• Journal of the Korean Wood Science and Technology
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• v.36 no.4
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• pp.37-43
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• 2008

The research attempted to develop an eco-friendly wood adhesive based on vegetable oil (soybean oil), the renewable and sustainable natural resources, using ozonification technology for the chemical structure modification. The soybean oils (SBO) were reacted with $O_3$ at the rate of 7.13 g/h for different times, 15 minutes, 30 minutes, 60 minutes, and 120 minutes. Modified chemical structure of the ozonized SBOs were examined by Fourier transform Infrared (FT-IR) spectrum. The FT-IR spectrum of SBO had an absorbance peak at $3010cm^{-1}$ that is the characteristic peak of the unsaturated double bonds. As ozone treatment time increased, the peak of the double bond was disappeared and aldehyde or carboxyl peak appeared at $1700cm^{-1}$. The dry, wet, and cyclic boiling bond strengths of the ozonized SBO mixed with polymeric diphenylmethane-4, 4-diisocyanate (pMDI) were also investigated. In the dry shear test, all strengths met constantly the standard requirement of $7.0kgf/cm^2$ (KS F3101 2006). The bond strengths gradually increased with increasing ozone treatment time. The highest strength showed at 60 minutes ozone treatment and decreased values at 120 minutes. In the cyclic boiling shear test, 30, 60 and 120 minutes exceeded the standard requirement.

• Journal of Life Science
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• v.11 no.5
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• pp.483-488
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• 2001

The antimicrobial substance produced by Pseudomonas aeruginosa KLP-2 strain was purified and identified. The substance was identified as a pyocyanine by the fast atom bombardment mass(FAB-MS). In physic-chemical properties, the pyocyanine was dark blue needles, and was soluble in various organic solvents such as chlorogorm, methanol, ethanol and ethyl acetae. The pyocyanine possessed a ultraviolet absorbance spectrum in methanol, 0.1 M HCl, and chlorogorm. The maximum absorption peak of the pyocyanine showed at 318 mm in methanol. The molecular formula of the pyocyanine was determined to the $C_{13}$ H$_{10}$ N$_{2}$O and protonate molecular ion species (M+H)$^{+}$ was observed at m/z 211 by FAB-MS. The pyocyanine showed antimicrobial against Bacillus cereus, Bacillus subtilis, Micrococcus luteus, Rodococcus equi, Staphylococcus aureus, Streptococcus faecalis, E. col, Legionella pneumophila, Shigella flexneri Shigella boydii, shgella sonnei, NAG Vibrio cholerae, Vibrio parahaemolyticus, Vibro vulnificus, Yersinia enterocolitica, and Saccharomyces cerevisiae. However, Salmonella spp. Shigela dysenteriae, 3 strains of Pseudomonas aeruginosa, Klebsiela pneumoniae, and Aspergillus niger were resistant to the pyocyanine. The pyocyanine showed the highest antimicrobial activity aganist Legionella pneumophila based on the size of inhibition zone by the disk contained 0.5 $\mu\textrm{g}$ of the pyocyanine.e.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.189-189
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• 2012

