• Journal of the Korean Chemical Society
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• v.35 no.3
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• pp.211-218
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• 1991

A series of samples in the $Nd_{-x}Sr_{x}CoO_{3-y}$ system (x = 0.00, 0.25, 0.50, 0.75 and 1.00) have been produced by heating the reactants at 1200${\circ}$C under atmospheric pressure. The solid solutions were analysed by X-ray diffraction spectra, thermal analysis, and SEM micrographs. X-ray powder diffraction assigns the compositions of x = 0.00, 0.25, 0.50 and 0.75 to the cubic system and the composition of x = 1.00 to the orthorhombic system. The reduced lattice volume is increased with increasing x values in the system. The mole ratio of $Co^{4+}$ or ${\tau}$ values are determined by the Iodometric titration method and are maximum at the composition of x = 0.50. The magnetic measurement shows that a ferromagnetism is appeared in the compositions of x = 0.00, 0.25, 0.50 and 0.75 and then an antiferromagnetism in the composition of x = 1.00. The measurement of the electrical conductivity shows that the semiconductivity is appeared in the composition of x = 0.00, 0.25 and 1.00 and the metallic conductivity in the composition of x = 0.50 and 0.75. The magnetic and electrical properties of the samples are discussed with the nonstoichiometric chemical formulas.

• Korean Journal of Food Science and Technology
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• v.37 no.6
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• pp.922-927
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• 2005

Total and individual organic acid contents of Malus domestica Borkh, cultivars, Tsugaru, Fuji Jonathan (Hong-Ok), and New Jonagold(Sin-Heung) apples, were investigated. Average titratable acidities measured by titration method and total organic acids content determined by HPLC were 241.64-444.52 and 364.23-680.80mg%, respectively. Average total organic acid contents were Jonathan 630.80mg%, New Jonagold 471.04mg%, Fuji 403.80mg%, and Tsugaru 364.23mg%, Contents of DL-malic, citric, fumaric, and quinic acid were 351.98 (Tsugaru)-579.88mg% (Jonathan), 2.14 (Fuji)-12.95mg% (Jonathan), 0.012 (Fuji)-0.060mg% (Jonathan), and 8.91 (Tsugaru)-14.20mg% (Fuji), respectively. Succinic acid was detected only from Jonathan (27.53mg%) and New Jonagold (5.20mg%), while maleic acid was not detected from all cultivars. Ratio of L-malic acid and DL-malic acid contents were 0.98-1.02 in all apple cultivars.

• Korean Chemical Engineering Research
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• v.55 no.2
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• pp.156-162
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• 2017

CuO(x)/0.3Al-0.7Ce catalysts with different CuO loadings (x = 2~20 wt%) were prepared by impregnation method and investigated the effects of CuO loadings on the low temperature CO oxidation. Of the used catalysts, the CuO(10)/0.3Al-0.7Ce catalyst showed the highest catalytic performance in the absence or presence of water vapor. In the presence of water vapor, the catalytic performance was drastically decreased, with a temperature of 50% CO conversion ($T_{50%}$) shifted to higher temperature by $50^{\circ}C$ compared to the those in dry conditions because of the competitive adsorption of water vapor on the active sites. The copper metal surface area calculated from $N_2O$-titration analysis and the oxygen capacity from CO-pulse experiments were increased with the CuO loadings and showed a maximum at 10 wt%CuO/0.3Al-0.7Ce catalyst. These trends are in good agreement with the tendency of $T_{50%}$ of the catalysts. From these characteristic aspects, it could be deduced that the catalytic performance was closely related to the oxygen capacity and the copper metallic surface area.

