pm}41.27minutes$ and the cross-clamping time was $60.85{\pm}27.08minutes$. The intubation time was $8.95{\pm}4.19hours$, and the intensive care unit and hospital stays were $2.89{\pm}1.42days$ and $7.86{\pm}1.42days$, respectively. The mean quantity of drainage from chest tubes was $407.69{\pm}149.28mL$. The hospital mortality rate was 3.1%. A total of five patients (7.69%) died during follow-up. The mean follow-up time was $687.24{\pm}24.76days$. The one-year survival rate was over 90%. Conclusion: In the last few years, several models of valvular sutureless bioprostheses have been developed. The present study evaluating the single-center early outcomes of sutureless aortic valve implantation presents the results of an innovative surgical technique, finding that it resulted in appropriate hemodynamic conditions with acceptable ischemic time.

• Journal of Life Science
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• v.20 no.10
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• pp.1458-1467
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• 2010

The present study was retrospectively designed to define whether preoperative levels of leukocytes and D-dimer are potentially useful factors in predicting perioperative outcomes of coronary heart disease (CHD). There was no relationship between preoperative leukocyte counts (Pre-OP leukocyte) and preoperative D-dimer levels (Pre-OP D-dimer). Pre-OP leukocyte counts each had positive correlation with cardiac troponin-I, creatine kinase-MB or C-reactive protein (cardiac markers) levels at preoperative and postoperative periods. Pre-OP D-dimer levels were positively associated with each cardiac marker at the same periods. Pre-OP leukocyte counts positively related with aspartate aminotransferase and alanine aminotransferase (liver markers), whereas Pre-OP D-dimer level positively or negatively correlated with bilirubin (liver marker), creatinine (renal marker) or glucose levels at preoperative and/or postoperative periods. Pre-OP leukocyte and Pre-OP D-dimer were inversely associated with Pre-OP high density lipoprotein cholesterol levels or left ventricular ejection fraction. Pre-OP leukocyte counts each had positive correlation operation duration and postoperative mechanical ventilation-time (PMVT), whereas Pre-OP D-dimer levels had positive relationship with PMVT, intensive care unit-staying period and hospitalization. The retrospective data suggest that Pre-OP leukocyte and Pre-OP D-dimer levels may be clinically useful factors for predicting perioperative outcomes in patients with CHD.