• Journal of Radiation Protection and Research
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• 제35권3호
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• pp.117-123
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• 2010

Pu 동위원소는 기원에 따라 각기 다른 $^{240}Pu/^{239}Pu$ 동위원소비를 나타내는 특성이 있다. 질량분석법은 극미량 장반감기핵종 분석에 매우 유용한 방법으로서 검출기 특성상 낮은 검출한계를 갖고 있으며, 소량의 시료를 이용하여 짧은 시간에 측정을 할 수 있다는 장점을 갖고 있으므로 Pu을 비롯한 장반감기 핵종 분석에 유용하다. 다중검출기유도결합플라즈마질량분석기(Multicollector ICP-MS)는 다중검출시스템을 이용하여 분석하고자 하는 여러 핵종의 동시분석이 가능하며, 특별히 본 연구에서는 극미량 핵종의 검출이 가능한 multiple ion counter (MIC)를 사용하여 Pu 동위원소 분석에 적용하였다. 본 연구방법의 검출한계(detection limit)는 최적화된 조건에서 $^{239}Pu$와 $^{240}Pu$ 각각 $0.10\;fg\;ml^{-1}$ ($0.24\;{\mu}Bq\;ml^{-1}$), $0.12\;fg\;ml^{-1}$ ($0.97\;{\mu}Bq\;ml^{-1}$)이었으며, 240Pu 기준으로 약 200 cps 정도의 매우 낮은 농도수준에서 1%이하의 $^{240}Pu/^{239}Pu$ 동위원소비 계측편차를 나타내었다. 본 연구방법은 표준용액 및 다양한 매트릭스의 표준물질 분석에 적용함으로써 검증 확인하였다.

• Journal of Radiation Protection and Research
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• 제27권2호
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• pp.101-110
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• 2002

한국 주변 연안 15개 정점의 퇴적물(0-20 cm)에서 $^{137}Cs,\;^{90}Sr\;^{239-240}Pu$의 농도와 농도 비를 조사했다. $^{137}Cs,\;^{90}Sr\;^{238}Pu$ 및 $^{239-240}Pu$의 평균 방사능 농도는 각각 $2.24{\pm0.79\;Bq{\cdot}kg^{-1}-dry,\;0.20{\pm}0.04 Bq{\cdot}kg^{-1}-dry,\;0.009{\pm}0.005\;Bq{\cdot}kg^{-1}-dry}$ 및 $0.27{\pm}0.17\;Bq{\cdot}kg^{-1}-dry$ 이다. $^{137}Cs,\;^{90}Sr$, $^{239-240}Pu/^{137}Cs$ 및 $^{238}Pu/^{239-240}Pu$의 평균 농도 비와 $^{239}Pu/^{240}Pu$의 평균 원자 비는 각각 $11.2{\pm}2.9,\;0.123{\pm}0.053,\;0.033{\pm}0.016$ 및 $0.218{\pm}0.036$이다. 퇴적물에서 핵종의 농도 범위와 핵종간의 농도 비는 그 동안 주변국가의 퇴적물에서 조사한 값과 비슷하였다. 퇴적물에서 $^{137}Cs$ 과 $^{239-240}Pu$의 상관계수는 0.80 이다. $^{137}Cs$과 SOM, $^{239-240}Pu$과 점토 함량과의 상관계수는 각각 0.69, 0.67 이다.

• 대한의생명과학회지
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• 제24권3호
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• pp.175-182
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• 2018

Aspergillosis is a life-threatening disease in individuals with compromised immune systems. Fungal invasion is a highly critical process during host cellular infection. Several papers have reported that transcription factors are responsible for the infection process. To investigate what transcription factors are involved in the process in an effort to inhibit fungal infection into cells, I checked the surfactant protein family and PU.1 transcription factor levels in A549 cells infected with A. fumigatus conidia. PU.1 and surfactant protein-D levels were reduced in cells infected with fungal conidia. I then observed an increase in surfactant protein-D on PU.1-overexpressed cells. Infection of A. fumigatus conidia was decreased in PU.1-overexpressed cells, whereas the suppression of PU.1 did not lead to any changes in cases of A. fumigatus conidia infection. These results indicate that PU.1 inhibits the infection of A. fumigatus conidia via the expression of surfactant protein-D, suggesting that PU.1 is a key transcription factor for protection against A. fumigatus invasion.

