• Korean Chemical Engineering Research
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• v.52 no.3
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• pp.279-288
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• 2014

Nuclear energy is expected to meet the growing energy demand while avoiding CO2 emission. However, the problem of accumulating spent fuel from current nuclear power plants which is mainly composed of uranium oxides should be addressed. One of the most practical solutions is to reduce the spent oxide fuel and recycle it. Next-generation fuel cycles demand innovative features such as a reduction of the environmental load, improved safety, efficient recycling of resources, and feasible economics. Pyroprocessing based on molten salt electrolysis is one of the key technologies for reducing the amount of spent nuclear fuel and destroying toxic waste products, such as the long-life fission products. The oxide reduction process based on the electrochemical reduction in a LiCl-$Li_2O$ electrolyte has been developed for the volume reduction of PWR (Pressurized Water Reactor) spent fuels and for providing metal feeds for the electrorefining process. To speed up the electrochemical reduction process, the influences of the feed form for the cathode and the type of anode shroud on the reduction rate were investigated.

• Journal of Life Science
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• v.18 no.11
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• pp.1606-1611
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• 2008

Outer membrane proteins (OMPs) expressed in the Gram negative bacteria such as Salmonella play multiple functions including material transports, adhesive factors and reception of external signals. This study has been focused on an OmpW protein known as a protein required to form a hydrophobic porin in outer membrane. We have constructed a S. typhimurium CK10 mutant deleting an ompW gene on chromosome. The CK10 strain was more tolerant to SDS than the wild-type strain did. As increase of salt concentration in the culture media, significantly decreased amount of OmpW protein in cells were detected. The maximum OmpW protein was expressed in the absence of salt supplement. However, the growth of CK10 strain was indistinguishable compared to that of the wild-type strain at the variable osmotic conditions. The biological role of differential OmpW expression in response to osmotic conditions remains to be investigated.

• Atmosphere
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• v.27 no.1
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• pp.29-40
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• 2017

The $PM_{10}$ and $PM_{2.5}$ particles over the Yellow Sea of Korea were collected by ship-borne observation during two cruises in spring, 2015. Their water-soluble ionic components such as $NH_4^+$, $Na^+$, $K^+$, $Mg^{2+}$, $Ca^{2+}$, $SO_4^{2-}$, $NO_3^-$, $Cl^-$, $F^-$, $CH_3COO^-$, $HCOO^-$, and $CH_3SO_3^-$ were analyzed, in order to examine the pollution characteristics of the secondary aerosol components. The comparative study of particle size distribution has resulted that $NH_4^+$, $nss-SO_4^{2-}$, $nss-Mg2+$, $nss-K^+$, $HCOO^-$, and $CH_3SO_3^-$ species mostly existed in fine particle mode. Meanwhile, nss-F-and sea-salt species were distributed in both fine and coarse particle mode, $NO_3^-$, $nss-Ca^{2+}$, $CH_3COO^-$ species were rich in coarse particle mode. The concentrations of secondary pollutants($nss-SO_4^{2-}$, $NO_3^-$, $NH_4^+$) increased in fine particles, and those of natural components ($nss-Ca^{2+}$, Sea-salt) increased in coarse particles. $NH_4^+$ exists as the form of $(NH_4)_2SO_4$ and $NH_4NO_3$, and mostly as $(NH_4)_2SO_4$ in fine particles. $NH_4NO_3$ has lower content compared to $(NH_4)_2SO_4$, and it mostly existed in fine particles at Yellow Sea I and in coarse particles at Yellow Sea II. The concentration ratios of $NO_3^-/nss-SO_4^{2-}$ for Yellow Sea I and Yellow Sea II were 0.52 and 0.16 in coarse particles, and they were 0.64 and 0.38 in fine particles, respectively, showing that the stationary source emissions were more important than mobile source emissions in Yellow Sea II (except Passage II-4).

• Journal of Korean Society for Atmospheric Environment
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• v.17 no.6
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• pp.475-485
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• 2001

