• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.3
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• pp.202-206
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• 2001

Using THz time-domain spectroscopy (THz-TDS), the power absorption, the index of refraction, and the real conductivity of silica sand are measured from 0.1[Thz] to 0.5[Thz] frequency range. It is impossible to measure the characterization of the silica sand by simple electrical measurements using mechanical contacts, e.g., Hall effect or four-point probe measurements. However, the THz-TDS technique can measure not only electrical but also optical characterization of he sample. Also this technique can measure frequency dependent results. Especially, the real conductivity was increased according to THz frequency. This is unusual material compare with metal and semiconductor materials; the measured real conductivity are not followed by the simple Drude theory.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.151-152
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• 2005

Both $Al_2O_3$ and AlN nanopowders with diameters from ${\mu}m$ to mm were bead-milled and surface-modified by stabilizing agent. The size of bead-milled nanoparticles compared with the primary powder was effectively decreased and was dependent on milling time and bead size. The results of dispersion stability analysis indicated that chemical bonding between nanoparticles and surfactant is more effective than chemical adsorption to prepare the stable transformer oils containing nanoparticles. In this study, the thermal conductivity of the transformer oils containing nanoparticles was measured by transient hot-wire and laser flash methods.

• 유체기계공업학회:학술대회논문집
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• 2005.12a
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• pp.825-828
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• 2005

Experimental and numerical study was done to confirm the effect of the flexible tube in pipeline on transient flow oscillation. Experiment was made for a pipeline with and without deformable flexible tube using a single pumping system of main stainless pipe. The wave speeds of main pipe and flexible tube were calculated from the pipe material properties, structures, and boundary conditions. Time dependent pressure fluctuations were calculated for the pipeline using the simple and the Kelvin-Voigt viscoelastic models for the deformation of main pipe and flexible tube. Pressure calculated by the Kelvin-Voigt viscoelastic model showed better agreement with measured one than pressure by the simple model. Experimental and numerical results show that the maximum pressure as well as amplitude of pressure oscillation was decreased by inserting short flexible tube in pipeline. Hence, inserted short flexible tube to pipeline was found to be effective for the suppression of strong pressure oscillation. Moreover, the wave speed in pipe was discussed based on numerical and experimental results.

• Tribology and Lubricants
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• v.8 no.2
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• pp.14-19
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• 1992

rate of growth of "protective" films of oxides and compounds derived from the lubricant. The protection afforded by the films is strongly dependent on lubricant and steel composition, initial composite surface roughness and the load/speed sequence or history in the early stages of sliding. The protective films, formed by chemical and mechanical action between lubricant and mating surfaces, delayed the surface roughening and offered higher load capacity. Given the great number of variables involved it is not possible to follow more than a few of the chemical changes on surfaces at the end of experiments. Ellipsometry was therefore used to monitor the formation and loss of dual protective films in real time, and also to find the effect of protective films on scuffing and break-in depending on lubricant conditions.

• Journal of Physiology & Pathology in Korean Medicine
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• v.25 no.3
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• pp.533-539
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• 2011

Sulfuretin is one of the main flavonoids produced by Rhusverniciflua. Sulfuretin has been shown to exhibit many pharmacological activities including anti-oxidant, anti-obesity, anti-inflammatory and anti-mutagenic activities. However, the anti-skin photoaging effects of sulfuretin has not yet been reported. In the present study, we investigated the inhibitory effect of sulfuretin on the expression levels of MMP-1 and -3 in the human dermal fibroblast cells. Western blot analysis and real-time PCR revealed sulfuretin inhibited UVB-induced MMP-1 and -3 expressions in a dose-dependent manner. UVB-induced MAPK/NF-${\kappa}B$/p50 activation and MMP expression were completely blocked by pretreatment of sulfuretin. Taken together, sulfuretin could prevent UVB-induced MMP expressions through inhibition of MAPK/NF-${\kappa}B$/p50 activation.

