• Journal of Korean Tunnelling and Underground Space Association
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• v.22 no.3
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• pp.323-335
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• 2020

In this study, a series of site measurement of particulate and gases pollutants at five tunnels were carried out along with case studies to review the suitability of the current road tunnel ventilation design standards. Previous studies by other researchers have shown that the ratios of the level of measurement to the standard were 27.9%, 1.6% and 3.4% for TSP, CO and NOx, respectively. Those measured in this site study shows even lower ratios; the ratios were 2.6%, 0.8% and 0.3%, for TSP, CO and NOx, respectively. The particle size analysis of TSP for the five tunnels shows that PM10 including tire wear and re-suspended road dust exceeded 20.4%. This implies that non-exhaust particulate matter must be taken into account, since the current design standards for the particulate matter (visibility) include only the engine emission. Based on the recent research results, for vehicle emission rate and slope-speed correction factors, revision of ventilation design standards for pollutants is required. WRA (PIARC) also emphasizes the necessity of the ventilation design standards for pollutants. In addition, enactment of a new road tunnel ventilation system operation standard or guideline is strongly recommended when considering the low operating rate of the ventilation system with jet-fans.

• Journal of Ginseng Research
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• v.45 no.3
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• pp.433-441
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• 2021

Background: Multiple sclerosis (MS) and its animal model, the experimental autoimmune encephalomyelitis (EAE), are primarily characterized as dysfunction of the blood-brain barrier (BBB). Ginsenoside-Rg3-enriched Korean Red Ginseng extract (Rg3-KRGE) is known to exert neuroprotective, anti-inflammatory, and anti-oxidative effects on neurological disorders. However, effects of Rg3-KRGE in EAE remain unclear. Methods: Here, we investigated whether Rg3-KRGE may improve the symptoms and pathological features of myelin oligodendroglial glycoprotein (MOG)_35-55 peptide - induced chronic EAE mice through improving the integrity of the BBB. Results: Rg3-KRGE decreased EAE score and spinal demyelination. Rg3-KRGE inhibited Evan's blue dye leakage in spinal cord, suppressed increases of adhesion molecule platelet endothelial cell adhesion molecule-1, extracellular matrix proteins fibronection, and matrix metallopeptidase-9, and prevented decreases of tight junction proteins zonula occludens-1, claudin-3, and claudin-5 in spinal cord following EAE induction. Rg3-KRGE repressed increases of proinflammatory transcripts cyclooxygenase-2, inducible nitric oxide synthase, interleukin (IL)-1 beta, IL-6, and tumor necrosis factor-alpha, but enhanced expression levels of anti-inflammatory transcripts arginase-1 and IL-10 in the spinal cord following EAE induction. Rg3-KRGE inhibited the expression of oxidative stress markers (MitoSOX and 4-hydroxynonenal), the enhancement of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase 2 (NOX2) and NOX4, and NADPH activity in the spinal cord of chronic EAE mice. Furthermore, apocynin, a NOX inhibitor, mimicked beneficial effects of Rg3-KRGE in chronic EAE mice. Conclusion: Our findings suggest that Rg3-KRGE might alleviate behavioral symptoms and pathological features of MS by improving BBB integrity through modulation of NOX2/4 expression.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.6
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• pp.1093-1101
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• 2000

The object of this study was to develop new BNR process using fixed-biofilm which could be applied to retrofit the existing wastewater treatment plant or to introduce as tertiary treatment plant. To achieve complete denitrification from typical raw sewage in Korea, external carbon source must be supplied because $SCOD_{cr}/T-N(NH_4{^+}-N+NOx-N)$of raw sewage was lower than other countries. In this study, the ratio of $SCOD_{cr}/NH_4{^+}-N$ was 2.49 and the influent $NH_4{^+}$-N concentration during the experimental period was varied from 25 to 37 mg/L. To enhance nitrogen removal from the sewage, the two processes using fixed biofilm were adopted as R-Hanoxic/mid.settler/aerobic/anoxic/ aerobic) and R-2(aerobic/mid.settlerlanoxic/anoxic/aerobic), respectively. In the comparison of $NH_4{^+}$-N, T-N effluent quality and T-N removal efficiency in both processes without external carbon source, R-1 process was better than R-2 process for nitrogen removal from raw sewage. With respect to $SCOD_{cr}$/NOx-N ratio and total nitrogen removal in each anoxic reactor of two processes, R-1's was more effective than R-2's for distributing organic matters of raw sewage. In the both processes using fixed biofilm, the amount of required alkalinity to remove unit $NH_4{^+}$-N were 5.18 and 5.76($g{\cdot}CaCO_3/g{\cdot}NH_4{^+}-N_{removed}$), respectively and were lower than activated sludge BNR process(7.14).

