• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.15 no.3
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• pp.254-263
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• 1986

공기의 제습 운전에 많은 에너지가 소요되므로 고효율과 경비절감이 가능한 새로운 기술의 연구가 필요하게 되었다. 이 글에서는 공기-공기 열점프 시스템과 흡수시스템을 새로이 제안한 MIDA 과정과 비교한다. LiCl 수용액을 사용한 흡수식 제습과 열펌프 사이클을 조합한 MIDA시스템으로 공기온도가 일정하거나 상승하게 되었다. 열펌프사이클로서 열을 흡수기에서 진공으로 작동되는 용액 재생기로 전달한다.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.1
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• pp.81-88
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• 2004

In this study, heat and mass transfer characteristics of five components solution (LiBr＋Lil＋LiNO$_3$＋LiCl＋$H_2O$) which could be substituted for commonly used LiBr solution are tested using a helical absorber. The arrangement of helical-typed heat exchangers allows to make the system more compact as compared to conventional one. The effects of experimental parameters, such as the solution flow rate, cooling water, solution temperature, solution concentration and surfactant have been investigated in view of the heat and mass transfer. The results of the experiment of heat and mass transfer performance show that five components solution should have 2％ higher concentration fur equal absorption capacity of LiBr solution. But considering that five components solution have higher solubility than LiBr solution about 4％ high concentration, five components solution could be applied to a small sized water cooled or air cooled absorption chiller/heater. The increase of heat and mass transfer coefficient by surfactant addition is about 25∼30％ and 23∼40％ respectively.

• Journal of the Mineralogical Society of Korea
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• v.20 no.1 s.51
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• pp.1-6
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• 2007

Hectorite was synthesized by a two-step hydrothermal process from $Mg(OH)_{2}$, water glass (${\sim}30\;wt%\;SiO_{2}$) and Li-compound at $90{\pm}5^{\circ}C$. The product shows excellent dispersion and swelling properties. The mixture of the starting materials was heated in a glass vessel for the first reaction with continuous stirring and the pH of the solution was adjusted to $6{\sim}8$, resulting in the formation of a precursor of hectorite. The excess salt components were washed out from the resulting slurry and then was matured in the glass vessel for the 2nd reaction. Li compound was added during the reaction. After a 10 h retention, the gel of hectorite was formed. The XRD pattern of the synthesized one was coincided with that of natural hectorite and SEM study revealed uniform grains 50 m in diameter. The d001 basal spacing of the product moved from 12 to $17.4\;{\AA}$ after glycolation treatment. The measured value of CEC and the swelling capacity was 90 cmol/kg and $60{\sim}70\;mL/2\;g$, respectively.

• Journal of the Korean Chemical Society
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• v.34 no.6
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• pp.561-568
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• 1990

Voltammetric behavior of some light lanthanide ions (La$^{3+}$, Pr$^{3+}$, Nd$^{3+}$, Sm$^{3+}$, and Eu$^{3+}$) in various supporting electrolytes has been investigated by several electrochemical techniques. The peak potentials and the peak currents, their dependency on the concentration, temperature and pH effects, the reversibility of the electrode reactions are described. The reduction of La$^{3+}$, Pr$^{3+}$ and Nd$^{3+}$ in 0.1 M lithium chloride proceeds by a three-electron change directly to the metallic state (Ln$^{3+}$ ＋ 3e- → Ln$^0$) and charge transfer is totally irreversible. However, the reduction of Sm$^{3+}$ in 0.1 M tetramethylammonium iodide and Eu$^{3+}$ in 0.1 M lithium chloride proceeds in two stages (Ln$^{3+}$ ＋ e- → Ln$^{2+}$ and Ln$^{2+}$ ＋ 2e- → Ln$^0$). At pH values lower than ca.4 the hydrated lanthanide species (Ln(OH)$^{2+}$) reduced before the lanthanide ions (Ln$^{3+}$) due to the catalytic effect of hydrogen ions, and peak current increase with in the order Eu$^{3+}$ < Sm$^{3+}$ < Nd$^{3+}$ < Pr$^{3+}$ < La$^{3+}$ in differential pulse polarography. Some representative plots of $i_{pc}V^{-1/2} (proportional to current function) vs. V show considerable influence of hydrogen ion/lanthanide ion concentration in cyclic voltammetry. It is shown that a reaction of lanthanide ions with proton and/or water and catalytic reaction is enhanced at lower pH and at decreased lanthanide ion concentration.