• Journal of the Korean Society of Food Science and Nutrition
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• v.18 no.4
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• pp.398-402
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• 1989

Moisture sorption and cooking properties of two varieties of Korean soybean(Jangyup and Whangkeum) were studied. When soybean was stored under the various relative humidities (RH) of 33-86% at 16'E for 125hours, its sorption behaviors were divided into two : desorption at the RHs of 33 and 44% and adsorption at the RHs of above 55%. The sorption rate was decreased rapidly during storage. In comparisons with only storage humidities, the sample stored at higher RH held the higher sorption rate. The relationships between storage time and sorption rate were applied well to the equation, log dw/dt= b log t+ log a, where w is the moisture content(%, db), t is time(hour) and a and b are the parameters which were calculated from the experimental data. The calculated moisture contents from the equation agreed well with the measured moisture contents. On the other hand, the cooking degrees of soybean which was steamed in an autoclave at $106-121^{\circ}C$ were compared by the maximum cutting forces. The cooking time to attain the same degree of cooking decreased logarithmically as the cooking temperature increased. The z-values which were calculated from the time-temperature combinations that gave the same degree of cooking for Jangyup and Whangkeum were $13.3^{\circ}C$ and $12.8^{\circ}C$ respectively.

• Analytical Science and Technology
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• v.8 no.1
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• pp.1-7
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• 1995

Spectrophotometric determination of U(VI) and Th(IV) by Flow injection method is described. Chrome Azurol S forms water soluble complexes with U(VI) and Th(IV) in the presence of cethyltrimethylammonium bromide. The maximum adsorption of U(VI) and Th(IV) complexes are at 600nm with molar absorptivity of $2.3{\times}10^5Lmol^{-1}cm^{-1}$ and 611nm with molar absorptivity of $3.8{\times}10^5Lmol^{-1}cm^{-1}$ in acetate buffer medium having pH 5.0 and 5.5. The calibration curves of U(VI) and Th(IV) are linear over the range of 0.1~0.8ppm and the correlation coefficients are ca. 0.9960 and 0.9930 respectively. The detection limits(S/N) are 20ppb for U(VI) and 15ppb for Th(IV). The relative standard deviation are ${\pm}1.8%$ for U(VI) and ${\pm}2.1%$ for Th(IV). The sample throughput was ca. $50hr^{-1}$.

• Analytical Science and Technology
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• v.27 no.6
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• pp.357-363
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• 2014

Isoprene is a one of the biogenic volatile organic compounds (BVOCs) and it is known as a source of the tropospheric ozone and formaldehyde. In addition, isoprene is a trace component of the exhaled breath and it is a potential biomarker for the diagnosis of diseases such as lung cancer. In these regards, isoprene gas standards are required for the accurate measurement of isoprene in air samples. To establish a standard for isoprene gas, gravimetric preparation and characterization of primary gas standards were studied. The primary gas standards were produced independently in 4 aluminum cylinders and concentrations were examined by GC-FID. As a result, the uncertainty of the gravimetric preparations including purity of the raw material was 0.01% and reproducibility of the preparation of independent 4 cylinders was 0.08%. The primary gas standards for isoprene showed 14 months of long-term stability. The relative expended uncertainty of 2.8% (95% of confidence level, k=1.96) was assigned to the certified value of 10 ${\mu}mol$/mol level of isoprene based on the quantitative evaluation of the purity, weighing, reproducibility, adsorption and long-term stability.

