• Journal of the Korean Applied Science and Technology
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• v.41 no.2
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• pp.159-171
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• 2024

This study confirmed the antioxidant activity and antimicrobial efficacy and formulation stability for the effectiveness experiment of Rumex crispus. L root extract. For antioxidant activity, DPPH radical scavenging, FRAP activity, ABTS+ radical scavenging, and SOD-like activity were performed. Antimicrobial activity was evaluated for Staphylococcus epidermidis, Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli and Candida albicans strains. In addition, skin containing Rumex crispus. L root extract is checked over time for pH, temperature, and daylight for 21 days. As a result of antioxidant evaluation, it was confirmed that the activity increased in a concentration-dependent manner at a concentration of 0.0625-1 mg/mL. The clear zones of each bacterium at 100mg/mL concentrations were 10.45±0.34, 9.77±0.59, 9.92±0.22, and 10.08±0.12, which were superior to the control group Methyl paraben, and the antibacterial power of S. aureus and E. coli was confirmed at 100mg/mL concentration for MIC. There was little change in absorbance when the pH of the skin was 4.0, 6.0, and 7.0 and At 4℃, 25℃, and 40℃, it was discolored as the temperature increased. It was also observed that discoloration occurred when exposed to daylight. This is presumed to be able to prevent discoloration when it is shielded and stored at low temperatures. When the results of this study are summarized, Rumex crispus. L root extract is considered to have high value in use as a cosmetic raw material that can expect antioxidant and antibacterial activities.

• Journal of the Korean Society of Food Science and Nutrition
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• v.11 no.3
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• pp.57-62
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• 1982

This study was conducted to investigate the changes in plant state, chlorophyll, free amino acids and vitamin C content of soybean sprouts during circulation periods. The experiment was carried out under the indoor natural light and complete darkness at $20^{\circ}C$. The results are summarized as follows; Soybean sprout was grown about one cm in the darkness for 7 or 24 hours, but under the indoor natural light it was not grown. Weight was decreased both in the darkness and under the light. In the darkness the color of sprouts were not changed, but under the light the color was changed in 7 or 24 hours. Chlorophyll contents was increased rapidly by light in the cotyledon. Chlorophyll formation brought about loss not only in amino acids but also porphyrins, but it did not in the amino acids of hypocotyl. The kinds of amino acids being brought about loss under the light were cystine, aspartic acid, serine, histidine and glycine. The 22$\sim$27% of vitamin C was lost in cotyledon by 7 hours exposured light and in hypocotyl after 5 hours.

• Korean Journal of Materials Research
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• v.5 no.7
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• pp.802-807
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• 1995

The electrochromic properties of vacuum deposited V$_2$O$_{5}$ thin films as a function of crystallinity and film thickness have been systematically investigated. The as-deposited films have slightly yellow appearance. V$_2$O$_{5}$ films deposited at higher substrate temperature(>14$0^{\circ}C$) are found to be crystalline while those deposited at low substrate temperature are amorphous. The optical modulation on lithium ion injection indicates that V$_2$O$_{5}$ films exhibit anodic coloration in the 300~500 nm wavelength range and cathodic coloration in the 500~1100nm wavelength range independent of crystallinity and film thickness. The optical band gap energy of crystalline and amorphous Li$_{x}$ VV$_2$O$_{5}$ films shifts to higher energies by 0.17 eV and 0.75 eV, respectively, with increasing lithium ion injection up to x=0.6. The coloration efficiency of amorphous Li$_{x}$ V$_2$O$_{5}$ exhibits very little dependence on film thickness and lithium ion injection amounts in the near-infrared while it increases significantly with increasing film thickness and decreasing lithium ion injection amounts in the blue and near-UV due to the shift in absorption edge below around 500nm. However, the coloration efficiency of crystalline Li$_{x}$ V$_2$O$_{5}$is relatively independent of film thickness and lithium ion injection in the 300~1100 nm wavelength range.

