• Korean Journal of Food Science and Technology
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• v.28 no.6
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• pp.1126-1134
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• 1996

The physical characteristics changes of carrots during drying were studied to minimize the quality degradation by applying improved drying process and pretreatment method. Physico-chemical properties of the product were analyzed, and then, drying mechanisms were explained by diffusion coefficients and drying models. In hot air drying process, the drying and rehydration efficiencies were high at low relative humidity and high temperature. Browning degree and specific volume also showed similar trend to drying efficiency. Diffusion coefficient, which describes moisture transfer, was also high at low relative humidity and at high temperature. It was verified using. Arrhenius equation that drying process was influenced by temperature. It was also observed during experiment that temperature changes were more effective in drying than relative humidity changes. Quadratic model was the most fittable in explaining the process. As a result of analyzing the experimental data with respect to the drying time, the contents of carotene and moisture could be modeled as a polynomial. As the air velocity increased, drying performance and rehydration efficiency increased.

• Applied Biological Chemistry
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• v.19 no.3
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• pp.145-154
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• 1976

Studies have been carried out to design a suitable consumer size package from flexible packaging material to hold 100 grams of Chilli powder and 250 grams of whole chilli which are moisture and color sensitive. 1. Sorption characteristics of the chilli powder has revealed that moisture sorption is rapid above 55 per cent R.H., and the product is fairly hygroscopic. Further, an equilibrium moisture content of about 15 per cent at 70 per cent R.H., appears to be critical from the point of microbial spoilage of chilli powder. 2. Studies on the colour (Capsanthin) changes of chilli powder equilibriated to different moisture content, have revealed that colour changes during storage is greatly influenced by the moisture content and temperature decreases the capsanthin content of chilli during storage. 3. From the studies, it can be inferred that the sunlight exhibits pronounced effect in bleaching of colour and brings about maximum discolouration of the red pigment in chilli. 4. From the packaging and storage studies of chilli powder in different flexible films, it can be concluded that for long-term storage, the aluminium foil laminate is unique in offering maximum protection from various physico-chemical changes. For short-term storage and for fairly good moisture and colour protection, amber or black polyethylene, high-density polyethylene and Saran/Cello/Saran poly laminate pouches appear to be suitable alternatives.

• Journal of the Korean Wood Science and Technology
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• v.36 no.3
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• pp.70-84
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• 2008

A series of the studies on the applied physical properties of domestic species have been conducted last three years. Pinus densiflora was one of the three species examined for the first year. Because the same apparatus and experimental procedures were used for all species, their results can be easily comparable. The experiments for sorption property were conducted with 20- and 80-mesh wood powder and resulted in their EMC's and sorption isotherms at various heating conditions. The thermal conductivity and diffusivity, and electric resistance and volumetric electric resistivity were measured with a thermal-wire device and a high electric resistance meter. The differences of the thermal and electric properties between quarter- and flat-sawn specimens were observed, which was partially attributed to their anatomical differences. An acoustic measurement system was used to evaluate dynamic MOE and internal friction. This paper provides the useful fundamental data for designing a wood structure, correcting a portable resistance-type moisture meter, and nondestructive testing wood.

• Journal of Life Science
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• v.13 no.4
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• pp.421-427
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• 2003

A natural habit at bacterium, Enterobacter intermedious KH410 was isolated from freshwater plant root and identified. Adsorption of heavy metals such as lead, cadmium, and copper by this strain was examined. The minimal inhibitory concentrations(MIC) for each metal were 1.78 mM for lead, 0.17 mM for cadmium and 1.39 mM for lopper, respectively. Maximum production of dried cell was 2.56 g/$\ell$ in LB medium containing 0.5% NaCl, 1% yeast extract and 1% of lactose. Optimal conditions for adsorption were 0.6 dry g-biomass, at pH 4.0 and the temperature of $20^{\circ}C$. Adsorption equilibrium reached maximum after 30 min in 400 mg/$\ell$ metal solution. The adsorption capacity (K) of copper was 1.5 times higher than that of cadmium and lead was 1.1 times higher than that of cadmium. from the results obtained in this study, Freundlich adsorption model was applicable for all metals. Adsorption strength (1/n) of heavy metal ions were in the order of cadmium>copper>lead. The adsorption of dried cell for lead, cadmium, and copper was 56.2, 58.0, 55.8 mg/g-biomass, respectively. Pretreatment to increase ion strength was the most effective with 0.1 M NaOH whereas slight difference was found both KOH and $CaCl_2$ upon same concentration. Effective desorption was induced by 0.1 M EDTA for lead and 0.1 M $HNO_2$ for cadmium and copper.

