• Carbon letters
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• v.5 no.4
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• pp.164-169
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• 2004

Carbon-ceramic composites refer to a special class of carbon based materials which cover the main drawbacks of carbon, particularly its proneness to air oxidation, while essentially retaining its outstanding properties. In the present paper, the authors report the results of a systematic study made towards the development of C-SiC-$B_4C$ composites, which involves the effects of compositional parameters, namely, carbon-to-ceramic and ceramic-to-ceramic ratios, on the oxidation behaviour as well as other characteristics of these composites. The C-SiC-$B_4C$ composites, heat-treated to $1400^{\circ}C$, have shown that their oxidation behaviour at temperatures of 800~$1200^{\circ}C$ depends jointly on the total ceramic content and the SiC : $B_4C$ ratio. Good compositions of C-SiC-$B_4C$ composites exhibiting zero weight loss in air at temperatures of 800~$1200^{\circ}C$ for periods of 4~9 h, have been identified. Composites with these compositions undergo a weight gain or a maximum weight loss of less than 3% during the establishment of a protective layer at the surface of carbon in a period of 1~6 h. Significant improvement in the strength of C-SiC-$B_4C$ composites has been observed which increases with an increase in the total ceramic content and also with an increase in the SiC : $B_4C$ ratio.

• Journal of Korean society of Dental Hygiene
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• v.13 no.3
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• pp.517-523
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• 2013

Objectives : The aim of the study is to investigate the antimicrobial activity of jaborandi and sorbitol to various oral microbes. Methods : Jaborandi leaves contain pilocarpine. The conditions for extraction were optimized on the basis of substances, temperatures and pHs. Total pilocarpine content after extraction was analyzed by HPLC. The herbal antimicrobial activity of jaborandi and sorbitol were evaluated for oral microbes containing ATCC 25175 S. mutans, ATCC 13419 S. salivarius, ATCC 6249 S. mitis, ATCC 33398 S. equi, ATCC 29213 S. aureus, ATCC 14053 C. albicans. Results : The optimum conditions for highest yielding extraction were pilocarpine content after boiling at $100^{\circ}C$ for 1 hour at pH 3. The level of total pilocarpine content was analyzed at 833 mg/kg by HPLC. The most effective antimicrobial activity was obtained by combination of pilocarpine and sorbitol rather than pilocarpine, menthol and sorbitol, respectively. Conclusions : This results supported the preventive oral health care using safe and convenient jaborandi herb.

• Progress in Superconductivity and Cryogenics
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• v.20 no.2
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• pp.24-28
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• 2018

To understand the effects of Cd substitution for Cu, $(Pb_{0.5}Cu_{0.5-x}Cd_x)Sr_2(Ca_{0.7}Y_{0.3})Cu_2O_z$ (x = 0 ~ 0.5) compounds were synthesized and the structural and superconducting properties of the compounds were characterized. Resistivity data revealed that superconducting transition temperature rises initially up to x = 0.25 and then decreases as the Cd doping content increases. Room-temperature thermoelectric power decreases at first up to x = 0.25 and then increases with higher Cd doping content, indicating that the change in $T_c$ is mainly caused by the change in the hole concentration on the superconducting planes by the Cd doping. The non-monotonic dependence of the lattice parameters and the transition temperature with Cd doping content is discussed in connection with the possible formation of $Pb^{+2}$ ions and the removal of excess oxygen caused by Cd substitution in the charge reservoir layer. A correlation between transition temperature and c/a lattice parameter ratio was observed for the $(Pb_{0.5}Cu_{0.5-x}Cd_x)Sr_2(Ca_{0.7}Y_{0.3})Cu_2O_z$ system.

