• International Journal of Highway Engineering
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• v.9 no.3
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• pp.75-82
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• 2007

Washed wastewater generated from the intermittent cleaning process of the three tunnel sites located in the Seoul area showed high concentrations of SS, $COD_{Cr}$, T-N, $NH_3-N$, $NO_3-N$, Zn, Cu, Cr(+6), Mn, Mg, Phenol, $CN^-$ and E-Coli based on the water quality analysis. These characteristics of the deteriorative wastewater depend on the sampling method, cleaning frequency, released amount of washing water, inner material of tunnel wall, traffic volume, and type of drainage systems. Gravitational separation experiment of SS with collected tunnel wastewater showed considerable removal of pollutants such as 80% of $COD_{Cr}$, 30% of T-N and 90% of T-P simultaneously. GAC isotherm test was conducted to remove dissolved portion of the pollutants, and resulted in high removal efficiencies above 80% of $COD_{Cr}$, T-N, Zn, Cu, Mn, Phenol, CN in the experimental condition of GAC dosage of $50g/1/{\ell}$.

• The Journal of Internal Korean Medicine
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• v.30 no.3
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• pp.451-464
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• 2009

Background and Objective : Cyperus rotundus L. (CR) is a commonly used herbal medicine in Asian countries such as Korea, China and Japan. The present study was designated to evaluate the direct effects of CR on helper T cell activities and on Th1/Th2 lineage development in vitro. Materials and Methods : Spleen cells from 8 week BALB/c mice were cultured in CR extracts containing medium without activation for 24 hours and with activation for 48 hours. CD4+ T cells were isolated and analyzed for mRNA expression levels of INF-$\gamma$, IL-4, T-bet and GATA-3 by RT-PCR and secretion cytokines levels of INF-$\gamma$, IL-4, IL-5 and IL-10 by ELISA. Results : The results demonstrated that CR had no mitogenic effects on unstimulated CD4+ T cells, but augmented CD4+ T-cell proliferation upon activation with anti-CD3/anti-CD28 antibodies in a dose-dependent manner. CR treatment significantly increased CD4+ T cell population and the IFN-$\gamma$ expression was significantly enhanced, while IL-4 expression was significantly decreased. In addition, in vitro Th1/Th2 polarization experiments revealed that CR enhanced IFN-$\gamma$ secretion in Th1 cells, but reduced the IL-4 in Th2 cells in a dose-dependent manner. Conclusion : These results suggest that CR treatment could be a desirable alternative therapy for the prevention or correction of Th2 dominant pathological disorders, such as allergy and asthma.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2007.04a
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• pp.114-115
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• 2007

The corrosion characteristics of Cr steels were investigated to protect Cr steels from the SO2-gas corrosion in the coal-fired power plant. The samples tested were low alloy ferritic steel (ASTM T22, 23), martensitic steel (ASTM T91, 92, 122), and austenitic stainless steel (ASTM 347HFG). The corrosion tests were performed between 600oC and 1000oC in Ar + (0.2, 1)%SO2 gas for 100 hr. Chromium was quite beneficial to corrosion resistance, while iron was not. The corrosion resistance increased in the order of T22, T23, T91, T92, T122, and 347HFG.

• Journal of the Korean Magnetics Society
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• v.20 no.6
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• pp.207-211
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• 2010

We have investigated the magnetoresistance effect in $Cr_5S_6$ single crystals prepared by vapor transport method. Room temperature X-ray diffraction (XRD) study reveals the phase formation of the single crystals with trigonal crystal structure. The magnetization was measured as a function of temperature (5 K~400 K) and applied magnetic field (0.1 T and 5 T). The magnetization curve as a function of temperature reveals the two transition states of $Cr_5S_6$: one from antiferromagnetic to ferrimagnetic state at ~150 K and the other from ferrimagnetic to paramagnetic state at ~300 K. Temperature dependent resistivity at 0 T and 5 T magnetic field shows the metallic behavior, showing the transition from antiferromagnetic to ferrimagnetic state at ~150 K. Magnetic field dependence of magnetization was measured at four fixed temperatures viz. 100 K, 150 K, 200 K, and 300 K. It is observed that at 200 K and 300 K it shows well M-H hysteresis behavior, whereas at 100 K and 150 K it shows non-hysteretic nature. A negative magnetoresistance (MR) of -2% is observed at 5 T for $Cr_5S_6$ single crystal at 150 K, near the antiferromagnetic transition temperature.

• Bulletin of the Korean Mathematical Society
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• v.51 no.3
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• pp.863-881
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• 2014

Many differential geometric properties of a submanifold of a Kaehler manifold are conceived via canonical structure tensors T and F on the submanifold. For instance, a CR-submanifold of a Kaehler manifold is a CR-product if and only if T is parallel on the submanifold (c.f. [2]). Warped product submanifolds are generalized version of CR-product submanifolds. Therefore, it is natural to see how the non-triviality of the covariant derivatives of T and F gives rise to warped product submanifolds. In the present article, we have worked out characterizations in terms of T and F under which a contact CR- submanifold of a Kenmotsu manifold reduces to a warped product submanifold.

