• Journal of the Korean Ceramic Society
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• v.39 no.1
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• pp.26-32
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• 2002

The effects of $Nd_2O_3$ addition to $Q{\cdot}f_{0}(GHz)$ ceramics with ${\varepsilon}_r$ of 126, $Q{\cdot}f_{0}(GHz)$ of 2240 and of $68\;ppm/^{\circ}C$ on their microwave properties were investigated. For the addition of 5 wt% $Nd_2O_3$, the dielectric constant (${\varepsilon}_r$) showed maximum value of 131, then decreased with the further addition of $Nd_2O_3$. $Q{\cdot}f_{0}(GHz)$ value was still increased to 3533 with 9 wt% $Nd_2O_3$ addition, it is influenced by densification of grain boundary. With more addition of $Nd_2O_3$ up to 18 wt%, the abnormal grain growth have influence on the decreasing of $Q{\cdot}f_{0}(GHz)$ value. But with the further addition of $Nd_2O_3$ over 25 wt%, the $Q{\cdot}f_{0}(GHz)$ value was again increased by the effect of the second phase ($Nd_2Ti_2O_7$) forming. The temperature coefficient of resonant frequency (${\tau}_f$) was decreased from $+\;68\;ppm/^{\circ}C$ with the addition of $Nd_2O_3$, reached $0\;ppm/^{\circ}C$ at 12 wt% addition, and became negative with the further addition of $Nd_2O_3$. The optimum microwave dielectric properties were obtained for $0.3CaTiO_3-0.7(Li_{1/2}Nd_{1/2})TiO_3$ with 9 wt% $Nd_2O_3$ sintered at $1425^{\circ}C$ for 3 hrs. The dielectric constant (${\varepsilon}_r$), the $Q{\cdot}f_{0}(GHz)$ value, and the temperature coefficient of resonant frequency (${\tau}_f$) were 108, 3533, and $+\;6\;ppm/^{\circ}C$, respectively.

• IMMUNE NETWORK
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• v.3 no.1
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• pp.47-52
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• 2003

Background: The megakaryopoiesis and platelet production is regulated by several hematopoietc factors such as thrombopoietin (TPO), interleukin-11 (IL-11) and interleukin- 3 (IL-3). IL-11 is a potent stimulator of megakaryopoiesis in vivo, and acts primarily as a megakaryocyte maturation factor in vitro and it can act synergistically with IL-3 and TPO. We performed this study to investigate the effects of recombinant human IL-11 (rhIL-11) with other hematopoietic factors on megakaryocyte colony formation in vitro. Methods: CD34+ cells were separated from umbilical cord blood and megakaryocyte colonies using MegaCult Assay Kit were cultured with rhIL-11, recombinant human IL-3 (rhIL-3), and recombinant human TPO (rhTPO) for 7 and 14 days. The number and percentage of CD34+ and CD41a+ cells were determined by flowcytometry. Results: The number of CD41a+ cells were $0.54{\pm}0.05{\times}10^4$ (rhIL-11 100 ng/ml), $5.32{\pm}0.23{\times}10^4$ (rhIL-3 100 ng/ml), and $8.76{\pm}0.15{\times}10^4$ (rhTPO 50 ng/ml) of total expanded cells during the culture of the purified CD34+ cells in liquid phase for 7 days. The number of CD41a+ cells were increased to $7.47{\pm}0.69{\times}10^4$ (rhIL-3+ rhIL-11), $11.92{\pm}0.19{\times}10^4$ (rhTPO+rhIL-11) of total expanded cells, respectively, during the culture of the purified CD34+ cells in liquid phase for 7 days in the presence of rhIL-11 (100 ng/ml). When the purified CD34+ cells were cultured in semisolid mediaincluding various concentration of rhIL-11, the megakaryocyte colonies were not formed. When the purified CD34+ cells were cultured with rhIL-11 and rhTPO or with rhIL-11 and rhIL-3, the number of megakaryocyte colonies were increased compared with rhTPO or rhIL-3 alone. Conclusion: These results indicate that IL-11 exerts a potent proliferative activity to colony forming unit-megakaryocyte from human umbilical cord blood, and it acts with other hematopoietic factors synergistically.

