• The Korean Journal of Malacology
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• v.27 no.4
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• pp.317-322
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• 2011

This study was performed to obtain the basic data on physiological responses of low water temperature stress of the cultured Pacific abalone, Haliotis discus hannai. Abalones were exposed at low water temperatures of $7^{\circ}C$ and $4^{\circ}C$. We have investigated survival rate, superoxide dismutase (SOD) activity and total protein (TP) in the abalone by the exposure times (0, 3, 6, 12, 24, 72, 120, 168 and 216 hours). Survival rate of the abalone at $7^{\circ}C$ experiment was 90.8%, whereas at $4^{\circ}C$ experiment was 0% after exposure 10 days. SOD activity was significantly increased until 12 hours after exposure to $4^{\circ}C$, and then was recovered to starting level after 24 hours. However, there was no significant difference between control ($12^{\circ}C$) and $7^{\circ}C$ experiments. TP was significantly increased until 216 hours after 24 hours at $4^{\circ}C$ experiment, but $7^{\circ}C$ experiment showed no significant differences compared to control ($12^{\circ}C$) experiment. Therefore, H. discus hannai was acclimated in low water temperature stress at $7^{\circ}C$, but at $4^{\circ}C$, all abalone died possibly because they exceed the limits of defense ability to too low temperature.

• Proceedings of the SCSK Conference
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• 2003.09a
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• pp.660-671
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• 2003

A chemical investigation of Peucedanum praeruptorum has resulted in the isolation of 3 khellactone derivatives, which have inhibitory effects on melanogenesis in B16 mouse melanoma cell lines. The khellactone derivatives were isolated from the crude extract of the roots of Pecedanum praeruptorum by a combination of adsorption chromatography and HPLC. The structures of isolated compounds were identified as 3', 4'-diangeloyl-cis-khellactone, 3'-angeloyl-4'-senecioyl-cis-khellactone and, 3', 4'-disenecioyl-cis-khellactone by $^1$H NMR, $^{13}$ C NMR and mass spectral studies and by comparisons of spectral data with reported literatures. These khellactone derivatives can be a good candidate for new skin whitening agent due to its strong inhibitory activity and safety.

• Journal of the Korean Ceramic Society
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• v.50 no.6
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• pp.402-409
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• 2013

The objective of this study was to develop a synthesis process for ${\beta}$-SiC powders to reduce the synthesis temperature and to control the particle size and to prevent particle agglomeration of the synthesized ${\beta}$-SiC powders. A phenol resin and TEOS were used as the starting materials for the carbon and Si sources, respectively. $SiO_2$-C hybrid precursors with various C/Si mole ratios were fabricated using a conventional sol-gel process. ${\beta}$-SiC powders were synthesized by a carbothermal reduction process using $SiO_2$-C hybrid precursors with various C/Si mole ratios (1.6 ~ 2.5) fabricated using a sol-gel process. In this study, the effects of excess carbon and the addition of Si powders to the $SiO_2$-C hybrid precursor on the synthesis temperature and particle size of ${\beta}$-SiC were examined. It was found that the addition of metallic Si powders to the $SiO_2$/C hybrid precursor with excess carbon reduced the synthesis temperature of the ${\beta}$-SiC powders to as low as $1300^{\circ}C$. The synthesis temperature for ${\beta}$-SiC appeared to be reduced with an increase of the C/Si mole ratio in the $SiO_2$-C hybrid precursor by a direct carburization reaction between Si and excess carbon.

• Korean Journal of Digital Imaging in Medicine
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• v.11 no.1
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• pp.21-26
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• 2009

In operation room, the use of the C-arm unit is increasing. So, the radiation dose of the person who work in operation room was even more increased than before. Thus, this study is shown the measurement of expose dose and the way for decrease of the radiation dose by using the C-arm unit. The experiment was performed with the C-arm unit and used a phantom which is similar to tissue of the human body and fluoro-glass dosimeter for dose measurement. The expose dose were measured by the tube position(over tube, under tube) of the C-arm unit, distance(50, 100$\sim$200cm), direction(I, II, III, IV), runtime(1min, 3min), wearing of the apron. The radiation dose was decreased twice and three times at under tube rather than over tube. The I direction was measured 20$\sim$30% more than the others. The biggest expose dose is 50cm from center on distance. The expose dose is decreased to far from center. In case of Wearing of the apron, the radiation dose was decreased 60$\sim$90% by the distance. But there weren't change of the radiation dose by C-arm tube position. In present, by increasing the usage of the C-arm unit, the radiation dose is inevitable. So, this study recommends us to use the under tube of the C-arm unit. Also, Wearing of the apron is required for minimum of the radiation exposure.

