• Journal of the Korean Chemical Society
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• v.37 no.1
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• pp.55-61
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• 1993

An application of the optoacoustic detection method to investigate the catalytic effect of a perovskite, $Gd_{1-x}Sr_xCoO_{3-y}$ (x = 0.00, 0.25, 0.50, 0.75) system, in the oxidation reaction of CO is described. The optoacoustic signals Of $CO_2$ produced from the oxidation reaction were measured for differing x values in $Gd_{1-x}Sr_xCoO_{3-y}$. By monitoring optoacoustic signals with respect to the time, the concentration ratios of CO and $O_2$, and the temperature, the kinetic information on the catalytic properties of the perovskite for CO oxidation reaction can be obtained. The effect of Sr substitution in $Gd_{1-x}Sr_xCoO_{3-y}$ has been found to show the maximum catalytic effect at x = 0.25 and the substantial increase in catalytic activity at temperatures above 200$^{\circ}C$. It demonstrates that the optoacoustic detection method allows the investigation of the integrated catalytic effect not only for the oxidation reaction of CO, but also for many reactions, in general, by continuously and directly detecting the species associated with the reactions.

• Food Science and Preservation
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• v.8 no.1
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• pp.37-46
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• 2001

To examine the effects of edible coatings on the quality of fresh-cut fruits, Shingo pear was coated with several concentration of albumin, WSF(whole soy flour), dextrin and SPE (sucrose polyester) solution and quality characteristics, sensory evaluation and respiration rate were determined during storage at $4^{\circ}C$ for 10 days. Weight loss rate was reduced in coated fresh-cut pears. 2% dextrin and 1% WSF for pears were more effective in reducing weight loss rate during storage. In preventing the browning of fresh cut fruits, browning was inhibited by coating with 0.5% WSF, 1% albumin, 3% dextrin for pears. Compared with non-coated pears, 0.5% WSF, 1% albumin and 3% dextrin coating were effective in inhibiting the color changes. Even if hardness had a tendency to decrease in coated and no71-coated fruits during storage dextrin coating induced texture softening in fresh-cut pears. The changes in decrease of titratable acidity and vitamin C content and increase of pH and soluble solid were recessed by coatings but there was no differences in accordance with coating materials. Sensory evaluation of coated pears was conducted in according to coating materials and concentrations. Pears coated with 0.5% albumin, 4% dextrin, 1.0% SPE and 0.5% WSF recorded high sensory score. Among the tested coating materials and concentrations, 4% dextrin was the best in all organoleptic quality of coated pears. Respiration rate was repressed by coating with WSF and dextrin in pears.

• Korean Chemical Engineering Research
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• v.51 no.4
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• pp.438-442
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• 2013

The study of bioproduct production from inexpensive biomass such as marine biomass has recently attracted considerable attention. Because, marine biomass which compared to land biomass, it can be grown rapidly and is easily cultivated without the need for expensive equipment. In addition, the carbohydrate contents are similar or higher than land biomass such as woody biomass and can be easily converted to chemicals through proper chemical processes. In the production of various biochemicals from marine biomass, levulinic acid is a highly versatile chemical with numerous industrial uses and has the potential to become a commodity chemical. It can be used as a raw material for resins, plasticizers, textiles, animal feed, coatings and antifreeze. In this study, experiments were carried out to determine the optimum conditions of temperature, acid concentration and reaction time for production of levulinic acid from marine biomass, Gelidium amansii, using two-step treatment. In the first hydrolysis step, solid-state cellulose which was used to produce ethanol by fermentation and liquid-state galactose which used to produce bioproduct such as levulinic aicd were obtained through acid soaking. In the second hydrolysis step, the liquid-state galactose was converted into levulinic acid via a high-temperature reaction in a batch reactor. As a result, the overall production yield of Gelidium amansii to levulinic acid in the two-step acid hydrolysis was approximately 20.6% on the initial biomass basis.

• Journal of the Korean Society of Food Science and Nutrition
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• v.34 no.2
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• pp.236-242
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• 2005

To develop a new detection method using irradiation-induced volatile marker compounds of red pepper powder (RP), the volatile compounds of irradiated RP (0, 1, 3, 5, and 10 kGy) were analyzed by purge and trap (P&T)/solid phase microextraction (SPME)/gas chromatography/mass spectrometry (GC/MS) methods. A total of 51 and 31 compounds were detected in IRP by SPME and P&T methods, respectively. Among these, 25 compounds, which were composed of 4 hydrocarbons, 7 aldehydes, 1 ketone, 3 alcohols, 4 aromatic compounds, 2 esters and 4 miscellaneous compounds, showed irradiation dependent manner with significant positive correlation (p<0.01 or p<0.05) between irradiation dose and relative concentration. However, all compounds except 1,3-bis(1,1-dimethylethyl)benzene were not suitable as marker compounds because of their low determination coefficients ($R^2$<0.80) between irradiation dose and their concentrations, and detectablilty in nonirradiated sample. Therefore, only one compound, 1,3-bis(1,1-dimethylethyl)benzene, was tentatively identified as a volatile marker compound to detect irradiated RP.