• Journal of the Korean Ceramic Society
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• v.40 no.5
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• pp.494-500
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• 2003

The effects of $Al_2$O$_3$ addition upon the sintering range of clay-EAF dust (the specified wastes produced from steel making process) system body which would be used as a constructing bricks were investigated. The slope of apparent density to sintering temperature decreased for Clay-dust body containing 5~15 wt% A1203 sintered at 1200-125$0^{\circ}C$, and the absorption(%) of specimen sintered above 125$0^{\circ}C$ decreased due to the formation of open pores produced by pore bloating. For the specimen without any $Al_2$O$_3$ addition sintered at 1275$^{\circ}C$, the major phase was cristobalite, the small amount of mullite (3Al$_2$O$_3$ 2SiO$_2$) formed and the hematite (Fe$_2$O$_3$) remained. In the Clay-dust system body containing $Al_2$O$_3$ 15 wt%, however, the cristobalite disappeared and the major phase was mullite. Also the part of $Al_2$O$_3$ reacted with hematite to form hercynite (FeAl$_2$O$_4$). From the these results, addition of $Al_2$O$_3$ to Clay-dust system body enlarges a sintering range; decreasing an apparent density and absorption slop to sintering temperature owing to consumption of liquid phase SiO$_2$ at higher temperature and gas-forming component Fe$_2$O$_3$ at reduced atmosphere which would decrease an amount of liquid formed and increase the viscosity of the liquid produced during the sintering process.

• Journal of Dental Rehabilitation and Applied Science
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• v.33 no.2
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• pp.71-79
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• 2017

Purpose: Ni-Cr alloy does not contain Beryllium, causing the metal compound to form oxides in the furnace but by using Titanium as a chemical catalyst the forming of the oxides can be controlled, and by controlling the impurities formed on the metal surface, the possibility of the Ni-Cr alloy bond strength being increased can be analysed. Materials and Methods: Titanium was used as a chemical catalyst in the porcelain for the oxidation of beryllium-free metal (Ni-Cr) alloy. The T1 group, which does not use Titanium power as a chemical catalyst is a reference model for comparison. The T2 group and T3 group used 10 g and 20 g of Titanium power, respectively. They are fabricated to observe the shear bond strength and surface properties. There was no significance when One-way ANOVA analysis/Tukey Honestly Significant Difference Test was conducted for statistical analysis among groups (P > 0.05). Results: Results of measuring the three-point flexural bond strength of the Ni-Cr alloy and thickness of the oxide film. Experiment T3 using 20 g Titanium chemical catalyst: $39.22{\pm}3.41MPa$ and $6.66{\mu}m$, having the highest bond strength and thinness of oxide film. Experiment T2 using 10 g Titanium chemical catalyst: $34.65{\pm}1.39MPa$ and $13.22{\mu}m$. Experiment T1 using no Titanium chemical catalyst: $32.37{\pm}1.91MPa$ and $22.22{\mu}m$. Conclusion: The T2 and T3 experiments using Titanium chemical catalyst showed higher bond strength for the Ni-Cr alloy and lower thickness of oxide film than experiment T1, and the titanium catalyst being able to increase bond strength was observed.

• Journal of the Korean Society of Food Science and Nutrition
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• v.43 no.11
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• pp.1665-1673
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• 2014

The objective of this study was to compare the compositions and immuno-enhancing effects of 6-year-old red ginseng powder (RGP) with those of its fractions. RGP was subjected to extraction with 100% ethanol to obtain an ethanol fraction (E) and residue 1 (R1). Then, R1 was subjected to extraction with distilled water to obtain water fraction (W) and residue 2 (R2). Chemical compositions were as follows: 4.94% acidic polysaccharides and 1.56% ginsenosides (amounts of Rg1, Re, Rf, Rg2, Rb1, Rc, Rd, and Rg3) in RGP, 0.11% acidic polysaccharides and 6.99% ginsenosides in E, 4.93% acidic polysaccharides and 0.40% ginsenosides in R1, 0.50% acidic polysaccharides and 0.30% ginsenosides in R2, and 7.46% acidic polysaccharides and 0.61% ginsenosides in W. Immuno-enhancing effects of fractions from RGP were examined based on suppression of immune responses by cyclophosphamide. In the first fraction test, the antibody response to SRBCs increased significantly in the R1-treated group, but not the E-treated group. In the second fraction test, W showed higher immuno-enhancing effect than R1 and R2. W, which contained the highest amount of acidic polysaccharides, restored numbers of T and B cells, macrophages, as well as $CD4^+$ and $CD8^+$ T cells in the spleen suppressed by cyclophosphamide. These results suggest that acidic polysaccharides from red ginseng may be more effective than saponin in enhancing immune functions and reducing immunotoxicity of cyclophosphamide.

