• Korean Journal of Materials Research
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• v.5 no.2
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• pp.151-156
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• 1995

Low temperature firing $(Ba, Sr)TiO_{3}$ dielectrics were successfully prepared with lead based glass and those electrical properties were investigated. Different amount of PbO content glass materials were added to dielectrics to investigate the sinterability and its dielectric properties. Also, various compositions of ceramic capacitors were prepared to applicate in multilayer ceramic capacitors. A large amount of experiment has been done with various Pb contented glasses and different sintering temperatures. The sintering temperature of $(Ba,Sr)TiO_{3}$can be reduced from $1350^{\circ}C$to as low as $1050^{\circ}C$ with 4wt% addition of $PbO-ZnO-B_{2}O_{2}$ glass materials. Its dielectric constant at room temperature was up to 8100 with low dielectric loss, 0.005. This ceramic capacitor showed fully fired microstructures with its grain size of 1-3$\mu \textrm{m}$. The sintered body which was sintered at $1150^{\circ}C$ for 2hr with 4wt% $PbO-ZnO-B_{2}O_{2}$ glass material addition satisfied the Z5U specification of the EIAS.

• Applied Chemistry for Engineering
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• v.7 no.6
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• pp.1125-1131
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• 1996

Ca or Sr-doped $PrMnO_3$ were prepared for cathode material of solid oxide fuel cell. The characteristics such as the electrical conductivity and the cathodic overpotential were investigated as to doping contents. Also the reactivity with yttria stabilized zirconia of electrolyte, and the thermal expansion coefficient were studied. The prepared perovskite powder had the mean particle size of $2{\sim}5{\mu}m$, and the particle size and the surface area was out of relation to the doping content. When Ca doping amount of electrode material was 30mol%, the electrical conductivity was the highest value of $266S{\cdot}cm^{-1}$ at $1000^{\circ}C$, and also the polarization characteristics showed the best property. The reactivity between YSZ and Ca-doped $PrMnO_3$ at $1200^{\circ}C$ for 100hours was lower than that between YSZ and Sr-doped $PrMnO_3$. The thermal expansion coefficient of $Pr_{0.7}Ca_{0.3}MnO_3$ was $1.19{\times}10^{-5}K^{-1}$ in the temperature range of $300{\sim}1000^{\circ}C$, and this value was similar to that of YSZ, $1.15{\times}10^{-5}K^{-1}$.

• Journal of Radiation Protection and Research
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• v.14 no.1
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• pp.16-23
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• 1989

To obtain the basic data for protective roles and first-aid of radiation hazard, the present studies were carried out to evaluate the decontamination of radiostrontium by the First-Aid drugs. Each mouse was administered intraperitoneally dose of sodium alginate 5mg, $CaNa_3DTPA$ 8.4mg and saline 5ml following the internal contamination with 1 $\mu$Ci of strontium as $^{85}SrCl_2$. $^{85}Sr$ was determined by the radioactivity of body burden, urinary excretion, fecal excretion and organ distribution by Ge-detector and MCA. The results are summarized as follows. 1. Effective half life on whole body retention $^{85}Sr$ was determined at 33 hours. 2. The decontamination effect of First-Aid durgs on the body $^{85}Sr$ burden were increased $CaNa_3DTPA$ (4.7 times), sodium alginate (1.7 times) and saline (2.4 times) respectively. 3. Strontium were excreted through urine (35.4%), feces (64.4%) and other (0.2%). But on the $^{85}Sr$ excretion routes following First-Aid drugs treatment, strontium-85 mainly were excreted through urine after $CaNa_3DTPA$ and saline treatment, and was excreted through feces after sodium alginate treatment. 4. The organ distribution of strontium-85 is vertebra, femur, sternum and liver in order Finally, the extrapolations from these data to victims were suggested that the rapid administration of $CaNa_3DTPA$, sodium alginate and saline simultaneously were markedly increased the decontamination effects on the internal contamination of radiostrontium.

