• 한국재료학회지
• /
• 제17권6호
• /
• pp.323-330
• /
• 2007

We fabricated thermaly evaporated 10 nmNi/(poly)Si films to investigate the energy saving property of silicides formed by rapid thermal annealing (RTA) at the temperature of $300{\sim}1200^{\circ}C$ for 40 seconds. Moreover, we fabricated $10{\sim}50$ nm-thick ITO/Si films with a rf-sputter as reference films. A four-point tester was used to investigate the sheet resistance. A transmission electron microscope (TEM) and an X-ray diffractometer were used for the determination of cross sectional microstructure and phase changes. A UV-VISNIR and FT-IR (Fourier transform infrared rays spectroscopy) were employed for near-IR and middle-IR absorbance. Through TEM analysis, we confirmed $20{\sim}70nm-thick$ silicide layers formed on the single and polycrystalline silicon substrates. Nickel silicides and ITO films on the single silicon substrates showed almost similar absorbance in near-IR region, while nickel silicides on polycrystalline silicon substrate showed superior absorbance above 850 nm near-IR region to ITO films. Nickel silicide on polycrystalline substrate also showed better absorbance in middle IR region than ITO. Our result implies that nano-thick nickel silicides may have exellent absorbing capacity in near-IR and middle-IR region.

• Bulletin of the Korean Chemical Society
• /
• 제32권5호
• /
• pp.1657-1661
• /
• 2011

In this study, CdSe-$TiO_2$ photocatalyst were synthesized by a facile solvothermal method and characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) analysis and UV-vis diffuse reflectance spectrophotometer. The photocatalytic activity was investigated by degrading methylene blue (MB) in aqueous solution under irradiation of UV light as well as visible light. The absorbance of degraded MB solution was determined by UV-vis spectrophotometer. The results revealed that the CdSe-$TiO_2$ photocatalyst exhibited much higher photocatalytic activity than $TiO_2$ both under irradiation of UV light as well as visible light.

• 한국식품영양과학회지
• /
• 제23권4호
• /
• pp.604-613
• /
• 1994

Hydrophilic brown pigments(HBPs) produced during fermentation and aging the domestic Meju and Doenjang were separated by dialysis and chromatography , and their antioxidant activity were measured . The chemical properties of HBP were determined by UV and IR spectrophotometry. HBPs contents were found to be 93.1 mg/g and 183.2mg/g in Meju fermentated for 30 days and 80 days , respectively. The ratio of dialysate to diffusate of the HBPs were appeared to be 70 : 30 and 87 :13 in the Meju fermented for 30 days and 80 days, respectively. and the rtio in the Doenjang aged for 60 days was 91 :9 , indicating that dialysate slowly days, respectively, and the ratio in the Doenjang aged for 60 days was 91 : 9, incidatin that dialysate slowly increased by the fermentation . Both portion exhibited strong antioxidant activity, but more stronger antioxidant activity was found in the dialysate. DEAE-celluose column chromatography showed that dialysate contained more materials eluted by 0.01-0.03M HCI solution than 0.01M acetate buffer, but diffusate showed opposite results. The degree of browning reaction and antioxdiant activity found in the fraction eluted by HCI solution was stronger than that of the fraction eluted by acetate buffer. The fraction eluted from DEAE-cellulose column chormatogrphy was further fractionaged by TLC and found that strong antioxidant activity was present in the fractions which did not possess fluorescenece and showed a negative ninhydrin reaction. TLC fractions of HCI eluant in Meju exhibited a strong absorbance at 260-280nm, but most of other fractions did not show any absorbance at UV region. TLC fractions from dialysate and diffusate showed fairly identical IR spectrum with absorbance at 3400cm-1, 2800cm-3000cm -1, 1600cm, -1 1400cm-1 and 1100 cm-1 , however, in addition to these absorbances, the spectrum from HCI eluant of Meju exhibited a strong absorbance at 1750cm , indicating the carbonic acid or carbonate ester.