Lead sulfide (PbS) nanocrystal quantum dots (NQDs) are promising materials for various optoelectronic devices, especially solar cells, because of their tunability of the optical band-gap controlled by adjusting the diameter of NQDs. PbS is a IV-VI semiconductor enabling infrared-absorption and it can be synthesized using solution process methods. A wide choice of the diameter of PbS NQDs is also a benefit to achieve the quantum confinement regime due to its large Bohr exciton radius (20 nm). To exploit these desirable properties, many research groups have intensively studied to apply for the photovoltaic devices. There are several essential requirements to fabricate the efficient NQDs-based solar cell. First of all, highly confined PbS QDs should be synthesized resulting in a narrow peak with a small full width-half maximum value at the first exciton transition observed in UV-Vis absorbance and photoluminescence spectra. In other words, the size-uniformity of NQDs ought to secure under 5%. Second, PbS NQDs should be assembled carefully in order to enhance the electronic coupling between adjacent NQDs by controlling the inter-QDs distance. Finally, appropriate structure for the photovoltaic device is the key issue to extract the photo-generated carriers from light-absorbing layer in solar cell. In this step, workfunction and Fermi energy difference could be precisely considered for Schottky and hetero junction device, respectively. In this presentation, we introduce the strategy to obtain high performance solar cell fabricated using PbS NQDs below the size of the Bohr radius. The PbS NQDs with various diameters were synthesized using methods established by Hines with a few modifications. PbS NQDs solids were assembled using layer-by-layer spin-coating method. Subsequent ligand-exchange was carried out using 1,2-ethanedithiol (EDT) to reduce inter-NQDs distance. Finally, Schottky junction solar cells were fabricated on ITO-coated glass and 150 nm-thick Al was deposited on the top of PbS NQDs solids as a top electrode using thermal evaporation technique. To evaluate the solar cell performance, current-voltage (I-V) measurement were performed under AM 1.5G solar spectrum at 1 sun intensity. As a result, we could achieve the power conversion efficiency of 3.33% at Schottky junction solar cell. This result indicates that high performance solar cell is successfully fabricated by optimizing the all steps as mentioned above in this work.

• Journal of Sensor Science and Technology
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• v.6 no.3
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• pp.214-220
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• 1997

A thin film optical waveguide sensor has been developed to measure and analyze quantitatively some inherent optical properties of biochemical substances. In this paper, two different kinds of thickness of thin film waveguide were prepared by RF sputtering of Corning-7059 glass(n = 1.588 at ${\lambda}=\;514nm$, Ar laser) on Pyrex glass substrates. We made a sensing membrane coated on the thin film waveguide with the poly(vinyl chloride-co-vinyl acetate-co-vinyl alcohol) (91 : 3 : 6) copolymer membrane based on $H^{+}$-selective chromoionophore and $K^{+}$-selective neutral ionophore and then proposed the thin film opptical waveguide ion sensor which can select a potassium ion. This sensor based ell the absorbance change by utilizing chromoionophore and neutral ionophore, which changes their absorption spectrum in the UV-vis region upon complexation of the corresponding ionic species, have been reported. The sensitivity dependence of the proposed sensor on interaction length, waveguide thickness, and content of a chromoionophore was investigated. This sensor has the measurement range of $10^{-6}M{\sim}1M$ for $K^{+}$ concentration and 90% response time of duration within 1 min. Also, our thin film optical waveguide sensor using the evanescent field was investigated as compared with conventional transmission sensor or optode sensor by the optical fiber. The sensitivity of thin-film waveguide $K^{+}$ sensor is higher than that of the conventional transmission sensor. The proposed sensor is expected to be useful to biochemical, medical, environmental inspection and so on.

• Korean Journal of Soil Science and Fertilizer
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• v.42 no.4
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• pp.274-279
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• 2009

To determine the critical level for optimum maturity of flue-cured tobacco leaves (KF118) at the stalk position from cutter to tips, the reflectance index using ground-based remote sensors and chlorophyll meter were investigated. The sensors estimated were Crop $Circle^{TM}$ (Holland Scientific), Green $Seeker^{TM}$ (Ntech Industries), Spectroradiometer (LICOR, LI-1800), Chlorophyll meter (SPAD502, Minolta), and Field $Scout^{TM}$ Chlorophyll meter (CM-1000, Spectrum). The L, a, b values and greenness for flue-cured leaf were measured and estimated for correlation with sensor's measurement of harvested leaf. On a reflectance curve of 340nm~1100 nm, the reflectance peaks on 550nm and 675 nm for the harvested leaf were lowered as change from light green to darker green. Darker green leaf harvested produced darker flue-cured leaf. The reflectance at 675 nm for flue-cured leaf decreased as greenness increased in the harvested leaf. This result means that the red edge band of 675 nm wavelength is related to the absorbance of chlorophyll for photosynthesis. The greenness of flue-cured leaf showed significantly positive correlation with the entire reflectance indexes for harvested leaf while the L value by colorimeter showed negative correlation with greenness of cured leaf. The critical level for optimum maturity of harvested leaf were less than 22, 135, and 0.43 for SPAD reading, CM-1000 reading, and gNDVI by Crop $Circle^{TM}$, respectively. Consequently, ground-based remote sensing providing a non-destructive real-time assessment of plant greenness could be a useful tool in the selection of optimum maturity of flue-cured tobacco leaves in relation to high quality of flue-cured tobacco.

