• 분석과학
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• 제24권6호
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• pp.493-502
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• 2011

본 연구에서는 가시광촉매의 특성을 나타낼 수 있는 촉매를 제조하여 촉매를 특성화 하였으며, toluene, xylene, MEK (methyl ethyl ketone), ammonia를 반응물로 하여 기존의 UV-광촉매와 분해능을 비교 실험하였다. UV-광촉매는 파장범위가 280~360 nm 근처에서 광촉매가 활성화된다. 그러나 가시광촉매는 가시광영역인 400~750 nm의 파장영역에서도 광촉매가 활성화 된다. 이것을 UV-Vis 흡수도로 파악하였다. 그리고 가시광촉매의 성능을 향상시키기 위하여 여러 가지 재료로 도핑하는데, 여기서는 망간에 Pt를 부가하여 성능향상을 꾀하였다. Pt를 첨가한 가시광 촉매의 경우 성능이 향상되었음을 알 수 있었다. 그리고 바인더로 MTMS (methyl tri methoxy silane)를 사용하였으며 바인더양에 따른 접촉각을 측정하였다. MTMS 함량이 증가할수록 접촉각이 커졌다. 따라서 친수성이 줄어든 것으로 나타났다. 그리고 Mn-$TiO_2$ 촉매의 항균성이 매우 우수한 것으로 나타났다.

• 한국토양비료학회지
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• 제47권5호
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• pp.319-323
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• 2014

This study investigates the prediction of soil chemical properties (organic matter (OM), pH, Ca, Mg, K, Na, total acidity, cation exchange capacity (CEC)) on 688 Korean soil samples using the visible-near infrared reflectance (VIS-NIR) spectroscopy. Reflectance from the visible to near-infrared spectrum (350 to 2500 nm) was acquired using the ASD Field Spec Pro. A total of 688 soil samples from 168 soil profiles were collected from 2009 to 2011. The spectra were resampled to 10 nm spacing and converted to the 1st derivative of absorbance (log (1/R)), which was used for predicting soil chemical properties. Principal components analysis (PCA), partial least squares regression (PLSR) and regression rules model (Cubist) were applied to predict soil chemical properties. The regression rules model (Cubist) showed the best results among these, with lower error on the calibration data. For quantitatively determining OM, total acidity, CEC, a VIS-NIR spectroscopy could be used as a routine method if the estimation quality is more improved.

• 한국세라믹학회지
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• 제50권6호
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• pp.504-509
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• 2013

In this study, ZnSe-$TiO_2$ composites were synthesized by a facile hydrothermal-assisted sol-gel process and characterized by nitrogen adsorption isotherms (77 K), X-ray diffraction (XRD), scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) analysis, transmission electron microscopy (TEM) and UV-vis diffuse reflectance spectrophotometry. The photocatalytic activity was investigated by decoloration methylene blue (MB), methyl orange (MO), and rhodamine B (Rh.B) in an aqueous solution under visible light irradiation. The results revealed that the photocatalytic activity of the ZnSe-$TiO_2$ photocatalyst was much higher than that of pure$TiO_2$. The ZnSe nanoparticles, which act as a photosensitizer, not only extend the spectral response of $TiO_2$ to the visible region but also reduce charge recombinations.

• Elastomers and Composites
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• 제48권3호
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• pp.209-215
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• 2013

가시광촉매를 이용하여 자동차 내장재에서 발생하는 VOCs의 저감 효과를 알아보았다. 가시광촉매는 sol-gel법으로 제조하였으며 UV-vis peak가 420 nm에서 적색이동 되어 가시광영역에서 감응하는 것으로 나타났다. 이러한 특성을 갖는 가시광촉매를 자동차 내장재에 코팅처리하고, 자동차 내장재에서 발생하는 VOCs를 측정한 결과 분해 저감율이 우수하게 나타났다.

• 지적과 국토정보
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• 제48권1호
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• pp.71-91
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• 2018

최근 영농분야에서 종자파종, 병충해 방제 등에 무인항공기(UAV ; Unmanned Aerial Vehicle)를 활용한 응용이 활발히 진행되고 있다. 본 연구는 UAV에 다양한 파장대의 영상센서를 탑재하고 SfM(Structure from Motion) 영상해석기법과 연계한'고해상 저고도 원격탐측시스템(UAS ; Unmanned Aerial System)'를 구성, UAS 기반 식생조사의 효용성을 고찰하여 정밀영농의 활용성을 검토하였다. 이를 위해 저가 UAV에 가시 컬러(VIS_RGB ; Visible Red, Green, and Blue) 영상센서, 수정된 BG_NIR(Blue Green_Near Infrared Red) 근적외 영상 센서, $7.5{\sim}13.5{\mu}m$ 분광대역의 열적외 영상(TIR ; Thermal Infrared Red)센서를 조합 연계한 UAS를 구성하였다. 또한, 가시 근적외 및 열적외 파장대를 기본요소로 광합성에 따른 식물의 엽록소, 질소 및 수분 함유량 등을 검토할 수 있는 총 10종의 식생지수를 선정, 식생상태 검출에 활용하였다. 시험대상지에 대한 각 파장대역의 영상을 획득하고 사전에 조사된 지상 피복현황을 기준으로 각 식생지수의 분포도 및 식생지수 간 상관성(결정계수 R2) 등을 비교 고찰하여 무인항공기를 활용한 가시 컬러, 근 적외 및 열 적외 영상에 의한 식생상태의 검측 수행능력을 검토하였다. 저가 무인항공기에 VIS_RGB, BG_NIR 및 TIR 영상 센서를 탑재, 식생조사의 효용성을 종합적으로 검토한 결과, 인공위성과 항공영상에 의존한 과거의 식생조사방식 대비, 영상해상도, 경제성 및 운용성 면에서 UAV기반 고해상 저고도 원격탐측시스템(UAS)의 효용성을 입증할 수 있었으므로 정밀농업, 수계 및 산림조사 등의 분야에 그 활용이 기대된다.

