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

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.19 no.6
• /
• pp.646-651
• /
• 2018

This paper reports that the electronic properties at a $P3HT/TiO_2$ interface associated with exciton dissociation and transport can be tailored by the insertion of a graphene quantum dot (GQD) layer. For donor/acceptor interface modification in an $ITO/TiO_2/P3HT/Al$ photovoltaic (PV) device, a continuous GQD film was prepared by a sonication treatment in solution that simplifies the conventional processes, including laser fragmentation and hydrothermal treatment, which limits a variety of component layers and involves low cost processing. The high conductivity and favorable energy alignment for exciton dissociation of the GQD layer increased the fill factor and short circuit current. The origin of the improved parameters is discussed in terms of the broad light absorption and enhanced interfacial carrier transport.

• Journal of Sensor Science and Technology
• /
• v.1 no.2
• /
• pp.107-116
• /
• 1992

The optimum base material was selected by the thermal decomposition temperature of $CH_{3}CN$ on the surface of various metal oxides, and the FT-IR analyses of its products. On the surface of $SnO_{2}$, $CH_{3}CN$ was initiated to decompose at $130^{\circ}C$ and produced a lot of products at $200^{\circ}C$. The products from the reaction were found to be $H_{2}O$, $NH_{3}$ and CO, but $N_{2}O$ has started to produce at $320^{\circ}C$. The sensing characteristics of $SnO_{2}$ sensor to $CH_{3}CN$ are influenced by the absorbed species which are produced by the oxidation reaction of $CH_{3}CN$ on the surface of metal oxide. The gaseous species produced from the surface of sensing material in the oxidation reaction were found to be CO, $NH_{3}$, $H_{2}O$ and $NO_{x}$ etc.. It was assumed that the amount of $NO_{x}$ play a great role to the determining sensing properties. In the condition of 170 ppm $CH_{3}CN$, the sensitivity and optimum operating temperature of $SnO_{2}$ were 70% and $300^{\circ}C$, respectively. In this research, the response time of $CH_{3}CN$ to $SnO_{2}/Al_{2}O_{3}/Pd$ sensor added with 0.2 wt % Pd was found about 10 sec and sensitivity was also found relatively high.

• Journal of the Korean Vacuum Society
• /
• v.7 no.1
• /
• pp.66-71
• /
• 1998

Two kinds of $Ga_2S_3:Er$ (type A and type B) single crystals were grown by the chemical transport reaction method using iodine as a transport agent. The single crystals were crystallized into a monoclinic structure. The optical energy band gaps were found to 3.375 eV for the $Ga_2S_3:Er$ (type A) single crystal and 3.365 eV fir the $Ga_2S_3:Er$ (type B) single crystal at 13K. When the $Ga_2S_3:Er$ (type A and type B) single crystals were excited by the 325 nm-line of a Cd-He laser, Photoluminescence spectra of the $Ga_2S_3:Er$ (type A) single crystal exhibited blue emission band peaked at 444 nm and green and red emission bands peaked at 518 nm and 690 nm. Pgitikynubescebce soectra if the $Ga_2S_3:Er$ (typeB) single crystal showed green and red emission bands peaked at 513 nm and 695 nm. Sharp emission peaks in the two kinds if $Ga_2S_3:Er$ single crystal were observed near 525 nm, 553 nm, 664 nm, 812 nm, 986 nm, and 1540 nm and analysed as originating from the electron transitions between the energy levels of $Er^{3+}$ ion.

• Journal of the Mineralogical Society of Korea
• /
• v.24 no.3
• /
• pp.151-164
• /
• 2011

Mineralogical and petrological characteristics were investigated on matrix of dense gray, vesiculate gray, brown and black pumice in Ulleung Island by using XRD, FT-IR, XRF, SEM and thermal analysis. According to the analysis, most of pumice matrix are amorphous and include very small amount of sanidine and anorthoclase. Since the adsorption moistures, which commonly observed as O-H peak in FT-IR spectrum, are not identified in thermal analysis, it seems reasonable to conclude that content of the adsorption moisture has very low level. Although pumice has a large specific surface area, with long time elapsed after eruption, pumice matrix shows very low degree of hydration alteration due to the low level of water content. In SEM images, most surfaces of pumice show morphological characteristics such as various shapes of vesicle with wrinkled and thin walls resulted from ductile coalescence. Dense gray pumice formed in the initial stage includes small vesicles less than $15{\mu}m$ in size with subangular to angular shapes, free of ovoid vesicle. These characteristics are interpreted to have related to the hydrous environment derived from phreato-plinian eruption. Submicron particles observed as amorphous alumina silicate assemblages in vesicle surface are considered as particles sticked to the matrix surface through rapidly cooling process during ascent of alkali phonolitic magma. It indicates that these particles coexisted partly with crystallized alkali feldspar.

• Economic and Environmental Geology
• /
• v.50 no.1
• /
• pp.15-26
• /
• 2017

Advanced argillic, argillic, and phyllic zones are the most important alteration patterns to predict the hidden ore body during exploration of hydrothermal deposits. We examined the quantitative relationship between the spectral absorption characteristics and the mineral content of the synthetic mixtures such as alunite-kaolinite and illite-kaolinite using short wavelength infrared (SWIR) spectroscopy. In the alunite-kaolinite mixtures, the spectral absorption characteristics of the alunite was highly correlated with the Hull quotient reflectance(0.99) and the kaolinite had the highest correlation with the Gaussian peak(0.92). Illite-kaolinite mixtures are essential for Gaussian deconvolution because of the overlap of absorption region. Illite and kaolinite mixtures indicate the high correlation of 0.93 and 0.98, respectively. The error ranges in the alunite-kaolinite(8%) and illite-kaolinite mixtures(5%) derived from SWIR were smaller than the ones(29% and 26%) obtained from X-ray diffraction(Rietveld) analysis. These results show that SWIR spectroscopic analysis is more reliable than XRD Rietveld analysis in terms of quantification of allowed minerals.