• Parasites, Hosts and Diseases
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• v.36 no.3
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• pp.171-182
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• 1998

A total of nine Korean native kids and two Corriedale lambs, 1-20 days old, were each inoculated per os with a single dose of 2 × 107 oocysts of Cwptospori,mum muris (strain MCR) originated from mice to elucidate the kinetics and developmental stages of the coccidium in small ruminants. Irrespective of host's age, the prepatent period for both animals ranged from 19 to 35 days (28.1 days, on the average) and the patent period 16-85 days (47.8 days), and the total oocyst outputs showed enormous differences. Infection with greater numbers of oocyst outputs was not ordinarily established by transmission experiments. Oocysts discharged from the kids retained their infectivity by the mouse titration method. The immunogenicity of the coccidium and oocyst reproduction were proven by challenge infection and administration of prednisolone acetate. respectively. All the developmental stages of the coccidium in parasitophorous vacuoles were found by transmission electron microscopy in the pits of the gastric glands of a kid inoculated with oocysts and then necropsied on day 44 postinoculation. It indicated the full course of the host-parasite relationship in kids and lambs as well as mice.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.28 no.1
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• pp.41-50
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• 2023

Dissolved oxygen sensors have characteristics in which data drift occurs over time. Therefore, in-situ calibration of the dissolved oxygen sensor is essential to accurately measure the concentration of dissolved oxygen in seawater. In order to provide a method for in-situ calibration, appropriate number of samples for calibration, and laboratory calibration interval of the dissolved oxygen sensor, the dissolved oxygen sensor values were compared with the measured values by titration on a total of 133 samples from three different cruises in the Indian Ocean, Pacific Ocean, and East Sea over a period of about one year. As a result, it is preferable to calibrate the sensor value using the correlation of a straight line obtained by directly comparing the final concentration value given by the sensor and the measured value. For the accurate calibration, at least 30 samples must be used to enable in-situ calibration within an accuracy range of about 1%. In addition, it is recommended that a laboratory calibration should perform within 1 year for the membrane type dissolved oxygen sensor for CTD to achieve a performance of 70% or more.

• Korean Journal of Soil Science and Fertilizer
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• v.26 no.1
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• pp.37-42
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• 1993

Influences of metal concentration, pH and temperature on metal-ligand precipitate formation were investigated, as a part of projects for removing heavy metals from aqueous solution employing the principles in metal-ligand complexation. Aqueous solutions of HA or FA were reacted with those of heavy metals with 1:1 ratio. Efficiency of humic (HA) or fulvic acid (FA) on removing metals was evaluated by separating the precipitates from soltuions with the filtering method. When HA was a counter ligand, there existed three ranges of metal concentrations affecting precipitation : precipitate fromation was not available, was reached to the maximum, and afterwards was decreased again. The concentration ratios of metal to HA for initiating complexation were dependent upon kinds of metal and concentrations of ligand. Amount of Pb to form maximum precipitates per unit mg of HA was 1.3 times higher than that of Cu. When FA was a counter ligand, concentrations of metal-FA precipitates were increased proportionally with the treated metal concentrations. Efficiency of FA fro removing Pb was nearly 100%, but it was ranged from 12 to 19% for Cu, depending on FA concentration. pH exerted a considerable effect on complexation between Pb and FA, showing precipitates were increased six times at most per unit increase of pH. Ranges of pH increasing significantly the mounts of precipitates were coincied with pH jump ranges of the titration curve of organic ligands. As increasing temperature from 15 to $55^{\circ}C$, increases of FA-Cu precipitates were doubled, but those of FA-Pb were accounted for only 6%, However, HA-metal complexation was not affected by temperature.

• Tuberculosis and Respiratory Diseases
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• v.55 no.5
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• pp.506-515
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• 2003

Background : A decreased level of serum arginine vasopressin(AVP) and an increased sensitivity to an exogenous AVP is expected in patients with septic shock who often require a high infusion rate of catecholamines. The goal of the study was to determine whether an exogenous AVP infusion to the patients with septic shock would achieve a significant decrement in infusion rate of catecholamine vasopressors while maintaining hemodynamic stability and adequate urine output. Method : Eight patients with septic shock who require a high infusion rate of norepinephrine had received a trial of 4-hour AVP infusion with simultaneous titration of norepinephrine. Hemodynamic parameters and urine output were monitored during the AVP infusion and the monitoring continued up to 4 hours after the AVP infusion had stopped. Results : Mean arterial pressure showed no significant changes during the study period(p=0.197). Norepinephrine infusion rate significantly decreased with concurrent AVP administration(p=0.001). However, beneficial effects had disappeared after the AVP infusion was stopped. In addition, hourly urine output showed no significant changes throughout the trials(p=0.093). Conclusion : Concurrent AVP infusion achieved the catecholamine vasopressor sparing effect in the septic shock patients, but there was no evidence of the improvement of renal function. Further study may be indicated to determine whether AVP infusion would provide an organ-protective effect to the septic shock patients.