• 한국대기환경학회지
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• 제15권2호
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• pp.79-87
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• 1999

$^{239+240}Pu$ concentrations in precipitation were determined for the period of May 1994 to August 1996 in oder to describe current $^{239+240}Pu$ deposition at the mid-western coat of Korea (Ansan, 37$^{\circ}$17'N, $126^{\circ}$50'E). $^{239+240}Pu$ concentration in daily precipitation varied from 0.05 to 131$\mu$Bq $kg^{-1}$ with a geometric mean of $1.26\mu$Bq $kg^{-1}$. The concentration was high in the period of Yellow Sand Storm in spring and low in wet summer monsoon. The specific $^{239+240}Pu$ concentration in daily precipitation appears to be controlled by the $^{239+240}Pu$ input to the atmosphere in spring and washout effects by precipitation in the wet summer monsoon. Wet depositional flux of $^{239+240}Pu$ varied from 4 to 123$\mu$Bq $m^{-2}d^{-1}$ with a geometric mean of $33.8\mu$Bq $m^{-2}d^{-1}$ and with a maximum in the period of Yellow Sand Storm and a minimum in the period of wet summer monsoon. $^{238}Pu$/$^{239+240}Pu$ activity raios(0.04~0.31) in precipitation for March-June period suggested that one of the major sources of Pu isotopes falling in Ansan area is the arid region of the Chinese continent.

• Environmental Engineering Research
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• 제11권1호
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• pp.1-13
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• 2006

In this study, conventional biofilters packed with flexible synthetic polyurethane (PU) foam carriers were operated to remove toluene from a contaminated air stream. PU foams containing various adsorbents (e.g., zeolite, sepiolite, dolomite and barite) were synthesized for the biofilter media and their adsorption characteristics of toluene were determined. Adsorption capacity of PU-adsorbent foam was in the order of PU-dolomite ${\approx}$ PU-zeolite > PU-sepiolite > PU-barite. During the biofiltration experiment, influent toluene concentration was in the range of 0-160 ppm and EBRT (i.e., empty bed residence time) was 45 seconds. Pressure drop of the biofilter bed was 4-5 mm $H_2O/m$ column height. The maximum removal capacity was in the order of PU-dolomite > PU-zeolite > PU-sepiolite > PU-barite, while the complete removal capacity was in the order of PU-dolomite > PU-sepiolite > PU-zeolite > PU-barite. The better biofiltration performance in PU-dolomite foam was because PU-dolomite foam had lower density and higher porosity than the others providing favorable conditions for microbial growth. The results of biodegradation kinetic analysis showed that PU-dolomite foam had higher maximum removal rate ($V_m\;=\;11.04\;g$ toluene/kg dry material/day) and saturation constant ($K_s\;=\;26.57\;ppm$) than the other PU foams. This supports that PU-dolomite foam was better than the others for biofilteration of toluene.

• 방사성폐기물학회지
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• 제4권1호
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• pp.1-7
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• 2006

염산매질에서 산화/환원제를 사용하여 Pu 산화수를 조절한 후, UV-Visible-Near IR 분광기를 이용하여 Pu(III, IV, V, VI) 산화수에 대한 흡수스펙트럼을 측정하여 그 분광학적 특성을 고찰하였다. Pu(III)으로 조절하기 위하여 환원제인 $NH_2OH$ HCl를 사용하였으며, Pu(IV)와 Pu(VI)로 조절하기 위하여 산화제인 $NaNO_2$ 및 $HClO_4$를 각각 사용하였다. 또한 Pu(VI)로 조절된 용액에 환원제인 $NH_2OH$ HCl를 사용하여 Pu(V)로 조절하였다. Pu(III)와 Pu(IV)의 대표적인 흡수피크는 470 nm 및 600 nm에서 각각 관찰되었고, Pu(VI)와 Pu(V)의 특성피크는 830 nm 및 1135nm에서 각각 관찰되었다. Pu(III, IV, VI) 산화상태의 시간 경과에 따른 흡수스펙트럼 변화는 관찰되지 않았으나 Pu(V)의 경우 매우 불안정하여 생성되자 마자 Pu(III)로 변화되었다.

• 분석과학
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• 제19권1호
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• pp.18-30
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• 2006

This paper describes the cumulative deposition of fallout Pu in soil and lichen at the present time and give the characteristics of fallout Pu deposits in the soil. In the soil of the forest, the accumulated depositions of $^{239,240}Pu$ were estimated to be in the range of 34.0 to $101.2Bq\;m^{-2}$ with an average value of $65.3{\pm}21.6Bq\;m^{-2}$. The average inventory of $^{239,240}Pu$ in the forest was calculated to be two times higher than that in the hill. Also, the deposited activities of $^{239,240}Pu$ in cultivated soil were significantly lower than those in the hill or forest. However, the cumulative depositions of fallout Pu in the volcanic ash soil on Cheju Island were much higher than those in the forest and hill soils. The measured activity concentrations of Pu isotopes in lichens and mosses showed large variations, due to characteristics of species and life span of lichen and moss colonies. From depth profiles, it was found that most of the fallout Pu has been accumulated in upper 10 cm layer of soil. Except for a few cases, the concentrations of $^{239,240}Pu$ in soil tended to decrease exponentially with increasing soil depth. Among parameters affecting the cumulative deposition of fallout Pu, organic substances and rainfall play an important role in the retention and relative mobility of fallout Pu in the soil. However, pH showed a weak correlation with the deposition of fallout Pu in the soil. From sequential leaching experiments, Pu was found to be associated predominantly with the "organic" and "oxy-hydroxy" fractions. Both the activity ratios of $^{238}Pu/^{239,240}Pu$ and $^{241}Pu/^{239,240}Pu$ in soils, lichens and mosses and the atomic ratios of $^{240}Pu/^{239}Pu$ in soils are close to those observed in the cumulative deposit global fallout from nuclear weapon testings. The results obtained from this research make it possible to interpret and predict the behavior of fallout Pu under natural conditions.

