• Journal of Environmental Science International
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• v.10 no.1
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• pp.9-12
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• 2001

In this study, development of new sound absorbent which is safety, economical and efficient with using recycled materials is tried for substitution of commercial sound absorbent. The sound absorbents, used in this investigation, were made of used paper or filters of cigarette butts. With the variation of the material densities, sound absorptions of materials were measured. The impedance tube method is used for measuring sound absorption coefficient of the new sound absorbent materials. The measured frequency range was 250Hz to 4000Hz in 1/3 octave band. The sound absorption coefficient of the commercial materials and that of the materials synthesized in the our laboratory show almost same value.

• KEPCO Journal on Electric Power and Energy
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• v.6 no.3
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• pp.297-303
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• 2020

The reaction of carbon dioxide with the amine-based absorbents which have various substituents in the molecule was described. In the case of MEA which is a representative primary amine, the absorption reaction was proceeded very fast while the regeneration reaction was took place slowly due to the strong bond strength between the absorbent and carbon dioxide. The more substituents on N atom of the absorbent, the slower the absorption reaction between carbon dioxide and the absorbent, which in turn causes faster the regeneration rate from the reaction intermediate, carbamate.

• Journal of the Korean Society of Food Science and Nutrition
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• v.43 no.4
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• pp.564-569
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• 2014

This study was conducted to reduce benzo(a)pyrene in sesame oil by addition of several kinds of absorbents (active carbon, diatomaceous earth, kaolin, acid clay, perlite, and silicate). Sesame oil containing 4.1 ppb benzo(a)pyrene was stirred with 0.2% (w/w) several kinds of adsorbents at $40^{\circ}C$ for 30 min. Active carbon resulted in the highest reduction of benzo(a)pyrene in sesame oil among the investigated adsorbents, and decolorization was observed only by using silicate. Reduction of benzo(a)pyrene was optimized by controlling amount the of active carbon, stirring time, and stirring temperature. Futher, 4.1 ppb benzo(a)pyrene in sesame oil was reduced by up to 0.91 ppb by adding 0.5% (w/w) active carbon and stirring for 30 min at $70^{\circ}C$. Optimized conditions were applied to sesame oil (2.14~4.11 ppb) purchased from a Gyeonggi traditional market, and benzo(a)pyrene in sesame oil was reduced by up 0.43~0.86 ppb.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.5
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• pp.340-349
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• 2013

The present paper investigates the availability of seawater as the absorbents to capture carbon dioxide ($CO_2$) emitted from the coal fired power plant (CFPP). For the purpose of the study, readily obtainable alkali materials in CFPP such as coal fly ash (FA), NaOH and $Ca(OH)_2$ are added to seawater to prepare the absorbents and their $CO_2$ capture performances are discussed. FA can be effectively used the additives to increase $CO_2$ capture capacity of seawater to a some extent. This is ascribed that some alkali components in FA are leached into seawater and they contribute to $CO_2$ capture in the solution. However, their leaching amount and rate are restricted by the various ions in seawater. The performance of NaOH added seawater is even lower than that of NaOH added water because $OH^-$ is substantially consumed on $Ma(OH)_2$ production prior to carbonation. $CO_2$ absorption capacity of $Ca(OH)_2$ added seawater is slightly larger than that of $Ca(OH)_2$ added water. This is because that $Ca^{2+}$ which originally present in raw seawater can participate in carbonation reaction.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.40 no.5
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• pp.619-628
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• 1995

Crude aqueous extracts from dried leaves, stems, roots, and flowers from both field grown and greenhouse grown alfalfa plants inhibited alfalfa seed germination and seedling growth. The degree of inhibition was greater in the field grown plant extracts. Flowers extract of field grown plant most inhibited alfalfa germination and seedling growth. In the concentration study, the highest concentration of extract (9.0%, w/v) significantly inhibited total alfalfa seed germination by 50% as compared to control. In partitioning study using pot hydroponic culture of plant biomass into leaves, stems, root, LAR products of LWR and SLA exhibited significant variation among four species. This result support that the inhibitory effect of autotoxic substances presenting in alfalfa tissue may be possible interference with the patitioning of biomass into leaf component relative to the total biomass produced by the alfalfa plant. Toxicity of extract was not reduced by adding activated charcoal, Dowex-50W, amberlite to the extract. Toxic substances existing in most plant tissues but mainly above ground foliage are water soluble and stable and may persist in old alfalfa fields. Thus, it is recommended to remove as much as possible of the above growth parts, especially vegetative stage, before one tries to re-establish alfalfa in former field of alfalfa.

