• Journal of Industrial and Engineering Chemistry
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• v.67
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• pp.210-218
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• 2018

Ethylenediaminetetraacetic acid (EDTA)-functionalized KIT-6 and KCC-1 mesoporous silicas were prepared via post-synthesis grafting and examined for their ability to promote the recovery of rare earth metal ions such as $Nd^{3+}$ from an aqueous medium. The obtained adsorption isotherms were fitted to the Langmuir model, which gave a maximum adsorption of $Nd^{3+}$ ions of 109.8 and 96.5 mg/g for KIT-6-EDTA and KCC-1-EDTA, respectively, at $25^{\circ}C$ and pH 6. The adsorption kinetic profile of KIT-6 was faster than KCC-1. KIT-6 was also proved to be more stable against desorption under acidic regeneration conditions.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2013.05a
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• pp.37-38
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• 2013

• Proceedings of the KSEEG Conference
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• 2005.04a
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• pp.3-6
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• 2005

• Journal of the Korean Institute of Gas
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• v.5 no.4 s.16
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• pp.79-84
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• 2001

In this study, the effect of polyol structure(OH-value, functionality) on the reactivity, mechanical property and cell morphology of polyurethane foam and the possibility of replacing HFC-36smfc was examined by evaluating how each blowing agent(CFC-11, HCFC-l4lb, HFC-36smfc) affects the reactivity, mechanical property and cell morphology. Results of the experiment showed that as the functionality and OH-value of polyol increased, there was an increase in the temperature profile, reaction rate, density and compressive strength. However. as the functionality and OH-value increased. the ceil size became smaller The use of different kinds of blowing agents did not appear to have and significant influence on the temperature profile, reaction rate, density and compressive strength. The foam using HFC-365mfc produced more uniform cells compared to the foam using HCFC-l4lb.

• Korean Journal of Food Science and Technology
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• v.29 no.6
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• pp.1131-1137
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• 1997

The production rates of leavening gases and textures of cookies were investigated with various chemical leavening agents(baking powders). The chemical leavening agents could be divided into three group of a fast-acting group such as potassium bicarbonate, tartaric acid, aluminium ammonium sulfate, and fumaric acid, a slow-acting group such as ammonium bicarbonate, sodium bicarbonate, $glucono-{\delta}-lactone$, and ammonium chloride. and a double-acting group such as anhydro monocalcium phosphate, disodium dihydrogenpyrophosphate, and aluminium potassium sulfate according to the different production rate of gases. The leavening rate of ammonium bicarbonate, which was the highest of all leavening agents used in this experiment, was 131.25%. But its after-taste in a cookie was not good due to the residual ammonia. $Glucono-{\delta}-lactone$ only had no after-taste. The higher leavening rate, the more peaks in texture profile graph. Ammonium bicarbonate showed the most peaks in this experiment. It was found that the number of peak had correlation with brittleness of cookies $(r^2=0.8176)$ and brittleness of cookies was different as to various chemical leavening agents.

• Restorative Dentistry and Endodontics
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• v.42 no.3
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• pp.176-187
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• 2017

Objectives: This study aimed to evaluate the chemical and biological properties of fast-set white mineral trioxide aggregate (FS WMTA), which was WMTA combined with calcium chloride dihydrate ($CaCl_2{\cdot}2H_2O$), compared to that of WMTA. Materials and Methods: Surface morphology, elemental, and phase analysis were examined using scanning electron microscope (SEM), energy dispersive X-ray microanalysis (EDX), and X-ray diffraction (XRD), respectively. The cytotoxicity and cell attachment properties were evaluated on human periodontal ligament fibroblasts (HPLFs) using methyl-thiazoldiphenyltetrazolium (MTT) assay and under SEM after 24 and 72 hours, respectively. Results: Results showed that the addition of $CaCl_2{\cdot}2H_2O$ to WMTA affected the surface morphology and chemical composition. Although FS WMTA exhibited a non-cytotoxic profile, the cell viability values of this combination were lesser than WMTA, and the difference was significant in 7 out of 10 concentrations at the 2 time intervals (p < 0.05). HPLFs adhered over the surface of WMTA and at the interface, after 24 hours of incubation. After 72 hours, there were increased numbers of HPLFs with prominent cytoplasmic processes. Similar findings were observed with FS WMTA, but the cells were not as confluent as with WMTA. Conclusions: The addition of $CaCl_2{\cdot}2H_2O$ to WMTA affected its chemical properties. The favorable biological profile of FS WMTA towards HPLFs may have a potential impact on its clinical application for repair of perforation defects.

• Journal of Environmental Health Sciences
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• v.30 no.5 s.81
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• pp.487-492
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• 2004

Building materials are composed of very complex chemical compounds, and these indoor building materials discharge very much Volatile Organic Compounds(VOCs). We performed the environmental chamber test to investigate the Total VOCs(TVOCs) emission characteristics and emission factors about chemical and natural coating materials. As the result, we concluded that TVOCs emission are high at initial time and decreased in course of time. Natural paint was low emission level for TVOCs than chemical paint by small chamber test. The TVOCs emission factor-time profile showed a good fit with the results from the measured and predicted value.

• 연구논문집
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• s.29
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• pp.151-162
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• 1999

In general, manufacturing processes of thermosetting composites consist of mold filling and resin cure. The important parameters used in modeling and designing mold filling are the permeability of the fibrous preform and the viscosity of the resin. To consolidate a composite, resin cure or chemical reaction plays an essential role. Cure kinetics. Therefore, is necessary to quantify the extent of chemical reaction or degree of cure. It is also important to predict resin viscosity which can change due to chemical reaction during mold filling. There exists a heat transfer between the mold and the composite during mold filling and resin cure. Cure kinetics is also used to predict a temperature profile inside composite. In this study, a new scheme which can determine cure kinetics from dynamic temperature scaning was proposed. The method was applied to epoxy resin system and was verified by comparing measurements and predictions.

• Journal of Photoscience
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• v.8 no.1
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• pp.9-12
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• 2001

The photoisomerization behavior of benzylideneacetophenones, known as chalcones, was studied. We synthesized the chalcone derivatives that have ether groups at 4 and 4＇ positions. Due to the electron donating ability of the ether oxygen, the bond order of the single bond between two phenyl ring of the chalcone strengthened, which eventually increased the rotational barrier of the single bond. The rotational barrier of the single bond is about 20-22 kcal/mole. Thermal recovery of this process took about 1 min. The UV-visible spectra of these chromophores exhibit two characteristic absorption peaks at 276 nm and 340 nm. The relative intensity of the peaks varies depending on the alkyl chain length of the substituent. Photo-irradiation with the 365 nm light monotonously decreases the 340 nm peak. However, the photo-irradiation with 254 nm light induce two competing processes and produced rather complicated absorption profile.

• Biotechnology and Bioprocess Engineering:BBE
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• v.5 no.1
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• pp.65-70
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• 2000

An approximated analytical solution of mathematical model for the three phase fluidized bed bioreactor (TFBBR) was proposed using the linearization technique to describe oxygen utilization rate in wastewater treatment. The validation of the model was done in comparison with the experimental results. Satisfactory agreement was obtained in the comparison of approximated analytical solution and numerical solution in the oxygen concentration profile of a TFBBR. The approximated solutions for three modes of the liquid phase flow were compared. The proposed model was able to predict the biomass concentration, dissolved oxygen concentration the height of efficient column, and the removal efficiency.