• 공업화학
• /
• 제32권1호
• /
• pp.61-67
• /
• 2021

본 연구에서는 천연 오일인 시벅턴 오일의 천연 자외선 흡수제로의 사용 가능성을 알아보기 위하여 시벅턴 원유에 대한 흡착 탈색공정을 수행하고, 이를 CCD-RSM (central composite design model-response surface methodology)을 이용하여 최적화하였다. CCD-RSM의 반응치로는 탈색과정의 탈색효과, 탈색 후 정제유의 산가 및 290 nm에서의 자외선흡광도로 설정하였으며, 독립변수로는 탈색제의 첨가량, 탈색온도, 탈색시간으로 설정하였다. CCD-RSM에 의한 통계학적 최적화 결과와 수학적 최적화 결과를 비교한 결과 3가지 반응치를 동시에 만족하는 최적조건으로 탈색제의 첨가량(4.32 wt.%), 탈색온도(134.9 ℃) 및 탈색시간(19.8 min)으로 나타났다. 이 최적 조건하에서 예측된 반응치 중 탈색과정의 탈색효과는 94.78%, 탈색 후 정제유의 산가는 2.08 mg/g KOH, 그리고 290 nm에서의 자외선 흡광도는 2.91로 나타났으며, 오차율은 2% 이하로 낮게 나타났다. 따라서 CCD-RSM을 시벅턴 원유의 흡착 탈색공정에 적용할 경우 매우 높은 수준의 만족하는 결과를 얻을 수 있음을 확인하였으며 천연 식물성 오일인 시벅턴 오일을 천연 자외선 흡수제로서 사용 가능함을 확인하였다.

• 생명과학회지
• /
• 제29권5호
• /
• pp.509-513
• /
• 2019

비어 람버트 법칙에 의하면 충분히 묽은 용액에서 주어진 파장에서 측정한 흡광도는 용질의 농도에 비례한다. 반대로 충분히 묽은 용액이란 측정한 흡광도 값이 용질의 농도에 비례관계를 가지는 범위에 있는 용액을 말하지만 실제 확신하기가 어렵다. 본 연구에서는 벼 잎에서 추출한 엽록소 80% 아세톤 용액을 사용하여, 측정한 흡광도 값의 신뢰도를 판단할 수 있는 기준으로서 엽록소 a/b 비례치의 사용 가능성을 4가지 다른 흡광분광분석기(Cary4E, UV-1650PC, Versamax, NanoDrop 100)을 사용하여 조사하였다: 우선 $0.2{\mu}g/ml$의 매우 저농도에서 $200{\mu}g/ml$까지의 다양하게 희석한 엽록소 용액을 사용하여, 645 nm와 663 nm에서 측정한 흡광도 값을 측정한 후, 흡광도 값과 엽록소 농도의 비례관계를 조사하였다. 그 결과, 이 비례관계로 판단한 측정치의 신뢰 범위에서 흡광도로부터 계산한 용액에서의 엽록소 농도와 이미 알고 있는 엽록소 농도 비교적 일치하였다. 그러나, 비례관계의 한계치 안에 있어 신뢰도가 인정된 일부 고농도와 저농도에서의 일부 값이 엽록소 a/b 비례치가 용액의 희석에 변화지 않을 것이라는 판단 기준에 있어 신뢰도가 떨어짐을 알 수 있었다. 그러므로, 본 연구결과는 엽록소 농도결정을 위하여 측정한 흡광도 값의 신뢰 여부는 대상 용액을 희석하여 측정한 흡광도의 비례관계로 본 비어-램버트 법칙의 기준 보다는 엽록소 a/b 비례치가 변하지 않는다는 기준으로 측정치의 신뢰도를 판단하는 것이 더 좋다는 것을 확인할 수 있었다.

• 한국환경보건학회지
• /
• 제39권2호
• /
• pp.187-195
• /
• 2013

Objectives: For the practical application of the dielectric barrier discharge plasma reactor, a plasma reactor able to manage large volumes of water is needed. This study investigated the possibility of the practical application of a multi-plasma reactor which is a scaled-up version of a single plasma reactor. Methods: The multi-plasma reactor consists of several high-voltage transformers and plasma modules (discharge, ground electrodes and quartz dielectric tubes). The effects of water characteristics such as voltage (30-120 V), air flow rate (1-5 l/min), number of high-voltage transformers and plasma modules, and water quality on Escherichia coli (E. coli) disinfection and decrease of COD and $UV_{254}$ absorbance were investigated. Results: The experimental results showed that at a voltage of over 80 V, most of the E. coli were disinfected within 90 seconds. E. coli inactivation was not affected by the air flow rate. E. coli disinfection in the multiplasma process showed the traditional log-linear form of the disinfection curve. E. coli inactivation performance by transformer 3-Reactor 5 and transformer 3-Reactor 3 were similar. The disinfection performance of the UV process was affected by artificial sewage water. However, the plasma process was less affected by the artificial sewage within the standards for effluent water quality. Conclusions: Disinfection performance with several low voltages and plasma modules of three to five in number applied to the plasma process was higher than that concentrating a small amount of high voltage through a single plasma reactor. Removal of COD, $UV_{254}$ absorbance, and E. coli disinfection with the plasma process were better than with the UV process.

