• 한국전기전자재료학회논문지
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• 제19권11호
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• pp.1020-1024
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• 2006

Europium$(Eu^{2+}\;or\;Eu^{3+})$-activated calcium aluminium silicate phosphors were synthesized for the first time and the structures and luminescence characteristics of these phosphors were investigated. The phosphors in this study emitted blue, green, and even red light depending on the starting milterials and annealing conditions for synthesis. In addition, the structure was also changed when the different starting materials were used. When $CaCO_3$ was used as a starting material, tetragonal $Ca_2Al_2SiO_7$ was formed. However, pure green light was emitted when the annealing was conducted in reduced atmosphere and red one was emitted by annealing in air. In the case of $CaSiO_3$ as a starting material, triclinic $CaAl_2Si_2O_8$ was formed and only pure blue emission was observed. Moreover, this blue phosphor exhibited higher intensity than that of commercial YAG:Ce phosphor, which showed the possibility of application on the phosphor for new light source such as a UV-LED.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 하계학술대회 논문집 Vol.7
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• pp.32-35
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• 2006

For the white UV-LED applications, $Eu^{2+}$-activated calcium aluminium silicate phosphors were synthesized for the first time and the structures and luminescence characteristics of these phosphors were investigated. The phosphors in this study emitted blue. green or blue-green light depending on the starting materials for synthesis. In addition, the structure was also changed when the different starting materials were used. When CaO and $CaCO_3$ was used as a starting material. tetragonal $Ca_2Al_2SiO_7$ was formed and blue-green and pure green light was emitted. respectively. However. in the case of $CaSiO_3$, triclinic $CaAl_2Si2O_8$ was formed and only pure blue emission was detected. The maximum emission intensity was obtained from $CaAl_2Si_2O_8:Eu^{2+}$ phosphors, which intensity was about 1.4 times higher than that of YAG:$Ce^{3+}$ phosphor used for blue LED.

• 한국수소및신에너지학회논문집
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• 제18권3호
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• pp.301-308
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• 2007

Silicate mineral serpentine with magnesium and calcium was selected as a mineral carbonation mediators for carbon dioxide storage. Serpentine has various metallic elements as an oxides form of magnesium, iron, calcium, aluminium etc. Magnesium and calcium could be carbonation salt preferentially than other metal component within serpentine. Systemic thermochemical treatment for serpentine could change physicochemical properties like a surface area and pore dimensions. Due to the rapid chemical reaction rate depended on dimensional values, carbonation formation could determined by surface property change of thermochemical treated serpentine.

• 대한토목학회논문집
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• 제26권2C호
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• pp.99-108
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• 2006

본 연구에서는 점성토의 강도를 증진시키기 위해, 일련의 동전기 주입 안정화 실내 실험을 수행하였다. 이를 위해 규산나트륨을 주입제로 선정하고 농도를 변화(500, 1000, 1500, 2000, 2500mM)시켜 동전기 주입 안정화 기법의 적용성을 파악하였고, 처리기간과 전압경사에 따른 영향을 파악하기 위해 2일 간격(2, 4, 6, 8, 10일)으로 처리기간을 설정한 실험과 0.25, 0.5, 1.0, 1.5, 2.0V/cm로 전압경사를 변화시킨 실험을 실시하였다. 또한 염화칼슘과 수산화알루미늄을 2차 주입제로 사용하여 첨가농도에 따른 전단강도 개량 효과를 파악하고자 하였다. 이를 위해 규산나트륨(1000mM)을 5일간 적용한 후 2차 주입제의 농도를 50, 250, 500, 750, 1000mM로 변화시켜 5일간 적용하였다. 규산나트륨의 농도 결정시험결과 1000mM 이상의 농도에서 일정한 값으로 수렴하는 양상을 띠었으며, 이 때 초기 강도보다 약 800% 크게 강도증진효과가 나타났다. 최적전기경사와 처리기간 결정시험결과 전압의 경우 1V/cm, 처리기간의 경우 6일 이상에서 강도증가치가 수렴하는 양상이 나타났다. 염화칼슘과 수산화알루미늄을 2차 주입제로 사용한 경우, 두 경우 모두 250mM 이상의 농도에서 일정한 강도값으로 수렴하는 양상이 나타났으며, 규산나트륨만 사용한 경우보다 약 20~30%의 강도증진효과가 발생했다.

• 생태와환경
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• 제35권3호통권99호
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• pp.213-219
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• 2002

녹조 제어를 위하여 수중의 인 제거에 관여하는 CellCaSi의 여러 가지 조건별 인 제거효과를 조사하였다. CellCaSi의 입도에 따른 인 제거효과는 직경 1, 2 그리고 4mm 이하의 3가지 중 1mm 이하의 작은 입자를 사용했을 때 가장 우수하였다. CellCaSi의 인 제거효과는 처리량의 증가에 비례하였다. 수중의 pH 5, 7, 9에서 초기 인 농도 0.20mg/l는 각각 0.09, 0.08및 0.08mg/l로 감소되어 상이한 pH조건에 따른 CellCaSi의 인 제거효과는 큰 차이를 보이지 않았다. CellCaSi에서 용출되는 양이온은 Ca이며, Al과 Fe양이온은 검출되지 않았다. 초기에 급격히 용출된 Ca양이온은 수중의 인과 반응하는 것으로 확인되었다. 초기 인 농도 0.10, 1.0mg/1는 CellCaSi와 Ca, Fe 화합물을 첨가한 처리구에서 8일 후 각각 0.03,0.47mg/l를 기록하며 가장 많이 감소하였다. 이에 따라 인 제거효과는 CellCaSi와 Ca, Fe 화합물을 동시에 처리하였을 때 가장 좋은 것으로 조사되었다. CellCaSi의 처리에 따라 pH가 약간 증가하였고, 전기전도도도 증가되지만 상수원수 기준 허용치 (500${\mu}$S/cm) 이내였다.

• Geomechanics and Engineering
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• 제19권1호
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• pp.37-47
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• 2019

The main objective of this study is to evaluate and compare the efficiency of ordinary Portland cement (OPC) in enhancing the unconfined compressive strength of soft soil alone and soft soil mixed with recycled tiles. The recycled tiles have been used to treat soft soil in a previous research by Al-Bared et al. (2019) and the results showed significant improvement, but the improved strength value was for samples treated with low cement content (2%). Hence, OPC is added alone in this research in various proportions and together with the optimum value of recycled tiles in order to investigate the improvement in the strength. The results of the compaction tests of the soft soil treated with recycled tiles and 2, 4, and 6% OPC revealed an increment in the maximum dry density and a decrement in the optimum moisture content. The optimum value of OPC was found to be 6%, at which the strength was the highest for both samples treated with OPC alone and samples treated with OPC and 20% recycled tiles. Under similar curing time, the strength of samples treated with recycled tiles and OPC was higher than the treated soil with the same percentage of OPC alone. The stress-strain curves showed ductile plastic behaviour for the untreated soft clay and brittle behaviour for almost all treated samples with OPC alone and OPC with recycled tiles. The microstructural tests indicated the formation of new cementitious products that were responsible for the improvement of the strength, such as calcium aluminium silicate hydrate. This research promotes recycled tiles as a green stabiliser for soil stabilisation capable of reducing the amount of OPC required for ground improvement. The replacement of OPC with recycled tiles resulted in higher strength compared to the control mix and this achievement may results in reducing both OPC in soil stabilisation and the disposal of recycled tiles into landfills.