• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2005년도 총회 및 춘계학술발표회
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• pp.405-407
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• 2005

To evaluate the main hydrogeochemical characteristics, river waters are investigated using element리 and isotopic compositions in South Korea. In this area, the chemical compositions are mostly classified into three groups; $Ca^{2+}-{HCO_3}^-$ type, $Ca^{2+}-Cl^{-}-{NO_3}^-$ type and $Ca^{2+}-{HCO_3}^{-}-Cl^{-}-{NO_3}^-$ type. These types are affected by two major factors: water-rock interaction and anthropogenic inputs such as sewage and fertilizers. Based on the values of ${\delta}^{18}O$ and ${\delta}D$, most of waters are originated from precipitation except two samples contaminated. The lithology and geography of basins mainly control the water chemistry. Elemental and isotopic compositions show that water chemistry are mainly controlled by three end members, especially by carbonate dissolution, and suggest that anthropogenic input affect the water chemistry. Also, three weathering sources are identified: silicates, dolomite and limestone.

• 신재생에너지
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• 제1권1호
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• pp.64-71
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• 2005

The stability of alumina-coated NiO cathodes was studied in $Li_{0.62}/K_{0.38}$ molten carbonate electrolyte. Alumina was effectively coated on the porous Ni plate using galvanostatic pulse plating method. The deposition mechanism of alumina was governed by the concentration of hydroixde ions near the working electrode, which was controlled by the temperature of bath solution. Alumina-coated NiO cathodes were formed to $A1_2O_3-NiO$ solid solution by the oxidation process and their Ni solubilities were were than that of NiO up to the immersion time of 100h. However, their Ni solubilities increased and were similar to that of the bare NiO cathode after 100h. It was because aluminum into the solid solution was segregated to $\alpha-LiAlO_2$ on the NiO and its Product did not Play a role of the Physical barrier against NiO dissolution.

• Journal of Electrochemical Science and Technology
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• 제13권2호
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• pp.269-278
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• 2022

Utilization of high-voltage electrolyte additive(s) at a small fraction is a cost-effective strategy for a good solid electrolyte interphase (SEI) formation and performance improvement of a lithium-rich layered oxide-based high-energy lithium-ion cell by avoiding the occurrence of metal-dissolution that is one of the failure modes. To mitigate metal-dissolution, we explored fluorinated dual-additives of fluoroethylene carbonate (FEC) and di(2,2,2-trifluoroethyl)carbonate (DFDEC) for building-up of a good SEI in a 4.7 V full-cell that consists of high-capacity silicon-graphite composite (15 wt% Si/C/CF/C-graphite) anode and Li_1.13Mn_0.463Ni_0.203Co_0.203O₂ (LMNC) cathode. The full-cell including optimum fractions of dual-additives shows increased capacity to 228 mAhg^-1 at 0.2C and improved performance from the one in the base electrolyte. Surface analysis results find that the SEI stabilization of LMNC cathode induced by dual-additives leads to a suppression of soluble Mn²⁺-O formation at cathode surface, mitigating metal-dissolution event and crack formation as well as structural degradation. The SEI and structure of Si/C/CF/C-graphite anode is also stabilized by the effects of dual-additives, contributing to performance improvement. The data give insight into a basic understanding of cathode-electrolyte and anode-electrolyte interfacial processes and cathode-anode interaction that are critical factors affecting full-cell performance.

• 한국전기화학회:학술대회논문집
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• 한국전기화학회 2002년도 연료전지심포지움 2002논문집
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• pp.93-98
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• 2002

• 한국결정성장학회지
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• 제10권2호
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• pp.166-170
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• 2000

굴 패각으로부터 탄산가스 화합법에 의해 제조된 결정질의 침강성 탄산칼슘을 출발원료로 하여, 습식법으로 비정질 탄산칼슘을 제조하였으며 그리고 형상제어를 행하였다. 그 결과 비정질 탄산칼슘은 결정질의 침강성 탄산칼슘을 묽은 염산용액으로 용해시킨 뒤 여기에 묽은 소다회 용액의 급속한 혼합, 침전 및 비속적인 여과과정에 따라 제조할 수 있었다. 그리고 니상 상태의 비정질 탄산칼슘을 이용하여 반응온도; 2~$85^{\circ}C$, 반응시간;5~60분의 범위에서 각각 결정화시켜 입방형, 침상형, 방추형, 구형, 판상형의 결정질 탄산칼슘을 선택적으로 제조하였다.