• Journal of Korean Society for Atmospheric Environment
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• v.20 no.4
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• pp.539-553
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• 2004

Up to the present time, many methods to estimate emissions from a particular diesel engines have wholly depended on the quantity of diesel fuel consumed. Then, the recommended emission factors were normalized by fuel consumption, and further total activity was estimated by the total fuel consumed. One of main purposes in the study is newly to develop emission factors for the railroad diesel rolling stock (RDRS) and to estimate a total amount of major gaseous pollutants from the RDRS in Korea. Prior to develop a Korean mode emission factor. the emission factor from the USEPA was simply applied for comparative studies. When applying the USEPA emission factors, total exhaust emissions from the RDRS in Korea were estimated by 28,117tons of NOx, 2,832.3tons of CO, and 1,237.5tons of HC, etc in 2001. In this study, a emission factor for the RDRS, so called the KoRail mode (the Korean Railroad mode) has been developed on the basis of analyzing the driving pattern of the Gyeongbu-Line especially for the line-haul mode. Explicitly to make the site specific emission factors, many uncertainty problems concerning weighting factors for each power mode, limited emission test, incomplete data for RDRS, and other important input parameters were extensively examined. Total exhaust emissions by KoRail mode in Korea were estimated by 10,960tons of NOx, and 4,622tons of CO, and so on in the year of 2001. The emissions estimated by the USEPA mode were 2.6 times higher for NOx, and 1.6 times lower for CO than those by the KoRail mode. As a conclusion, based on the emission calculated from both the USEPA mode and the KoRail mode, the RDRS is considered as one of the significant mobile sources for major gaseous pollutants and thus management plans an(1 control strategies for the RDRS must be established to improve air quality near future in Korea.

• The Korean Journal of Physiology and Pharmacology
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• v.8 no.4
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• pp.213-218
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• 2004

Primary fish-odor syndrome (FOS) is a genetic disorder caused by defective flavin-containing mono-oxygenase 3 gene (FMO3) with deficient N-oxidation of trimethylamine (TMA), causing trimethylaminuria (TMAU). By contrast, secondary FOS can be acquired by decreased FMO activities in patients with chronic liver diseases, but the underlying mechanisms are unknown. In the present study, we examined plasma NOx concentrations and viral DNA contents as well as in vivo FMO activities and their correlations in chronic viral hepatitis (CVH) patients. Plasma concentration of NOx was significantly increased by 2.1 fold $(56.2{\pm}26.5\;vs.\;26.6{\pm}5.4\;{\mu}M,\;p<0.01)$, and it was positively correlated with plasma hepatitis B virus (HBV) DNA contents $(r^2=0.2838,\;p=0.0107)$. Furthermore, the elevated plasma NOx values were inversely and significantly correlated with in vivo FMO activities detected by ranitidine-challenged test $(8.3%\;vs.\;20.0%,\;r^2=0.2109,\;p=\0.0315)$. TMA N-oxidation activities determined in CVH patients without challenge test were also significantly low (73.6% vs. 95.7%, p< 0.05). In conclusion, these results suggested that secondary FOS could be acquired by the endogenously elevated NO in patients with CVH.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.4
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• pp.1923-1930
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• 2012

Mn-Cu catalysts were tested for selective catalytic reduction of NOx with NH3. Influence of initial reaction temperature was studied for NOx conversion in which reaction temperature was changed three patterns. NOx conversion of catalysts calcined at 200, 300 and $340^{\circ}C$ was measured during the changing temperature. Hydrogen conversion efficiency of calcined catalysts was also measured in the $H_2$-TPR system. The deactivation effect of $SO_2$ on catalyst was investigated with the on-off control of $SO_2$ supply. The catalyst which calcined above $340^{\circ}C$ was somewhat deactivated with thermal shock. The reason of deactivation was draw from the results of surface area and hydrogen conversion.

