• 대한화학회지
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• 제58권3호
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• pp.283-288
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• 2014

A column solid phase extraction procedure based on modified polyurethane foam (PUF) by a newly synthesized Schiff base ionophore, named 2,2'-{iminobis[propane-3,1-diylnitrilo(1E)prop-1-yl-1-ylidene]}diphenol, was developed for preconcentration step of trace amounts determination of copper ions in water samples by atomic absorption flame spectroscopy. The influence of parameters on the adsorption process such as sample pH, amount of modified PUF packed in the column, type and volume of stripping reagent and its flow rate were investigated and optimized. Under optimum experimental conditions, the calibration graph was linear in a relatively wide range ($0.005-210{\mu}g/ml$) with a limit of detection $0.002{\mu}g/ml$ of copper. The proposed method allows achieving to a concentration factor of >133. The capacity of a column (1.6 cm i.d.) packed by 6 g of PUF modified by 12 mg of the Schiff base was found to be $247.7({\pm}2.1){\mu}g$ of copper. It was found that the adsorption process was highly selective towards copper ions with respect to some associated metal ions. The presented procedure was successfully applied for determination of copper in some water samples.

• 한국주조공학회지
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• 제26권6호
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• pp.272-276
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• 2006

[ $CaCO_3$ ]를 발포제로 사용하여 균일한 기공구조를 가지는 AZ91과 AM60 마그네슘 합금의 발포 금속을 주조법을 통하석 제조하였다. 발포 금속의 제조가 가능한 이유와 발포 마그네슘 합금의 기공구조가 연구를 통하여 논의되었다. 마그네슘 합금의 용탕은 $CaCO_3$의 분해 거동에 영향을 미친다. 제조된 AZ91 마그네슘 합금의 발포 금속은 높은 기공률과 큰 기공의 크기를 가졌으며, 발포 금속들 중에서 상대적으로 쉽게 발포되는 것으로 판단된다.

• 한국화재소방학회:학술대회논문집
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• 한국화재소방학회 1997년도 International Symposium on Fire Science and Technology
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• pp.130-137
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• 1997

Intumescent inorganic and organic coatings which dintr one from the other by the type of gas formers and the mechanisms of foam formation have been obtained and investigated. Inorganic intumescent coatings are the compositions based on water glass and mineral additives with different dispersity. Mineral additives contain adsorbed and absorbed water and carbonates which are destructed with the carbon dioxide and water evolution during the flame action on coating. The decreasing of mineral additives particle sizes under the mechanical milling with the fraction precipitation promotes the foam coke formation with less defects. Here the main structure of comparing compositions does not change. In organic coatings based on epoxy-polymers the polyammonium phosphate additive is used. It is the cabonization catalyst and the foam agent. The polyammonium phosphate of various dispersity employed is uniformly distributed on the polymeric matrix. The decreasing of the particle sizes leads to the increasing of the fire resistant properties of the intumescent coa-ting. The fire resistant analysis of the coating during more than an hour: the coating back side the temperature on plastic or wooden materials does not exceed 423K, and on metal-573K.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2012년도 춘계학술발표대회 논문집
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• pp.463-469
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• 2012

Solar thermochemical syngas and hydrogen production process bv redox system of metal oxide was performed under direct irradiation of the metal oxide on the SiC ceramic foam device using solar simulator. $CeO_2/ZrO_2$ nanotube has been synthesized by anodic oxidation method. Syngas and hydrogen production process is one of the promising chemical pathway for storage and transportation of solar heat by converting solar energy to chemical energy. The produced syngas had the $H_2/CO$ ratio of 2, which was suitable for methanol synthesis or Fischer-Tropsch synthesis process. After ten cycles of redox reaction, $CeO_2$ was analyzed using XRD pattern and SEM image in order to characterize the physical and chemical change of metal oxide at the high temperature.

• 한국재료학회지
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• 제12권9호
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• pp.729-734
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• 2002

Porous Al metal was produced by batch type casting process. In this foaming process, the viscosity and surface tension of molten Al as two most important factors have been investigated in the temperature range of 680-95$0^{\circ}C$ by the ring method and rotational method respectively. The experimental results showed that both the surface tension and viscosity of the melt decreased linearly with increasing temperature. Addition of Ca decreased surface tension, but increased viscosity significantly.

• Geomechanics and Engineering
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• 제35권6호
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• pp.637-646
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• 2023

At present, the research on wave propagation in graphene platelet reinforced composite plates focuses on the propagation behavior of bulk waves, in which the effect of boundary condition is ignored, there is no literature report on propagation behaviors of guided waves in graphene platelet reinforced metal foams (GPLRMF) plates. In fact, wave propagation is affected by boundary conditions, so it is necessary to study the propagation characteristics of guided waves. The aim of this paper is to solve this problem. The effective performance of the material was calculated using the mixing law. Equations of motion of GPLRMF plate is derived by using Hamilton's principle. Then, the eigenvalue method is used to obtain the expressions of bending wave, shear wave and longitudinal wave, and the degradation verification is carried out. Finally, the effects of graphene platelets (GPLs) volume fraction, elastic foundation, porosity coefficient, GPLs distribution types and porosity distribution types on the dispersion relations are studied. We find that these factors play an important role in the propagation characteristics and phase velocity of guided waves.