• Publications of The Korean Astronomical Society
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• v.27 no.4
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• pp.353-356
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• 2012

We present new constraints on the cosmic optical background (COB) obtained from an analysis of the Pioneer 10/11 Imaging Photopolarimeter (IPP) data. After careful examination of the data quality, the usable measurements free from the zodiacal light are integrated into sky maps at the blue (${\sim}0.44{\mu}m$) and red (${\sim}0.64{\mu}m$) bands. Accurate starlight subtraction was achieved by referring to all-sky star catalogs and a Galactic stellar population synthesis model down to 32.0 mag. We find that the residual light is separated into two components: one component shows a clear correlation with the thermal $100{\mu}m$ brightness, whilst the other shows a constant level in the lowest $100{\mu}m$ brightness region. The presence of the second component is significant after all the uncertainties and possible residual light in the Galaxy are taken into account, thus it most likely has an extragalactic origin (i.e., the COB). The derived COB brightness is ($(1.8{\pm}0.9){\times}10^{-9}$ and $(1.2{\pm}0.9){\times}10^{-9}\;erg\;s^{-1}\;cm^{-2}\;sr^{-1}\;{\AA}^{-1}$ in the blue and red spectral regions, respectively, or $7.9{\pm}4.0$ and $7.7{\pm}5.8\;nW\;m^{-2}\;sr^{-1}$. Based on a comparison with the integrated brightness of galaxies, we conclude that the bulk of the COB is comprised of normal galaxies which have already been resolved by the current deepest observations. There seems to be little room for contributions from other populations including "first stars" at these wavelengths. On the other hand, the first component of the IPP residual light represents the diffuse Galactic light (DGL)-scattered starlight by the interstellar dust. We derive the mean DGL-to-$100{\mu}m$ brightness ratios of $2.1{\times}10^{-3}$ and $4.6{\times}10^{-3}$ at the two bands, which are roughly consistent with previous observations toward denser dust regions. Extended red emission in the diffuse interstellar medium is also confirmed.

• The Bulletin of The Korean Astronomical Society
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• v.36 no.2
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• pp.117.1-117.1
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• 2011

We present the smoothness of mid-infrared sky brightness from the Japanese infrared astronomical satellite, AKARI observations. AKARI monitored the north ecliptic pole (NEP) during its cold phase with nine wavebands from 2.4 to 24 ${\mu}m$, out of which six mid-infrared bands are used in this study. Simple sinusoidal fit to the seasonal variation of the sky brightness shows that the mid-infrared brightness towards the NEP is not affected by small-scale features of the interplanetary dust cloud. We applied the power spectrum analysis to the images to search for the fluctuation of sky brightness. The fluctuation powers at 200 arcsecond are estimated to be at most $1.58{\pm}0.33\;nW\;m^{-2}sr^{-1}$ or 0.13% of the total brightness at $7{\mu}m$ and a tleast $0.64{\pm}0.11\;nW\;m^{-2}sr^{-1}$ or 0.02% at $18{\mu}m$. The residual fluctuations at a few arcminute scales at short mid-infrared wavelengths (7, 9, and 11 ${\mu}m$) are consistent with those expected from the diffuse galactic light. At long mid-infrared wavelengths (15, 18, and 24 ${\mu}m$) the measured fluctuations are comparable to or smaller than the one caused by photon noise and their sources are not identified. We conclude that the upper limit of the fluctuation in the zodiacal light is about 0.02% of the sky brightness.

• The Korean Journal of Nuclear Medicine
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• v.27 no.1
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• pp.130-134
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• 1993

Radiostrontium is one of fallouts. It can be absorbed through intestine and causing radiation injury to bones. The purpose of this study is to evaluate the inhibitory effect of 10% chitosan (water soluble and insoluble) and 10% alginate (water soluble and insoluble) on radiostrontium adsorption. Water soluble and insoluble chitosans and alginates were given to 10 NIH male mice in each group for 7 days. At the 7th day, 74 MBq of $^{85}Sr$ were given through orogastric tube. Chitosans and alginates were given for additional 7 days. During the 7 days, radioactivities of feces were counted daily. Finally animals were sacrificed, and radioactivities of bones were counted. Fecal excretion was significantly higher in chitosan and alginate group as compared to control from the 1st day (p < 0.01). Water soluble chitosan group showed highest fecal excretion. Bony retention was significantly lower in the treated group than the control (p < 0.01). There was no difference among treated groups. In conclusion, both water soluble and insoluble chitosans and alginates were effective agents on lowering orally ingested radiostrontium ($^{85}Sr$).