• The Korean Journal of Food And Nutrition
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• v.31 no.4
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• pp.457-463
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• 2018

In this study, we analyzed the protective effects of the vitamin C in the streptozotocin (STZ)-induced apoptosis using the SH-SY5Y, a neuroblastoma cell line. The cells were pretreated with the vitamin C ($100{\mu}g$) for 30 min, followed by the 24-hr treatment with the 2.5-mM STZ. The cell-viability assay using the Cell Counting Kit (CCK)-8 revealed the cell-survival rate increased by 15% following the vitamin-C pretreatment compared to the STZ-only treatment. Moreover, we conducted the western-blot analysis to determine the protective effect of the vitamin C regarding the apoptosis. Compared to those in the STZ-only-treatment group, the p-ERK and Bcl-2 expressions increased in the vitamin-C-pretreatment group, whereas the p-JNK and Bax expressions decreased. The vitamin-C pretreatment increased the expression of the SOD-1, an antioxidant enzyme, by more than 30%, indicating its protective role in the STZ-induced oxidative stress. Also, we found both the intrinsic- and extrinsic-pathway mechanisms of the STZ-induced apoptosis. The results of this study $s{\mu}ggest$ vitamin C may help prevent the neurodegenerative diseases.

• Proceedings of the Korean Vacuum Society Conference
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• 2007.08a
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• pp.337-337
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• 2007

• JSTS:Journal of Semiconductor Technology and Science
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• v.4 no.2
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• pp.88-93
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• 2004

We, for the first time, present novel test patterns and conclusive on-chip data indicating that the variation of coupling capacitance, ${\Delta}C_C$ by crosstalk can be larger than static coupling capacitance, $C_C$. The test chip is fabricated using a generic 150 nm CMOS technology with 7 level metallization. It is also shown that ${\Delta}C_C$ is strongly dependent on the phase of aggressive lines. For antiphase crosstalk ${\Delta}C_C$ is always larger than $C_C$ while for in-phase crosstalk $D_{\Delta}C_C$is smaller than $C_C$.

• 한국신재생에너지학회:학술대회논문집
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• 2005.11a
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• pp.711-711
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• 2005

• Journal of the Korean Ceramic Society
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• v.50 no.6
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• pp.410-415
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• 2013

$ZrB_2$-SiC ceramics are fabricated via hot pressing with different ratios of submicron or nano-sized SiC in a $ZrB_2$-20 vol%SiC system, in order to examine the effect of the SiC size ratio on the microstructures and physical properties, such as thermal conductivity, hardness, and flexural strength, of $ZrB_2$-SiC ceramics. Five different $ZrB_2$-SiC ceramics ($ZrB_2$-20 vol%[(1-x)SiC + xnanoSiC] where x = 0.0, 0.2, 0.5, 0.8, 1.0) are prepared in this study. The mean SiC particle sizes in the sintered bodies are highly dependent on the ratio of nano-sized SiC. The thermal conductivities of the $ZrB_2$-SiC ceramics increase with the ratio of nano-sized SiC, which is consistent with the percolation behavior. In addition, the $ZrB_2$-SiC ceramics with smaller mean SiC particle sizes exhibit enhanced mechanical properties, such as hardness and flexural strength, which can be explained using the Hall-Petch relation.

• The Journal of Korean Society for Radiation Therapy
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• v.31 no.1
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• pp.43-49
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• 2019

Purpose : We apply the Layered Rescanning PBS designed to complement the Pencil Beam Scanning(PBS), which is vulnerable to moving organs with the Moving Phantom, and compare the homogeneity with the single scan PBS. Methods and materials: Matrix X (IBA, Belgium) and Moving Phantom (standard imaging, USA) were used. A dose of 200 cGy was measured in the AP direction on a hypothetical tumor $10{\times}10{\times}5cm$. The plan type was planned as 4 kinds of sinlge scan PBS, rescan number 4, 8, 12 times. Were measured three times for each types. During the measurement, the respiratory cycle of the Moving Phantom was generally set to 4 seconds per cycle, and the movement radius in the S-I direction was set to 2 cm. In addition, beam on time was measured. Results : The mean values of $D_{max}$ in the PTV were $246.47{\pm}18.8cGy$, $223.43{\pm}8.92cGy$, and $222.47{\pm}7.7cGy$, $213.9{\pm}6.11cGy$ and the mean values of $D_{min}$ were $165.53{\pm}4.32cGy$, $173.13{\pm}11.94cGy$, $184.13{\pm}8.04cGy$, $182.67{\pm}4.38cGy$ and the mean values of $D_{mean}$ $192.77{\pm}6.98cGy$, $196.7{\pm}4.01cGy$, $198.17{\pm}4.96cGy$, $195.77{\pm}3.15cGy$ respectively. As the number of rescanning increased, the Homogeneity Index converged to 1. The beam on time was measured as 2:15, 3:15, 4:30, 5:37 on average. In the measurement process, in the low dose layer of the MU, the problem was found that it was not rescanned as many times as the set number of rescan. Conclusions : In the treatment of tumors with long-term movements, the application of layered rescanning PBS showed a more uniform dose distribution than single scan PBS. And as the number of rescan increase, the distribution of homogeneity is uniform. Compared with single scan plan and 12 rescan plan, HI value was improved by 0.32. Further studies are expected to be applicable to patients who can not be treated with respiratory synchronous radiation therapy.