• 한국지구물리탐사학회:학술대회논문집
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• 한국지구물리탐사학회 2003년도 Proceedings of the international symposium on the fusion technology
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• pp.654-657
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• 2003

We obtained amorphous calcium carbonate through the carbonation reaction of $Ca(OH)_2$, and through this reaction, observed changes in particle shape and phase by electric conductivity, XRD and TEM analysis. According to the result of the analysis, in the first declining stage of electric conductivity, amorphous calcium carbonate that has formed is coated on the surface of $Ca(OH)_2$ and obstructs its dissolution, and in the first recovery stage of electric conductivity, amorphous calcium carbonate is dissolved and re-precipitated and forms chains of fine calcite particles linearly joined. In the second decline of conductivity, viscosity increases due to the growth of chains of calcite particles, and finally the calcite particles are dissolved and separated into colloidal crystalline calcite, thereby increasing electric conductivity again.

• Bulletin of the Korean Chemical Society
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• 제28권3호
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• pp.457-462
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• 2007

Amorphous calcium carbonate (ACC) can readily be prepared using ethanol as the reaction medium and ammonium carbonate as the source of carbon dioxide. Other additives, or any elaborate pH control are not needed to form the initial calcium carbonate precipitate. Ammonia generated from ammonium carbonate maintains the reaction medium in a neutral or weakly basic condition, retarding the crystallization of ACC, while ethanol itself inhibits the dissolution of ACC. The ACC prepared in this way provides a rare opportunity to fabricate molded biomimetic crystals in vitro, but the ACC is too fragile to be fabricated into proper shapes. The malleability of ACC is, however, greatly enhanced by incorporating poly(ethylenimine) (PEI). The ACC/PEI composite can then be fabricated, using a proper mold or template, into mechanically durable biomimetic crystals of definite shape. The ACC in the ACC/PEI composite can further be transformed into vaterite by heating under N2 atmosphere, while the native ACC simply converts into calcite.

• Geomechanics and Engineering
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• 제29권1호
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• pp.79-90
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• 2022

Soybean-urease induced carbonate precipitation (EICP), as an alternative to microbially induced carbonate precipitation (MICP), was employed for soil improvement. Meanwhile, soluble calcium produced from industrial waste carbide slag powder (CSP) via the acid dissolution method was used for the EICP process. The ratio of CSP to the acetic acid solution was optimized to obtain a desirable calcium concentration with an appropriate pH. The calcium solution was then used for the sand columns test, and the engineering properties of the EICP-treated sand, including unconfined compressive strength, permeability, and calcium carbonate content, were evaluated. Results showed that the properties of the biocemented sand using the CSP derived calcium solution were comparable to those using the reagent grade CaCl₂. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses revealed that spherical vaterite crystals were mainly formed when the CSP-derived calcium solution was used. In contrast, spherical calcite crystals were primarily formed as the reagent grade CaCl₂ was used. This study highlighted that it was effective and sustainable to use soluble calcium produced from CSP for the EICP process.

• 대한자원환경지질학회:학술대회논문집
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• 대한자원환경지질학회 2007년도 춘계 지질과학기술 공동학술대회
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• pp.439-440
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• 2007

See Full Text

• 대한전기학회:학술대회논문집
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• 대한전기학회 1991년도 하계학술대회 논문집
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• pp.255-258
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• 1991

MCFC are expected as an electric and thermal power source of the urban cogenerating system because MCFC have higher electric power efficiency and better thermal power quality. However, the MCFC which use strorgly corrosive molten Carbonate at $650^{\circ}C$ have many problems. Material issues with the molten carbonate fuel cell in clude anode creep, conthode dissolution and bipolar plate corrosion. The objectives of this study are to examied fabrication process and characteristics of anode electrode.