• 한국응용과학기술학회지
• /
• 제17권3호
• /
• pp.178-182
• /
• 2000

We have investgated UV-Vis absorbance to observe the photoisomerization using the mixture solutions in chloroform and LB monolayers mixed with DLPE and 8A5H containing azobenzene which showed reversible cis-trans photoisomerization irradiated by alternate lights. We have found that the absorbance spectrums of the mixture solutions and LB monolayers were reversibly induced to cis-trans photoisomerization irradiated by alternate lights. In addition, the absorbance of both solution and LB monolayer mixed with 8A5H and DLPE were reversibly by alternate temperatures. As a results, the 1:1(by volume) mixture ratio of 8A5H and DLPE was more flexible and reversible cis-trans photoisomerization than the others.

• 한국고분자학회:학술대회논문집
• /
• 한국고분자학회 2006년도 IUPAC International Symposium on Advanced Polymers for Emerging Technologies
• /
• pp.230-230
• /
• 2006

Density functional theory (DFT) calculations using the B3LYP hybrid functional and the 6-311++G(d,p) basis set have been performed to predict the wavelength dispersion of optical absorbance and refractive indices for organic compounds and polymers in the range between the vacuum UV (${\sim}157\;nm$) and near-IR (${\sim}850\;nm$). The DFT calculations can reproduce the experimental dispersions of absorbance and refractive indices with high accuracy and low costs. The calculated dispersions demonstrate that the judicious introductions of $-F\;and\;-CF_{3}$ into alicyclic and heterocyclic compounds are effective in reducing the absorption at shorter wavelengths. In addition, the calculated Abbe numbers that represent the refractive index dispersion in the visble region are linearly proportional to the calculated refractive indices at 589 nm.

• 한국산학기술학회논문지
• /
• 제12권1호
• /
• pp.559-564
• /
• 2011

PVC 기재에 자외선 차단제를 첨가하는 종래의 방법 대신, 점착제에 차단제를 혼합하여, 유리창에 부착하는 창문용 점착시트를 제조 하였다. 무기계차단제와 유기계차단제를 모두 사용 하였으며, 파장 280-400 nm 구간에서 흡광도를 측정하여 자외선 차폐성능을 평가하였다. 무기계보다는 유기계차단제의 성능이 우수하였으며, 1%만 첨가하여도 투명도나 점착력에는 영향을 주지 않고 대부분의 자외선을 차단하였다.

• Journal of Microbiology and Biotechnology
• /
• 제33권4호
• /
• pp.419-429
• /
• 2023

Ultraviolet C (UV-C, 200-280 nm) light has germicidal properties that inactivate a wide range of pathogenic and spoilage microorganisms. UV-C has been extensively studied as an alternative to thermal decontamination of fruit juices. Recent studies suggest that the efficacy of UV-C irradiation in reducing microorganisms in fruit juices is greatly dependent on the characteristics of the target microorganisms, juice matrices, and parameters of the UV-C treatment procedure, such as equipment and processing. Based on evidence from recent studies, this review describes how the characteristics of target microorganisms (e.g., type of microorganism/strain, acid adaptation, physiological states, single/composite inoculum, spore, etc.) and fruit juice matrices (e.g., UV absorbance, UV transmittance, turbidity, soluble solid content, pH, color, etc.) affect the efficacy of UV-C. We also discuss the influences on UV-C treatment efficacy of parameters, including UV-C light source, reactor conditions (e.g., continuous/batch, size, thickness, volume, diameter, outer case, configuration/arrangement), pumping/flow system conditions (e.g., sample flow rate and pattern, sample residence time, number of cycles), homogenization conditions (e.g., continuous flow/recirculation, stirring, mixing), and cleaning capability of the reactor. The collective facts indicate the immense potential of UV-C irradiation in the fruit juice industry. Existing drawbacks need to be addressed in future studies before the technique is applicable at the industrial scale.