• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.8 no.1
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• pp.57-63
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• 2010

Layer crystallization process was tested for the separation(or concentration) of cesium and strontium fission products in a LiCl waste salt generated from an electrolytic reduction process of a spent oxide fuel. In a crystallization process, impurities (CsCl and $SrCl_2$) are concentrated in a small fraction of the LiCl salt by the solubility difference between the melt phase and the crystal phase. Based on the phase diagram of LiCl-CsCl-$SrCl_2$ system, the separation possibility by using crystallization was determined and the molten salt temperature profile during layer crystallization operation was predicted by using mathematical calculation. In the layer crystallization process, the crystal growth rate strongly affects the crystal structure and therefore the separation efficiency. In the conditions of about 20-25 l/min cooling air flow rate and less than 0.2g/min/$cm^2$ crystal flux, the separation efficiency of both CsCl and $SrCl_2$ showed about 90% by the layer crystallization process, assuming a LiCl salt reuse rate of 90wt%.

• The Korean Journal of Pesticide Science
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• v.11 no.2
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• pp.87-94
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• 2007

Pyrethroid insecticide have widely been used for agricultural sector and residential environments. To assess the exposure of insecticide which is absorbed through skin the analysis of urinary metabolite is essential. At present, the urinary 3-PBA was analyzed using liquid-phase extraction. But LPE have many limitations, such as long pre-treatment time and low recovery. So, this study was conducted to determine the optimum conditions for analysing 3-PBA in urine using solid phase extraction. Furthermore, this study intend to investigate the relation of concentrations of pyrethroid, deltamethrin in air and 3-PBA in urine. The optimum condition for hydrolysis was found to be done with hydrochloric acid for one hour. The recovery rates of 3-PBA were $84.6%{\pm}1.2%$, $54.8{\pm}0.9%$, $99.8{\pm}1.2%$ with XAD-2, XAD-7, XAD-16 using as the aborbents and acetone as eluents respectively. But acetonitrle and methanol gave low recovery rate and methyl cellosolve could not elute the compound. The amount of acetone for elution were 6mL, 9mL, 3mL for XAD-2, XAD-7, XAD-16 as absorbents respectively. The non-absorbed rates was $0.8{\pm}0.5%$, and $0.7{\pm}0.3%$ under XAD-16, mesh size 140-200, amount of resin 1.4g and the flow rate of eluent was 0.1mL/min. In the concentration process, we obtained 11 times higher concentration of material. The amounts of urinary 3-PBA were. The LODs of 3-PBA and deltamethrin were 0.004 mg/L, 0.038 mg/L, respectively. The further research of minute monitoring which include spray pattern, environmental condition is needed And more research about the relation between total pyrethroid exposure and urinary various metabolite are also necessary.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.14 no.6
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• pp.77-90
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• 2015

An increasing number of vehicles is causing various traffic problems such as chronic congestion of highways and air pollution. Local governments have been managing traffic by constructing systems such as Intelligent Transport Systems (ITS) and Advanced Traffic Management Systems (ATMS) to relieve such problems, but construction of an infrastructure-based traffic system is insufficient in resolving chronic traffic problems. A more sophisticated system with enhanced operational management capabilities added to the existing facilities is necessary at this point. As traffic patterns of the urban traffic flow is time-specific due to the different vehicle populations throughout the time of the day, a local network-wide signal operation plan that can manage such situation-specific traffic patterns is deemed to be necessary. Therefore, this study is conducted for the purpose of establishment of a plan for contextual signal control management through signal optimization at the network level after setting the Frame Signal in accordance to the traffic patterns gathered from the short-term traffic forecast data as a means to mitigate the problems with existing standardized signal operations.