The presence of airborne particles in the earth atmosphere expert important controls on the global climate because of their effects on the radiative balance. However, there are major uncertainties associated with the direct and indirect radiative effects of aerosols. In addition, their physicochemical properties cannot only the decline of air quality but also damage human health. Airborne particles were collected by two different commercial air samples, high volume sampler(for TSP) and low volume sampler(for P $M_{10}$ ) at the campus of Kunsan National University during February to September, 2000. In most cases, TSP and P $M_{10}$ were sampled once a week for the duration of 24 hours from 9:00 a.m. In addition samples were collected more intenisve, when the yellow dust was expected. Each sample was analyzed for pH and major ions concentration (C $l^{[-10]}$ , S $O_4$$^{2-}$, N $O_3$$^{[-10]}$ , N $a^{+}$, N $H_4$$^{+}$, $K^{+}$, $Mg^{2+}$, $Ca^{2+}$) by ion chromatography and atomic absorption spectrophotometry. Acidity (pH) of TSP and P $M_{10}$ ranged from 5.09 to 8.51 and from 6.22 to 7.54, respectively. The concentrations of airborne particles were found to satisfy both the short and long-term air quality standards during the sampling period. If the ratio of ionic concentrations originating from None sea salt(Nss) to sea salt(ss) in aerosol samples was concerned, it was found that the ionic concentrations from marine environment contributed dominantly in total mass concentration in the airborne particles. When seasonal trends were examined, the TSP concentrations in spring were higher than those of other seasons. It may result form frequent occurrences of yellow dust and during the spring season. The concentration ratio of P $M_{10}$ to TSP ranged from 0.78 to 1 during the sampling period. pH in the airborne particle was highest during spring, but the other seasons maintained almost same level. These results suggest that alkaline species in yellow dust can directly neutralize aerosol acidity. During spring season, yellow dust could be a positive factor that can defer the acidification of surface soil and water by neutralizing acidic aerosols in the atmosphere.osphere.

• Journal of Food Hygiene and Safety
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• v.24 no.4
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• pp.332-337
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• 2009

Most propionic acid is added to food (especially breads) as preservatives and its form is sodium or calcium salt. Most countries admitted propionic acid as food preservatives but a tolerance limit is somewhat different according to countries. Recoveries of the official method for propionates reported as 50.0~60.0%. Accordingly new rapid determination method for propionates was developed using formic acid added sodium chloride (5 g) and ether (formic acid : ether = 1 : 2) as the extraction solvent to improve the official method with the complex processes. Propionate was dissolved from the samples with formic acid omitting steam distillation and ion exchange procedure. Then propionate in formic acid was extracted with ether and sodium chloride again. A $1\;{\mu}l$ aliquot of the filtrate of ether was analyzed by gas chromatograph. Recoveries from sample A and B fortified with propionic acid sodium salt were 85.0 % and 90.0 %, respectively.

• Membrane Journal
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• v.24 no.6
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• pp.453-462
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• 2014

Thin film composite (TFC) polyamide (PA) membranes were prepared on polyester (PET) nonwoven reinforced polysulfone supports for forward osmosis (FO) processes. PSF (polysulfone) supports were prepared via the phase inversion process from PSF casting solutions in dimethyl formamide (DMF) solvents (19 wt%) by using a PET nonwoven (thickness of $100{\mu}m$) as a mechanical reinforcing material for reverse osmosis (RO) membrane. The PSF support from 19 wt% of DMF/PSF casting solution showed sponge-like morphology and asymmetric internal structure. To reduce the internal concentration polarization in FO operation, thin ($20{\mu}m$ of thickness) nonwoven-supported PSF supports were prepared by using PSF/DMF casting solution (9~19 wt%). A desirable support structure with a highly porous sponge-like morphology were achieved from the thin nonwoven-supported PSF layer prepared with 9~12 wt% casting solution. A crosslinked aromatic polyamide layer was fabricated on top of each support to form a TFC PA membrane. The tested sample from 12 wt% of DMF/PSF casting solution presented outstanding FO performance, almost 5.5 times higher water flux (24.3 LMH) with low reverse salt flux (RDF, 1.5 GMH) compared to a thick nonwoven rainforced membrane (4.5 LMH of flux and 3.47 GMH of RSF). By reducing the thickness of the nonwoven and optimizing PSF concentration of casting solution, the morphology of the prepared membranes were changed from a dense structure to a porous sponge structure in the boundary area between nonwoven and PET support layer.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.16 no.2
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• pp.125-132
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• 1983

Dielectric properties of sardine-starch paste with moisture content of 4 to $13\%$ were investigated as functions of moisture and frequency. And the effects of the levels of fat and starch of the mixtures upon dielectric permittivity, critical moisture, were also mentioned. In addition, a theoretical prediction of frequency dependence of dielectric constant which was computed by the lumped circuit of two layer condenser model was evaluated. For the preparation of sardine-starch paste, comminuted sardine meat was washed thoroughly several times in chilled water by soaking and decanting, and finally centrifuged. This procedure was extended longer to provide a low fat sample. The centrifuged meat was mixed with adequate amounts of starch and salt, and ground for 25 minutes in a stone mortar, moulded in the form of disk with 7cm diameter and 1.2cm thickness and then freeze dried. Dried meat disks were cut off for the size of 5.5cm diameter and 1.0cm thickness and their moisture contents were controlled in humidified desiccators with saturated solutions. Dielectric constants of sardine-starch paste tended to decrease frequency was increased showing a critical charge at the moisture called critical moisture content. In case of the sample with $20\%$ starch and $2\%$ salt an average complex permittivity($\epsilon^{\ast}$) at 7 to $8\%$ morsture as the critical moisture content was presented; $\epsilon^{\ast}$=3.37+j 0.39 at 0.1 MHz, $\epsilon^{\ast}$=2.54+j 0.19 at 15 MHz, and $\epsilon^{\ast}$=2.15+j 0.08 at 1.8 GHz, respectively. The theoretically obtained complex permittivity values from the two layer condoner model were in close agreement with these actual measurements under the same conditions, that appeared as $\epsilon^{\ast}$=2.53+i 0.09 at 0.1 MHz and $\epsilon^{\ast}$=2.28+j 0.06 at 15 MHz, respectively. The fast level of the mixture also revealed an influence on dielectric property that defatted neat with $1.0\%$ fat showed a higher hc and $\epsilon^{\ast}$ value than the meat with $4.8\%$ fat. Complex permittivity being related to the moisture level remained nearly unchanged or slightly changed at the moisture range of 4 to $8\%$ but was dispersed widely at higher moisture contents.