• Economic and Environmental Geology
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• v.8 no.3
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• pp.117-124
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• 1975

Wet chemical analysis (for $MnO_2$, MnO, and $H_2O$(+)) and electron microprobe analysis (for $Fe_2O_3$ and PbO) give $MnO_2$ 74.91, MnO 11.33, $Fe_2O_3$ (total Fe) 4.19, PbO 0.03, $H_2O$ (+) 9.46, sum 99.92%. 'Available oxygen determined by oxalate titration method is allotted to $MnO_2$ from total Mn, and the remaining Mn is calculated as MnO. Traces of Ba, Ca, Mg, K, Cu, Zn, and Al were found. Li and Na were not found. The existence of (OH) is verified from the infrared absorption spectra. The analysis corresponds to the formula $Mn^{4+}{_{4.85}}(Mn^{2+}{_{0.90}}Fe^{3+}{_{0.30}})_{1.20}O_{8.09}(OH)_{5.91}$, on the basis of O=14, 'or ideally $Mn^{4+}{_{5-x}}(Mn^{2+},Fe^{3+})_{1+x}O_{8}(OH)_{6}$ ($x{\approx}0.2$). X-ray single crystal study could not be made because of the distortion of single crystals. But the x-ray powder pattern is satisfactorily indexed by an orthorhombic cell with a 9.324, b 14.05, c $7.956{\AA}$., Z=4. The indexed powder diffraction lines are 9.34(s) (100), 7.09(s) (020), 4.62(m) (200, 121), 4.17(m) (130), 3.547(s) (112), 3.212(vw) (041), 3.101(s) (300), 2.597(w) (013), 2.469(m) (331), 2.214(vw)(420), 2.098(vw) (260), 2.014 (vw) (402), 1.863(w) (500), 1.664(w) (314), 1.554(vw) (600), 1.525(m) (601), 1.405(m) (0.10.0). DTA curve shows the endothermic peaks at $250-370^{\circ}C$ and $955^{\circ}C$. The former is due to the dehydration: and oxidation forming$(Mn,\;Fe)_2O_3$(cubic, a $9.417{\AA}$), and the latter is interpreted as the formation of a hausmannite-type oxide (tetragonal, a 5.76, c $9.51{\AA}$) from $(Mn,\;Fe)_2O_3$. Infrared absorption spectral curve shows Mn-O stretching vibrations at $515cm^{-1}$ and $545cm^{-1}$, O-H bending vibration at $1025cm^{-1}$ and O-H stretching vibration at $3225cm^{-1}$. Opaque. Reflectance 13-15%. Bireflectance distinct in air and strong in oil. Reflection pleochroism changes from whitish to light grey. Between crossed nicols, color changes from yellowish brown with bluish tint to grey in air and yellowish brown to grey through bluish brown in oil. No internal reflections. Etching reactions: HCl(conc.) and $H_2SO_4+H_2O_2$-grey tarnish; $SnCl_2$(sat.)-dark color; $HNO_3$(conc.)-grey color; $H_2O_2$-tarnish with effervescence. It is black in color. Luster dull. Cleavage one direction perfect. Streak brownish black to dark brown. H. (Mohs) 2-3, very fragile. Specific gravity 3.59(obs.), 3.57(calc.). It occurs as radiating groups of flakes, flower-like aggregates, colloform bands, dendritic or arborescent masses composed of fine grains in the cementation zone of the supergene manganese oxide deposits of the Janggun mine, Bonghwa-gun, southeastern Korea. Associated minerals are calcite, nsutite, todorokite, and some undetermined manganese dioxide minerals. The name is for the mine, the first locality. The mineral and name were approved before publication by the Commission on New Minerals and Mineral Names, I.M.A.