• Korean Chemical Engineering Research
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• v.48 no.3
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• pp.283-291
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• 2010

In this review, the studies on the electrochemical properties of $TiO_2$ nanotube as an anode material of lithium-ion battery, which was prepared by an alkaline hydrothermal reaction and anneling process, were investigated andanalyzed in terms of charge-dischage characteristics. Up to date, a maximum discharge capacity of $338mAh\;g^{-1}$(x=1.01) was achieved by the nanotube with $TiO_2(B)$ phase, whereas the theoretical capacity of $TiO_2$ anode was $335mAh\;g^{-1}$(x=1) in the basis of $Li_xTiO_2$ as a product of electrochemical reaction between $TiO_2$ and lithium. This was due to fast lithium transport by a shortened diffusion path provided by controlling the nanostructure of $TiO_2$, because the self-diffusion of lithium was slow in a basis of its activation energy as 0.48 eV. Due to an excellent ion storage capabilities in both the surface and the bulk phase, the $TiO_2$ nanotube could be a promising active material as both an anode of lithium-ion battery and an electrode of capacitor with high-rate performances.

• Korean Journal of Weed Science
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• v.5 no.2
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• pp.143-148
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• 1985

Water hyacinth, unused and tropical plant was examined in order to know the feasibility of application for purification of municipal drainage and industrial wastewater. This plant was effective to remove the COD from wastewater, although its removal ability was dependent on the organic sources. The effects of pH, NaCl concentration, water temperature and shading condition on the growth of water hyacinth were investigated. The optimum ranges of pH were weak acid- neutral, of water temperature were 17-$21^{\circ}C$, and unshading condition was better. The rapid propagation of this plant was also observed during hot summer season.

• Food Science and Preservation
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• v.13 no.3
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• pp.382-388
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• 2006

Physicochemical properties of chufa starch were investigated The result are summarized as follow: Moisture content crude protein and crude fat were 10.10%, 0.31% and 0.41,% respectively. Amylose content of chufa starch was 41.6% and blue value was 0.49. Lightness and whiteness of chufa starch was 96.36 and 92.23 of Hunter's color value. In iodine reaction, maximum absorbance wavelength (${\lambda}max$) was 628 nm. Water binding capacity was 83% and swelling power and solubility of chufa starch were increased slowly to $60^{\circ}C$, but increased rapidly after $60^{\circ}C$. Scanning election microscope(SEM) showed that granule type of chufa starch was round or elliptic type, and average granule size was $10{\mu}m$. The results by differential scanning calorimetry(DSC) revealed that gelatinization patterns were similar to those of potato or rice starch. In rapid viscoanalyzer(RVA) examination, pasting temperature was $79.95^{\circ}C$ and peak viscosity of chufa starch was 385.08.

• Journal of the Korea Organic Resources Recycling Association
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• v.20 no.2
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• pp.36-43
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• 2012

Objective of this study was to investigate the effects of pre-treatment of rice straw by sizes(3cm, milled), temperatures($35^{\circ}C\;and\;55^{\circ}C$), with/without NaOH treatment, and RPM on the characteristics of volatile fatty acids production. The concentration of total volatile fatty acids (TVFAs) was increased with the hydrolyzed time. Concentration of VFAs in milled rice straw was higher than that in 3 cm cut. With the alkali treatment, the concentration of TVFAs were sharply increased, which showed 3 times higher than non-treatment. Concentration of VFAs was high at 150 rpm at $35^{\circ}C$, and at 80rpm and 200 rpm at $55^{\circ}C$. Among them acetic acid was dominant, which showed the similar increase with TVFAs. It was also observed that in the case of fibrous material, the contents of cellulose and hemi-cellulose were reduced a little, but no change in lignin.