• Membrane Journal
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• v.26 no.5
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• pp.391-400
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• 2016

In this work, novel thin film composite (TFC) forward osmosis (FO) membranes are developed via interfacial polymerization on the polysulfone (PS) substrate, using TEOS as the a sol-gel reagent to form hydrophilic interlayer polymer between PS and polyamide (PA). The PS substrate was cast on a very thin polyester nonwoven to reduce membrane resistance. With the incorporation of TEOS (tetraethoxy silane) polymer in the interface between PS and PA, the formed TFC FO membrane exhibits better hydrophilicity and improved water flux, and therefore superior membrane performance. By changing the polymerization sequence of PA interfacial polymerization and TEOS sol-gel condensation, the surface properties and performance of FO membranes are changed significantly. The permeability of FO membranes were estimated using the bench-scale FO test equipment. The distribution of the polysiloxane on composite membrane and morphology are also studied with FE-SEM and EDAX. The PS_PA_TEOS membrane showed highly enhanced water flux (79.2 LMH) but reverse salt flux (RSF) value (7.10 GMH) also increased. However, the flux of PS_TEOS_PA membrane increased moderately (54.1 LMH) without increasing RSF value (1.60 GMH) compare with PS_PA membrane.

• Korean Journal of Soil Science and Fertilizer
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• v.41 no.2
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• pp.83-93
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• 2008

Assessing for flora distribution is necessary for land management and environmental research in reclaimed lands. This study was conducted to find out the relationship between vegetation distribution and soil salinity on three reclaimed tidal flats of Kyonggi-bay in the mid-west coast of Korea. We investigated the soil salinity and identified the vegetation at the continuum distribution spots, and describe the characteristics of continuum distribution. On the reclaimed tidal flats, spatial variation of vegetation formed partially, however as the result for connection of each spatial variation along with the soil salinity, continuum distribution formed and it was overlapped edaphic gradient with vegetation distribution, it means that the continuum distribution correspond with soil salinity gradient, as the evidence high salt tolerance species occurred at high saline spots, non salt tolerance species occurred at low saline spots. On the aged reclaimed tidal flats, continuum type was various and also clearly distinguished but it was not clear on the early stage of reclamation. The continuum distribution distinguished sequential and non-sequential type. Sequential type started from high saline zone and connected to low saline zone gradually, on this type, vegetation changed from pioneer halophyte to facultative halophyte and glycophyte along with the salinity gradient. Non-sequential type formed by non-sequential change of soil salinity, on this type, vegetation distribution was non-regular form because it has not changed gradually. In the aged reclaimed land, vegetation wilted zone existed with high salinity, and continuum distribution started from this zone with bare patch.

• Molecules and Cells
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• v.27 no.4
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• pp.475-480
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• 2009

The transcription of soybean (Glycine max) calmodulin isoform-4 (GmCaM-4) is dramatically induced within 0.5 h of exposure to pathogen or NaCl. Core cis-acting elements that regulate the expression of the GmCaM-4 gene in response to pathogen and salt stress were previously identified, between -1,207 and -1,128 bp, and between -858 and -728 bp, in the GmCaM-4 promoter. Here, we characterized the properties of the DNA-binding complexes that form at the two core cis-acting elements of the GmCaM-4 promoter in pathogen-treated nuclear extracts. We generated GUS reporter constructs harboring various deletions of approximately 1.3-kb GmCaM-4 promoter, and analyzed GUS expression in tobacco plants transformed with these constructs. The GUS expression analysis suggested that the two previously identified core regions are involved in inducing GmCaM-4 expression in the heterologous system. Finally, a transient expression assay of Arabidopsis protoplasts showed that the GmCaM-4 promoter produced greater levels of GUS activity than did the CaMV35S promoter after pathogen or NaCl treatments, suggesting that the GmCaM-4 promoter may be useful in the production of conditional gene expression systems.