• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.1254_1255
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• 2009

The composites were fabricated by adding 30, 35, 40, 45[vol.%] Zirconium Diboride(hereafter, $ZrB_2$) powders as a second phase to Silicon Carbide(hereafter, SiC) matrix. The physical, mechanical and electrical properties of electroconductive SiC ceramic composites by Spark Plasma Sintering(hereafter, SPS) were examined. Reactions between $\beta$-SiC and $ZrB_2$ were not observed in the XRD analysis. The relative density of SiC+30[vol.%]$ZrB_2$, SiC+35[vol.%]$ZrB_2$, SiC+40[vol.%]$ZrB_2$ and SiC+45[vol.%]$ZrB_2$ composites are 88.64[%], 76.80[%], 79.09[%] and 88.12[%], respectively. The XRD phase analysis of the electroconductive SiC ceramic composites reveals high of SiC and $ZrB_2$ and low of $ZrO_2$ phase. The electrical resistivity of SiC+30[vol.%]$ZrB_2$, SiC+35[vol.%]$ZrB_2$, SiC+40[vol.%]$ZrB_2$ and SiC+45[vol.%]$ZrB_2$ composites are $6.74{\times}10^{-4}$, $4.56{\times}10^{-3}$, $1.92{\times}10^{-3}$ and $4.95{\times}10^{-3}[{\Omega}{\cdot}cm]$ at room temperature, respectively. The electrical resistivity of SiC+30[vol.%]$ZrB_2$, SiC+35[vol.%]$ZrB_2$, SiC+40[vol.%]$ZrB_2$ and SiC+45[vol.%]$ZrB_2$ are Positive Temperature Coefficient Resistance(hereafter, PTCR) in temperature ranges from 25[$^{\circ}C$] to 500[$^{\circ}C$]. It is convinced that SiC+40[vol.%]$ZrB_2$ composite by SPS can be applied for heater or electrode.

• Journal of Electrical Engineering and Technology
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• 제4권4호
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• pp.538-545
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• 2009

The SiC-$ZrB_2$ composites were fabricated by combining 30, 35, 40 and 45vol.% of Zirconium Diboride (hereafter, $ZrB_2$) powders with Silicon Carbide (hereafter, SiC) matrix. The SiC-$ZrB_2$ composites, the sintered compacts, were produced through Spark Plasma Sintering (hereafter, SPS), and its physical, electrical, and mechanical properties were examined. Also, the thermal image analysis of the SiC-$ZrB_2$ composites was examined. Reactions between $\beta$-SiC and $ZrB_2$ were not observed via X-Ray Diffractometer (hereafter, XRD) analysis. The relative density of the SiC+30vol.%$ZrB_2$, SiC+35vol.%$ZrB_2$, SiC+40vol.%$ZrB_2$, and SiC+45vol.%$ZrB_2$ composites were 88.64%, 76.80%, 79.09% and 88.12%, respectively. The XRD phase analysis of the sintered compacts demonstrated high phase of SiC and $ZrB_2$ but low phase of $ZrO_2$. Among the SiC-$ZrB_2$ composites, the SiC+35vol.%$ZrB_2$ composite had the lowest flexural strength, 148.49MPa, and the SiC+40vol.%$ZrB_2$ composite had the highest flexural strength, 204.85MPa, at room temperature. The electrical resistivities of the SiC+30vol.%$ZrB_2$, SiC+35vol.%$ZrB_2$, SiC+40vol.%$ZrB_2$ and SiC+45vol.%$ZrB_2$ composites were $6.74\times10^{-4}$, $4.56\times10^{-3}$, $1.92\times10^{-3}$, and $4.95\times10^{-3}\Omega{\cdot}cm$ at room temperature, respectively. The electrical resistivities of the SiC+30vol.%$ZrB_2$, SiC+35vol.%$ZrB_2$ SiC+40vol.%$ZrB_2$ and SiC+45[vol.%]$ZrB_2$ composites had Positive Temperature Coefficient Resistance (hereafter, PTCR) in the temperature range from $25^{\circ}C$ to $500^{\circ}C$. The V-I characteristics of the SiC+40vol.%$ZrB_2$ composite had a linear shape. Therefore, it is considered that the SiC+40vol.%$ZrB_2$ composite containing the most outstanding mechanical properties, high resistance temperature coefficient and PTCR characteristics among the sintered compacts can be used as an energy friendly ceramic heater or electrode material through SPS.