• Journal of the East Asian Society of Dietary Life
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• v.26 no.1
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• pp.80-87
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• 2016

This study was conducted to investigate the physicochemical properties and antioxidant activities of strawberries from different cultivars and ripening stages grown in Korea. Fragaria ananassa 'Seolhyang' and 'Janghee' in unripe and ripe stages were used in this study. Overall, firmness of unripe fruits was harder than that of ripe fruits, whereas firmness of 'Seolhyang' was harder than that of 'Janghee'. There was no significant difference in soluble solid content (SSC) between the two cultivars, whereas SSC increased when fruits matured. Total phenolic and flavonoid concentrations of 'Seolhyang' were greater than those of 'Janghee' cultivar. However, there was no ripening effect on total phenolic concentration in both cultivars. Total anthocyanin concentrations of the two cultivars were higher in ripe stage while that of 'Janghee' was greater than that of 'Seolhyang' statistically. Total antioxidant activities of 'Seolhyang' were greater than those of 'Janghee'. Total phenolic and flavonoid concentrations were highly correlated with antioxidant activities but there was no correlation between total anthocyanins and total antioxidant activities.

• YAKHAK HOEJI
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• v.52 no.6
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• pp.419-425
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• 2008

A qualitative and quantitative analytical method was developed for detection of methamphetamine (MA) and its main metabolite amphetamine (AM) in oral fluid. Oral fluids of eleven drug abusers were provided by Police, specimens were collected by stimulation with a cotton swab treated with 20 mg of citric acid ($Salivette^{(R)}$; Sarstedt, USA). As the preliminary test, oral fluid samples were screened for amphetamines by Fluorescence Polarization Immunoassay (TDxFLx, Abbott Co.). Extraction for MA was performed using solid-phase extraction (SPE) by $RapidTrace^{TM}$ (Zymark, USA) with mixed mode cation exchange cartridge, CLEAN $SCREEN^{(R)}$ (130 mg/3 ml, UCT) after dilution with phosphate buffer. Samples were evaporated and derivatized by pentafluoropropionic acid anhydride (PFPA). Quantitation of MA and AM was performed by gas chromatography-mass spectrometry (GC-MS) using selective ion monitoring (SIM), the quantitation ions were m/z 204 (MA), 208 (MA-$D_5$), 190 (AM) and 194 (AM-$D_5$). The selectivity, linearity of calibration, limit of detection (LOD) and quantification (LOQ) within- and between day precision, accuracy and recoveries were examined as parts of the method validation. All oral fluid samples gave positive results to immunoassay for MA (cut-off level, 50 ng/ml as d-amphetamine). Concentrations of MA and AM by GC-MS in eleven samples were ranged 104.2${\sim}$4603.3 ng/ml and 32.4${\sim}$268.6 ng/ml, respectively. Extracted calibration curves of MA and AM were linear over the two concentration range of 1${\sim}$100 and 50${\sim}$1000 ng/ml with correlation coefficient of above 0.999. LOQ of MA and AM was 1 and 3 ng/ml, respectively. The intraand inter-day run precisions (CV) for MA and AM were less than 10%, and the accuracies (bias) for MA and AM were also less than 10% at the two different concentrations 5 and 100 ng/ml at low calibration range, 50 and 1000 ng/ml at high calibration range. The absolute recoveries of MA and AM at low and high calibration ranges were more than 82% and 75%, respectively. In this study the qualitative and quantitative analytical method of MA in oral fluid was established. Oral fluid testing may detect drug use in past hours because of its shorter detection window than urine, and be useful in post-accident situations. So oral fluids will be most useful for testing drug abuse in the driving under the influence of drug (DUID) as the alternative specimens of urine.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.30 no.2
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• pp.279-294
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• 2004

