• Journal of the Korean Applied Science and Technology
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• v.22 no.2
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• pp.168-174
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• 2005

Aluminum tri-butoxide was mixed with the water/ethanol solution and then chloroplatinic acid was added to the solution. The solution was dried at $100^{\circ}C$ for 15hrs to remove the solvent and water then it was calcined at $500^{\circ}C$. The catalyst was activated with a gas mixture. During the activation, the temperature was increased from $150^{\circ}C$ to $500^{\circ}C$. The necessary amount of urea was dissolved in 50mL water and injected. Aqueous urea solution was then mixed with the feed gas stream. At low temperatures, nitrogen containing compounds of urea decomposition are used as reductants in the reducton of $NO_X$. However at high temperatures the nitrogen containing compounds are oxidized to NO and $NO_2$ by oxygen instead of being used in the reduction. The activity of the catalyst was dependent on urea concentration in the feed stream when there was not adequate water vapor in the feed. The maximum conversion was shifted from $250^{\circ}C$ to $150^{\circ}C$ when water concentration was increased from 2 to 17%. It seems that the maximum temperature shifts to lower temperatures because the hydrolysis rate of HNCO increases with water, resulting in higher amounts of $NH_3$.

• Journal of the Korean Applied Science and Technology
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• v.30 no.3
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• pp.494-503
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• 2013

In this study, $CO_2$ adsorbent was produced for minimizing energy loss due to ventilation within the building. For improved selectivity about low concentration of $CO_2$ in multiple-use facilities, the ball type adsorbent was modified from a commercial zeolite, alumina, alkali metals and activated carbon with mixing LiOH, binder, and $H_2O$. We measured specific surface area, pore characteristic, and crystal structure of the modified adsorbent. Effects of alkalization on the absorptive properties of the adsorbents were investigated. Continuous column tests (2,000 ppm) and batch chamber tests ($4m^3$, 5,000ppm) showed that the modified adsorbent indicated about the selectivity of $CO_2$ more than 9.7% (0.613 mmol/g) compared with ordinary adsorbents and $CO_2$ removal efficiency of 88.8% within l hour, respectively. It was estimated that the modified adsorbent was applicable to indoor environments.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.04a
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• pp.413-417
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• 2003

The last few decades have seen drastic growth in the use of brominated flame retardants(BFRs). There is the problems of polybrominated dibenzo-p-dioxins(PBDDS) and polybrominated dibenzofurans(PBDFs) generation as by-products in combustion process of BFRs. PBDDs/PBDFs are highlighted the new pollutants of environmental contamination, recently. In this study, the 10 kinds of PBDDs/PBDFs standards were used to perform the experiments of recoveries. The analysis of PBDDs/PBDFs in soil environmental samples. was carried out. In silica gel column cleanup, PBDDs/PBDFs eluted until 80mL of n-hexane, and the recovery was obtained 73∼105%. In multi-layer silica gel column cleanup, the recovery was obtained 56∼125% with various elution solvents. In alumina clean process, the standard mixture(PBDES, PBDDs/PBDFs) eluted the first fraction of 2% dichloromethane with n-hexane in the range of 0∼100mL, PBDEs compounds eluted in the second fraction of 50% dichloromethane with n-hexane. In activated carbon column cleanup, the PBBEs eluted to the first fraction(n-hexane) and second fraction(toluene), but PBDDs/PBDFs only eluted to the second fraction. The analytical methods of PBDDs/PBDFs for soil was established based on the experimental results of the environmental samples.

• Restorative Dentistry and Endodontics
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• v.26 no.5
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• pp.387-392
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• 2001

When cavity floor is near the pulp, polymerization of light-activated restorations results in temperature increase. This temperature increase cause by both the exothermic reaction process and the energy absorbed during irradiation. Therefore instating base is required. Most frequently used insulating base is glass ionmer. The purpose of this study was to evaluate intrapulpal temperature changes of glass ionomer according to various curing intensity and curing time. Caries and restoration-free mandibular molars extracted within three months were prepared Class I cavity of 3$\times$6mm with high speed handpiece. 1mm depth of dentin was evaluated with micrometer in mesial and distal pulp horns. Pulp chambers were filled with 37.0$\pm$0.1$^{\circ}C$ water to CEJ. Chromium-alumina thermocouple was placed in pulp horn for evaluating of temperature changes. glass ionomer material was placed in 2mm. total curing time was 40s: continuous 40s, intermittent 20s, intermittent 10s. Glass ionomer material was cured with 300mW/$\textrm{cm}^2$, 550mW/$\textrm{cm}^2$ light curing unit. The results were as follows : 1. Temperature in pulp increased as curing unit power is increased. 2. Temperature in pulp more increased continuous emission than intermittent emission.

• Journal of Industrial and Engineering Chemistry
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• v.68
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• pp.173-179
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• 2018

Electrochemical characterization was conducted on poly(vinyl alcohol) (PVA)-ceramic composite (PVA-CC) separators for supercapacitor applications. The PVA-CC separators were fabricated by mixing various ceramic particles including aluminum oxide ($Al_2O_3$), silicon dioxide ($SiO_2$), and titanium dioxide ($TiO_2$) into a PVA aqueous solution. These ceramic particles help to create amorphous regions in the crystalline structure of the polymer matrix to increase the ionic conductivity of PVA. Supercapacitors were assembled using PVA-CC separators with symmetric activated carbon electrodes and electrochemical characterization showed enhanced specific capacitance, rate capability, cycle life, and ionic conductivity. Supercapacitors using the $PVA-TiO_2$ composite separator showed particularly good electrochemical performance with a 14.4% specific capacitance increase over supercapacitors using the bare PVA separator after 1000 cycles. With regards to safety, PVA becomes plasticized when immersed in 6 M KOH aqueous solution, thus there was no appreciable loss in tear resistance when the ceramic particles were added to PVA. Thus, the enhanced electrochemical properties can be attained without reduction in safety making the addition of ceramic nanoparticles to PVA separators a cost-effective strategy for increasing the ionic conductivity of separator materials for supercapacitor applications.

