• Journal of the Korean Ceramic Society
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• v.48 no.2
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• pp.168-172
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• 2011

Alumina powder was added in a general porcelain (Backja) with clay, feldspar and quartz contents to promote the mullite ($3Al_2O_3{\cdot}2SiO_2$) generation in the porcelain. Low melting materials ($B_2O_3(450^{\circ}C)$, $MnO_3(940^{\circ}C)$, CuO($1080^{\circ}C$)) were doped at ~3 wt% to modify the sinterability of porcelain with a high alumina contents and promote the mullite generation. Green body was made by slip casting method with blended slurry and then, they were fired at $1280^{\circ}C$ for 1hr by a $2^{\circ}C/min$. Densifications of samples with high alumina contents (20~30 wt%) were impeded. As the doping contents of low melting materilas increased, the sinterability of samples was improved. The shrinkage rate and bulk density of samples were improved by doping with low melting materials. Mullite phase increased with increasing the low melting contents in the phase analyses. This means lots of alumina and quartz were transformed into mullite phase by low melting contents doping. In the results, high bending strength of samples with high alumina contents was accomplished by improving the densification and mullite generation in the porcelain.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.3
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• pp.283-289
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• 2010

Owing to the increasing worldwide interest in green technology and renewable energy sources, flywheel energy storage systems (FESSs) are gaining importance as a viable alternative to traditional battery systems. Since the energy storage capacity of an FESS is proportional to the principal mass-moment of inertia and the square of the running speed, a design that maximizes the principal inertia while operatingrunning at the highest possible speed is important. However, the requirements for the stability of the system may impose a constraint on the optimal design. In this paper, an optimal design of an FESS that not only maximizes the energy capacity but also satisfies the requirements for system stability and reduces the sensitivity to external disturbances is proposed. Cross feedback control in combination with a conventional proportional-derivative (PD) controller is essential to reduce the effect of gyroscopic coupling and to increase the stored energy and the specific energy density.

• Journal of People, Plants, and Environment
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• v.24 no.6
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• pp.585-593
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• 2021

Background and objective: Illegal open-air incineration, which is criticized as a leading source of air pollutants among agricultural activities, currently requires constant effort and attention. Countries around the world have been undertaking studies on the emission of heavy metal substances in fine dust discharged during the incineration process. A precise analytical method is required to examine the harmful effects of particulate pollutants on the human body. Methods: In order to simulate open-air incineration, the infrastructure needed for incineration tests complying with the United States Environmental Protection Agency (EPA) Method 5G was built, and a large-area analysis was conducted on particulate pollutants through automated scanning electron microscopy (SEM)-energy-dispersive X-ray spectroscopy (EDS). For the test specimen, high-density polyethylene (HDPE) waste collected by the DangJin Office located in Choongcheongnam-do was used. To increase the identifiability of the analyzed particles, the incineration experiment was conducted in an incinerator three times after dividing the film waste into 200 g specimens. Results: Among the metal particulate matters detected in the HDPE waste incineration test, transition metals included C (20.8-37.1 wt%) and O (33.7-37.9 wt%). As for other chemical matters, the analysis showed that metal particulate matters such as metalloids, alkali metals, alkaline earth metals, and transition metals reacted to C and C-O. Si, a representative metalloid, was detected at 14.8-20.8 wt%, showing the highest weight ratio except for C and O. Conclusion: In this study, the detection of metal chemicals in incinerated particulate matters was effectively confirmed through SEM-EDS. The results of this study verified that HDPE waste adsorbs metal chemicals originating from soil due to its own properties and deterioration, and that when incinerated, it emits particulate matters containing transition metals and other metals that contribute to the excessive production and reduction of reactive oxygen species.

• Journal of the Korean Ceramic Society
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• v.38 no.9
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• pp.853-859
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• 2001

The dispersion stability of nano $Y_2O_3-CeO_2$ system was investigated using colloid surface chemistry. Green body of $Y_2O_3$ doped $CeO_2$ was prepared by slip casting in and aqueous system. The dispersion stability of suspension between powders and organic additive was accomplished through electrokinetic behavior of suspension, which was done by ESA apparatus. The dynamic mobility of particles was enhanced when the anionic dispersant of the amount of 1wt% was added. The dissolution of $Y^{3+}$ ion in suspension occurred in the acidic region so that pH value in slurries did not move to below 7.0. In the $CeO_2-Y_2O_3$ system, optimal preparation of suspension was made after adding the anionic dispersant as the amount of 1wt% and pH value of 11.0, and then slip-cast and sintered at 1400$^{\circ}$C, 2 hrs. It appeared relative density of >98% and homogeneous distribution of Y element in depth direction as well as in the microstructure of surface.

