• Korean Journal of Soil Science and Fertilizer
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• v.47 no.5
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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.

• Journal of the Korean Society for Precision Engineering
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• v.33 no.9
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• pp.699-706
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• 2016

Assay of biomolecules based on absorption spectroscopy is a sensitive, minute, quantitative, rapid and real-time process. UV-vis spectrometry has inherent advantages for use in analytical applications. To reduce the consumption of scarce samples, a new generation of miniaturized UV-vis spectrometric systems has been developed. This study determined empirically and through simulations the feasibility of assaying biomolecules by means of UV-vis spectrometry. This paper also reports a fully integrated portable micro-detection equipment system that utilizes a micro-optical path for analysis of micro-volume samples.

• Bulletin of the Korean Chemical Society
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• v.23 no.7
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• pp.957-963
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• 2002

We successfully synthesized the addition-type polynorbonenes (PNB) exhibiting photochromic properties and excellent thermal stability. Three norbornene-based monomers with different azobenzene moiety (R=NO2, H,OCH3) were synthesized by transesterification method. The corresponding PNB copolymers were synthesized by transition metal-catalyzed addition polymerization method, and characterized by GPC, UV-Vis spectroscopy, NMR, and thermal analysis. For comparison of the photochromic properties depending on the rigidity of polymer backbone, we prepared the polymethylmethacrylate (PMMA) copolymer with the corresponding azobenzene moiety. We investigated the photoisomerization behavior by means of optical muitichannel analyzer with Xe lamp as well as real-time UV-Vis spectroscopy with high-pressure mercury lamp. Among three PNB copolymers, a polymer with azobenzene (R=H) was the most adaptable for observation of photoisomerization behavior. It was found that the rate of photoisomerization and relaxation depended on the structure of azobenzene chromophore, rather than that of polymer backbone.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.45 no.6
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• pp.78-87
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• 2013

Even though the notice No. 2010-11 of the Ministry of Food and Drug Safety Administration that has been applied to analyze the content of the water soluble residue eluted from multi-layer paperboard was abolished in 2011, its application for the analysis on evaporation residue is still valid. There are very high possibilities that the noticed existing method gives the misleading result on the evaporation residue due to the water soluble starch eluted from the multi-layer paperboard. The quantitative analysis on water-soluble residue with starch content correction has been carried in the study using UV/Vis spectroscopy and HPLC. The UV/Vis spectroscopy absorbance analysis showed the large amount of the oxidized starch obtained from the aqueous residue eluted out of the multi-layer paperboard after the iodine, ${\alpha}$-amylase reaction, and starch hydrolysis. The residual content decreased by the correction through the enzyme hydrolysis.

• Applied Chemistry for Engineering
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• v.33 no.3
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• pp.279-283
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• 2022

UV-vis spectroscopy is one of the powerful tools for measuring the concentrations of reactant and products during a chemical reaction. However, there is an limitation of using the technique when the reaction undergoes in high concentration and high temperature. Color analysis using camera images can provide the identical results with UV-vis analysis with regardless of the sample concentration and temperature. The catalytic reduction reaction of resazurin to resorufin was investigated using the color analysis with the color spaces such as CIE L^*a^*b^*. Moreover, the color analysis enabled the independent analysis of two different material's concentrations without the deconvolution of overlapped wavelengths unlike the case of using UV-vis spectroscopy.

• Journal of the Korean Ceramic Society
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• v.51 no.4
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• pp.350-356
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• 2014

Recently, Chemical Vapor Deposition (CVD) synthetic diamonds have been introduced to the jewelry gem market, as CVD technology has been making considerable advances. Unfortunately, CVD diamonds are not distinguishable from natural diamonds when using the conventional gemological characterization method. Therefore, we need to develop a new identification method that is non-destructive, fast, and inexpensive. In our study, we employed optical microscopy and spectroscopy techniques, including Fourier transform infra-red (FT-IR), UV-VIS-NIR, photoluminescence (PL), micro Raman, and cathodoluminescent (CL) spectroscopy, to determine the differences between a natural diamond (0.30 cts) and a CVD diamond (0.43 cts). The identification of a CVD diamond was difficult when using standard gemological techniques, UV-VIS-NIR, or micro-Raman spectroscopy. However, a CVD diamond could be identified using a FT-IR by the Type II peaks. In addition, we identified a CVD diamond conclusively with the uneven UV fluorescent local bands, additional satellite PL peaks, longer phosphorescence life time, and uneven streaks in the CL images. Our results suggest that using FT-IR combined with UV fluorescent images, PL, and CL analysis might be an appropriate method for identifying CVD diamonds.