• 한국축산식품학회지
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• 제42권4호
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• pp.655-671
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• 2022

There are differences of spectral characteristics between different types of meat cut, which means the model established using only one type of meat cut for meat quality prediction is not suitable for other meat cut types. A novel portable visible and near-infrared (Vis/NIR) optical system was used to simultaneously predict multiple quality indicators for different commercial meat cut types (silverside, back strap, oyster, fillet, thick flank, and tenderloin) from Small-tailed Han sheep. The correlation coefficients of the calibration set (R_c) and prediction set (R_p) of the optimal prediction models were 0.82 and 0.81 for pH, 0.88 and 0.84 for L^*, 0.83 and 0.78 for a^*, 0.83 and 0.82 for b^*, 0.94 and 0.86 for cooking loss, 0.90 and 0.88 for shear force, 0.84 and 0.83 for protein, 0.93 and 0.83 for fat, 0.92 and 0.87 for moisture contents, respectively. This study demonstrates that Vis/NIR spectroscopy is a promising tool to achieve the predictions of multiple quality parameters for different commercial meat cut types.

• 농업과학연구
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• 제43권5호
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• pp.715-722
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• 2016

Rapid determination of food quality is important in food distribution. In this study, the chemical properties of oats were analyzed using visible-near infrared (VIS-NIR) spectroscopy. The objective of this study was to develop and validate a predictive model of oat quality by VIS-NIR spectroscopy. A total of 200 oat samples were collected from domestic and import markets. Reflectance spectra, moisture, protein, fat, Fe, and K of oat samples were measured. Reflectance spectra were measured in the wavelength range of 400 - 2,500 nm at 2 nm intervals. The reflectance spectrum of an oat sample was measured after sample cell and reflectance plate spectrum measurement. Preprocessing methods such as normalization and $1^{st}$ and $2^{nd}$ derivations were used to minimize the spectroscopic noise. The partial-least-square (PLS) models were developed to predict chemical properties of oats using a commercial software package, Unscrambler. The PLS models showed the possibility to predict moisture, protein, and fat content of oat samples. The coefficient of determination ($R^2$) of moisture, protein, and fat was greater than 0.89. However, it was hard to predict Fe and K concentrations due to their low concentrations in the oat samples. The coefficient of determinations of Fe and K were 0.57 and 0.77, respectively. In future studies, the stability and practicability of these models should be improved by using a high accuracy spectrophotometer and by performing calibrations with a wider range of oat chemicals.

• Journal of Biosystems Engineering
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• 제38권1호
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• pp.48-54
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• 2013

Purpose: This study evaluated the feasibility of using a discrete wavelet transform (DWT) method as a preprocessing tool for visible/near-infrared spectroscopy (VIS/NIRS) with a spectroscopic transmittance dataset for predicting the internal quality of cherry tomatoes. Methods: VIS/NIRS was used to acquire transmittance spectrum data, to which a DWT was applied to generate new variables in the wavelet domain, which replaced the original spectral signal for subsequent partial least squares (PLS) regression analysis and prediction modeling. The DWT concept and its importance are described with emphasis on the properties that make the DWT a suitable transform for analyzing spectroscopic data. Results: The $R^2$ values and root mean squared errors (RMSEs) of calibration and prediction models for the firmness, sugar content, and titratable acidity of cherry tomatoes obtained by applying the DWT to a PLS regression with a set of spectra showed more enhanced results than those of each model obtained from raw data and mean normalization preprocessing through PLS regression. Conclusions: The developed DWT-incorporated PLS models using the db5 wavelet base and selected approximation coefficients indicate their feasibility as good preprocessing tools by improving the prediction of firmness and titratable acidity for cherry tomatoes with respect to $R^2$ values and RMSEs.

• Bulletin of the Korean Chemical Society
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• 제33권4호
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• pp.1269-1274
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• 2012

A visible light responsive N, Mo co-doped $TiO_2$ were prepared by sol-gel method. X-ray diffraction, TEM, $N_2$ adsorption, UV-vis spectroscopy, photoluminescence, and X-ray photoelectron spectroscopy were used to characterize the prepared $TiO_2$ samples. Doping restrained the phase transformation from anatase to rutile and reduced the particle sizes. The band gap was much narrowed after N, Mo co-doping. The photocatalytic activities were tested in the degradation of an aqueous solution of a reactive dyestuff, methylene blue, under visible light. The photocatalytic activities of doped $TiO_2$ were much higher than that of neat $TiO_2$. The photocatalytic stability of N, Mo co-doped $TiO_2$ was much better than that of N doped $TiO_2$.

• 한국염색가공학회지
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• 제13권5호
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• pp.10-10
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• 2001

The Purpose of this study was to investigate spectrophotometric characteristics of Korean knotweed extracts. The properties were evaluated by it′s extracting solvent, effect of metallic ion, variations of pH values and effect of light exposure. The results were as following; The highest absorbance was found in methanol extract of Korean knotweed, while the lowest absorbance was carbon tetrachloride extract. The UV-vis. spectra of Korean knotweed colors in several solvents showed hypsochromic shift of n-π/sup ＊/ transition with the polarity of solvent. Absorbance and peak of UV-vis. spectra of Korean knotweed colors became lower and broader by addition of metallic ion. The light stability in irradiation with xenon ]amp of the color solution with Cu were higher than those of Al and Fe. The UV-vis. spectra of Korean knotweed extracts in various pH values showed bathochromic shift under alkaline condition, and their peaks disappeared after 5 hours exposure.