• Communications of Mathematical Education
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• v.25 no.2
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• pp.403-430
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• 2011

The purpose of the study was to investigate how the use of graphing calculators influence on forming students' mathematical concept of algebra, students' mathematical connection, and attitude toward mathematics. First, graphing calculators give instant feedback to students as they make students compare their written answers with the results, which helps students learn equations and linear inequalities for themselves. In respect of quadratic inequalities they help students to correct wrong concepts and understand fundamental concepts, and with regard to functions students can draw graphs more easily using graphing calculators, which means that the difficulty of drawing graphs can not be hindrance to student's learning functions. Moreover students could understand functions intuitively by using graphing calculators and explored math problems volunteerly. As a result, students were able to perceive faster the concepts of functions that they considered difficult and remain the concepts in their mind for a long time. Second, most of students could not think of connection among equations, equalities and functions. However, they could understand the connection among equations, equalities and functions more easily. Additionally students could focus on changing the real life into the algebraic expression by modeling without the fear of calculating, which made students relieve the burden of calculating and realize the usefulness of mathematics through the experience of solving the real-life problems. Third, we identified the change of six students' attitude through preliminary and an ex post facto attitude test. Five of six students came to have positive attitude toward mathematics, but only one student came to have negative attitude. However, all of the students showed positive attitude toward using graphing calculators in math class. That's because they could have more interest in mathematics by the strengthened and visualization of graphing calculators which helped them understand difficult algebraic concepts, which gave them a sense of achievement. Also, students could relieve the burden of calculating and have confidence. In a conclusion, using graphing calculators in algebra and function class has many advantages : formulating mathematics concepts, mathematical connection, and enhancing positive attitude toward mathematics. Therefore we need more research of the effect of using calculators, practical classroom materials, instruction models and assessment tools for graphing calculators. Lastly We need to make the classroom environment more adequate for using graphing calculators in math classes.

• Korean Journal of Soil Science and Fertilizer
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• v.25 no.4
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• pp.342-356
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• 1992

Kinetic studies using stirred-flow methods were conducted with the Luisiana soil at three pH levels(pH 5, 6.5, and 8) and three temperature levels(10, 25, and $40^{\circ}C$) to explore effects on the rate of silica retention and release and to find out reaction mechanisms. In this study the maximum silica retention could not be obtained for long enough experimental time. The silica sorption isorption was C type fitted well to Freundlich equation. The pH of the soil suspension increased by the silica release process at low pH treatments(pH 5 and 6.5), while decreased at high pH treatment(pH 8). From the above findings It can be deduced that the mechanism of silica retention is a multilayer forming process to change the ligand form depending on pH condition. In the proposed mechanism the sorbed silica provide new binding sites for additional sorption of silica, while the activation energy for the formation of subsequent layers increases correspondingly. The silica retention and release process were well described by first-order and parabolic diffusion equation. However, clear interpretation for silica sorption mechanism using these equations could not be made. The validity of the fraction term (Fa and Fd) included in first-order and parabolic diffusion equation requires further examinations because the temperature effect on apparent rate constant shows no constant trends among temperature treatments, while there was a good trend in Elovich and modified Freundlich equation where the fraction term was not included.

• Applied Biological Chemistry
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• v.16 no.3
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• pp.146-165
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• 1973

Crop damages caused by sulfur dioxide poisoning were studied with respect to physiology of lesion, yield loss and prevention measures. The results are summarized as follows; 1. On the physiology of injury: The sulfur dioxide gas did no: affect the pH and $E_h$ values of the tested leaf juice of plants. Peroxidase activity was inhibited just after sulfur dioxide treatment but gradually recovered to normal after 10 hours. Methanolic chlorophyll solution was instantaneously and irreversibly bleached by the addition of sulfur dioxide gas with no evidence of pheophytin formation. It seems that chlorophyll forms colourless addition product or is reduced to colourless form with either sulfur dioxide gas or sulfurous acid. Chlorophyll in the chloroplast was also bleached by the sulfur dioxide treatment, as in the case of methanolic solution of chlorophyll, except that the rate of bleaching was rather slow, requiring 1-2 hours. It appears that the most inflicting cause of sulfur dioxide gas to plants may be the destruction of chlorophyll by the poisoning gas. 2. On the effects to crop yield: The crop yield losses were proportional to the concentration of inflicting sulfur dioxide gas. The order of tolerence of the crops to the sulfur dioxide gas was as follows - chinese cabbage being the most susceptible; wheat, paddy rice, barley, soybean, welsh onion, radish and chinese cabbage. The crucifer crops were generally found more susceptible than other crops studied. With respect to the growing stages of crops exposed to sulfur dioxide gas, it was found that the flowering stage was the most susceptible fellowed by panicle forming, milky and tillering in the decreasing order of susceptibility. 3. On the preventive measures of yield losses: Soil applications of potassium, wollastonite, lime or spray of lime water were effective to prevent yield losses from sulfur dioxide fumigation of paddy rice, barley, and soybeans. The most responsive treatment was lime water spray for all crops tested. In case of sulfur dioxide fumigated paddy rice, the lime water spray also increased carbon assimilation.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.42 no.1
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• pp.75-85
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• 2016