• Journal of Adhesion and Interface
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• v.17 no.4
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• pp.141-148
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• 2016

In this work, mesoporous silica (SBA-15) was synthesized via self-assembly process using triblock copolymer ($PEO_{20}PPO_{70}PEO_{20}$, P123) as template and tetraethyl orthosilicate (TEOS) as silica source under acidic condition. SBA-15 have high surface area ($704m^2g^{-1}$) and uniform pore size (8.4 nm) with well-ordered hexagonal mesostructure. Spiropyran-functionalized SBA-15 (Spiropyran-SBA-15) was synthesized via post-synthesis process using 3-(triethoxysilyl)propyl isocyanate (TESPI) and 1-(2-Hydroxyethyl)-3,3-dimethy-lindolino-6'-nitrobenzopyrylo-spiran (HDINS). Spiropyran-SBA-15 was produced with hexagonal array of mesopores without damage of mesostructre. Surface area and pore size of Spiropyran-SBA-15 were $651m^2g^{-1}$ and 8.0 nm, respectively. Optochemical properties of Spiropyran-SBA-15 was studied with chemical vapors such as EtOH, THF, $CHCl_3$, Acetone and HCl. Main peaks of photofluorescence of Spiropyran-SBA-15 exhibited blue shift in the range of 603.4~592.1 nm after exposure under EtOH, THF, $CHCl_3$, and Acetone vapors. Normalized peak intensities decreased in the range of 0.8~0.3. The main peak of photofluorescence of Spiropyran-SBA-15 showed significant blue shift of 592.1 nm after exposure under HCl vapor, while normalized peak intensity decreased to 0.1.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.11
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• pp.949-956
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• 2016

There are a number of effects by solar radiation in many aerospace industrial fields, such as degradation of mechanical properties, sealing effect of sealants or decolorization. Because it takes long time to investigate these effects by using the light of natural state, new methods are developed for accelerating this phenomenon. In this paper, we developed an apparatus to simulate accelerated solar radiation phenomenon selecting irradiation intensity $1,120W/m^2$ as the designed environment. Epoxy polymer as the composite material was chosen and processed by ASTM-D638, a reference for tensile test of polymer and plastic. Total color shift was selected as the test category to evaluate acceleration of the test. We obtained acceleration factors and numerical model from test data and concluded it can shorten test periods by accelerated irradiation intensity of $1,120W/m^2$.

• Korean Chemical Engineering Research
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• v.52 no.4
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• pp.436-442
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• 2014

In this study, we developed an optical-fiber sensor using cobalt chloride solution to monitor temperature in real-time between long distance points unaffected by the electro-magnetic wave and the vibration. Cobalt chloride solutions were made using 10% water and 90% ethanol (v/v) solution. The transmittance of these solutions was analyzed on 655 nm using UV-Visible spectrometer regarding temperature change. Also 30.8 mM cobalt chloride solution was gelled by dissolving polyvinyl butyral and the transmittance of this was analyzed on 655 nm regarding temperature change. The results of transmittance and optical power measurement showed decrease of both transmittance and optical power with increase of temperature from 66.8% and 149.5 nW at $25^{\circ}C$ to 7.1% and 48 nW at $70^{\circ}C$, respectively. These results support the possibility of gelled cobalt chloride/polyvinyl butyral as an optical-fiber sensor to monitor temperature change.

• Journal of the Semiconductor & Display Technology
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• v.4 no.1 s.10
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• pp.29-34
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• 2005

Tungsten oxide($WO_{3}$) is suitable to materials for photochromic window in the visible region. The resistivities of CdS, $WO_{3}$, and $WO_{3}$/CdS films prepared by thermal evaporation method were $4.61\times 10\^{3}$, $7.59\times10^{3}$, and $6.29\times10^{3}$ $\omega$ cm. And x-ray diffraction patterns of CdS, $WO_{3}$/CdS films showed a preferred orientation of hexagonal(002), and the monoclinic(020) structure, respectively. The optical transmission were measured that the cut-on wavelength were 510nm, 380nm for CdS and $WO_{3}$ films respectively, and the transmission spectrum of $WO_{3}$/CdS was shifted into the visible region. Photoluminescence(PL) spectra showed the two peaks at 2.8 eV and 3.2 eV for the as-grown sample($WO_{3}$/CdS ($500{\AA}$), but the other sample($WO_{3}$/CdS ($1000{\AA}$)) had a peak energy value of 2.8 eV. The photochromism of $WO_{3}$/CdS films showed that the excitation of electron-hole pairs and subsequent coloration is shifted into visible-light range. And the spectral behavior of coloration turned out to be proportional to the excited electron-hole pairs creation rate of CdS film. This result is interpreted in terms of charge carrier injection from the CdS-layer into the $WO_{3}$ films. We found a value of about 2.8 eV of $WO_{3}$/CdS film which is somewhat higher than peak energy of 2.54 eV using CBD prepared by Bechinger et. al.