• Biomolecules & Therapeutics
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• 제19권3호
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• pp.348-356
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• 2011

Liriope platyphylla is a medical herb that has long been used in Korea and China to treat cough, sputum, neurodigenerative disorders, obesity and diabetes. The aims of this study were to study the antidiabetic effects of the aqueous extract of L. platyphylla (AEtLP) through pancreatic and extrapancreatic actions. AEtLP were orally administrated to ICR mice once a day for 7 days. Of three different concentrations of AEtLP, only 10% AEtLP were low toxic to liver, based on body weight and serum biochemical analyses. However, 10% AEtLP-treated mice displayed signifi cant reduction of the glucose concentration and increased insulin concentration; no changes were noted using 5% and 15% AEtLP. Also, the increase of glucose transporter (Glut)-1 expression in liver was dependent on the concentration of AEtLP, and was regulated by the phosphorylation of Akt. The lowest expression of Glut-3 was observed in 15% AEtLP treated mice, followed by 10% AEtLP- and 5% AEtLP-treated mice. This pattern of Glut-3 expression was roughly in accord with the phosphorylation of c-Jun N-teminal kinase (JNK) in the mitogen-activated protein kinase (MAPK) pathway. Furthermore, a signifi cant rise of the superoxide dismutase activity (SOD) was detected in AEtLP-treated mice. The fi ndings suggest that AEtLP should be considered as a diabetes therapeutic candidate to induce insulin secretion from pancreatic ${\beta}$-cells and glucose uptake in liver cells.

• 대한한방내과학회지
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• 제32권3호
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• pp.345-360
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• 2011

Objectives : This study was examined to investigate the effects of Cheonmagudeng-um gagam (CGG) extract on spontaneous hypertension. Methods : For the study of CGG, we divided rats into three groups. The normal group was Wister Kyoto rats (WKY). The control group was spontaneously hypertensive rats (SHR). The treatment group was SHR which were administered CGG extract (SHR-CGG). SHR-CGG were orally administered CGG extract that was diluted in distilled water at the various concentrations for 4 weeks (234.5 mg/kg) and SHR were orally administered the same dosage of plain distilled water as SHR-CGG. Then we measured anti-oxygen effects, ACE inhibitory activity, weight of heart and kidney, blood pressure, heart rate, plasma aldosterone, electrolyte, creatinine, uric acid, BUN, and observed the cortex of the cardiac muscle, kidney, and adrenal gland. Results : CGG increased DPPH scavenging activity and SOD similar activity depending on the concentration. CGG significantly decreased ROS, TNF-${\alpha}$, IL-6, IL-$1{\beta}$, heart weight, blood pressure, heart rate, aldosterone, and BUN in SHR. CGG increased ACE inhibition activity depending on the concentration. CGG inhibited the heart, kidney and adrenal gland tissue injury that is caused by hypertension. Conclusions : These results suggest that CGG is effective in treatment and prevention of hypertension.

• 동의생리병리학회지
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• 제27권4호
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• pp.431-436
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• 2013

Bone homeostasis is maintained by co-ordination of bone-resorbing osteoclasts and bone-forming osteoblasts. Imbalance between osteoclasts and osteoblasts leads to many bone diseases such as osteoporosis, rheumatoid arthritis. Taxillus chinensis is a herb that has been widely used to improve bone health. However, the effect and mechanism of Taxillus chinensis extract on osteoclast differentiation and bone resportion has been unknown. Thus, We investigated the effect of Taxillus chinensis on expression of receptor activator of nuclear factor-${\kappa}B$ ligand (RANKL)-induced osteoclast differentiation and bone resorption. Also, the action of Taxillus chinensis on mechanisms relating to osteoclast differentiation was studied. In this results, we identified that Taxillus chinensis significantly inhibited RANKL-induced osteoclast differentiation and bone resportion. Moreover, Taxillus chinensis was suppressed the activation of NF-${\kappa}B$ in bone marrow macrophage treated RANKL and M-CSF. Taxillus chinensis was down-regulated the mRNA expression of c-Fos, nuclear factor of activated T-cells (NFAT)c1, osteoclast-associated receptor (OSCAR), tartrate-resistant acid phosphatase (TRAP). The cell adhesion-related molecules such as integrin ${\alpha}v$ and integrin ${\beta}3$, and the filamentous actin (F-actin) rings of mature osteoclasts-related molecules such as dendritic cell-specific transmembrane preotein (DC-STAMP) and cathepsin K are also suppressed. Taken together, these results indicated that Taxillus chinensis will be a good candidate to treat osteoclast-mediated bone diseases.