Pectin, a naturally occurring polysaccharide, has in recent years attracted considerable attention. Its benefits are increasingly appreciated by scientists and consumers due to its safety and usefulness. The chemistry and gel-forming characteristics of pectin have enabled to be used in pharmaceutical industry, health promotion and treatment. Yet, it has been rarely used in cosmetics because of its incompatibility with many cosmetic ingredients, including alcohols, and unstable viscosity of pectin gels under various pH and salt conditions. However, low-molecular-weight pectin oligomers have excellent biological activities, and depolymerization of pectin to produce cosmetic ingredients would be very useful. In this study, we attempted the development of cosmetic ingredients using pectin with an excellent effect on human skin. We developed a bio-conversion process that uses enzymatic hydrolysis to produce pectin hydrolysates containing mainly low-molecular-weight pectin oligomers. Gel permeation chromatography was used to determined the ratio of hydrolysis. The molecular weight of the pectin hydrolysates obtained varied between 200 and 2,700 Da. The two newly developed low-molecular-weight pectin hydrolysates, LMPH A and B, had higher anti-oxidative activities than pectin or D-galacturonic. Exposure to UVB radiation induces apoptotic cell death in epidermal cells. Annexin V binding and propidium iodide uptake were measured by flow cytometry to evaluate UVB-induced cell death in HaCaT cells. Both LMPH A and B reduced UVB-induced cell death and increased cell proliferation by 22% and 30% at 0.5% concentration respectively, while pectin had no significant activity. In conclusion, this study suggests that the newly developed low-molecular-weight pectin hydrolysates can be used as safe and biologically active cosmetic ingredients.

• Korean journal of applied entomology
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• v.18 no.1 s.38
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• pp.1-10
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• 1979

An inclusion forming virus isolated from a fan webworm, Hyphantria cunea, in 1975 was identified as a nuclear polyhedrosis virus. With the virus isolated in Korea, it was considered that the virus would be one of the valuable microorganism in microbial control. In this connection, 1) the shape and size of the virus for identification, 2) susceptibility of the various instar larvae to the virus, 3) the effects of storage condition on the pathogenicity and the cross infection of the virus to the larvae of Bombyx mori were examined. The results are summarized as follows; 1. The polyhedron was tetrahedron or hexahedron of $2\mu$ in size and the rod-shaped virus particles consisting of $2\~14$ rods in a bundle were $330m{\mu}\times35m{\mu}$ in size. 2. The hexagonal nuclear polyhedra were found only in the nucleus of the midgut cells but were variable in size. 3. The $LD_{50}$ values for the various instar larvae of H. cunea were $8.377\times10^4\;PIBs/ml$ for the second, $4.974\times10^5\;PIBs/ml$ for the fifth instar larvae. The $LT_{50}values$ for $10^6\;PIBs/ml$ were 9.6 days for the second, 11.5 days for the third, 12.0 days for the fourth and 17 days for the fifth instar larvae. 4. The susceptibility of H. cunea to the nuclear polyhedrosis virus was greater in the first generation than in the second generation. 5. The effect of the storage conditions on the pathogenicity of the nuclear polyhedra was less in refrigerator $(5^{\circ}C)$ and in freezing $(-80^{\circ}C)$ than in room temperature $(18.5^{\circ}C)$, especially as air-dried polyhedra than as suspension. The pathogenicity of the polyhedra seemed to decrease by sunlight during storage as cadavers, since rather greater decrease in pathogenicity was found in sunny condition than in shady condition. 6. The effective spray concentration was $6.4\times10^7\;PIBs/ml$ in the field and its $LT_50$ values for the third and the fifth instar larvae were 4.8 days and 14.2 days, respectively. 7. No cross infections were found in the nuclear polyhedrosis virus between H. cunea and B. mori. larvae.