• Journal of The Korean Society of Grassland and Forage Science
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• v.34 no.3
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• pp.155-162
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• 2014

This study was conducted to investigate the influence of the mixed application of chemical fertilizer (CF) and liquid swine manure (LSM) on the agronomic characteristics, dry matter yield, amino acids, minerals, and free sugars in cultivating Sorghum ${\times}$ Sudangrass hybrid (SSH) on paddy soil. The field experiment was designed in a randomized block design with three replications and consisted of CF 100% (C), CF 70% + LSM 30% (T1), CF 50% + LSM 50% (T2), CF 30% + LSM 70% (T3), and LSM 100% treatment (T4). The application of LSM was based solely on the nitrogen. Plant length, leaf length, leaf width and number of leaf were significantly higher in T4 (p<0.05), but stem diameter did not show significant differences among treatments. Stem hardness increased significantly (p<0.05) as the LSM application rate decreased, but sugar degree decreased significantly (p<0.05) as the LSM application rate decreased. Fresh yield, dry matter yield and TDN yield were the highest in T4, whereas the lowest in T2 (p<0.05). Crude protein, crude fat and crude ash were the highest in C, T4 and T2, respectively (p<0.05). However, NDF and ADF did not show significant difference among treatments. Crude fiber decreased significantly (p<0.05) as the LSM application rate increased. The total mineral content was decreased significantly (p<0.05) as the LSM application rate increased. Total amino acid content was higher in the order of T1> C> T3> T4> T2 (p<0.05). Free sugar content increased significantly (p<0.05) as the LSM application rate increased. The analysis of all the above results suggests that the application of liquid swine manure is very effective, considering the yield performance and the content of sugar degree and free sugar. In addition, liquid swine manure may be possible to grow Sorghum ${\times}$ Sudangrass hybrid without chemical fertilizer.

• Proceedings of the Korean Society of Crop Science Conference
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• 2022.10a
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• pp.317-317
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• 2022

Seakso 5, a maize hybrid, was applied for variety in 2021 by Gangwon Agricultural Research and Extension Services in Korea. This variety was bred to produce a purple extract of com husk. It shows purple color in the husk and cob and contains abundant anthocyanins. In this study, to obtain basic data on purple com 'Seakso 5' husk extract (PCHE), a husk extract was prepared and the contents of vitamins, amino acids and fatty acids were analyzed. The Seakso 5 husks were extracted with 30% alcohol and concentrated, after adding dextrin to the concentrate, it was spray-dried to prepare an extract. The PCHE were analyzed for vitamins, amino acids, and fatty acids by referring to the Food Code. As a result, three types of vitamins were detected, and their contents were vitamin B₁ 0.14 mg/100g, vitamin B₂ 2.30 mg/100g, and vitamin C 11.32 mg/100g. A total of 15 amino acids were detected in the PCHE, including aspartic acid and glutamic acid, and the content of aspartic acid was the highest at 3.02 mg/g. Simultaneous analysis of fatty acids Among 37 types, saturated fatty acids were palmitic acid (C16:0), stearic acid (C18:0), monounsaturated fatty acids were oleic acid (C18:1(n-9)), polyunsaturated fatty acids were linoleic acid(C18:2(n-6)c) and a-Linolenic Acid (C18:3(n-3)) were detected. Among the detected fatty acids, the content of palmitic acid was the highest at 40.75 mg/100g. In the future, These analysis results will be used as reference data for temporary food ingredient applications by the Ministry of Food and Drug Safety.

• Journal of the Korean Society for Heat Treatment
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• v.3 no.3
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• pp.5-12
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• 1990

This study has been conducted to establish the carburizing characteristics of low carbon alloy steels with varying amount of Ni element gas-carburized for 2 hours at $930^{\circ}C$ in an atmosphere of 94% $N_2$-6% $C_3H_8$ gas mixture with some changes in gas pressure passing through the diffusion plate in the fluidized-bed furnace. The results obtained from the experiment are as follows : (1) Optical micrograph has shown that the carburized layer consists of retained austenite and plate martensite and that retained austenite increases as the pressure of gas mixture passing through the diffusion plate as well as Ni content increase. (2) Chemical analysis has shown that carbon potential increases and carburizability is also improved due to a less degree of fluidization as the pressures of gas mixtures passing through the diffusion plate increase, resulting in, however, a severe formation of soot, and the gas pressure is necessarily regulated. (3) It has been revealed that carbon concentration hardness values at a given distance measured from the surface within the carburized case. Increase with increasing the pressure of gas mixtures passing through the diffusion plate and decrease with increasing Ni content. (4) The effective case depth has been shown to almost linearly increase as the pressure of gas mixtures passing through the diffusion plate is increased and to decrease with increasing Ni content.

