• 한국구조물진단유지관리공학회 논문집
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• 제15권5호
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• pp.218-226
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• 2011

본 연구에서는 스트론튬계 잠열재를 사용한 저발열 콘크리트를 레미콘 배처플랜트에서 시험생산한 후 생산된 콘크리트의 기초성능 및 모의부재에 의한 수화온도 특성을 평가하였으며, 그 결과 스트론튬계 잠열재를 사용한 저발열 콘크리트의 현장적용 가능성을 확인하였다. 이후 스트론튬계 잠열재를 사용한 콘크리트를 실제 교각 건설현장에 적용하였으며, 적용부재에 대한 수화열 해석 및 타설 콘크리트의 성능평가 결과 수화열 및 온도균열 저감효과가 우수한 것으로 나타나, 향후 대형 매스콘크리트의 수화열 및 온도균열 저감대책으로서 활용이 기대된다.

• Nuclear Engineering and Technology
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• 제3권1호
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• pp.9-13
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• 1971

방사성 낙진에 의한 우리나라 식품의 오염도를 파악할 목적으로 우리나라의 우유중의 스트론튬-90의 양을 측정하였다. 스트론튬의 분석은 발연질산법에 의하였으며, 스트론튬 단위로 결과를 정리하기 위하여 칼슘의 함량도 동시에 정량하였다. 방사능의 측정은 $^{90}$ Sr＋$^{90}$ Y의 방사평형이 이루어진 후에 $^{90}$ Y의 방사능을 측정하였다. 액체 우유의 스트론튬-90의 함량이 가장 많았던 것은 1966년의 34.9 pCi$^{90}$ Sr/g.Ca이었으며, 1966년을 고비로 현저한 감소를 보여주고 있다. 분유의 스트론튬-90의 함량은 액체 우유와 같은 값을 보여 주고 있으며, 방사선 장해면에서 고려할때 안전한 함량임을 알 수 있다.

• 방사성폐기물학회지
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• 제18권4호
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• pp.421-437
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• 2020

This study provides an assessment on a proposed method for separation of cesium, strontium, and barium using electrochemical reduction at a liquid bismuth cathode in LiCl-KCl eutectic salt, investigated via cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and scanning electron microscopy with energy dispersive X-ray spectrometry (SEM-EDS). CV studies were performed at temperatures of 723-823 K and concentrations of the target species up to 4.0wt%. Redox reactions occurring during potential sweeps were observed. Concentration of BaCl2 in the salt did not seem to influence the diffusivity in the studied concentration range up to 4.0wt%. The presence of strontium in the system affected the redox reaction of lithium; however, there were no distinguishable redox peaks that could be measured. Impedance spectra obtained from EIS methods were used to calculate the exchange current densities of the electroactive active redox couple at the bismuth cathode. Results show the rate-controlling step in deposition to be the mass transport of Cs+ ions from the bulk salt to the cathode surface layer. Results from SEM-EDS suggest that Cs-Bi and Sr-Bi intermetallics from LiCl-KCl salt are not thermodynamically favorable.

• 한국환경보건학회지
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• 제20권3호
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• pp.61-77
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• 1994

Sprague Dawley rats were exposed to electric fields (6,000 V, 10 kV/m, 30 min/day, 6 days per week) and injected strontium 90 (681 kbq/rat, one time) through abdominal cavity (strontium 90 and electric field complexed exposure group). In parallel, series with the electric field exposure only, strontium 90 injection only and control groups were run. Every group was consisted of 110 rats (55 male and 55 female). This animal experiment was performed from May to December in 1993. This results were conducted to investigate the effect of electric field for 11 weeks. The results are summarized as follows: 1. Ornithine decarboxylase (ODC) activity in rat's bone marrow cells: The ODC values was significantly increased in Sr$^{90}$ injection group and Sr$^{90}$ and electric field complexed exposure group as compared with that of control group (p<0.05). The ODC value was significantly decreased in electric field and Sr$^{90}$ complexed exposure group in comparison with Sr$^{90}$ injection group (p<0.05). The ODC values of electric field only exposure group was not different to that of control group (p>0.05). 2. The amount of Sr$^{90}$ accumulation in the femur, kidney and spleen:The accumulation amount of Sr$^{90}$ in the femur of Sr$^{90}$ injection group represented higher value than that of electric field and Sr$^{90}$ complexed exposure group (p<0.05). In the kidney and spleen, the difference between electric field and Sr$^{90}$ complexed exposure group and Sr$^{90}$ injection group wasn't observed. 3. The counts of white cells in blood of Sr9?injection group was decreased as compared with the value from control group and electric field and Sr$^{90}$ complexed exposure group (p<0.05). The rat's body weight, red blood cell counts and the weight data of liver, kidney and spleen did not show differences among four groups.