• 한국미생물·생명공학회지
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• 제44권4호
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• pp.479-487
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• 2016

대식세포에 대하여 구멍갈파래 에탄올 추출물의 독성결과를 확인해본 결과 독성은 나타나지 않았으며, LPS에 의하여 유도되는 NO와 염증성 cytokine의 분비량은 구멍갈파래 에탄올 추출물의 농도 의존적으로 감소함을 확인하였다. 또한 구멍갈파래 에탄올 추출물로 인해 $NF-{\kappa}B$ 및 MAPKs의 신호전달을 억제함으로써 염증매개성 물질의 발현 억제에 효과가 있는지 알아본 결과, 구멍갈파래 에탄올 추출물은 각각 iNOS, COX-2, $NF-{\kappa}B$ 및 MAPKs의 활성을 효과적으로 억제하였고 그에 따른 염증 매개인자들의 생성도 효과적으로 억제되는 것을 확인하였다. 마지막으로 추출물이 마우스 귀부종에 미치는 영향을 살펴본 결과, 대조군의 경피와 진피의 두께에 비해 추출물 처리군의 조직 두께가 상대적으로 현저히 줄어들었으며 귀 조직에 침윤된 mast cell의 감소에도 추출물이 그 효과를 현저하게 나타냄을 확인하였다. 본 연구결과들을 종합해 보았을 때, 구멍갈파래의 에탄올 추출물은 항염증 활성을 가지는 새로운 천연물질로 이용 가능하여 고부가 가치 제품 개발이 가능한 천연 소재로 판단된다.

• 한국식품과학회지
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• 제36권1호
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• pp.97-104
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• 2004

저식염 고추장을 제조하기 위하여 고추장의 소금농도를 9%에서 6%로 줄인 후 알콜 또는 겨자, 키토산을 첨가하여 숙성중의 품질특성을 비교하였다. 고추장의 전분액화효소의 활성은 키토산 첨가구에서 낮았으나 전분당화효소와 protease의 차이는 적었다. 고추장 숙성중의 효모수와 세균수는 알콜과 겨자, 키토산의 첨가로 감소되었으며, 효모수의 감소는 키토산 첨가에 비하여 알콜과 겨자의 첨가 고추장에서 심하였다. 고추장의 점 조성은 숙성중에 감소하나, 알콜 첨가구에서 높았다. 고추장의 산화환원전위는 키토산 첨가구에서 낮았으며 수분활성도의 저하는 알콜 첨가구에서 심하였다. 키토산 첨가 고추장이 숙성후에 L-과 a-, b-값이 높아 밝고 붉은 색이 진했으나, 저식염 무첨가구가 ${\Delta}E$의 변화가 적었다. 고추장의 pH는 알콜 첨가구에서 높았고 키토산의 첨가로 적정산도의 증가가 심하였다. 고추장의 총당과 환원당은 알콜과 겨자 첨가구에서 높았으며, 알콜의 생성은 겨자의 첨가로 현저하게 억제되었다. 고추장의 아미노태 질소는 저식염 무첨가구에서 높았으며 암모니아태 질소의 생성은 겨자 첨가구에서 낮았다. 12주 숙성시킨 고추장의 맛과 색, 종합적인 기호도는 알콜 첨가 고추장이 양호하여 저식염 고추장의 제조는 소금의 일부를 알콜로 대체하여 첨가하는 것이 효과적이었다.

• Journal of Microbiology and Biotechnology
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• 제16권8호
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• pp.1255-1261
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• 2006