• Journal of Life Science
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• v.22 no.12
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• pp.1697-1703
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• 2012

Obesity is a risk factor for numerous metabolic diseases. Recently, naturally occurring compounds that may improve obesity have received increasing attention. Xanthigen is a mixture of fucoxanthin and punicic acid derived from brown seaweed and pomegranate seed, respectively, which have been traditionally used for lipid-lowering effects in humans. In this study, we investigated whether Xanthigen attenuates high-fat diet-induced obesity in C57BL/6N mice. The mice were fed on a normal diet (ND), high-fat diet (HFD), HFD plus 1% Xanthigen or HFD plus 1% green tea extract (GTE) for 11 weeks. Food efficiency ratio (FER) and body weight were significantly reduced in mice fed HFD plus Xanthigen compared to HFD-fed mice. Consistent with the results in body weight change, Xanthigen also significantly decreased the weights of epididymal adipose tissue, retroperitoneal adipose tissue, and liver in HFD plus 1% Xanthigen-fed mice. The serum level of low-density lipoprotein (LDL)-cholesterol was significantly decreased in HFD plus Xanthigen-fed mice compared to HFD-fed mice. These results suggest that Xanthigen may be useful in the development of a functional health food for anti-obesity.

• Korean Journal of Food Science and Technology
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• v.46 no.6
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• pp.743-749
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• 2014

The aim of this study was to develop hydroponic-cultured ginseng vinegar (HGV) containing ginsenoside Rg2 in order to its anti-obesity and anti-hyperlipidemic effects in C57BL/6J mice. HGV was prepared by two-stage fermentation. The ginsenoside Rg2 contained in acetic acid-fermented HGV increased by 4.0 times compared to that in pre-fermented HGV. To measure the anti-obesity effect of HGV, thirty two mice were randomly divided into four groups: normal diet group (ND), high-fat diet group (HFD), high-fat diet-supplemented with HGV group (HGV), and high-fat diet-supplemented with green tea extract group (GT). Body weight, fat weight, and liver weight decreased in the HGV group. The HGV group also showed lower plasma levels of low-density lipoprotein (LDL)-cholesterol and triglycerides, and higher levels of high-density lipoprotein (HDL)-cholesterol compared to the corresponding levels in the HFD group. Furthermore, there were significant decreases in plasma aspartase aminotransferase (AST) and alanine aminotransferase (ALT) levels in the HGV group compared to the corresponding levels in the HFD group. These results suggest that HGV can be used as an anti-obesity therapeutic agent or functional ingredient.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.18 no.5
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• pp.211-216
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• 2008

The artificial lightweight aggregate (ALA) was manufactured in a rotary kiln at $1125^{\circ}C$ using green body formed by pelletizing the batch powder composing of coal bottom ash (CBA) produced from power plant, clay and dredged soil (DS). The TCLP (Toxicity characteristic leaching procedure) results showed that the dissolution concentration of heavy metal ions of ALA fabricated in this study was below the limitation defined by the enforcement regulations of wastes management law in Korea. The ALA containing 60$\sim$70 wt% CBA had a bulk density of 1.45$\sim$1.49 and a water absorption of 17.2$\sim$18.5 %. The impact values for oven-dry state and saturated-surface dry state of ALA were 27.4$\pm$1.3 and 23.4$\pm$2.6 % respectively. The 28-days compressive strength of concrete made with various ALA was $22.7\sim27.8 N/mm^2$. The slump of concrete with ALA containing CBA 60 and 70 wt% were 7.9 and 14.3 cm respectively. The unit weight of concrete made with any ALA fabricated in this study was satisfied with the standard specifications of lightweight concrete for the civil engineering and construction presented by Korea as below $1.84 ton/m^3$.