• Journal of Environmental Science International
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• v.14 no.8
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• pp.793-800
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• 2005

We isolated and identified microorganisms from the aerial environment of domestic museums. The fungi, Penicillium spp., Alternaria spp., and Cladosporium spp. were isolated in many museums. It seems that these fungi are related to biological degradation of textile remains. A total of 14 kinds of bacterial strains were isolated: Acinetobacter spp., Pseudomonas spp., Neisseria spp., Alcaligenes spp., Shigella spp., Klebsiella spp., Corynebacterium spp., Aerococcus spp., Bacillus spp., Micrococcus spp., Citrobacter spp., Erwinia spp., Salmonella spp., and Providencia spp. Acinetobacter spp., Pseudomonas spp., Neisseria spp., and Alcaligenes spp. were the predominate bacteria found in samples with a variety of bacteria. This suggests that there is a relationship between bacteria and the damage of textile remains. In the museum, we isolated Alternaria spp, Geotrichum spp., Penicillium spp. Acinetobacter spp., Pseudomonas spp., Alcaligenes spp. from the entrance, exhibit hall and storage, but they were found in smaller number and species in the exhibit cases and paulownia cases. We concluded that paulownia cases were not influenced by the microorganisms because of quality of care provided by the museum staff. Corynebacterium spp., and Bacillus spp. were not detected at the entrance and exhibit hall but were detected in paulownia cases. It is presumed that those bacteria did not flow in from outside, but resulted from contaminants in paulownia cases. In the distribution of microorganisms associated with textile remains, more fungi were detected than bacteria. Acinetobacter spp., Pseudomonas spp., and Neisseria spp., were isolated from silk items. Penicillium spp. and Cladosporium spp. were isolated in the silk and hump items. Aspergillus spp. and Penicillium spp. were isolated from the cotton items. On the other hands, there were no fungi strains in the wool items. Most of the isolated strains from textile remains were aerial microorganisms from the museum environment. These results suggest that textile remains were apt to contaminated by contact with the air.

• Journal of the Korean Recycled Construction Resources Institute
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• v.8 no.3
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• pp.317-324
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• 2020

Plastic wastes generated from domestic waste are separated by mixed discharge with foreign substances, and the cost of the separation and screening process increases, so recycling is relatively low. In this study, as a fundamental study for recycling mixed plastic wastes generated from domestic waste into concrete aggregates, changes in concrete properties according to the plastic waste types and the substitution rate were evaluated experimentally. The mixed plastic waste aggregate(MPWA) was found to have a lower density and a higher absorption rate compared to the coarse aggregate with good particle size distribution. On the other hand, the single plastic waste aggregate(SPWA) was composed of particles of uniform size, and both the density and the absorption rate were lower than that of the fin e aggregate. It was found that the MPWA substitution concrete did not cause a material separation phenomenon due to a relatively good particle size distribution even with the largest amount of plastic waste substitution, and the amount of air flow increased little. The compressive strength and flexural strength of the PWA substitution concrete decreased as the amount of substitution of the PWA increased due to the low strength of the PWA, the suppression of the cement hydration reaction due to hydrophobicity, and the low adhesion between the PWA and the cement paste. It was found that the degree of deterioration in compressive strength and flexural strength of concrete substituted with MPWA having good particle size distribution was relatively small.

• Korean Chemical Engineering Research
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• v.43 no.2
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• pp.324-329
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• 2005

The efficiency of reducing nitric oxide using urea combined with alkali salt additives is reported in this study. The inlet concentration of NO is 500 ppm with air flow rates of 3 and 5 L/min. Reduction of NO was studied from 650 to $1,050^{\circ}C$ with urea concentrations of 0.3 to 1 mol/L. The efficiency for the reduction of NO increased by 44% when urea is added alone. A further increase in efficiency was observed in the presence of NaOH as additive in fact, the efficiency was increased by more than 25% and 75% when 0.5 mol/L and 1 mol/L NaOH were added with the urea. The efficiency for the reduction of NO increased with all additives, but descended in the order NaOH, $Na_2CO_3$, $NaNO_3$, HCOONa, and CHCOONa. The maximum efficiency of NaOH and $Na_2NO_3$ are 74% and 73%, respectively. All these additives did not alter the comparatively wide operating temperature window for reducing NO. However, sodium compounds do not shift the maximum NO concentration towards lower temperatures when the NO removal activity enhances.