• Korean Journal of Plant Resources
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• v.24 no.5
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• pp.499-506
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• 2011

The purpose of this study was to search available resources for new natural colorants. The extraction efficiency of colorants from black cowpea seed coats and their storage stability were examined according to the various extraction and storage conditions in this study. The results obtained were as follows: the optical density (O.D.) values of the extracted colorants increased with increasing extract time and temperature. Extraction at pH 4 was seen to be the most efficient among the various pH conditions. The color of the extract solutions were seen to change with variation in pH, for example, anthocyanins display color changes from orange-red, to orange, to blue, to greenish-blue at pH 3.0, 4.0-6.0, 7.0 and 9.0-11.0, respectively. The color changes of the extract solutions over various storage periods were determined using UV/Vis spectra these color changes indicate characteristic absorption patterns and a discoloration index which indicates the rate of absorbance (532 nm/454 nm). Methionine addition influenced the storage stability of the colorant solutions and this addition led to better storage stability than non-addition. In paper chromatography of juice extracted colorant, a long stripe was seen on development. Among three colorants obtained via paper chromatography according to development rate, at least two different colorants were mixed indicated by the appearance, or not, of a shoulder at 552 nm depending on the extent of development.

• Journal of the Microelectronics and Packaging Society
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• v.25 no.3
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• pp.1-5
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• 2018

In this study, the effects of indium (In) doping in InGaN/GaN multi quantum well (MQW) on photoelectrochemical (PEC) properties were investigated. Each quantum well (QW) layer with controlled In content were grown on sapphire substrate. Before growth of MQW, GaN growth consisted of various stages in the following order: buffer GaN growth, undoped GaN growth, and Si-doped n-type GaN growth. Absorbance of InGaN/GaN MQW having different In composition was higher than that of the InGaN/GaN MQW having a constant In composition. It indicates that InGaN layer having different In composition absorbs light having a broad spectrum energy. These results are in agreement with those in photoluminescence (PL). After evaluation of PEC properties, it demonstrated that InGaN/GaN MQW having different In composition was improved InGaN/GaN MQW having constant In composition in PEC water splitting ability.

• Journal of the Korean Applied Science and Technology
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• v.37 no.5
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• pp.1138-1150
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• 2020

In this study, an experiment was conducted to develop a sunscreen with antioxidant effects by simultaneously investigating the antioxidant and UV protection capabilities of various plant extracts. First, to investigate the UV-blocking ability of 33 kinds of plant extracts, the absorbance spectrum between the UV wavelength of 280 to 400 nm was investigated. Arrowroot, graviola, wheat sprout, sangbaek skin, thorn meal, lacquer, etc. 11 species were selected. The total polyphenol content, total flavonoid content, and DPPH radical scavenging activity of the selected plant extracts are measured to examine the degree of antioxidant activity, and from this, it is a plant extract that has excellent UV protection and antioxidant activity at the same time. The species was selected. A gel-shaped cream is prepared by mixing the selected gold, hops, and licorice extracts in a ratio of 1:1:1, and the UV protection effect of this cream is measured when the cultured cells are irradiated with UV rays. Determined by the method. As a result of the study, it was confirmed that the selected mixture of plant extracts complemented each other in terms of ultraviolet absorption ability and increased cell damage protection effect. Through these results, it was confirmed that it was possible to develop a sunscreen with an antioxidant effect if the antioxidant and sunscreen capabilities of various plant extracts were determined at the same time.

