• 한국대기환경학회지
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• 제29권1호
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• pp.56-63
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• 2013

This study was aimed at developing and evaluating a diffusive sampling method using a barium hydroxide solution as an absorbent for measuring carbon dioxide ($CO_2$) in ambient air. The collected $CO_2$ concentration was calculated by the change of conductivity resulted in the reaction of $CO_3{^{2-}}$ and $Ba^{2+}$ in aqueous solution. The sampling rate for the diffusive sampler was determined 0.218 mL/min, as obtained from the slope of the linear correlation between the $CO_2$ mass collected by the diffusive sampler and the time-weighted $CO_2$ concentration with the active sampling method. The unexposed blank sampler sealed in aluminium foil-polyethylene laminated packets has remained stable during at least one-month storage period. A good correlation was observed between the diffusive sampler and active sampler with a coefficient of determination of 0.956. This diffusive sampler would be suitable for the indoor $CO_2$ concentration monitoring.

• Nuclear Engineering and Technology
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• 제55권5호
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• pp.1519-1526
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• 2023

For the first time Aluminium-BariumeZinc oxide nanocomposite (ZABONC) was synthesized by solution combustion method where calcination was carried out at low temperatures (600℃) to study the electromagnetic (EM) (X/γ) radiation shielding properties. Further for characterization purpose standard techniques like PXRD, SEM, UV-VISIBLE, FTIR were used to find phase purity, functional groups, surface morphology, and to do structural analysis and energy band gap determination. The PXRD pattern shows (hkl) planes corresponding to spinel cubic phase of ZnAl₂O4, cubic Ba(NO₃)₂, α and γ phase of Al₂O₃ which clearly confirms the formation of complex nano composite. From SEM histogram mean size of nano particles was calculated and is in the order of 17 nm. Wood and Tauc's relation direct energy band gap calculation gives energy gap of 2.9 eV. In addition, EM (X/γ) shielding properties were measured and compared with the theoretical ones using standard procedures (NaI (Tl) detector and multi channel analyzer MCA). For energy above 356 keV the measured shielding parameters agree well with the theory, while below this value slight deviation is observed, due to the influence of atomic/crystallite size of the ZABONC. Hence synthesized ZABONC can be used as a shielding material in EM (X/γ) radiation shielding.

• 시멘트
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• 통권59호
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• pp.26-38
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• 1975

본고는 일본 소야전Cement Co.의 중앙연구소주임연구원으로 있는 Hiroshi Uckikawa 박사가 일본의 Ceramics-Japan지(''74.10)에 기고한 것을 번역한 것으로서 그 내용에 의한 목차는 다음과 같다. 즉 근년에 개발된 새로운 cement로서는 1. 속경성 cement 2) 초속경 cement(jet cement, regulated set cement) 2) Alumina cement 3) 초조강 cement 4) 급경 cement 2. 고강도 cement 3. 내구성 cement 1) 내유산균 cement 2) 내화 cement (1) alumina cement 계 (2) barium, strontium 계 cement (3) 인산 aluminium 계 cement 3) 방사선차폐용 cement 4. 팽창 cement 1) alumine 산, 유산 calcium 수화물의 생성에 의한 것 2) 수산화 calcium의 생성에 의한 것 3) 기타 5. 시공성을 개선한 cement (예: 유정용 cement, 도장용 cement) 등이 있다. 머지 않아 우리나라에서도 cement 품종의 다양화가 필연적인 문제로 대두될 것을 생각하여 본번역문이 다소나마 도움이 되기를 바란다.

• 한국세라믹학회지
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• 제16권1호
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• pp.31-37
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• 1979

