• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.2506-2511
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• 2007

The coupled simulation is performed to find out the interaction of arc plasmas with surrounding materials in a thermal puffer plasma chamber. In order to be more realistic, PTFE nozzle ablation and Cu electrode evaporation, which are caused by high temperature of arc plasmas, are considered together. Pressure rise and temperature inside the chamber generated during the whole arcing history are investigated with the applied currents. It is very important to define how thermal flow and mass transfer are processing between the arc plasma and surrounding materials for further understanding complex physics inside the chamber. It is concluded that the result might be very useful to understand the mechanism happened inside and to design thermal puffer plasma chambers, but further experimental studies are required to verify the results for the more practical applications.

• 환경생물
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• 제26권4호
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• pp.303-310
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• 2008

Heavy metal concentration of Fe, Zn, Cu, Cd and Pb were analysed from seaweeds (Ulva pertusa, Sargassum thunbergii, Caulacanthus okamurae), sediments and seawater at the two experimental sites of Daebul and Sabjin industrial complex in Mokpo coastal area with a control site (Heugsando). Highest values of heavy metals were found at two experimental sites influencing by various pollution sources such as industrial drains, sewage and harbours. In contrast, the lowest concentrations was observed at the control site without any pollution source. The concentration levels of accumulated heavy metals were in the following order: seaweeds > sediments > seawater. Similar spatial distribution patterns were observed at the seaweeds, sediments and seawater for the highest mean values of the different heavy metals. This result show that seaweeds could be used as a biomonitors of heavy metals at coastal region.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.151.1-151.1
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• 2016

Complex oxide heterointerfaces have been extensively explored in the past due to the novel phenomenon emerging at such interfaces that differ from their individual bulk counterparts. The integration of a ferromagnetic (FM) material with the superconducting (SC) material leading to proximity effect is one of the commonly studied phenomenon in these heterostructures. In continuation, we have stabilized the FM layer La0.7Ca0.3MnO3 (LCMO) on SC material YBa2Cu3O7-${\delta}$ (YBCO) using pulsed laser deposition technique and explored the structural, magnetic, electrical and magneto-transport properties of this heterostructure. ${\Phi}$-scan measurements confirm the epitaxial nature of LCMO/YBCO heterostructure grown on single crystalline SrTiO3 substrate. The FM transition of LCMO and SC transition of YBCO are observed in the magnetization measurements of the bilayer structure. Through electrical measurements, we understood that the proximity effect leads to lowering of the SC transition of YBCO. The role of interface in the bilayer structure is also realized through electrical transport measurements.

• Bulletin of the Korean Chemical Society
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• 제27권10호
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• pp.1593-1596
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• 2006

The polymeric membrane electrodes based on N,N'-bis-pyridin-2-ylmethylene-naphthalene-1,8-diamine as an ion carrier were prepared and tested for the copper-ion selective electrode. The membrane has a linear dynamic range between $10^{-6}$ and $10^{-2}$ M with a Nernstian slope of 29.6 mV per decade, and its detection limit was $10^{-5.62}$M. The potentiometric response is independent of the pH range of 3-5. The proposed electrode showed good selectivity and response for $Cu^{2+}$ over a wide variety of other metal ions in pH 4.0 buffer solutions.

• 약학회지
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• 제36권6호
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• pp.577-581
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• 1992

Norfloxacin complexes of $Fe^{2+}$, $Cu^{2+}$ and $Al^{3+}$ have been prepared as solids. The stoichiometry of the complexes has been established. IR investigation indicates the metal-ligating sites in norfloxacin. The bioactivities of complexes all lower than that of norfloxacin. The solubilities and partition coefficients have been measured as a function of temperature. The data are used to evaluate the thermodynamic parameters ${\Delta}G$, ${\Delta}H$, ${\Delta}S$ for the solute transfer process and compared with the parent quinolone, norfloxacin. The existence of such complexes is discussed in the light of quinolone mode-of-action theories.

• 한국환경보건학회지
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• 제24권3호
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• pp.124-130
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• 1998

This study was to examine the utilization of waste egg snells for removal of heavy metals in laboratory wastewater. It was estimated that pH increasing formed heavy metals into a hydroxide and then settled to remove them. Removal rate of heavy metals were increased as increased dosage, low adsorbate concentration and passed reaction time. Average adsorption volumes of Cr, Cu, Mn and Pb per g were about 1.21 mg, 1.1 mg, 0.96 mg and 1.04 mg, respectively. If we reflected the adsorption capacity(k) and adsorption intensity(1/n) of Freundlich isotherm, we couldn't consider waste egg shells as a good adsorbent. It seemed that heavy metals contained in complex wastewater was removed to be influenced by inital pH, solubilities with passed reaction rime and competitive reaction.

• 한국분말재료학회지
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• 제15권1호
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• pp.18-22
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• 2008

The electromagnetic (EM) wave absorption properties with a variation of crystallization annealing temperature have been investigated in a sheet-type absorber using the $Fe_{73}Si_{16}B_7Nb_3Cu_1$ alloy powder. With increasing the annealing temperature the complex permeability (${\mu}_r$), permittivity (${\varepsilon}_r$) and power absorption changed. The EM wave absorber shows the maximum permeability and permittivity after the annealing at $610^{\circ}C$ for 1 hour, and its calculated power absorption is above 80% of input power in the frequency range over 1.5 GHz.

• 한국유체기계학회 논문집
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• 제11권4호
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• pp.7-13
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• 2008

The computational investigation is performed to find out the interaction of arc plasmas with surrounding materials and the thermal flow characteristics in a PASB (Puffer-Assisted Self-Blast) chamber, which is one of new breaking concepts in $SF_6$ switchgears. It is very important to define the flow and mass transfer happened during the full arcing history for further understanding complex physics inside the chamber. In this study, we have considered two diffusion processes by the hot arc plasma, one is PTFE nozzle ablation and the other is Cu electrode evaporation, simultaneously. It was found that the principle of the pressure-rise inside the chamber is confirmed by the computational results and the increase of the electrical conductivity of the residual gas near current zero is critical to the chamber design.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2010년 춘계학술대회논문집
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• pp.201-207
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• 2010

In this study, we calculated arc discharges happened in high-voltage circuit breakers for understanding the complex physics and the probability of thermal breakdown. The four main parts of arc model for this virtual-reality are radiation, PTFE abaltion, Cu evaporation and turbulence. Among these important parts the turbulence model can be critical to the reliability of computation results during high-current period because the plasma flow is affected by high eat energy and mass momentum. Two kinds of turbulence model, zero-equation model and two-equation model, are applied for these calculations and are compared with the measured pressure data inside a chamber.

• 한국전산유체공학회지
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• 제15권3호
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• pp.9-15
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• 2010

In this study, we calculated arc discharges and flow characteristics driven by arcs in a thermal puffer chamber, which is one of most outstanding high-voltage interrupters, for understanding the complex physics and the probability of thermal breakdown. The four main parts of arc model for this virtual-reality are radiation, PTFE ablation, Cu evaporation, and turbulence. Among these important parts the turbulence model can be critical to the reliability of computation results during the whole arcing history because the plasma flow is affected by high heat energy and mass momentum. Two turbulence models, the Prandtl's mixing length model and the standard $k-\varepsilon$ model, are applied for these calculations and are compared with pressure-rise inside chamber and arc voltage between the contacts as well as flow characteristics near current zero.