• Korean Journal of Materials Research
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• v.9 no.11
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• pp.1144-1147
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• 1999

The effect of the heat treatment on electrochromic properties of $\textrm{MoO}_3$ thin films is investigated by studing optical modulation, optical density, response time, and cyclic voltammetry. From the results of XRD analysis, heat-treated at $450^{\circ}C$ in air for 1 hour Moo3 thin films are found to be crystalline while as-deposited and heat- treated at low temperature ($\leq\;300^{\circ}C$) film are amorphous. The electrochromic devices using as-deposited $\textrm{MoO}_3$ films exhibit good electrochromic properties compared to those using the heat treated $\textrm{MoO}_3$ films. It has shown that the heat-treatment affected the reversible color change and the electrochromic properties of $\textrm{MoO}_3$ films.

• Journal of the Korean Chemical Society
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• v.50 no.2
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• pp.99-106
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• 2006

The electronic absorption spectra of [3-(2-thenoyl) 3-(p-NO2-phenylhydrazone) ethyl pyruvate] (I), p-Br (II) and p-CH3 (III) were studied in ethanol and the spectra comprise four absorption bands which assigned to the corresponding electronic transition. The pK values of these compounds have been determined spectrophotometrically and pH-metrically, the results shown that the interval range for color change of compound (I) is (8-10) similar to that of phenolphethalin indicator, indicating that this compound can be used as acid-base indicator. The successive stability constants of the compounds under study with some transition elements (Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II), UO2(II), La(III) and Zr(IV) have been determined pH- metrically. Stoichiometric complexes with ratios 1:1 and 1:2 (M: L) were formed for all metals. The pK of the three derivatives and the values of the stability constant (logK) of the complexes have the order; III > II > I. Also conductometric titrations have been carried out and the results show that this titration can be used for determination of both the metal ion and the ligand concentrations by each others.

• Restorative Dentistry and Endodontics
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• v.25 no.2
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• pp.254-261
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• 2000

본 연구에서는 35개의 구치부 2급 와동에 고밀도 구치부 복합레진(Surefil, Caulk, U.S.A.)을 수복하였다. 단일 충전군은 18개 치아의 인접면 와동을 한꺼번에 충전한 후 광중합하였고 분할 충전군은 17개 치아의 인접면 와동을 두 층으로 나누어 충전 및 광중합하였다. 6개월 후의 임상검사 결과 다음과 같은 결론을 얻었다. 1. 기초검사에서 단일 충전군과 분할 충전군 모두 색상조화도(Color match)를 제외한 다른 검사 항목들에서 Alfa로 나타났다. 2. 단일 충전군은 6개월 후 모든 검사(색상 조화도 제외)에서 인접면 접촉도(Proximal contact), 변연부 변색(Marginal discoloration), 술후 과민증(Postoperative sensitivity) 검사에서 소수의 치아가 Bravo, Charlie로 나타났으나 기초 검사와 3개월 후 검사 사이에 통계적으로 유의한 차이는 보이지 않았다. 3. 분할 충전군은 6개월 후 시행된 모든 검사(색상 조화도 제외)에서 인접면 접촉도(Proximal contact), 술후 과민증(Postoperative sensitivity) 검사에서 소수의 치아가 Bravo, Charlie로 나타났으나 기초 검사와 6개월후 검시 사이에 통계적으로 유의한 차이는 보이지 않았다. 4. 모든 검사항목에서 단일 충전군과 분할 충전군을 비교한 결과 통계적으로 유의한 차이는 보이지 않았다. 따라서 고밀도 구치부 복합레진(Surefil, Caulk, U.S.A)은 색상 재현의 어려움을 제외하고는 여러 평가에서 우수하게 나타났으므로 본 연구 결과를 기준으로 보면 이전 복합레진의 단점이 보완되어 구치부 2급 와동에 적절하게 사용될 수 있다고 사료되며 단일 충전군과 분할 충전군 사이에 통계적으로 유의한 차이를 보이지 않으므로 시술 시간을 좀 더 단축시킬 수 있을 것으로 사료된다.