• Applied Chemistry for Engineering
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• v.19 no.5
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• pp.574-581
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• 2008

The optimum regeneration conditions for the regeneration of three way spent catalysts (TWCs), which were taken from automobiles with different driving conditions, were investigated to evaluate the suitability as alternative catalysts for removing VOCs. The spent catalysts were washed with five different acids ($HNO_3$, $H_2SO_4$, $C_2H_2O_4$, $C_6H_8O_7$, and $H_3PO_4$) to remove contaminants and examine the optimum conditions for recovering the catalytic activity. The physicochemical properties of spent and its regenerated TWCs were evaluated by using nitrogen adsorption-desorption isotherms, XRD, and ICP. The relative atomic ratios of contaminants and platinum group metals (PGMs) of the spent TWCs were greatly dependent on the placed positions. The main contaminants formed were lubricant oil additives and metallic components. Also, the regeneration treatment increased the PGMs ratio, BET surface area, and average pore diameter of TWCs. The catalytic activity results indicated that the spent TWCs have the possibility for removing VOCs. Moreover, the employed acid treatments greatly enhanced the catalytic activity of the spent TWCs. Especially, nitric and oxalic acids provided the most improvement in the catalytic behavior. The catalytic activities of the regenerated TWCs were significantly influenced by the containing platinum ratios rather than the removal ratios of contaminants and the changes in the structural properties offered by the acid treatments.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.3
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• pp.316-322
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• 2006

The current study evaluated the technical feasibility of the application of $TiO_2$ photocatalysis for the removal of nocotine which has well known as a representative material of environmental tobacco smoke(ETS). Four different preliminary experiments were performed for the evaluation of nicotine removal using photocatalyst-coated construction materials. The photocatalytic removal of nicotine was investigated for five parameters: dry condition of coating tiles, type of coating sol, number of coatings, relative humidity(RH), and input concentrations. Prior to performing the parameter tests, adsorption of nicotine onto the current experimental system was surveyed. All the variables tested in the present study exhibited to influence the photocatalytic decomposition of Nicotine. A dry condition of high temperature and short dry period presented higher photocatalytic oxidation(PCO) efficiency compared to that of low temperature and long dry period. ST-KO3 sol showed higher decomposition efficiency than E-T Sol. The PCO efficiency increased as the number of coating increased. High humidity and low input concentrations exhibited higher PCO efficiency. Consequently, it is noted that the five parameters tested in the present study should be considered for the application of photocatalyst-coated construction materials in cleaning nicotine in ETS.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.34 no.1
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• pp.57-62
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• 2008

No matter how small amount of heavy metals it may be cause skin allergies through percutaneous adsorption when existing in cosmetic products as impurities. In order to develop a highly sensitive method for simultaneous determination of $Pb^{2+},\;Fe^{2+},\;Cu^{2+},\;Ni^{2+},\;Zn^{2+},\;Co^{2+},\;Cd^{2+},\;and\;Mn^{2+}$ in coloring agents and cosmetic products with rapidity and accuracy, we carried out the determination on ion chromatography. All of these metals are well separated through a bifunctional ion-exchange column(IonPac CS5A) and detected by post-column reaction and spectrophotometric detection. The calibration graphs are linear($r^2>0.999$) in the range $0.1{\sim}1000{\mu}g/mL$. Detection limits for 200 ${\mu}L$ of sample solution are at the level of ${\mu}g/L$, which is sufficient for judging whether the product is safe or not. The relative standard deviations(RSDs) of the retention time and the peak area are less than 0.21 and 1.24%, respectively. The recovery rates are $97{\sim}104%$. The new method was applied to analyze the amount of heavy metals which were contained in 22 cosmetic products and 11 coloring agents.

• Korean Journal of Materials Research
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• v.10 no.10
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• pp.671-676
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• 2000

$BaTiO_3$-based ceramics with partially oxidized Ti powders were prepared by sintering at $1350^{\circ}C$ for 1 h in v vacuum, and then heated in air. In this study, the effect of partially oxidized Ti powders on electrical properties and microstructures of $BaTiO_3$-based ceramics was investigated. It was found out that the semiconductive $BaTiO_3$-based ceramics beζame to show excellent PTCR (more than $10^5$) characteristic by adding 5~7 vol% of partially oxidized Ti powder. Also, it was found out that the sintered compact had extremely porous and fine-grained microstructure. The relative density and grain size of sintered compact with 5 vol% of partially oxidized Ti powders were 54% and $1.3\;{\mu\textrm{m}}$, respectively. The mechanism for the development of PTCR characteristic in $BaTiO_3$-based ceramics with partially oxidized Ti powders due to the adsorption of oxygen at grain boundaries, and could be explained, based on Heywang model.