• Fire Science and Engineering
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• v.16 no.3
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• pp.32-38
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• 2002

The synthesis of $CF_3$I and $C_2F_5I from $CF_3Br$ was studied for the reuse of $CF_3Br$ which is abolished to save the ozone layer of the earth. Reaction experiments were carried out in experimental scale synthesis equipment with catalysts, such as CuI, Kl, $K_2$$CO_3$, KF metal salt/active carbon and alumina support at $400~600^{\circ}C$. Main products of reaction were $CF_3i$ and $C_2F_5I$ with small amounts of $C_2F_5I$, $CF_4$, $CF_2Br_2$ by-products. 7.5wt% KI and $K_2CO_3$over activated carbon catalysts show the highest yield of $CF_3$I and 7.5wt% CuI over alumina catalysts show the highest yield of $C_2F_5i$. And optimal reaction temperature was about $500^{\circ}C$.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.39 no.3
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• pp.180-191
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• 2016

Optimizing energy usage for maximum efficiency is an essential goal for manufacturing plants in every industrial manufacturing sector. The generation and distribution of purifying compressed air is a large expense incurred in practically all manufacturing processes. Not only is the generation and treatment expensive equipment of compressed air, but frequent maintenance and effective operation is also required. As a plant's compressed air system is often an integral part of the production process, it needs to be reliable, efficient, and easy to be maintain. In this paper, we study to find operating method to save energy from the adsorption dryer in the process of purifying compressed air, which is required for a clean room production site in "A" company. The compressed air passes through a pressure vessel with two "towers" filled with a material such as activated alumina, silica gel, molecular sieve or other desiccant material. This desiccant material attracts the water from the compressed air via adsorption. As the water clings to the desiccant, the desiccant particle becomes saturated. Therefore, Adsorption dryer is an extremely significant facility which removes the moisture in the air $70^{\circ}C$ below the dew point temperature while using a lot of energy. Also, the energy consumption of the adsorption dryer can be varied by various operating conditions (time, pressure, temperature, etc). Therefore, based on existing operating experiments, we have searched operating condition to maximize energy saving by changing operating conditions of the facility. However, due to a short experiment period (from September to October), further research will be focused on considering seasonality.

• Applied Chemistry for Engineering
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• v.9 no.1
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• pp.115-120
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• 1998

The surface chemistry of $Re_2(CO)_{10}$ deposition for preparing highly dispersed rhenium catalysts and the formation of active site for the metathesis were studied. Alumina as support was treated at 1223K(DA) and 773k(PDA), respectively. The metathesis activity of the catalysts at 298K was measured by using pure propene under atmospheric pressure. The oxidation number of rhenium on PDA was very high, and that on DA was zero-valent with highly dispersed state. The prepared Re/DA catalyst was easily activated by treating with oxygen gas at low temperatures after thermal decomposition at high temperatures. The activity of Re/DA catalyst, even with very low rhenium loading, was much higher than that of Re/PDA or conventional $Re_2O_7/Al_2O_3$ catalysts. Therefore, rhenium carbonyl was effective for preparing a highy active metathesis catalyst with very low rhenium loading. Rhenium ion on Re/DA catalyst seemed to be bonded to two oxygen atoms on DA surface, that is, two-valent. The two-valent rhenium ion was changed to about six-valent by treating with oxygen. It could be considered that propene metathesis occurred through carbene complex which was formed on the six-valent rhenium ions.

• Journal of the Korean Applied Science and Technology
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• v.29 no.2
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• pp.339-347
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• 2012

This study focuses on developing catalysts for the removal of toluene produced from paint booth. Toluene is one of the major VOC in painting, coating process. Pd catalysts have been used in hydrogenation oxidation and low temperature combustion reaction for toluene removal. Pd catalysts, even though it is very precious and expensive. Therefore, the prepared catalysts from minimizing the amount of Pd ratio (0.1~1.0wt%) were measured. As a result, 1.0wt% Pd(R) catalyst under all conditions showed the highest activity. These results may suggest that the catalytic activity is related to Pd dispersion according sintering atmosphere and Pd ratio in the manufacturing process through the analysis of SEM, XRD.

• Journal of the Korean Chemical Society
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• v.33 no.4
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• pp.350-356
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• 1989

The analysis of adsortion behaviors of some cigarett aerosol ingredients such as tar, nicotine, carbon monoxide and a number of organic acids has shown that the rates of adsorption of the adsorbates of lower boiling point had increased in accordance with increasing cumulative pore volume, while that of higher doiling point decreased with increasing pore volume of smaller radius. The adsorbents used here were charcoal, silica gel, alumina, and activated clay. The common principle that the adsorbents of greater specific surface area adsorb the larger amount of adsorbates appeared to be disturbed in the adsortion of higher boiling point adsorbates. This confirmation was made mainly by analyzing the adsorption behaviors with regard to the pore volume distributions evaluated on the bases of desorption isotherms.