• 한국가금학회지
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• 제16권1호
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• pp.17-22
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• 1989

난백의 열광수성을 순화시키기 위하여 각종금속염(Fe$^{2＋}$, Fe$^{3+}$ , $Al^{3+}$ , Cu$^{2＋}$)을 첨가하고 가훈처리($60^{\circ}C$, 5분간) 전후 난백의 기능성을 검토하였으며 알루미늄염(Al$^{3+}$ )이 첨가된 난백의 pH에 대한효과도 검토하였다. 금속염의 첨가에 의해 가열처리 전후 난백의 탁도는 대체로 증가하였으나 알루미늄염의부가시 탁도의 변화가 가장 작았다. 난백의 기포력은 금속염의 첨가에 의해 전반적으로 증가하였으며 Fe$^{3+}$ 의 첨가효과가 가장 컸다. 특히 가열처리 후 난백의 기포력은Fe$^{3+}$ , Al/ sup 3＋/ 및 Cu$^{2＋}$의 첨가에 의해 크게 증가되었다. 기포안정성의 경우 열처리 전에는 Fe$^{3+}$ , Al/ sup 3＋/의 첨가효과가 있었으나 열처리 후에는 Fe$^{3+}$ 와 Al/ sup 3＋/의 첨가가 효과적이었다. 한편 알루미늄염을 첨가한 난백을 pH 7 -10의 범위에서 가열처리한 결과 pH 7-8.5 범위에서는 탁도 및 기포성의 변화가 크지 않았고 pH 9이상에서는 탁도와 기포성은 낮아졌으나 기포안정성은 향상되었다. 난백액에 Salmonella typhimurium을 $10^{6}$ cells/$m\ell$수준으로 접종 후 $60^{\circ}C$, 5분간의 가열처리 결과 pH에 상관없이 모두 사멸되었다.

• 한국분말재료학회지
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• 제19권6호
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• pp.435-441
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• 2012

A new manufacturing process of Fe-Cr-Al powder porous metal was attempted. First, ultra-fine fecralloy powders were produced by using the submerged electric wire explosion process. Evenly distributed colloid (0.05~0.5% powders) was dispersed on PU (Polyurethane) foam through the electrospray process. And then degreasing and sintering processes were conduced. In order to examine the effect of sintering temperature in process, pre-samples were sintered for two hours at temperatures of $1350^{\circ}C$, $1400^{\circ}C$, $1450^{\circ}C$, and $1500^{\circ}C$, respectively, in $H_2$ atmospheres. A 24-hour TGA (thermo gravimetric analysis) test was conducted at $1000^{\circ}C$ in a 79% $N_2$+21% $O_2$ to investigate the high temperature oxidation behavior of powder porous metal. The results of the high temperature oxidation tests showed that oxidation resistance increased with increasing sintering temperature (2.57% oxidation weight gain at $1500^{\circ}C$ sintered specimen). The high temperature oxidation mechanism of newly manufactured Fe-Cr-Al powder porous metal was also discussed.

• 한국분말재료학회지
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• 제21권1호
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• pp.55-61
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• 2014

Fe-Cr-Al powder porous metal was manufactured by using new electro-spray process. First, ultra-fine fecralloy powders were produced by using the submerged electric wire explosion process. Evenly distributed colloid (0.05~0.5% powders) was dispersed on Polyurethane foam through the electro-spray process. And then degreasing and sintering processes were conduced. In order to examine the effect of cell size ($200{\mu}m$, $450{\mu}m$, $500{\mu}m$) in process, pre-samples were sintered for two hours at temperature of $1450^{\circ}C$, in $H_2$ atmospheres. A 24-hour thermo gravimetric analysis test was conducted at $1000^{\circ}C$ in a 79% $N_2$ + 21% $O_2$ to investigate the high temperature oxidation behavior of powder porous metal. The results of the high temperature oxidation tests showed that oxidation resistance increased with increasing cell size. In the $200{\mu}m$ porous metal with a thinner strut and larger specific surface area, the depletion of the stabilizing elements such as Al and Cr occurred more quickly during the high-temperature oxidation compared with the 450, $500{\mu}m$ porous metals.

• Nuclear Engineering and Technology
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• 제55권5호
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• pp.1802-1813
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• 2023

Conjugate heat transfer between liquid metal and solid is a common phenomenon in a liquid-metal-cooled fast reactor's fuel assembly and heat exchanger, dramatically affecting the reactor's safety and economy. Therefore, comprehensively studying the sophisticated conjugate heat transfer in a liquid-metal-cooled fast reactor is profound. However, it has been evidenced that the traditional Simple Gradient Diffusion Hypothesis (SGDH), assuming a constant turbulent Prandtl number (Pr_t,, usually 0.85 - 1.0), is inappropriate in the Computational Fluid Dynamics (CFD) simulations of liquid metal. In recent decades, numerous studies have been performed on the four-equation model, which is expected to improve the precision of liquid metal's CFD simulations but has not been introduced into the conjugate heat transfer calculation between liquid metal and solid. Consequently, a four-equation model, consisting of the Abe k - ε turbulence model and the Manservisi k_𝜃 - ε_𝜃 heat transfer model, is applied to study the conjugate heat transfer concerning liquid metal in the present work. To verify the numerical validity of the four-equation model used in the conjugate heat transfer simulations, we reproduce Johnson's experiments of the liquid lead-bismuth-cooled turbulent pipe flow using the four-equation model and the traditional SGDH model. The simulation results obtained with different models are compared with the available experimental data, revealing that the relative errors of the local Nusselt number and mean heat transfer coefficient obtained with the four-equation model are considerably reduced compared with the SGDH model. Then, the thermal-hydraulic characteristics of liquid metal turbulent pipe flow obtained with the four-equation model are analyzed. Moreover, the impact of the turbulence model used in the four-equation model on overall simulation performance is investigated. At last, the effectiveness of the four-equation model in the CFD simulations of liquid sodium conjugate heat transfer is assessed. This paper mainly proves that it is feasible to use the four-equation model in the study of liquid metal conjugate heat transfer and provides a reference for the research of conjugate heat transfer in a liquid-metal-cooled fast reactor.