• Journal of the Korean Geographical Society
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• v.39 no.6 s.105
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• pp.955-970
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• 2004

With the flow of globalization, world aviation markets are showing growing trends toward liberalization, deregulation, and privatization. At the same time, also apparent is a strong trend toward regionalism on aviation markets to realize open skies at the regional level. This research examines the recent trend of regionalism in the world aviation market from a political economic perspective, taking a single European aviation market as an example. The results show that the creation of a single European aviation market is the EU's strategic response against the US to enhance the European aviation industry's competitiveness. More specifically, the results show that the European countries are creating a single European aviation market in order to stand against the US' so-called 'divide and nile policy' and 'encirclement strategy' and to make their airliners to have competitive advantages over the US airliners on the lucrative North-Atlantic air routes. Recently, the single European aviation market is expanding by including the Mediterranean and Balkan states to pursue Pan European aviation cooperation and to develop European Common Aviation Area so that it can continuously enhance its negotiating leverage against external markets. The results imply that it is urgent for the Northeast Asian countries to create their own regional aviation bloc to develop their aviation industry and to increase their negotiating power against external countries.

• Clean Technology
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• v.6 no.2
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• pp.113-119
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• 2000

Due to the toxicity of dioxin in the incinerator flue gas, it becomes a severe social problem. Activated carbon adsorption process is one of the methods for removing dioxin in the flue gas and was investigated its performance for removing hazardous organic compounds. Since dioxin is very hazardous material, 1,2-dichlorobenzene(o-DCB), one of the precursor material of dioxin, was used as adsorbate. The effects of air flow rate, pressure drop in the bag filter, operation temperature of bag filter, and kinds of adsorbents on the removal of o-DCB were measured and analysed. Experimental results showed that the operating temperature was recommended within the range of $140{\sim}170^{\circ}C$ considering the operating condition of incinerator. Also it was necessary to maintain the pressure drop of bag filter $120mmH_2O$ for enhancing the adsorption at the surface layer of activated carbon formed on the bag filter. The use of mixture of same amount of activated carbon and diatomite showed more than 90% removal of o-DCB and also reduced the consumption of activated carbon.

• Proceedings of the Safety Management and Science Conference
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• 1999.11a
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• pp.543-563
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• 1999

For hazardous air pollutants(HAP) such as NO and $NO_2$ decomposition efficiency, power consumption, and applied voltage were investigated by SPCP(surface induced discharge plasma chemical processing) reactor to obtain optimum process variables and maximum decomposition efficiencies. Decomposition efficiency of HAP with various electric frequencies(5~50 kHz), flow rates(100~1,000 mL/min) initial concentrations(100~1,000 ppm), electrode materials(W, Cu, Al), electrode thickness(1, 2, 3 mm) and number of electrode windings(7, 9, 11) were measured. Experimental results showed that for the frequency of 10 kHz, the highest decomposition efficiency of 94.3% for NO and 84.7% for $NO_2$ were observed at the poser consumptions of 19.8 and 29W respectively and that decomposition efficiency decreased with increasing frequency above 20 kHz. Decomposition efficiency was increased with increasing residence times and with decreasing initial concentration of pollutants. Decomposition efficiency was increased with increasing thickness of discharge electrode and the highest decomposition efficiency was obtained for the electrode diameter of 3mm in this experiment. As the electrode material, decomposition efficiency was in order : tungsten(W), copper(Cu), aluminum(Al).

• Journal of the Korean Magnetics Society
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• v.22 no.5
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• pp.167-172
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• 2012

In order to analyze the formation mechanism of iron oxide nanoparticles, we measured the heat flow of $Fe(OL)_3$ precursor with temperature, and TEM images and AC susceptibility of aliquots samples sequentially taken from the reaction solution, respectively. The thermal decomposition of two OL-chain from $Fe(OL)_3$ produced the Fe-OL monomer, which were contributed to the formation of iron oxide nanoparticles. In the initial stage of nanoparticles formation, the small iron oxide nanoparticles had ${\gamma}-Fe_2O_3$ structure. However, as the iron oxide nanoparticles were rapidly growth, the iron oxide nanoparticles showed ${\gamma}-Fe_2O_3$-FeO core-shell structure which the FeO layer was formed on the surface of ${\gamma}-Fe_2O_3$ nanoparticles by insufficient oxygen supply from the reaction solution. These nanoparticles were transformed to $Fe_3O_4$ structure by oxidation during long aging time at high temperature. Finally, the $Fe_3O_4$ nanoparticles with high saturation magnetization and stable in the air could be easily synthesized by the thermal decomposition method.