• YAKHAK HOEJI
• /
• v.49 no.1
• /
• pp.11-19
• /
• 2005

The root of Astragalus membranaceus (Leguminosae) has been used in traditional chinese prescriptions for strengthning the superficial resistance, promoting pus discharge and tissue regeneration, diuretis and alleviating edema. Lipid peroxidation has been suggested as a major cause of atherosclerosis, cancer, liver disease, and the aging process. In order to investigate the anti-lipid peroxidation activity, Astragali Radix was extracted with $80\%$ MeOH and fractionated with hexane, $CH_{2}Cl_2$, EtOAc, BuOH and Water. The antilipid peroxidation activities of them were determined by human erythrocyte ghost and $CCl_4$-induced lipid peroxidation. $CH_{2}Cl_2$ and EtOAc fractions, especially, isoflavonoids, 7,2'-dihydroxy-3',4'-dimethoxyisoflavan-7-O-${\beta}$-D-glucoside and calyco sin-7-O-${\beta}$-D-glucoside from EtOAc fraction showed anti-lipid peroxidation activities.

• The Transactions of the Korean Institute of Electrical Engineers
• /
• v.45 no.2
• /
• pp.289-293
• /
• 1996

The basic study on laser triggered lightning was carried out for the active protection of lightning in power transmission system. The lengths of generated plasma channels were simulated numerically for variations of energy and pulse width of CO$_{2}$ laser by Runge-Kutta-Gill method. As results, the effective lengths of plasma channels were 2.3m, 2.67m and 3.4m respectively for energy of 45J, 60J and 100J of CO$_{2}$ laser pulse with pulse width of 50nsec using focusing mirror with focal length of 10m. And also the effects of pulse width of first pulse and tail pulse of CO$_{2}$ laser on the length of plasma channel were examined.

• The Transactions of the Korean Institute of Electrical Engineers C
• /
• v.48 no.11
• /
• pp.724-729
• /
• 1999

We developed the correlated color temperature (CCT) control technique for electrodeless sulfur lamp (ESL) by adding a few milligrams of NaI into sulfur discharge bulb. Nal produces intense Na D-line that changes the CCT of the ESL. We can adjustthe CCT in the range of 8,400 K to 3,600 K. Color rendering index can be maintained between 79 and 90 for the adjustable range of the CCT. the NaI helps the ESL dischargeable at below 0.5 kW of forward microwave power into the bulb. We have shown that this technique did not cause reduction of luminance compared to electrodeless elemental sulfur lamp.

• Electrical & Electronic Materials
• /
• v.7 no.5
• /
• pp.409-416
• /
• 1994

A double layered photoreceptor using phthalocyanine dye was made by dip-coating method. The under cutting layer(UCL) was coated with A1$\_$2/O$\_$3/ or polyamide, and the charge generation layer(CGL) was formed by .tau.-type metal-free phthalocyanine. The oxadiazole was used as a charge transport layer(CTL) and polycarbonate and poly(vinyl butyral) was employed as a host polymer. The .tau.-H$\_$2/Pc had an absorption peak around 780nm, which coincided with the emitting wavelengths of GaAlAs diode lasers. Maximum charge acceptance of CTL that gives thickness of 12.mu.m was -900V by corona charge of -6.0kV. In photo-induced discharge measurements, residual potential was less than -20V and sufficient for ordinary use, and sample films using of poly(vinyl butyral) was showed good charge retention. In printing test, drum that was employed polycarbonate as a host polymer showed the good print quality.

• Journal of The Korean Society of Agricultural Engineers
• /
• v.54 no.5
• /
• pp.113-121
• /
• 2012

The study was carried out to investigate the dimension of irrigation canal, and measure the water flow of those diverted from Kimje main canal in Dongjin irrigation area. The rating curves indicating the relationships between water level and discharge of the lateral canals were induced using the measured data with high regression coefficients of 0.957~0.999 at inlet points and 0.932~0.998 at end points, respectively. And Manning's roughness coefficients were estimated as the ranged from 0.015 to 0.074 at inlet points and 0.056 to 0.089 at end points with rectangular type of concrete open irrigation canals, the Manning's roughness coefficients of the end points were less than those values of the end points, which may be considered as the deposition of the bottom sediments.

• Journal of the Optical Society of Korea
• /
• v.8 no.4
• /
• pp.188-191
• /
• 2004

A new laser Doppler velocimeter employing a $CO_2$ laser has been developed by using its photoacoustic effect. A change in the pressure of a discharge, induced by mixing of a returned wave with an originally existing wave inside the cavity, is employed to detect the Doppler frequency shift. We found that a Doppler frequency shift as small as 50 kHz was detected, and also a good linear relationship between the velocity and the Doppler frequency shift was obtained.