• 한국결정성장학회지
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• 제28권1호
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• pp.1-8
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• 2018

The 23 wt% polyvinylidene fluoride (PVDF)/15 wt% polyurethane (PU) fibers were electrospun using the conjugated nozzle at a flow rate of 1.0 mL/h and an electric field of 1 kV/cm. The formation of ${\beta}$ crystal phase in the PVDF and the PVDF/PU fibers was confirmed by Fourier transform infrared spectroscopy. After electrospinning, the asspun fibers were immersed in a boiling water and then dried at $100^{\circ}C$ in a convection oven to make a crimp phenomenon. The crimps with a diameter of $2.0{\pm}0.08{\mu}m$ were observed for the PVDF/PU fibers after hydrothermal treatment without sacrificing the extent of ${\beta}$ crystal phase. All the PU, PVDF and PVDF/PU fibers exhibited average cell viability of more than 98 %. The cell proliferation results suggested that L-929 cells adhered well to the PU, PVDF and PVDF/PU fibers and proliferated continuously with increasing time, indicating that the PVDF/PU fibers are highly applicable to the biomedical applications.

• 한국염색가공학회지
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• 제20권5호
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• pp.35-40
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• 2008

Dyeing and washing fastness properties of polyurethane-impregnated polyester (PU-impregnated PET), and the distribution of two disperse dyes between PET and PU film were studied to investigate the effect of PU portion to exhaustion and washing fastness. Dyeing properties of PU-impregnated PET were quite different with those of PET: PU-impregnated PET absorbed disperse dye linearly from the early stage of dyeing to equilibrium, and it exhibited excellent build-up property up to 4 %owf dyeing. The absorbed dye on PU film at early dyeing stage migrated to more substantive PET at the temperature higher than $115^{\circ}C$. The amount of exhausted dye on PET portion was larger than on PU film and the distribution ratio was $2.08{\sim}2.34$. The grade of washing fastness of PU-impregnated PET was the same as or lower by $0.5{\sim}1$ grade than PU film whose washing fastness was lower by $0.5{\sim}1$ than PET.

• 한국해양환경ㆍ에너지학회지
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• 제4권1호
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• pp.3-13
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• 2001

황해의 주요 인공방사성 핵종인 /sup 137/Cs, /sup 239.240/Pu, /sup 238/Pu, /sup 90/Sr의 분포 특성을 규명하기 위하여, 동계 및 춘계의 해양 관측을 실시하여 시료를 채집하였다. 표층 시료 (100리터)는 양수 펌프를 이용하였고, 10m 이하 수심에서는 대용량 해수채수기를 이용하였다. 표층수의 인공방사성 핵종들의 농도 범위는 /sup 137/Cs이 1.78～3.38 mBq kg/sup -l/, /sup 239.240/Pu은 2.17～13.35 μBq kg/sup -l/, /sup 90/Sr이 1.97～3.96 mBq kg/sup -1/이었다. /sup 239.240/Pu의 경우 양자강 하구 인접 해역 (61～83 μBq kg/sup -1/)에 비해서 약 1/10 수준으로 낮았다. 표ㆍ저층수간에 수직별 /sup 239.240/Pu 농도는 3.0 μBq kg/sup -1/ 이내로 작다. 이것은 수심이 얕고, 입자성부유물질 농도가 상대적으로 높은 황해의 경우 /sup 239.240/Pu이 스카벤징에 의해 가라앉아 해저퇴적물에 빨리 축적되기 때문이다. 대기낙진 형태로 입력된 /sup 239.240/Pu중 약 0.7～0.9 % 정도만 해수에 머무른다. 인공방사성 핵종 비는 /sup 239.240/Pu//sup 137/Cs 및 /sup 137/Cs//sup 90/Sr 비는 각각 0.001-0.005, 0.79～l.65 범위로서, 대기경로가 인공방사성핵종의 유일한 공급원인 대양과 유사함으로서, 환해 해수의 인공방사성 핵종 기원은 대기 낙진이 우세함을 가리킨다.