• 한국전기전자재료학회논문지
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• 제19권2호
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• pp.145-152
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• 2006

The densification behavior and electrical conductivity of $Ce_{0.8}Gd_{0.2}O_{1.9}$ ceramics were investigated with the strontium gallate concentration ranging from 0 to $5\;mol\%$. Both the sintered density and grain size were found to increase rapidly up to $0.5\;mol\%$ $Sr_2Ga_2O_5$, and then to decrease with further addition. Dense $Ce_{0.8}Gd_{0.2}O_{1.9}$ ceramics with $97\%$ of the theoretical density could be obtained for $0.5\;mol\%$ $Sr_2Ga_2O_5$-added specimen sintered at $1250^{\circ}C$ for 5 h, whereas pure $Ce_{0.8}Gd_{0.2}O_{1.9}$ ceramics needed to be sintered at $1550^{\circ}C$ in order to obtain an equivalent theoretical density, Electrical conductivity was measured as a function of dopant content, over the temperature range of $350\;-\;600^{\circ}C$ in air. Total conductivity of $0.5\;mol\%$ $Sr_2Ga_2O_5$-added specimen showed the maximum conductivity of $2.37{\times}10^{-2}{{\Omega}-1}{\cdot}cm^{-1}$ at $500^{\circ}C$, The addition of strontium gallate was found to promote the sintering properties and electrical conductivities of $Gd_2O_3$-doped $CeO_2$.

• Bulletin of the Korean Chemical Society
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• 제26권5호
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• pp.786-790
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• 2005

A new ternary strontium germanium nitride, ${\beta}-Sr_2GeN_2$, was obtained as single crystal from constituent elements in molten Na. It crystallizes in space group Cmca (No. 64) with a = 5.441(1) $\AA$, b = 11.377(2) $\AA$, c = 12.229(2) $\AA$, and Z = 8. Its crystal structure is closely related to that of polymorphic companion, ${\alpha}-Sr_2GeN_2$, both of which contain isolated bent anions of ${GeN_2}^{4-}$.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2003년도 추계학술발표강연 및 논문개요집
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• pp.185-185
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• 2003

백색 LED를 실현하는 방법의 하나로 UV LED와 적, 녹, 청의 3색 형광체를 이용하는 방법이 주목받고 있다. 이것은 연색성과 색온도 제어 특성이 뛰어나다. 그러나 기존의 형광체는 단파장, 약 250nm 전후, 에서 여기되는 특성을 갖고 있기 때문에 near UV(nUV), 약 380-410nm, 의 LED에 응용하기에는 발광특성에 문제점을 갖고 있다. 본 연구에서는 nUV 여기가 가능한 strontium aluminate를 flux를 이용한 고상반응법으로 합성하고 발광 특성을 분석하였다. SrO와 A1$_2$ $O_3$의 조합비와 반응조건에 따라서 SrA1$_2$ $O_4$ 흑은 Sr$_4$Al$_{14}$ $O_{25}$ 가 합성되었고, 이들은 도핑과 함께 각각 약 520nm에서의 녹색발광과 약 480nm에서의 청녹색 발광 특성을 보이고 있었다. 도펀트로는 Eu, Dy, Ce, Pr 등이 단독 혹은 혼합되어 첨가되었고, 종류와 양에 따라서 발광 파장의 이동이 관찰 되었고, 강도도 이것에 크게 의존하고 있었다. 또한 발광강도는 여기 파장에도 의존하고 있었으며, 약 350-390nm의 nUV에서 가장 높은 발광강도가 관찰되었다.다.

• Nuclear Engineering and Technology
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• 제14권3호
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• pp.116-121
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• 1982

해조류인 미역(Undaria pinnatifida)에 있어서 해수로부터 Sr-90의 농축 및 잔류현상을 실험실적조건하에서 실험한 바 다음과 같은 결과를 얻었다. 해수로 부터 Sr-90의 농축계수는 식물체의 부위, 노출시간, 해수의 염도, 안정원소인 Ca, Sr의 농도에 따라 달리 나타났다. 해조체내에 한번 흡수된 Sr-90은 깨끗한 해수에 대한 노출시간, Ca의 농도와 킬레이트제의 존재여부에 따라 다시 유출되는 패턴이 달리 나타났다. 해조에 의한 Sr-90의 흡수는 표면흡착에 크게 의존하는 것으로 판단되었다.

• 한국지하수토양환경학회지:지하수토양환경
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• 제20권2호
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• pp.32-40
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• 2015

Laboratory column experiments were conducted to evaluate the feasibility of injectable apatite method for the sequestration of Sr-90 in groundwater. The columns were tested to evaluate the rate of citrate biodegradation, the amounts of apatite formed, and the treatability of strontium by the sediment and apatite. The results showed the decreases in citrate, calcium, and phosphate concentrations and the increases in alkalinity and citrate degradation products (acetate and formate) in the columns, suggesting that the citrate degradation and formation of calcium phosphate are occurring. Although the calcium and phosphate were not completely consumed within the columns, some amounts of apatite were formed and it showed an ability to treat strontium in groundwater. This study provides a fundamental understanding of reaction mechanisms for the injectable apatite sequestration method for Sr-90 removal.

• Bulletin of the Korean Chemical Society
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• 제16권12호
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• pp.1180-1184
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• 1995

The precursors of Ba1-xSrxTiO3(x=0.0-0.3) were prepared by the rapid addition of aqueous solution of titanyl oxalate to the mixed aqueous solution of barium and strontium at room temperature. The optimum pH was theoretically calculated from the equilibrium constants and solubility products. The chemical formula of the precursors obtained corresponded to Ba1-xSrxTiO(C2O4)2·4H2O(x=0.0-0.3) as determined by thermal gravimetric analysis. The precursors were converted to stoichiometric Ba1-xSrxTiO3(x=0.0-0.3) with a particle size of 0.01-0.04 μm. As increasing the amount of strontium substituted to barium sites, the structure of crystal changed from the tetragonal phase to the cubic and the unit cell volume was decreased.