• Nuclear Engineering and Technology
• /
• v.53 no.1
• /
• pp.322-336
• /
• 2021

This paper presents a numerical prediction of the transient hydraulic loads acting on the tubes and external supports of a pressurized water reactor (PWR) steam generator (SG) during blowdown following a sudden feedwater line break (FWLB). A simplified SG model was used to easily demonstrate the prediction. The blowdown discharge flow was treated as a flashing flow to realistically simulate the transient flow fields inside the SG and the connected broken feedwater pipe. The effects of the SG initial pressure or the broken feedwater pipe length on the intensities or magnitudes of transient hydraulic loads were investigated. Then predictions of the decompression pressure wave-induced impulsive pressure differential loads on SG tubes and the transient blowdown loads on SG external supports were demonstrated and the general aspects of transient responses of such transient hydraulic loads to the FWLB were discussed.

• Korean Journal of Veterinary Research
• /
• v.28 no.1
• /
• pp.203-211
• /
• 1988

The present study was carried out to investigate the estrous behavior and vaginal smear after induction of estrus with exogenous hormones in the premature, metestrous and anestrous bitches. A total of 21 bitches(Mixed breed: 16, Jindo breed: 5), from 10 months to 5 years of age and weighing 8 to 15 kg was studied the change of vaginal smear and the estrous behavior before and after induction of estrus. The results obtained are as follows: 1. In the treatment A(They were given the $PGF_2{\alpha}$, estrone, estradiol-$17{\beta}$, PMSG and HCG) proestrus commenced in $10.16{\pm}1.44$($Mean{\pm}SEM$) days after treatment, The mean duration of proestrus, and estrus was $7.50{\pm}1.44$ and $13.50{\pm}3.44$ days, respectively. In the treatment B(They were given the PMSG and HCG) proestrus commenced in $5.53{\pm}0.59$ days after treatment. The mean duration of proestrus and estrus was $6.60{\pm}0.71$ and $14.60{\pm}1.14$ days, respectively. 2. All of the 6 bitches in the treatment A showed vulval swelling and vaginal discharge, 14 of the 15 bitches in the treatment B showed vulval swelling and vaginal discharge. However, all of the treatment A and B showed male acceptance. 3. The main change of vaginal smear in proestrus and estrus after induction of estrus was a increase in the proportion of anuclear and superficial cells associated with a decrease in small intermediate and parabasal cells. By the estrous behavior and vaginal smear the estrus was induced in all the premature, metestrous and anestrous bitches.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.6 no.1
• /
• pp.40-50
• /
• 1994

For an accurate prediction of the temperature field induced by heated water discharged into a shallow crossflow, a two-dimensional near-field numerical model is developed. It is based on a 4-equation turbulence model in which the transport equations for mean of the temperature fluctuation squared and its dissipation rate are added to those of a 2-equation turbulence model which cannot give the information of the thermal time scale ratio. Vertical diffusion is also considered by including buoyancy production and turbulence heat flux terms. The developed model is applied to a steady flow in an open channel with simple geometry and the results are compared with existing experimental data and those of the already established 2-equation turbulence model. Numerical results of the model agree with the experimental data better than those of the 2-equation model. The present model also simulates quite adequately the physical characteristics of thermal discharge in the jet entrainment and stable regions.

• Korean Journal of Materials Research
• /
• v.22 no.3
• /
• pp.118-122
• /
• 2012

We synthesized porous $Co_3O_4/RuO_2$ composite using the soft template method. Cetyl trimethyl ammonium bromide (CTAB) was used to make micell as a cation surfactant. The precipitation of cobalt ion and ruthenium ion for making porosity in particles was induced by $OH^-$ ion. The porous $Co_3O_4/RuO_2$ composite was completely synthesiszed after anealing until $250^{\circ}C$ at $3^{\circ}C$/min. From the XRD ananysis, we were able to determine that the porous $Co_3O_4$/RuO2 composite was comprised of nanoparticles with low crystallinity. The shape or structure of the porous $Co_3O_4/RuO_2$ composite was studied by FE-SEM and FE-TEM. The size of the porous $Co_3O_4/RuO_2$ composite was 20~40 nm. From the FE-TEM, we were able to determine that porous cavities were formed in the composite particles. The electrochemical performance of the porous $Co_3O_4/RuO_2$ composite was measured by CV and charge-discharge methods. The specific capacitances, determined through cyclic voltammetry (CV) measurement, were ~51, ~47, ~42, and ~33 F/g at 5, 10, 20, and 50 mV/sec scan rates, respectively. The specific capacitance through charge-discharge measurement was ~63 F/g in the range of 0.0~1.0 V cutoff voltage and 50 mAh/g current density.