• Membrane Journal
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• v.28 no.6
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• pp.379-387
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• 2018

This study was conducted to improve the membrane characteristics and performance by increasing hydrophilicity by adding additives to the ultrafiltration polysulfone (PSf) hollow fiber membrane. The mixed matrix membranes (MMMs) were prepared by dispersing 15 nm of fumed silica (FS) in the spinning solution at 0.1, 0.3 and 0.5 wt%. SEM analysis was carried out to confirm the cross-section and surface condition. It was confirmed that mean pore radius of the hollow fiber increased by 4 nm as FS was added. In addition, contact angle measurement was carried out for the hydrophilicity analysis of hollow fiber membranes, and it was confirmed that the hydrophilicity of MMMs were increased by adding of FS. In the case of water permeability, the membrane including FS showed 91~96 LMH and showed 5~11% more increase than PSf membrane. In the antifouling performance test, relative flux reduction ratios of FS mixed hollow fiber membranes were lower than that of PSf membranes, and it was confirmed that increase of hydrophilicity hinders adsorption of hydrophobic BSA on the membrane surface.

• Ecology and Resilient Infrastructure
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• v.10 no.3
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• pp.64-72
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• 2023

Biopolymer is a versatile material used in food processing, medicine, construction, and soil reinforcement. 𝛽-glucan is one of the biopolymers that improves the soil water content and ion adsorption in a drought or toxic metal contaminated land for plant survival. We analyzed drought stress damage reduction in sweet potatoes (Ipomoea batatas L. cv. Sodammi) by measuring the growth and major protein expression and activity under 𝛽-glucan soil amendment. The result showed that sweet potato leaf length and width were not affected by drought stress for 14 days, but sweet potatoes grown in 𝛽-glucan-amended soil showed an effect in preventing wilting caused by drought in phenotypic changes. Under drought stress, sweet potato leaves did not show any changes in electrolyte leakage, but the relative water content was higher in sweet potatoes grown in 𝛽-glucan-amended soil than in normal soil. 𝛽-glucan soil amendment increased the expression of plasma membrane (PM) H⁺-ATPase, but it decreased the aquaporin PIP2 (plasma membrane intrinsic protein 2) in sweet potatoes under drought stress. Moreover, water maintenance affected the PM H⁺-ATPase activity, which contributed to tolerance under drought stress. These results indicate that 𝛽-glucan soil amendment improves the soil water content during drought and affects the water supply in sweet potatoes. Consequently, 𝛽-glucan is a potential material for maintaining soil water contents, and analysis of the major PM proteins is one of the indicators for evaluating the biopolymer effect on plant survival under drought stress.

• Analytical Science and Technology
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• v.22 no.3
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• pp.219-227
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• 2009

The steroid compounds in Rhodiola sachalinensis were determined with adsorption column chromatographic purification and GC/MS. Sterols were extracted by sonication and Soxhlet with ethanol and dichloromethane, respectively. The extract was partitioned with chloroform and water using liquid-liquid extraction, and purified with a silica column after the sterols had been converted to the corresponding silyl derivatives with BSTFA. Eighteen free sterols, including $\beta$-sitosterol, stigmasterol and cycloartenol, and nine sterol conjugates were found from Rhodiola sachalinensis by GC/MS. Among them, cholest-5-ene-3-ol, cholesterol, stigmasterol, $\beta$-sitosterol were confirmed and quantified with sterol standards. Most sterols were presented in the chloroform part, with $C_{29}$ being the most abundant group in this sterol group. $\beta$-sitosterol was the most abundant compound with a relative content of 45.94% followed by ergost-7-ene-3-ol (11.33%), 4,14-dimethyl-ergosta-8,24(28)-diene-3-ol (7.07%), stigmasterol (6.09%), cycloartenol (5.43%) and 4-methyl-cholest-5-ene-3-ol (5.39%).