This study described about a liquid crystalline technology that is used in cosmetics industry. Various intermediate phases may exist between solid and liquid. At high surfactant concentration, several liquid crystalline phases can be made to have formed. Although molecular arrangement with crystallization is not regular, it is known that more relative regular state is liquid crystalline or meso-phase than liquid phase. Usually, it described in detail about manufacturing method that explained about a kind of liquid crystalline technology in cosmetics, a new liquid crystalline technology, and makes liquid crystalline. Specialty, it introduced about kind of special an emulsifier to form liquid crystalline. There were hydrogenated lecithin, ceramide, dipalmitoylhydroxyproline, DEA-cetyl phosphate, Gemini-surfactant in representative raw material to form liquid crystalline. Liquid crystalline extent that used polarization microscope to observe formation, and appears best from 400times, 600times, 1,000times well appeared. Also, droplet particle size that liquid crystal is made best 1.0-10.0$\mu\textrm{m}$ be. General emulsion more than superior result that measures the skin moisturizing effect to take advantage of liquid crystalline technology of vitamin was seen. As presence at a clinical result, wave and general emulsion more than superior result (more than 20%) that measures skin moisturizing effect about liquid crystalline of vitamin B$\_$5/ were seen (ANOMA t-test, p<0.05)

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.10 no.4
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• pp.292-296
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• 2000

Mechenochemical reaction by planetary type ball mill is applied to prepare $Sm_2$$Fe_{17}$$N_{x}$ permanent magnet powders. Starting from pure samarium and iron powders, the formation process of hard magnetic $Sm_2$$Fe_{17}$$N_{x}$ phase by ball milling and a subsequent solid state reaction were studied. At as-milled stage powders were found to consist of amorphous Sm-Fe and $\alpha$-Fe phases in all composition of $Sm_2$$Fe_{100-x}$(x = 11, 13, 15). The dependence of starting composition of elemental powder on the formation of Sm-Fe intermetallic compound was investigated by heat treatment of as-milled powders. When Sm concentration was 15 at%, heat-treated powder consists of mostly $Sm_2$$Fe_{17}$$N_{x}$single phase. For synthesizing of hard magnetic $Sm_2$$Fe_{17}$$N_{x}$ compound, additional nitriding treatment was carried out under $N_2$gas atmosphere at $450^{\circ}C$. The increase in the coercivity and remanence was parallel to the nitrogen content which increased drastically at first and then gradually as the nitriding time was extended. The ball-milled Sm-Fe-N powders were expected to be prospective materials for synthesizing of permanent magnet with high performance.

• Journal of the Korean Magnetics Society
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• v.14 no.6
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• pp.219-223
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• 2004

L $i_{0.5}$F $e_{2.5-{\chi}}$R $h_{\chi}$ $O_4$ ($\chi$ = 0.25, 0.50, 0.75, 1.00) has been prepared by solid state reaction. Crystallographic and magnetic properties were investigated by Mossbauer spectroscopy, SQUID magnetometry, and x-ray diffraction. The crystal structure is found to be a cubic spinel structure with space group Fd3m for all the samples. The lattice constant $a_{0}$ increases from 8.3365 $\AA$ to 8.3932 $\AA$ with increasing Rh concentration $\chi$. The migration of Li ion has been confirmed by x-ray patterns and the results of applied field Mossbauer analysis. The temperature dependence of the absorption area of each site was analyzed with the Debye model for the recoil-free fraction. The Debye temperature for the octahedral sites is almost as large as for the tetrahedral sites, thereby suggesting similar inter-atomic binding forces for the octahedral and the tetrahedral sites. The saturated magnetic moment and the Mossbauer spectra taken at 4.2 K under the applied field (6 T) show that the spin structure of L $i_{0.5}$F $e_{2.5-{\chi}}$R $h_{\chi}$ $O_4$ is compatible with the collinear Neel Model.

• Journal of Radiation Protection and Research
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• v.16 no.2
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• pp.27-39
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• 1991

The diffusion of Sr-85, Cs-137, Co-60 and Am-241 in compacted domestic bentonite was studied, using a diffusion cell unit in which diffusion took place axially from the center of cylindrical bentonite sample body. The effects of compaction density and heat-treated bentonite on diffusion were analysed. And the diffusion mechanism of radionuclide was also analysed by evaluating the measured diffusivity of anion Cl-36. The apparent diffusivities obtained for Sr-85, Cs-137, Co-60 and Am-241 were $l.07{\times}10^{-11},\;6.705{\times}10^{-13},\;l.226{\times}10^{-13}\;and\; l.310{\times}10^{-14}m^2/sec$, respectively. When the as-pressed density of bentonite increased from $1.8\;to\;2.0g/cm^3$, the apparent diffusivity of Cs-137 decreased by quarter. In the case of bentonite heat-treated to $150^{\circ}C$, no significant change in diffusivity was observed, which showed the possibility that the domestic bentonite could be used as a chemical barrier to retard the radionuclide migration at below $150^{\circ}C$. From the calculated pore and surface diffusivity, the surface diffusion due to the concentration gradient of radionuclide sorbed on the solid phase was found to dominate greatly in total transport process.