• Biomolecules & Therapeutics
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• v.17 no.1
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• pp.43-46
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• 2009

The immunosuppressive properties of flavonoids were examined for the first time by testing their effects on T-cell-mediated antibody production, using a classical plague-forming cell (PFC) assay in mice. Among the tested flavonoids including naringenin, chrysin, flavonol, galangin, quercetin, morin, myricetin and biochanin A, only quercetin, orally administered at 25 mg/kg, significantly inhibited the number of IgMproducing PFCs induced by sheep red blood cells (SRBC). Interestingly, biochanin A (isoflavone) increased the number of PFCs, suggesting an immunostimulatory effect. The other flavonoids tested did not inhibit or enhance PFC response significantly. Quercetin was also found to show thymus atrophy dose-dependently at 5-500 mg/kg. All these results indicate that quercetin inhibits in vivo antibody production probably by inhibiting T-cell function.

• Proceedings of the KIEE Conference
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• 1990.07a
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• pp.177-179
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• 1990

Recently, it is reported that the behaviour of PECVD under high electric field and current condition has a major effect on MNS device degradation. In this paper, we evaluated the breakdown and TDDB characteristics of Laser assisted PECVD SiN films which is introduced new deposited method. And also, long term insulator breakdown reliability is described by examing time dependent dielectric breakdown under positive voltage. Failure tines against electric field are examined and acceleration factors are obtained for each case. From these data, breakdown wearout limitation for Laser Assisted PECVD SiN film can be characterized.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.1005-1009
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• 2002

The objective of this research is to suggest the noise prediction method of the centrifugal compressor. It is focused on the Blade Passing Frequency (BPF) component which is regarded as the main part of the rotating impeller noise. Euler solver is used to simulate the flow-field of the centrifugal compressor and time-dependent pressure data are calculated to perform the near-field noise prediction by Ffowcs Williams-Hawkings (FW-H) formulation. Indirect Boundary Element Method (IBEM) is applied to consider the noise propagation effect. Pressure fluctuations of the inlet and the outlet in the centrifugal compressor impeller are presented and Sound Pressure Level (SPL) prediction results are compared with the experimental data.

• Journal of the Optical Society of Korea
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• v.4 no.1
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• pp.48-53
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• 2000

In Optical Scanning Holography(OSH), 3-D holographic information of an object is generated by 2-D active optical scanning. The optical scanning beam can be a time-dependent Gaussian apodized Fresnel zone plate. In this technique, the holographic information manifests itself as an electric signal which can be sent to an electron-beam-addressed spatial light modulator for coherent image reconstruction. In this paper, we briefly review optical scanning holography and analyze the resolution achievable with the system. We also present mathmatical expressions of real and virtual images which are responsible for holographic image reconstruction. We then show the twin-image noise effect on the reconstruction in conjunction with the size of the Fresnel zone pattern through computer simulation.

• Korean Journal of Pharmacognosy
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• v.47 no.1
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• pp.38-42
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• 2016

Caragana sinica (Leguminosae) is a plant, which has been used as a traditional medicine for the treatment of lots of diseases including neuralgia, goat, hypertension and eczema. However, scientific studies of C. sinica in pharmacological aspects are not carried out. In this study, the anti-nociceptice effect of methanolic extract of C. sinica (MCS) was evaluated using various pain models. Our data represented that MCS significantly delayed the latency time under central pain condition which are arose from thermal stimuli, indicating MCS possess analgesic potential against central nociception. In addition, MCS showed strong and dose-dependent anti-nociceptive activities on acetic acid-induced peripheral pain, compared to positive control such as indomethacin. Further combination studies using naloxone, a non-selective opioid receptor antagonist, have revealed that analgesic activity of MCS was not changed in the presence of naloxone, indicating MCS exerts anti-nociceptive activity independent of opioid receptor. These results suggest that MCS may be an effective medicine in managing pain.