The middle point of composition within the system $MgO-Al_2O_3-SiO_2$ has been studied for applicability as ceramics dielectrics. A Kyul Sung Tale of high purity, magnesia clinker of Sam-wha chemical company, C.P. aluminium oxide, calcium carbonate, red lead, barium carbonate which was made into frit were used the raw materials. A number of steatite ceramics were prepared under carefully controlled condition and the water absorption, linear shrinkage, power factor, dielectric constant and dielectric loss were measured at elevated temperature. When we used magnesia clinker as flux, the quantity of this flux was 0.05mole, sintering temperature was continued for 2 hrs. at 1, 27$0^{\circ}C$. From this conditions, we could get the data whose power factor was 0.142%, water absorption was zero, linear shrinkage was 8.76%, dielectric constant was 5.63, dielectric loss was 0.00799. When we used red lead as flux, the quantity of this flux was 0.033mole and 0.066mole, sintering temperature was continued for 2hrs. at 1, 26$0^{\circ}C$. From this conditions, we could get the data whose water absorption was zero, linear shrinkage was 8.03%, and 8.48%, power factor was 0.136% and 0.062%, dielectric loss was 0.0072 and 0.0037. When we used barium carbonate made into frit as flux, the quantity of this flux was 0.02mole, sintering temperature was continued for 2hrs. at 1, 27$0^{\circ}C$. From this conditions, we could get the data whose water absoption was zero, linear shrinkage was 8.44%, power factor was 0.138%, dielectric constant was 5.69, dielectric loss was 0.0074.

• 멤브레인
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• 제18권3호
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• pp.241-249
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• 2008

본 연구의 목적은 제주도 지하수에 미량으로 함유되어 있는 바나듐을 역삼투 공정을 이용하여 고농도로 농축하고 이를 바나듐수로 이용하는데 있다. 이를 위하여 바나듐 농도가 서로 다른 와흘 지역, 어음 지역 및 서귀포 지역의 지하수를 원수로 선정하였으며, 이 지역 지하수의 바나듐 농도는 각각 31.8, 44.5 및 53.0 ppb이었다. 지하수 중의 모든 성분에 대한 배제율은 막간차압의 증가에 따라 증가하였다. 막간차압을 8 $kg_f/cm^2$로 하였을 때, 바나듐(V)의 배제율은 $97.4%{\sim}99.0%$이였고, 나트륨(Na), 칼륨(K), 알류미늄(Al), 철(Fe), 및 바륨(Ba)의 배제율은 각각 $97.7%{\sim}97.8%,\;98.0%{\sim}98.3%,\;94.8%{\sim}97.5%,\;88.0%{\sim}96.4.0%$ 및 $97.9{\sim}98.0%$이었으며, 그 외의 마그네슘(Mg), 칼슘(Ca), 크롬(Cr), 망간(Mn) 및 스트론 튬(Sr)의 배제율은 3 지역 지하수 모두 99.0% 이상이었다. 와흘 지역, 어음 지역 및 서귀포 지역의 지하수를 각각 회수율 15%로 6단 처리하였을 때, 와흘 지역, 어음 지펴 및 서귀포 지역 지하수의 바나듐 함량을 각각 88.6, 118.9 및 165.1 ppb로 농축 할 수 있었으며, 농축수(바나듐수)의 유해물질은 먹는 물 기준 미만이었다.

• 멤브레인
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• 제19권4호
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• pp.277-284
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• 2009

지하수 중의 바나듐 및 실리카의 농축에 적합한 막을 선정하기 위하여 2종류의 나노여과 막모듈(NE2540-90, NF90-2540)과 3종류의 역삼투 막모듈(BW30-2540, RE2540-TE 및 XLE-2540)에 대한 투과선속과 배제율을 측정하였다. 투과선속과 배제율에 대한 실험 결과 본 연구에 사용된 나노여과 막모듈과 역삼투 막모듈 중에서 NE2540-90 막모듈이 바나듐과 실리카의 농축에 가장 적합하였다. NE2540-90 막모듈을 사용하여 막간차압을 $8\;kgf/cm^2$로 하였을 때, 바나듐 및 실리카의 배제율은 각각 98.2% 및 99.0%이였고, 알루미늄, 크롬, 철, 붕소, 스트론튬 및 바륨에 대한 배제율은 각각 92.0%, 83.6%, 96.0%, 45.1%, 98.6% 및 69.5%이였다. 서귀포지역 지하수를 각각 회수율 15%로 6단 처리하였을 때, 바나듐과 실리카 함량은 각각 $148.9\;{\mu}g/L$ 및 85.8 mg/L로 농축되었다. 나노여과 공정에 의한 농축수는 고농도의 바나듐과 실리카를 함유하고 있어 기능성음료로의 상품개발이 가능할 것으로 판단된다.