• Bulletin of the Korean Chemical Society
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• v.32 no.3
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• pp.921-926
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• 2011

This study investigates a root cause of the improved rate performance of $LiFePO_4$ after metal doping to Fesites. This is because the metal doped $LiFePO_4$/C maintains its initial capacity at higher C-rates than undoped one. Using $LiFePO_4$/C and doped $LiFe_{0.97}M_{0.03}PO_4$/C (M=$Al^{3+}$, $Cr^{3+}$, $Zr^{4+}$), which are synthesized by a mechanochemical process followed by one-step heat treatment, the Li content before and after chemical delithiation in the $LiFePO_4$/C and the binding energy are compared using atomic absorption spectroscopy (AAS) and X-ray photoelectron spectroscopy (XPS). The results from AAS and XPS indicate that the low Li content of the metal doped $LiFePO_4$/C after chemical delithiation is attributed to the low binding energy induced by weak Li-O interactions. The improved capacity retention of the doped $LiFePO_4$/C at high discharge rates is, therefore, achieved by relatively low binding energy between Li and O ions, which leads to fast Li diffusivity.

• Food Science and Preservation
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• v.18 no.6
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• pp.907-915
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• 2011

Moju is a low-alcoholic beverage made by filtering after boiling a mixture of makgeolli, ginseng, arrowroot, licorice root, cinnamon, jujube, ginger, and raw sugar. It is known to alleviate hangovers. To provide information for use in the development of palatable Moju, this study evaluated the physicochemical and sensory properties of 22 kinds of Moju being sold at different restaurants in Jeonju city. The mean values of obtained in the physicochemical analysis were as follows: water content, 91.28%; alcohol content, 1.09%; pH, 4.25; total acidity, 0.27%; reducing sugar content, 40.68 mg/mL; soluble solid content, 13.75 $^{\circ}Brix$; and viscosity 11.19 cP. The Lactic-, malic-, and citric- acid contents were higher than the contents of other organic acids. The sucrose content was higher than the contents of other free sugars. The mean value of the free amino acids was 175.3 mg%, lower than that of Takju, the main ingredient of Moju. It was considered that the free amino acids in Takju can be used as a substrate for the browning reaction in the process of Moju manufacture. In the sensory evaluation, the Moju with 0.15~0.25% total acidity, 10.6~13.4 $^{\circ}Brix$, and 5.73~9.57 cP was preferred.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.50 no.11
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• pp.539-543
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• 2001

ln this paper, the $Sr_{l-x}Ca_xTiO_3(0\leqx\leq0.2)-based$ grain boundary layer ceramics were fabricated to measure dielectric properties with the sintering temperature and the thermal treatment time. The sintering temperature and time were $1420~15206{\circ}C$, 4hours, and the thermal treatment temperature and time of the specimen were $l150^{\circ}C$, 1, 2, 3hours, respectively. The structural and the dielectric properties were investigated by SEM, X-ray, HP4194A and K6517. The average grain size was increased with increasing the sintering temperature, but it decreased up to 15mo1% with increasing content of Ca. X-ray diffraction analysis results showed that all specimens were the cubic structure, and the main peaks were moved to right and the lattice constant were decreased with increasing content of Ca. The appropriate thermal treatment time and temperature of CuO to obtain dielectric properties of $\varepsilon_r>50000,\; tan \delta<0.05\; and \;\DeltaC<\pm10%$ were 2hrs and $l150^{\circ}C$, respectively.

• Journal of the Korean Ceramic Society
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• v.25 no.5
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• pp.502-508
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• 1988

The $\alpha$ to $\beta$ phase transformation of $\alpha$-Si3N4 whisker and related microstructural changes have been investigated. When only $\alpha$-Si3N4 whisker was heat treated in the range 1650~175$0^{\circ}C$, the $\alpha$ to $\beta$ phase transformation occured. In this case, it eas suggested that the oxygen content in $\alpha$-Si3N4 whisker affected the transformation behavior. Although $\alpha$-Si3N4 whisker with Si was heat treated under the same condition, however, the variation of $\beta$- fraction had a similar tendency with heat treating time. Therfore, it was considered that the oxygen content in $\alpha$-Si3N4 whisker affected the transformation behavior dominently rather than the content of added Si. The added $\beta$ phase did not affect the transformation behaviro of $\alpha$-Si3N4 whisker.