• Journal of Biosystems Engineering
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• v.35 no.6
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• pp.450-457
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• 2010

Although cherry tomato is one of major vegetables consumed in fresh vegetable market, the quality grading method is mostly dependant on size measurement using drum shape sorting machines. Using Visible/Near-infrared spectroscopy, apparatus to be able to acquire transmittance spectrum data was made and used to estimate firmness, sugar content, and acidity of cherry tomatoes grown at hydroponic and soil culture. Partial least square (PLS) models were performed to predict firmness, sugar content, and acidity for the acquired transmittance spectra. To enhance accuracy of the PLS models, several preprocessing methods were carried out, such as normalization, multiplicative scatter correction (MSC), standard normal variate (SNV), and derivatives, etc. The coefficient of determination ($R^2_p$) and standard error of prediction (SEP) for the prediction of firmness, sugar, and acidity of cherry tomatoes from green to red ripening stages were 0.859 and 1.899 kgf, with a preprocessing of normalization, 0.790 and $0.434^{\circ}Brix$ with a preprocessing of the 1st derivative of Savitzky Golay, and 0.518 and 0.229% with a preprocessing normalization, respectively.

• Elastomers and Composites
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• v.54 no.1
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• pp.14-21
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• 2019

Main-chain/side-chain liquid crystalline polymers (MCSCLCPs) combined with an azobenzene group and a cholesteryl group were synthesized to impart light and temperature sensitivity to the polymer. The polymers were designed with the azobenzene unit as the mesogenic group of the main-chain and various compositions of the azobenzene and cholesteryl units as the mesogenic group of the side-chain. The chemical structures and physical properties of the synthesized polymers were investigated by Fourier transform infrared spectroscopy, proton nuclear magnetic resonance spectroscopy, differential scanning calorimetry, thermogravimetric analysis, polarized optical microscopy, and ultraviolet-visible (UV-Vis) spectroscopy. All the MCSCLCPs were amorphous and exhibited enantiotropic liquid crystal phases; these polymers achieved the nematic phase with increasing content of the azobenzene group and exhibited the cholesteric phase with weak liquid crystallinity as the content of the cholesteryl group was increased. Furthermore, the polymers containing the azobenzene group showed photoisomerization when exposed to UV-Vis light, and the CP-A3C7 and CP-A5C5 polymers exhibited thermochromism in the temperature range of the liquid crystal phase.

• Clean Technology
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• v.26 no.4
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• pp.251-256
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• 2020

The biocompatibility and plasmonic properties of Au nanoparticles make them useful for photothermal therapy, drug delivery, imaging, and many other fields. This study demonstrated a novel, facile, economic, and green synthetic method to produce gold nanoparticles. Gold nanoparticles (AuNPs) with spherical and triangular shapes were effectively synthesized using only Schisandra chenesis fruit extract as the capping and reducing agent. The shape of the AuNPs could be engineered simply by adjusting the molar concentration of HAuCl4 in the reaction mixture. The as-synthesized AuNPs were characterized using UV-VIS spectroscopy, transmission electron microscopy (TEM), X-ray diffraction (XRD), dynamic light scattering (DLS), and energy dispersive X-ray analysis (EDXA). This study revealed that by using the HAuCl4 concentration in the AuNP synthesis, the shape and size of the AuNPs could be controlled by the concentration of HAuCl4 and Schisandra chinensis fruit extract as a surfactant. The as-synthesized AuNPs samples had sufficient colloidal stability without noticeable aggregation and showed the predominant growth of the (111) plane of face-centered cubic gold during the crystal growth. The catalytic efficiency of the AuNPs synthesized using Schisandra chenesis fruit extract was examined by monitoring the catalytic reduction of 4-nitrophenol to 4-aminophenol using Ultraviolet-visible spectroscopy (UV-Vis spectroscopy). The synthesized AuNPs showed good catalytic activity to reduce 4-nitrophenol to 4-aminophenol, revealing their practical usefulness.

• Korean Journal of Environmental Biology
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• v.39 no.4
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• pp.581-589
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• 2021

Using visible-near infrared(Vis-NIR) spectra combined with machine learning methods, the feasibility of quick and non-destructive classification of Convolvulaceae species was studied. The main aim of this study is to classify six Convolvulaceae species in the field in different geographical regions of South Korea using a handheld spectrometer. Spectra were taken at 1.5 nm intervals from the adaxial side of the leaves in the Vis-NIR spectral region between 400 and 1,075 nm. The obtained spectra were preprocessed with three different preprocessing methods to find the best preprocessing approach with the highest classification accuracy. Preprocessed spectra of the six Convolvulaceae sp. were provided as input for the machine learning analysis. After cross-validation, the classification accuracy of various combinations of preprocessing and modeling ranged between 43.4% and 98.6%. The combination of Savitzky-Golay and Support vector machine methods showed the highest classification accuracy of 98.6% for the discrimination of Convolvulaceae sp. The growth stage of the plants, different measuring locations, and the scanning position of leaves on the plant were some of the crucial factors that affected the outcomes in this investigation. We conclude that Vis-NIR spectroscopy, coupled with suitable preprocessing and machine learning approaches, can be used in the field to effectively discriminate Convolvulaceae sp. for effective weed monitoring and management.