• Korean Journal of Food Science and Technology
• /
• v.15 no.4
• /
• pp.333-341
• /
• 1983

Tannase of Aspergillus sp. AN-11 isolated from contaminated acorns was purified by a procedure involving ammonium sulfate precipitation, DEAE-cellulose column chromatography and Sephadex G-200 gel filtration. Physiochemical properties of the purified tannase was investigated. Tannase was purified about 37 folds with the yield of 49% from the culture broth of Aspergillus sp. AN-11. The purified tannase was homogeneous on polyacrylamide gel disc electrophoresis and was dissociable into two identical subunits on SDS-polyacrylamide gel electrophoresis. The molecular weight of the tannase was determined to be 200,000 by gel filtration on Sephadex G-200. The purified tannase showed a typical protein ultraviolet spectrum. The enzyme had a optimum pH 5.5 and optimum temperature at 30 to $40^{\circ}C$. The enzyme was stable at a pH range from 5.0 to 6.5 and at the temperature below $30^{\circ}C$. The enzyme was inactivated remarkably by $CuCl_2$ and $ZnCl_2. The Km value of the enzyme was $7.58{\times}10^{-4}\;M$.

• Korean Journal of Food Science and Technology
• /
• v.13 no.3
• /
• pp.209-218
• /
• 1981

Free fatty acid and total saponin, which were extracted from the spent media and colony of the strain Phizopus delemar Rh-1, were qualitatively examined by GLC and spectroscopic methods and compared with these of intact ginseng media. The 18, 18, and 14 free fatty acids were respectively identified from the control, spent media and colony. Among them, $iC_{12:0},\;C_{16:2},\;C_{17:0},\;C_{18:3}\; and\;C_{20:0}$ acids were not detectable from the colony. In add ition, $C_{16:2}\;and\;C_{20:0}$ peaks were rot found in the spent media and control, respectively. The isible absorption spectra of free fatty acids and total saponins in the control, spent media and colony were invariable. In contrast, however, the infrared and ultraviolet absorption spectra showed significant spectral variations, particularly in the it finger-print region, demonstrating that the ginseng components were considerably utilized by the strain Rhizopus delemar Rh-1.

• Journal of the Korean Magnetics Society
• /
• v.17 no.1
• /
• pp.47-50
• /
• 2007

[ $ZnCr_2O_4$ ] shows geometrically frustrated magnet. Recently, $CoCr_2O_4$ has been investigated for multiferroic property and dielectric anomalies by spin-current model. Polycrystalline $CoCr_2O_4$ and $CoCrFeO_4$ compounds was prepared by wet-chemical process. Crystallographic and magnetic properties of $CoCr_2O_4$ and $CoCrFeO_4$ were investigate by using the x-ray diffractometer(XRD), vibrating sample magnetometer(VSM), superconducting quantum interference device magnetometer(SQUID), and $M\"{o}ssbauer$ spectroscopy. The crystal structure was found to be single-phase cubic spinel with space group of Fd3m. The lattice constants of $CoCr_2O_4$ and $CoCrFeO_4$ $a_0$ were determined to be 8.340 and 8.377 ${\AA}$, respectively. The ferrimagnetic transition temperature for the both samples were observed at 97 K and 320 K. The $M\"{o}ssbauer$ absorption spectra at 4.2 K show that the well developed two sextets are superposed with small difference of hyperfine field($H_{hf1}=507\;and\;H_{hf2}=492\;kOe$). Isomer shift values($\delta$) of the two sextets are found to be 0.33 and 0.34 mm/s relative to the Fe metal, respectively, which are consistent with the high spin $Fe^{3+}$ charge state.

• Korean Journal of Optics and Photonics
• /
• v.22 no.2
• /
• pp.67-71
• /
• 2011

In the paper, we have demonstrated an azobenzene-coated fiber Bragg grating (FBG) for monitoring ultraviolet light (UV) intensity in remote measurement. The elasticity of the coated azobenzene polymer is changed by the UV light, which induces a center wavelength change corresponding to the change of the FBG's grating period. The wavelength shift resulting from both UV light and other light with the wavelength out of the UV range was about 0.18 nm. In order to improve the accuracy of the measurement, the center wavelength shift caused by radiant heat of the light source was sufficiently removed by using a thermal filter. The amount of the center wavelength shift was consequently reduced to 0.06 nm, compared to the result without the thermal filter. Also, the FBGs coated by using azobenzene polymer were produced by two different methods; thermal casting and UV curing. Considering temperature dependence, UV curing is more suitable than thermal casting in UV sensor application of the azobenzene-coated FBG. In addition, we have confirmed the wavelength dependence of the optical sensor by means of four different band pass filters. Thus, we found out that the center wavelength shift per unit intensity is 0.029 [arb. unit] as a maximum value at 370 nm wavelength region and that the absorption spectrum of the azobenzene polymer was very consistent with the wavelength dependence of the azobenzene-coated FBG.