• Applied Chemistry for Engineering
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• v.10 no.6
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• pp.857-862
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• 1999

Aminated poly(ether sulfone)(APES) was prepared by amination of nitrated poly(ether sulfone)(NPES) after poly(ether sulfone)(PES) was nitrated with mixed acid of nitric acid and sulfuric acid(sulfuric acid is a catalyst). As a results of the FT-IR spectrum analysis, the nitration of PES was confirmed by the bands of asymmetric stretching and symmetric stretching of $NO_2$ group at 1537 and $1351cm^{-1}$, respectively. Also when the NPES was aminated, it was disappeared to absorbance peaks of $NO_2$ group. And It was confirmed by the bands of asymmetric stretching and symmetric stretching of $NH_2$ group at 3470 and $3374cm^{-1}$, respectively. The optimum condition of the nitration on PES(5 g; 21.55 mmol.) was 12 hr of reaction time, $120^{\circ}C$ of reaction temperature, nitric acid of 28.00 mmol. and sulfuric acid of 52.00 mmol. As a result of the elemental analysis of APES, reapeating unit per amine groups were induced to 0.89. The adsorption rate of NO gas was lower than that of silica gel and active carbon. But the adsorption capacity of NO gas was higher than that of these. When the APES was absorbed to NO gas, the chemical adsorption rate was lower than the physical adsorption rate. But the chemical adsorption capacity of it was higher than physical adsorption capacity.

• The Korean Journal of Food And Nutrition
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• v.27 no.3
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• pp.339-347
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• 2014

This study investigated the classification of olive oils that are mainly distributed in Korea via imports. The fatty acid contents, degree of color, pigments, anti-oxidants, and sterol contents are analyzed on the different types of olive oil as follows: 10 kinds of extra virgin olive oil, 5 kinds of pure olive oil, and 5 kinds of refined olive-pomace oil. As a result of fatty acid analysis, the majority of oleic acid ($C_{18:1}$) and palmitic acid ($C_{16:0}$), and minority of linoleic acid ($C_{18:2}$) and stearic acid ($C_{18:0}$) were detected without any significant differences between the grades of olive oils. The UV spectrum is related to the ${\Delta}K$, and it is a part of the analysis factor for the purity and degree of degradation of the oil. Extra virgin olive oil had ${\Delta}K$ of almost 0, pure olive oil had 0.07~0.12, and refined olive-pomace oil had 0.1~0.13. These differed from extra virgin oil, and the pure or pomace oil ${\Delta}K$ had a confirmed distinct difference. The color degrees of chlorophyll with a low $L^*$ value and $(-)a^*$ (green) and carotenoid with $(+)b^*$ (yellow) were confirmed to have correlation between extra virgin and other olive oils. To compare chlorophyll and carotenoid as natural pigment in olive oils, 417 nm and the ratio of the absorbance at 480 nm (417/480) was calculated at 1.62 of extra virgin, 1.85 of pure olive oil, and 3.32 of refined olive-pomace oil. Therefore, it will be possible to distinguish when the extra virgin or pure olive oil are mixed with olive-pomace oil. The total amount of tocopherol, an anti-oxidant, were 19.06 in extra virgin, 10.91 in pure olive oil, and 27.88 in refined olive-pomace oil. The high content of tocopherol in pomace oil caused recovery of solvent extraction from olive pulp. Thus, extra virgin oil and pure olive oil were distinguished by olive-pomace oil. Polyphenol compounds in extra virgin olive oil measured high only in ferulic acid with 0.543 mg/kg, caffeic acid with 0.393 mg/kg, and other vanillic acid, vanillin, and p-coumaric acid had similar amount of 0.3 mg/kg. All grade of olive oils had the highest ${\beta}$-sitosterol content. Af (Authenticity factor) value were estimated with campesterol and stigmasterol content ratio (%). Af value was 19.2 in extra virgin olive oil, 17.1 in pure olive oil, 16.9 in refined olive-pomace oil, which were distinctive from sunflower oil with 3.7, corn oil with 2.4, and soybean oil with 2.0. It can provide important indicator of olive oil adulteration with other cheap vegetable oils. The results of this study can be used as a database for the classification of olive oil grade and distinguishing between the different types of oils.