• Resources Recycling
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• v.29 no.5
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• pp.55-63
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• 2020

In order to investigate the separation of Co(II) and Ni(II) by ionic liquids from weak hydrochloric acid solutions, extraction experiments were performed by changing the type and concentration of ionic liquids and the initial pH of the aqueous phase. Two kinds of ionic liquids based on Aliquat 336 were employed in this work; one was synthesized by reacting organophosphorus acids(D2EHPA, PC88A, Cyanex 272, Cyanex 301) with Aliquat 336 and the other was prepared by exchanging the chloride ion of Aliquat 336 with SCN^-. The three types of ionic liquids (ALi-D2, ALi-PC, and ALi-CY272) showed better extraction of Co(II) than Ni(II), and the equilibrium pH was higher than the initial pH. In the case of ALi-CY301, the selectivity of Co(II) and Ni(II) depended on the extraction conditions. In addition, the effect of the addition of TBP to the ionic liquid on the extraction of two metals was also investigated. Employment of ALi-SCN as an extractant resulted in selective extraction of Co(II) and complete separation of the two metal ions was possible.

• Food Science and Preservation
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• v.12 no.4
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• pp.323-328
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• 2005

This study were investigated to analyzed an optimum preparation condition of coating film and its antimicrobial activity on pathogenic and deteriorative bacteria to obtain fundamental data for development of active packaging film using antimicrobial peptide, polysine. In the preparation conditions of coating film, antimicrobial activity was depending on the concentration of polylysine and polyamide respectively, and relatively high activity was obtained in the film prepared with more than $1.0\%$ (w/v) of polylysine, $40\%$ (w/v) polyamide, and more than $50\;{\mu}m$ of film thickness. Concentration of polylysine migrated from coated film to distilled water was reached at the maximum concentration, about 20 ppm after 3 days and in equilibrium after 7 days of soaking in sterilized water. An antimicrobial activity of coated film showed bactericidal effect of about $10^5\;CFU/mL$ comparing with the control against Bacillus cereus having $4.8{\times}10^5\;CFU/mL$ of initial viable cell numbers, and of about $10^2\;CFU/mL$ comparing with the control against Klebsiella pneumoniae having $6.8{\times}10^5\;CFU/mL$ of initial viable cell numbers. Consequently, it was revealed that polylysine coating film has a potential of applicable possibility as antimicrobial packaging film.

• Korean Journal of Plant Resources
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• v.20 no.5
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• pp.398-403
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• 2007

This study was carried out to enhance germination of the seed by different immersion temperatures(15, 20, 25, 30 and $35^{\circ}C$) and times(1, 6, 12, 18, 24, 36 and 48 hours) in Cryptomeria japonica that is a major plantation species in the southern Korea. Optimum germination temperature was between $20^{\circ}C$ and $25^{\circ}C$, and the lowest germination was observed at $35^{\circ}C$ Moisture absorption increased with increasing immersion time as a whole and was high at $30^{\circ}C$ and $35^{\circ}C$. Initial moisture absorption rate was highest at $30^{\circ}C$ whereas was lowest at $15^{\circ}C$ Moisture absorption rate constant was also high at $30^{\circ}C$ and $35^{\circ}C$, however, it was relatively low at $15^{\circ}C$ and $20^{\circ}C$ Germination was the highest when the seeds were immersed for 48 hours at $30^{\circ}C$. In mean germination time(MGT) the seeds immersed for 48 hours at $30^{\circ}C$ did not differ from non-treatment, while the others showed higher values than non-treatment. Consequently, germination could be enhanced and MGT was kept by optimum immersion temperature and time.