• Asian-Australasian Journal of Animal Sciences
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• v.16 no.12
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• pp.1732-1737
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• 2003

An experiment was conducted to investigate the effect of feeding transgenic cottonseed (Bt.) vis-a-vis non-transgenic (non-Bt.) cottonseed on blood biochemical constituents in lactating Murrah buffaloes. Twenty Murrah buffaloes in mid-lactation were divided into 2 groups of 10 each. Animals of group I were fed with 39.5% non-transgenic cottonseed in concentrate mixture while the same percentage of transgenic (Bt.) cottonseed was included in the concentrate mixture fed to the animals of group II. Animals of both groups were fed with concentrate mixture to support their milk production requirements. Each buffalo was also offered 20 kg mixed green fodder (oats and berseem) and wheat straw ad libitum. The experimental feeding trial lasted for 35 days. There was no significant difference in the dry matter intake between the two groups of buffaloes. All the buffaloes gained body weight, however, the differences were non significant. Total erythrocyte count, hemoglobin content and packed cell volume were $9.27{\pm}0.70${\times}10^6/{\mu}l$, $13.01{\pm}0.60gdl$ and $34.87{\pm}1.47%$, respectively in group I with the corresponding figures of $8.88{\pm}0.33$, $12.99{\pm}0.52$ and $31.08{\pm}1.52$ in group II. The values of total erythrocyte count, haemoglobin content and packed cell volume did not differ significantly between the two groups of buffaloes. The concentration of plasma glucose, serum total proteins, albumin, globulin, triglycerides and high density lipoprotein were non significantly higher in buffaloes fed non-transgenic cottonseed than in buffaloes fed transgenic cottonseed. The cholesterol concentration was significantly (p<0.01) higher in buffaloes of group I ($136.84{\pm}8.40mg/dl$) than in buffaloes of group II ($105.20{\pm}1.85mg/dl$). The serum alkaline phosphotase, glutamic-oxaloacetate transaminase and glutamic-pyruate transaminase activities did not differ significantly between two groups of buffaloes. However, serum glutamic-pyruate transaminase activity was considerably high in buffaloes fed nontransgenic cottonseed as compared to buffaloes fed transgenic cottonseed. Bt. proteins in serum samples of animals of group II were not detected after 35 days of feeding trial. It was concluded that transgenic cottonseed and non-transgenic cottonseed have similar nutritional value without any adverse effects on health status of buffaloes as assessed from haematobiochemical constituents.

• Korean Journal of Remote Sensing
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• v.27 no.4
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• pp.457-466
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• 2011

The objectives of this study are to produce level 3 type LULC map and analysis of phenological features of North Korea, ISODATA clustering of the 88scenes of MVC of MODIS NDVI in 2008 and 8scenes in 2009 was carried out. Analysis of phenological phases based mapping method was conducted, In level 2 type map, the confusion matrix was summarized and Kappa coefficient was calculated. Total of 27 typical habitat types that represent the dominant species or vegetation density that cover land surface of North Korea in 2008 were made. The total of 27 classes includes the 17 forest biotopes, 7 different croplands, 2 built up types and one water body. Dormancy phase of winter (${\sigma}^2$ = 0.348) and green up phase in spring (${\sigma}^2$ = 0.347) displays phenological dynamics when much vegetation growth changes take place. Overall accuracy is (851/955) 85.85% and Kappa coefficient is 0.84. Phenological phase based mapping method was possible to minimize classification error when analyzing the inaccessible land of North Korea.

• Journal of the Korean Electrochemical Society
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• v.10 no.1
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• pp.7-13
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• 2007

We synthesized and investigated $La_{0.75}Sr_{0.25}FeO_3$ by Glycine Nitrate Process(GNP) method used as cathode materials for SOFC(solid oxide fuel cell). Optimized amount of glycine is 3.17 mol. ICP elemental composition analysis indicated that the stoichiometry of the synthesized powders have nearly nominal values. SEM images and XRD patterns reveal that the synthesized powder has uniform size distribution and high degree of crystallinity. The sample powders were isostatically pressed to form a pellet. The green body was sintered at $1200^{\circ}C$ and the relative density of the sintered specimens were measured by Archimedes mettled. We measured electrochemical performance of LSF by AC impedance spectroscopy. Resistance of LSF shows lower value than that of LSM throughout all temperature region. The anode-supported solid oxide fuel cell showed a performance of $342mW/cm^2(0.7V,\;488mA/cm^2)$ at $750^{\circ}C$. The electrochemical characteristics of the single cell were examined by at impedance method.