• 대한핵의학회:학술대회논문집
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• 1997.05a
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• pp.158-158
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• 1997

• Journal of the Optical Society of Korea
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• v.14 no.3
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• pp.215-220
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• 2010

Aerosol observation with Raman LIDAR in NIES (National Institute for Environmental Studies, Japan) LIDAR network was conducted from 17 April to 12 June 2008 over Beijing, China. The aerosol optical properties derived from Raman LIDAR were compared with the retrieved data from sun photometer and sky radiometer observations in the Aerosol Robotic Network (AERONET). The comparison provided the complete knowledge of aerosol optical and physical properties in Beijing, especially in pollution and Asian dust events. The averaged aerosol optical depth (AOD) at 675 nm was 0.81 and the Angstrom exponent between 440 nm and 675 nm was 0.99 during experiment. The LIDAR derived AOD at 532 nm in the planetary boundary layer (PBL) was 0.48, which implied that half of the total AOD was contributed by the aerosol in PBL. The corresponding averaged LIDAR ratio and total depolarization ratio (TDR) were 48.5sr and 8.1%. The negative correlation between LIDAR ratio and TDR indicated the LIDAR ratio decreased with aerosol size because of the high TDR associated with nonspherical and large aerosols. The typical volume size distribution of the aerosol clearly demonstrated that the coarse mode radius located near 3 ${\mu}m$ in dust case, a bi-mode with fine particle centered at 0.2 ${\mu}m$ and coarse particle at 2 ${\mu}m$ was the characteristic size distribution in the pollution and clean cases. The different size distributions of aerosol resulted in its different optical properties. The retrieved LIDAR ratio and TDR were 41.1sr and 19.5% for a dust event, 53.8sr and 6.6% for a pollution event as well as 57.3sr and 7.2% for a clean event. In conjunction with the observed surface wind field near the LIDAR site, most of the pollution aerosols were produced locally or transported from the southeast of Beijing, whereas the dust aerosols associated with the clean air mass were transported by the northwesterly or southwesterly winds.

• Journal of Technologic Dentistry
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• v.20 no.1
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• pp.51-60
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• 1998

The artificial resin teeth used for removable prosthesis have good physical properties, but they have great wear rate. The purpose of this study is to compare the wear characteristics of several artificial resin teeth, such as Myerson teeth(Myerson Crop), Trubite IPN(Dentsply), Endura Posterio(Shofu), SROrthosit(Ivoclar), Trubite Biotone(Dentsply), Five samples of each resin tooth were abraded against natural teeth, type III gold for 150,000 cycles on the wear machine. The results obtained were as follow 1. The wear rate of artificial resin teeth when opposing enamel was the lowest in Myerson teeth($8.60{\mu}m$), followed by Trubite IPN($41.30{\mu}m$), Endure poster($63.00{\mu}m$), SR-Orthosit($68.40{\mu}m$), Trubite Biotone($209.90{\mu}m$) 2. The wear rate of artificial teeth when opposting type III gold specimens was the lowest in Myerson teeth($13.50{\mu}m$) followed by Endura Posterio($14.75{\mu}m$), Trubite IPN($53.40{\mu}m$), SROrthosit($54.20{\mu}m$), Trubite Boitone($341.50{\mu}m$)

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.10 no.1
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• pp.92-99
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• 2005

To discriminate the provenance of shelf sediments in the East China Sea, textural and elemental compositions along with strontium isotopic ratio ($^{87}Sr/^{86}Sr$) were analyzed and compared with the sediments originated from Chinese rivers. The sediments in the study area are composed of fine-grained mud with a mean grain size of $47\;{\phi}$ and their $CaCO_3$, contents range from 3.9 to 11.5% (average 7.6%). In the study area, the content of most metallic elements are strongly constrained by sediment grain size (quartz dilution effect) and that of biogenic material and, thereby, their spatial distribution seems not enough for understanding sediment provenance in the study area. The muddy sediments of the Yangtze river have much lower $^{87}Sr/^{86}Sr$ ratio ($0.71197{\sim}0.71720$) than the Yellow Sea shelf muddy sediments which are supposed to be originated from the Huanghe river ($0.72126{\sim}0.72498$), suggesting the distribution pattern of $^{87}Sr/^{86}Sr$ ratios as a new tracer to discriminate the provenance of shelf sediments in the study area. Different source rock compositions and weathering processes between both drainage basins may account for the differences in $^{87}Sr/^{86}Sr$ ratio. Although the ratios show wide range, from 0.71445 to 0.72184 with an average 0.71747 in the study area, they are close to the values of the Yangtze river sediments, suggesting that the sediments were mainly originated from the Yangtze river. The previous studies on the dispersal pattern of modern sediments and the physico-chemical properties of seawater in the Yellow and East China seas support the possibility that the fine-grained Yangtze river sediments can reach to the East China Sea shelf as well as to the southeastern Yellow Sea.