• Clean Technology
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• v.25 no.3
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• pp.189-197
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• 2019

In this study an optimization of the preparation conditions of activated carbon with a ternary metal ion material to treat $H_2S$, which is classified as a representative odor substance, was carried out. For a metal ion material for enhancing the adsorption performance of hydrogen sulfide, performance enhancement was confirmed by combining Li and Fe or a ternary combination (K, Li, Fe) based on KI, which is a substance promoting hydrogen sulfide adsorption performance. Also, it was determined by XRD analysis that the reaction of each active substance with $H_2S$ was because of binding. The adsorption performance increased more than 3 times with heat treatment of the adsorbent with nitrogen compared with heat treatment with air. The maximum adsorption constant ($q_m$) value of the optimum adsorbent was 97.07, which is 6 times higher than that of the existing K-based impregnated activated carbon. It was confirmed that the objective adsorption amount ($0.3g\;g^{-1}$) was secured by an equilibrium between the mass transfer rate and adsorption rate. From the results, it was confirmed that the performance improvement was noticeable even when activated carbon with a reagent grade activated carbon particle size was modified. It was confirmed that the adsorption performance exists at high relative humidity levels of 60 and 100%, and the optimized preparation can be applied to a wet process such as a scrubber downstream.

• Journal of the Korean Geotechnical Society
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• v.25 no.2
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• pp.55-66
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• 2009

At the mudstone slope located on the roadside of the Seokri area in Donghae-myeon, Pohang, Gyeongsangbuk-do, this study was performed to analyze the effects of rainfall on the stability of slope through seepage analysis according to the precipitation type of the mudstone slope, referring to the actual case of slope failure. For this, precise geological survey, geophysical exploration and drilling survey for the slope where the failure occurred were performed and followed by analysis of detailed soil layer. For the section where failure surface located, the durability reduction of rocks was measured through slaking/swelling tests and the permeability was measured through in-situ permeability tests for each soil layer. In addition, the change of strength parameter and process of instability were analyzed by back analysis, using Talren 97 and Slope/W programs, in the slope. By applying different precipitation conditions to the geographical conditions of the slope that had actual failure records, the slope stability was analyzed by seepage analysis according to duration of rainfall and rise of groundwater level resulting from the flow of rainfall caused by development of geological structures and the slope surface condition.

• Resources Recycling
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• v.32 no.1
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• pp.21-32
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• 2023

Because the application of lithium has gradually increased for the production of lithium ion batteries (LIBs), more research studies about recycling using solvent extraction (SX) should focus on Li⁺ recovery from the waste solution obtained after the removal of the valuable metals nickel, cobalt and manganese (NCM). The raffinate obtained after the removal of NCM metal contains lithium ions and other impurities such as Na ions. In this study, we optimized a selective SX system using di-(2-ethylhexyl) phosphoric acid (D2EHPA) as the extractant and tri-n-butyl phosphate (TBP) as a modifier in kerosene for the recovery of lithium from a waste solution containing lithium and a high concentration of sodium (Li⁺ = 0.5 ~ 1 wt%, Na⁺ = 3 ~6.5 wt%). The extraction of lithium was tested in different solvent compositions and the most effective extraction occurred in the solution composed of 20% D2EHPA + 20% TBP + and 60% kerosene. In this SX system with added NaOH for saponification, more than 95% lithium was selectively extracted in four extraction steps using an organic to aqueous ratio of 5:1 and an equilibrium pH of 4 ~ 4.5. Additionally, most of the Na⁺ (92% by weight) remained in the raffinate. The extracted lithium is stripped using 8 wt% HCl to yield pure lithium chloride with negligible Na content. The lithium chloride is subsequently treated with high purity ammonium bicarbonate to afford lithium carbonate powder. Finally the lithium carbonate is washed with an adequate amount of water to remove trace amounts of sodium resulting in highly pure lithium carbonate powder (purity > 99.2%).