• The Korea Journal of Herbology
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• v.21 no.1
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• pp.101-107
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• 2006

Objectives : It is well known that hexavalent chromium has toxic effect on normal cells. Recently, toxic effect of hexavalent chromium is diminished by the some extracts derived from herbs or plants. But, the toxic or protective mechanism of hexavalent chromium is well unknown. This study was performed to examine the protective effect of poncirin against $Na_2Cr_2O_7$-induced cytotoxicity on NIH3T3 fibroblasts. Methods : The protective effect of the cytotoxicity induced by $Na_2Cr_2O_7$ was measured by the cell viability after NIH3T3 fibroblasts were cultured with or without $Na_2Cr_2O_7$ for 48 hours. Antitoxic effects of poncirin on the cytotoxicity induced by $Na_2Cr_2O_7$ were examined by colorimetric assays such as MTT or XTT assay. Results : $Na_2Cr_2O_7$ decreased cell viability by the decreased absorbance in MTT or XTT assay, but, the poncirin increased cell viability which was decreased by $Na_2Cr_2O_7$-induced cytotoxicity on NIH3T3 fibroblasts. Conclusion : These results suggest that $Na_2Cr_2O_7$ showed cytotoxicity effect on NIH3T3 fibroblasts by the decrease of cell viavility, and poncirin was effective in the protection of $Na_2Cr_2O_7$-induced cytotoxicity in these cultures.

• Journal of Korean Society on Water Environment
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• v.22 no.2
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• pp.203-208
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• 2006

A continuous feed and cyclic draw SBR process was developed to overcome flow rate fluctuation and to maximize organic matters utilization efficiency for nitrogen and phosphorus removal. The developed SBR process was operated with two parallel reactors. Influent was supplied to one reactor which was not obligately aerated. At the same time, the other reactor was just aerated without supplying influent. In addition this mode was changed periodically. Cycle time was 6hr and aeration time ratio($t_{aer}/t_{total}$) was 0.33, respectively. $COD_{cr}$ and SS removal efficiencies of 95% or higher were achieved. Nitrogen removal was so greatly influenced by influent $COD_{cr}/T-N$ ratio. At influent $COD_{cr}/T-N$ ratio of 5.7, removal efficiencies of ammonia-N, T-N and T-P were 96%, 78% and 55%, respectively. Influent $COD_{cr}/T-N$ of 4 or higher ratio was necessary to achieve 60% or higher nitrogen removal. Organic matters of influent was efficiently utilized in denitrification reaction and consumed COD has a good correlation with removed T-N(about 6.5 mgCOD/mgTN). Continuous feed and cyclic draw SBR process could be one of alternative processes for the removal of nutrients in rural area where $COD_{cr}/T-N$ ratio was low and fluctuation of flow rate was severe.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.582-585
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• 2015

In the aging society, TKRA is steadily increased because of joint diseases. Artificial joint used in TKRA generates metal artifacts in the MRI. Metal artifact may affect diagnosis. In study, We are going to minimize the effect of metal artifact to improve the value of diagnosis by changing the sequence and the type of artificial joint(Co-Cr, Ni-Ti). 1.5T AVANTO, plastic containers and each of the artificial joint (Normal, Co-Cr, NiTi) were used. After the artificial joints fixed in a paper cup was inserted in a plastic container of cylindrical, Signal intensity was measured. To obtain strong and uniform signal intensity, the plastic container was filled with water. We changed Sequences(T1 TSE, T2 TSE, PD TSE) and obtained an Axial image. After excepting the maximum and minimum values, We calculated the average of SNR, CNR and PSNR. Consequently, The SNR, CNR value of PD TSE are measured higher than these of T1 TSE, T2 TSE and The PSNR of Co-Cr is higher than this of Ni-Ti. The SNR of Co-Cr is similar to the SNR of normal comparing this of Ni-Ti. As a result, Using sequence of PD Tse and Co-Cr alloy is considered to be useful.

• Journal of the Korean Institute of Gas
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• v.16 no.5
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• pp.28-34
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• 2012

Material degradation of Cr steels in using for boiler tubes was studied in the relation of microstructural changes like carbide behavior and mechanical properties of hardness and creep-rupture life. The carbide dissolution was occurred in 2Cr steel of T22 during high temperature operation. And the grain refinement within martensite lath of 12Cr steel of X20 was derived by the high temperature-long time exposure. But the specific phenomena of material degradation which might be represented by hardness or creep-rupture time of the used tubes were not shown in all the tubes of T22 and X20 even in the fire-side using.

• Journal of the Korean Ceramic Society
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• v.28 no.2
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• pp.109-118
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• 1991

Steady-state sublimation vapour pressures of anhydrous bismuth triiodide have been measured by the torsion-effusion method from 488.8 to 570.5 K and equilibrium sublimation pressures were obtained from the steady-state data. The standard sublimation enthalpy changes derived by both second(modified sigma function) and third(average enthalpy method) law methods were 159.316${\pm}$0.055, 137.67${\pm}$1.43 kJ$.$mol-1 respectively. The standard sublmation entropy change derived by modified sigma function was 232.88${\pm}$0.10 J$.$K-1$.$mol-1. The reliable standard sublimation enthalpy change based on a correlation of {{{{ { TRIANGLE }`_{cr } ^{g } }} H{{{{ { 0} atop {m } }}(298.15K) and {{{{ { TRIANGLE }`_{cr } ^{g } }} S{{{{ { 0} atop {m } }}(298.15K), a recommended p(T) equation has been obtained for BiI3(cr) ; lg(p/Pa)=-(C$.$K/T)+5.071lg(T/K)-2.838${\times}$10-3(T/K)-7.758${\times}$103(K/T)2+1.4519 where C={{{{{ { TRIANGLE }`_{cr } ^{g } }} H{{{{ { 0} atop {m } }}(298.15K)/0.019146 kJ$.$mol-1}-456.27.