• Korean Journal of Medicinal Crop Science
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• v.13 no.4
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• pp.171-177
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• 2005

This study was carried out to investigate the distribution and habitat feature of Glehnia littoralis as a part of establishment of conservation plan for important natural agro-plant resources in South Korea. Habitat of Glehnia littoralis was generally found 28.2 m from high tide water line and 2.7 m above sea level at sand dunes near three seashore areas. Density and coverage of Glehnia littoralis were higher in east seashore among three seashore areas. The number of plant species growing with Glehnia littoralis in natural habitat was found 35 species. Among 35 species Ixeris repens Carex pumila, Carex kobomugi, Elymus mollis, Ischaemum anthephoroides, Imperata cylindrica var. koenigii were shown higher density and coverage. Average yearly precipitation and temperature of habitat for Glehnia littoralis were 1250.3 mm and $12.5^{\circ}C$, respectively. Among three seashores, the precipitation and temperature of south seashore were much more and higher than those of other two seashores. Soil characteristics of habitat for Glehnia littoralis were that average pH was 7.9 and organic matter was 0.23%. Content $P_2O_5$ and Ca were relatively higher, but the level K and Na were very low.

• Journal of the Mineralogical Society of Korea
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• v.20 no.3
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• pp.203-212
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• 2007

Mineral compositions of 89 Yellow Sea surface sediments collected at the second cruise in 2001, were determined using the high resolution X-ray diffractometer and Siroquant v.3.0 program. Yellow Sea surface sediments are composed of major minerals (quartz 57.8%, plagioclase 16.0% and alkali feldspar 10.0%), clay minerals, and calcite. Illite (8.7%) is the most abundant clay mineral, chlorite (2.6%) is the second, and kaolinite (0.6%) is few. however smectite is not detected. Quartz content is very high around the margin of the Yellow Sea, however is very low along the northwest to southeast direction extending from southeast of Sandong Peninsula to southwest of Jeju Island. It has similar distribution pattern with that of coarse sediment (sand). The coarse sediment, is mainly consisted of quartz, may be much supplied from the eastern part and southwestern part of the Yellow Sea. Illite distribution pattern is opposite to that of quartz. It is similar to those of clay and mud particles, therefore it can be suggested that fine sediment may be largely supplied from the northwestern part of the Yellow Sea. It is necessary to continue this kind of investigation, because it is difficult to interpret the sediment provenance of the Yellow Sea only from the result of this study.

• Journal of the Mineralogical Society of Korea
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• v.22 no.1
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• pp.49-61
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• 2009

We studied the mineral composition and mineral distribution pattern of 131 surface sediments collected at the cruise in 2000 and 2007 from Southeastern Yellow Sea, South Sea of Korea and Southern part of Jeju Island. Mineral compositions of surface sediments were determined using the quantitative X-ray diffraction analysis. Surface sediments were composed of rock forming minerals (quartz 37.4%, plagioclase 11.7%, alkali feldspar 5.5%, hornblende 3.1%), clay minerals (illite 19.2%, chlorite 4.7%, kaolinite 1.8%) and carbonate minerals (calcite 10.7%, aragonite 3.4%). Distribution of clay minerals is very similar with fine-grained sediments, and especially same as the distribution of HSMD (Hucksan Mudbelt Deposit), SSKMD (South Sea of Korea Mudbelt Deposit) and JJMD (Jeju Mudbelt Deposit). The coarse sediment seemed to be relic sediment during the last glacial maximum and mainly consisted of rock forming minerals. Whereas the fine sediments mainly composed of clay minerals. Based on the clay mineral composition, main ocean current and geographical factor, HSMD and SSKMD might have derived from the rivers around the Korean Peninsula. However, JJMD is complex mudbelt deposit, which formed by Korean rivers and oceanic sediments.

• Journal of the Korean Chemical Society
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• v.19 no.4
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• pp.269-279
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• 1975

Photosensitive properties of naphthoquinone-1,2-diazide-5-sulfonyl esters (PGND, BEND and PVAND) of polyglyceryl phthalate(PG), bisphenol A-epichlorohydrin condensate(BE) and polyvinyl alcohol(PVA) were investigated by the change of solubility before and after exposing to light. Various samples coated on glass or quartz plates were exposed to light under various conditions and steeped in aqueous alkali solution, and then the yield of residual film(W/W0) was determined. The yield of residual film, which was closely related to the sensitivity of the film, was affected by the degree of polymerization of the backbone resin, sensitizers and their concentration. In polymer homologs, the sensitivity was dependent on the degree of polymerization(the higher, the better). And also, it was most effective when 5 % of sensitizers to esters was used. The minimum exposed time was 0.6 min. for PGND-1, 1.0 min. for BEND-1, and 3.0 min. for PVAND-1. Most effective sensitizers for PGND, BEND and PVAND among those used here were benzanthrone, 5-nitroacenaphthene and picramide, respectively. The spectral sensitivities of PGND, BEND and PVAND were examined by comparing their spectrograms with UV-spectra in a solid state. Also, the sensitization and spectral sensitivity of the above polymers were studied. All the polymers containing the sensitizers showed optical sensitization. From the fact that in either case of sensitized or unsensitized sample, the ranges of absorption-maximum wave length were almost consistent with sensitivity maximum wave length, it was proved that the light absorbed by a sample served efficiently for photochemical reactions. Benzanthrone was found to be an excellent sensitizer for PGND.