• Proceedings of KOSOMES biannual meeting
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• 2007.11a
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• pp.133-137
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• 2007

An experimental study is conducted to evaluate and compare the use of BiodieseDI Fuel supplements at blend ratio of 10/90(BDF10) and 20/80(BDF20), in four stroke, direct injection diesel engine located at the authors' laboratory. especially this Biodiesel is produced from Rape oil at the authors' laboratory. The tests are conducted using each of the above fuel blends, in the engine working at a speed of 1800rpm and at a various loads. In each test, specific fuel consumption, exhaust emissions such as nitrogen oxides(NOx), carbon monoxide(CO) and Soot are measured. The results of investigation at various operating conditions are as follows (1) Specific fuel consumption is increased average 1.52%, maximum 1.84% at load 25% in case of BDF10, and average 1.98%, maximum 2.80% at load 25% in case of BDF20. (2) CO emission is decreased average 5.14%, maximum 6.09% at load 0% in case of BDF10, and average 7.75%, maximum 9.13% at load 0% in case of BDF 20. (3) NOx emission is increased average 2.97%, maximum 3.74% at load 0% in case of BDF10, and average 3.84%, maximum 4.67% at load 0% in case of BDF20. (4) Soot emission is decreased average 9.36%, maximum 10.85% at load 75% in case of BDF10, and average 11.99%, maximum 13.95% at load 75% in case of BDF20.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.3
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• pp.275-282
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• 2010

The effect of swirl flow on NOx in a nonpremixed turbulent hydrogen jet with coaxial air was studied. The swirl vane angle was varied from $30^{\circ}$ to $90^{\circ}$. The fuel jet air velocity and coaxial air velocity were varied in an attached flame region as $u_F=85{\sim}160m/s$ and $u_A=7{\sim}14m/s$. The objective of the current study was to analyze the characteristics of nitrous oxide emission in a swirl flow and to propose a new parameter for EINOx scaling. The experimental results show that EINOx decreases with the swirl vane angle and increased with flame length. Further, EINOx scaling factors can be determined by considering the effective diameter ($d_{F,eff}$) in a far field concept. The EINOx increased in proportion to the flame residence time (${\sim}{\tau_R}^{1/2.8}$) and the global strain rate (${\sim}{S_G}^{1/2.8}$).

• 한국연소학회:학술대회논문집
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• 2003.05a
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• pp.231-239
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• 2003

In this study, the waste of landfill was treated using advanced enriched oxygen combustion system. The oxygen concentration of this study was 21%, 25%, 30% and 40% and the operating capacity was 200 g/min and the residence time was 10 minutes. As increased the oxygen concentration of combustion air. temperature of the incinerator was increased and the temperature was increased rapidly when the oxygen concentration was 30%. As increased the oxygen concentration, the NOx (ppm) of flue gas increase d for thermal NOx, however the CO (ppm) of flue gas decreased according to the increase of combustion efficiency . The optimum operation condition of incineration was obtained when the oxygen concentration is 30%${\sim}$40%. The unburned carbon of ash decreased from 10% to 4% when the oxygen concentration was increased from 21% to 30%, therefore the high combustion efficiency can be obtained if used the oxygen enriched combustion system.

• Transactions of the Korean Society of Automotive Engineers
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• v.8 no.4
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• pp.34-41
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• 2000

The purpose of this research was to investigate the effects of exhaust gas recirculation(EGR) with diesel particulate filter(DPF) on heavy duty diesel engine. The exhaust gas was recirculated to the intake manifold after the smoke was eliminated in the DPF, The major conclusions of this research are i)at each engine speed EGR ratio was able to 60% maximum ii) the amount of NOx emissions was decreased to 90% at high engine load and to more than 60% at low engine load and iii) the amout of NOx emissions was increased to five times according to the increase of engine load but the effect of EGR is more effective at high engine load.