An alkaliphilic bacterium, Bacillus sp. strain BK, was found to produce extracellular cellulase-free xylanolytic enzymes with xylan-binding activity. Since the pellet-bound xylanase is eluted with 2% TEA from the pellet of the culture, they contain a xylan-binding region that is stronger than the xylan-binding xylanase of the extracellular enzyme. The xylanases had a different molecular weight and xylan-binding ability. The enzyme activity of xylanase in the extracellular fraction was 6 times higher than in the pellet-bound enzyme. Among the enzymes, xylanase had the highest enzyme activity. When Bacillus sp. strain BK was grown in pH 10.5 alkaline medium containing xylan as the sole carbon source, the bacterium produced xylanase, arabinofuranosidase, acetyl esterase, and $\beta$-xylosidase with specific activities of 1.23, 0.11, 0.06, and 0.04 unit per mg of protein, respectively. However, there was no cellulase activity detected in the crude enzyme preparation. The hydrolysis of agricultural residues and kraft pulps by the xylanolytic enzymes was examined at 50$^{\circ}C$ and pH 7.0. The rate of xylan hydrolysis in com hull was higher than those of sugarcane bagasse, rice straw, com cop, rice husk, and rice bran. In contrast, the rate of xylan hydrolysis in sugarcane pulp was 2.01 and 3.52 times higher than those of eucalyptus and pine pulp, respectively. In conclusion, this enzyme can be used to hydrolyze xylan in agricultural residues and kraft pulps to breach and regenerate paper from recycled environmental resources.

• Journal of Microbiology and Biotechnology
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• 제14권3호
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• pp.553-562
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• 2004

To investigate protective activity in pepper plants, which were pre-inoculated with arbuscular mycorrhizal (AM) fungi Glomus intra radices (Gi), against pathogenic strain Phytophthora capsici (Pc), pathogenesis-related (PR) proteins and antioxidant enzymes were examined. The growth of root and shoot was the highest in peppers inoculated with G. intraradices, compared with non-inoculated control plants and those challenged by the pathogen with and without mycorrhizae after nine days of infection. Mycorrhizal colonization rate was reduced by about 10% in pathogen-challenged plants, but disease pressure was reduced. The activities of PR proteins, $\beta$-1- 3-glucanase and chitinase, were increased in Pc-treated plants compared to Gi+Pc-treated plants in leaves, but those in roots were suppressed. Superoxide dismutase activity and $H_2O_2${/TEX> content in Gi+Pc and Pc-treated plants were gradually increased in leaves. However, those in roots continuously increased up to 5 days, and then decreased dramatically. Peroxidase activity in leaves and roots increased after P. capsici infection both in plants inoculated with or without G. intraradices. These results suggest that AM fungi, G. intra radices, potentially act as one of the protective agents against plant pathogens. Changes of PR proteins and antioxidative enzymes in mycorrhizae-inoculated pepper appear to be regulated differently in leaves and roots by pathogen infection.

• Asian-Australasian Journal of Animal Sciences
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• 제23권8호
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• pp.1080-1088
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• 2010

This experiment was conducted to investigate the effects of dietary energy levels of gestating gilts on physiological parameters and reproductive performance for primiparous sows. A total of 40 F1 gilts (Large White${\times}$Landrace) were allocated to 4 treatments using a completely randomized design (CRD). Four different experimental diets contained 3,165, 3,265 3,365 and 3,465 kcal of ME/kg and each diet was provided to gilts at 2.0 kg/d during gestation. Consequently, energy intake of each treatment of gestating gilts was 6,330, 6,530, 6,730 and 6,930 kcal ME/kg, respectively. During the whole gestation period, body weight, fat mass gain and backfat thickness of gilts were increased in proportion to dietary energy levels (p<0.01). However, estimated protein mass gain of gilts was not affected by dietary energy level (p>0.10). At farrowing, the total number of pigs born per litter did not show any significant difference among treatments. However, the number of pigs born alive per litter in treatment 6,730 kcal ME/d was significantly higher than that of other treatments (p<0.05). Moreover, litter weight at birth was improved as dietary energy level was increased (p<0.05). Feed intake of sows during lactation tended to decrease as dietary energy level of gestation was increased, but litter weight gain was not affected by dietary treatment during the gestation period. Fat content in colostrum was higher as dietary energy level was increased during gestation. The concentration of blood estradiol-$17{\beta}$ was increased and was higher at the first trimester of gestation in 6,730 kcal ME/d treatment compared to other treatments. These results suggested that increased dietary energy level during gestation resulted in higher body weight and backfat thickness of sows. In addition, reproductive performance of the sow, such as litter weight at farrowing and the number of pigs born alive, was improved when 6,730 kcal of ME/d treatment diet was provided. Consequently, the NRC (1998) recommendation of energy for gestating gilts (6,015 to 6,150 kcal of ME/d) should be reevaluated to maximize reproductive performance because recent high-producing sows require much more energy to produce a large litter size and heavier piglets from the first parity.