• Journal of Environmental Health Sciences
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• v.24 no.1
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• pp.132-140
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• 1998

Laboratory-scale experiments were conducted using a three-stage rotating biological contactor unit followed by lime precipitation and sedimentation with effluent recycle to the first stage. The purpose of this study was to evaluate the effects of hydraulic loadings of 0.031-0.076 $m^3/m^2/d and recycle ratio of 1 to 3 on the simultaneous removal of organics and nutrients from domestic wastewater. Lime was added to maintain pH of 10.4-11.0 in the coagulation-flocculation reactor. Results showed that the highest nitrogen removal rate of 70.5% occurred at the lower hydraulic loading of 0.031 $m^3/m^2/d at a recirculation rate of 300%, and similarly, highest nitrification occurred at the same hydraulic loading and recycle ratio. Concentration of ammonia nitrogen in the effluent was less than 1 mg/l at the same operating conditions for higher nitrogen removal. Whereas, high BOD and COD removal was observed at hydraulic loading rate of 0.054 $m^3/m^2/d, and high removal of organic matter was evident from the consistent low COD and BOD value. Results obtained from the operating condition of higher loading rate, 300% of recycle rate showed the highest removals. Increasing in recycle rate and hydraulic loading rate increased the volatile solids fraction of the sludges generated to the extent of 47% at 0.076 $m^3/m^2/d hydraulic loading and 300% recirculation rate. Since pH in the flocculator was maintained at the pH of 10.4-11.0, above 90% removal of phosphorus was obtained. Average concentration of suspended solids was always maintained over 40 mg/l in the effluent. Therefore an RBC unit operating at a hydraulic loading near 0.031 $m^3/m^2/d with a recycle rate of 300% is a viable and feasible alternate conditions to produce an effluent with relative low organic matter and phosphorus, provided that there is a neutralization unit to control the pH and SS of the effluent.

• Korean Chemical Engineering Research
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• v.53 no.1
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• pp.71-77
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• 2015

A fluidized biofilter was filled with Pseudomonas sp. and Bacillus cereus/thuringiensis-fixed waste-tire crumb media and was run to treat authentic textile-dyeing wastewater mixed with alkaline polyester-weight-reducing wastewater. As a result, its removal efficiency of $COD_{Cr}$ and color were 75~80% and 67%, respectively. In addition, upon constructing hybrid-recirculating system composed of the fluidized biofilter and a 450 W-UV/photocatalytic reactor, only fluidized biofilter was run bypassing UV/photocatalytic reactor at stage I. Subsequently, the hybrid system was continuously run at stage II-i, ii and iii. At stage II-i, the total removal efficiency of $COD_{Cr}$ was enhanced to be 80~85%, compared to 75% at stage I, owing to 20~30% removal efficiency of the UV/photocatalytic reactor. However, at stage II-i, the total removal efficiency of color was enhanced to be 65~70%, compared to 45~65% at stage I, even though the removal efficiency of the UV/photocatalytic reactor was tantamount to merely 0~5%. As far as the removal efficiency of fluidized biofilter of the hybrid-recirculating system is concerned, its removal efficiency of color was enhanced by the synergy effect of the hybrid-recirculating system unlike $COD_{Cr}$. Besides, despite of the increase of hybrid-recirculating system-recycle ratio, the deactivation of photo-catalytic activity was scarcely observed to eliminate the color while its irreversible deactivation was observed to eliminate $COD_{Cr}$.