• Korean Journal of Food Science and Technology
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• v.31 no.2
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• pp.368-374
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• 1999

This study was designed to investigate effects of pulsed electric field (PEF) treatment on physiological changes of microbial cells, using domestically fabricated pilot scale PEF device. The effect of non-thermal PEF treatment on physiological characteristics of microorganisms was determined by salt resistance, the amount of UV absorbents, cell staining, recovery rate of defected cells, and changes in structure of cell membrane. Salt resistance of Escherichia coli, Bacillus subtilis and Rhodotorula minuta was examined after PEF treatment at 40 kV/cm, 84 pulse, $10{\mu}s$ pulse duration. Approximately $1\;log_{10}$ cell number of viable microorganisms was decreased by addition of salt. PEF treatment significantly increased the amount of UV absorbents at 260 and 280 nm because of leakage from damaged cell membrane by PEF treatment. Although three kinds of microorganisms treated by PEF were difficult to be observed due to their cell membrane damage, untreated cells were clearly observed by a microscope. PEF-treated R. minuta was not stained by methylene blue due to cell membrane defect. When E. coli, B. subtilis and R. minuta were cultured after PEF treatment, they showed 5, 4, and 8 hr longer lag phase, respectively, compared to control, but growth rates were not affected.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.2
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• pp.282-287
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• 2018

Due to limitations in responding to oil spill incidents that are urgent or that cover a wide area with only oil spill response vessels, Korea Coast Guard (KCG) patrol vessels are utilized. In this study, we have developed an oil sweep system suitable for small patrol vessels. The equipment consists of three components - fixed support, poles, and slide fixers - and can be fastened with a toggle pin to a fall prevention bar on small patrol vessels without welding or additional efforts for installation. The respective weights of each component - fixed support, poles (2 pcs), and slide fixers (4 pcs) - are approximately 9.2 kg, 6.5 kg, and 3.5 kg. The 3 m-pole, which is rotatable 180 degrees horizontally, is folded deckward when replacing oil absorbents. As the development of this equipment has improved the method of deploying and retrieving oil absorbents on KCG small patrol vessels, we expect that more efficient oil spill cleanup will be possible.

• Korean Chemical Engineering Research
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• v.50 no.2
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• pp.348-352
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• 2012

Amine volatility occurring on the $CO_2$ capture process may result in significant economic losses and environmental impact. In this study, using an volatility measurement apparatus, we measured a amine volatility of various amines including MEA(Monoethanolamine), MDEA(N-Methyldiethanolamine), Pz(Piperazine), AMP(2-Amino-2-methyl-1-propanol), 2-MP(2-Methylpiperazine), DGA(Diglycolamine). For the quantitative analysis of volatility, we analyzed the effects of temperature and $CO_2$ loading using an gas chromatography analysis. The result shows that the amine volatility was increased by increasing Henry's constant(MDEA$-CH_3$)(for AMP).

• Journal of Korean Society of Environmental Engineers
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• v.34 no.1
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• pp.55-62
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• 2012

The present paper investigates the performance of the KOH aqueous solution as an absorbent to capture carbon dioxide ($CO_2$). The chemical absorption was carried out according to consecutive reactions that are generated in the order of $K_2CO_3$ and $KHCO_3$. The overall absorption was completed with following the physical absorption. When the absorption was conducted with the KOH as the limiting reactants in batch a reactor, $K_2CO_3$ production rate was the 1st order reaction for $OH^-$. However, $KHCO_3$ generation reaction was independent of the $CO_3^{2-}$ concentration and the rate was calculated to be $0.18gCO_2/min$ for all KOH absorbents, which is the same value of the reaction rate using $K_2CO_3$ aqueous solution as the absorbents. The overall $CO_2$ capture ratio of the 5% KOH absorbent was estimated to be 19% and the individual value in section 1 and 2 was 57 and 12%, respectively. The amount of $CO_2$ absorbed in the solution was very slightly less than the theoretical value, which was ascribed to the side reaction that produces $K_2CO_3{\cdot}KHCO_3{\cdot}1.5H_2O$ during the reaction and the consequent diminish in $CO_2$ absorption in the KOH solution.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.4
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• pp.584-591
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• 2017

Metal removal from water has not been explained clearly by either adsorption onto the surface of absorbents or precipitation as metal hydroxides because those occur simultaneously to a certain extent. For a better understanding of the metal removal mechanisms, batch experiments were performed using soil calcined at $850^{\circ}C$ under various pH conditions for Cu, Pb, Zn, Cd, and Cr. The results showed that the metal removal efficiency with the exception of Cr decreased abruptly, even within 5 min, showing more than 90% removal. The pH of each reactant increased gradually from around 7 to 9 with time. The increases in metal removal at higher pH appear to be associated with metal hydroxides precipitation. Comparative experiments, which were carried out changing the pH by reacting with commercial activated carbon (CAC), natural yellow soil (NYS), and calcined yellow soil (CYS), showed that the pH of the CYS only increased with time. Calcination processes might lead to a change in the physical properties of the soil matrix resulting in a high pH when reacted with water. Apart from adsorption onto the surface of the absorbents, these results show that the adsorption and/or precipitation of hydroxides onto the surface of adsorbents also play important roles in regulating the dissolved metals under alkaline conditions.