• Journal of the Korea Institute of Military Science and Technology
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• v.26 no.5
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• pp.422-430
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• 2023

To build an automated system detecting toxic chemicals from Raman spectra, we have to obtain sufficient data of toxic chemicals. However, it usually costs high to gather Raman spectra of toxic chemicals in diverse situations. Tackling this problem, we develop methods to generate synthetic Raman spectra of DMMP and 2-CEES without actual experiments. First, we propose certain mathematical transforms to augment few original Raman spectra. Then, we train deep generative models to generate more realistic and diverse data. Analyzing synthetic Raman spectra of toxic chemicals generated by our methods through visualization, we qualitatively verify that the data are sufficiently similar to original data and diverse. For conclusion, we obtain a synthetic dataset of DMMP and 2-CEES with the proposed algorithm.

• Journal of Biosystems Engineering
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• v.37 no.6
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• pp.404-410
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• 2012

Purpose: The objective of this research was to select high quality cucumber (cucumis sativus) seed by classifying into viable or non-viable one using Raman spectroscopy. Method: Both transmission and back-scattering Raman spectra of viable and non-viable seeds in the range from $150cm^{-1}$ to $1890cm^{-1}$ were collected with a laser illumination. Results: The Raman spectra of cucumber seed showed Raman peaks with features of polyunsaturated fatty acids. The partial least squares-discriminant analysis (PLS-DA) to predict viable seeds was developed with measured transmission and backscattering spectra with Raman spectroscopy and germination test results. Various types of spectra pretreatment were investigated to develop the classification models. The results of developed PLS-DA models using the transmission spectra with mean normalization or range normalization, and back-scattering spectra with mean normalization treatment or baseline correction showed 100% discrimination accuracy. Conclusions: These results showed that Raman spectroscopy technologies can be used to select the high quality cucumber seeds.

• Advances in nano research
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• v.1 no.2
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• pp.111-124
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• 2013

Surface-enhanced Raman scattering (SERS) effect deals with the enhancement of the Raman scattering intensity by molecules in the presence of a nanostructured metallic surface. The first observation of surface-enhanced Raman spectra was in 1974, when Fleischmann and his group at the University of Southampton, reported the first high-quality Raman spectra of monolayer-adsorbed pyridine on an electrochemically roughened Ag electrode surface. Over the last thirty years, it has developed into a versatile spectroscopic and analytical technique due to the rapid and explosive progress of nanoscience and nanotechnology. This review article describes the recent development in field of surface-enhanced Raman scattering research, especially fabrication of various SERS active substrates, mechanism of SERS effect and its various applications in both surface sciences and analytical sciences.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.11a
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• pp.52-55
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• 1997

In this study, PLZT stock solutions were prepared by sol-gel processing to fabricate PLZT thin films. The stock solutions were spin-coated on ITO-glass and the film were annealed by rapid thermal annealing(RTA). The variation of tile crystallographic structure of the thin films and the phase transition with respect to it were observed using Raman spectra. Raman result showed that the band of spectra are broad as the amount of Zr substitution increased and specially, abrupt change occurs in the raman spectra upon crossing the tetragonal-rhombohedral phase boundry at 2/55/45 PLZT thin film. So, the fact that the crystallographic structure was transitted from tetragonal to rhombohedral structure was certified.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.5
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• pp.2393-2399
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• 2013

In this paper, we proposed a method to screening of Alzheimer's disease (AD) from Raman spectra of platelet with synthesis of basis spectra using singular value decomposition (SVD). Raman spectra of platelet from AD transgenic mice are preprocessed with denoising, removal background and normalization method. The column vectors of each data matrix consist of Raman spectrum of AD and normal (NR). The matrix is factorized using SVD algorithm and then the basis spectra of AD and NR are determined by 12 column vectors of each matrix. The classification process is completed by select the class that minimized the root-mean-square error between the validation spectrum and the linear synthesized spectrum of the basis spectra. According to the experiments involving 278 Raman spectra, the proposed method gave about 97.6% classification rate, which is better performance about 6.1% than multi-layer perceptron (MLP) with extracted features using principle components analysis (PCA). The results show that the basis spectra using SVD is well suited for the diagnosis of AD by Raman spectra from platelet.

• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.135-135
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• 1999

It is well known that Raman spectroscopy is powerful tool in analysis of sp3/sp3 bonding fraction in diamond-like carbon(DLC) films. Raman spectra of DLC film is composed of D-peak centered at 1350cm-1 and G-peak centered at 1530cm-1. The sp3/sp3 fraction is qualitatively acquired by deconvolution method. However, in case of DLC film, it is generally observed that G-peak position shifts toward low wavenumber as th sp3 fraction increases. However, opposite results were frequently observed in ta-C films. ta-C film has much higher residual compressive stress due to its high sp3 fraction compared to the DLC films deposited by CVD method. Effect of residual stress on G-peak position is most recommendable parameter in Raman analysis of ta-C, due to its smallest fitting error among many parameters acquired by peak deconvolution of symmetric spectra. In current study, the effect of residual stress on Raman spectra was quantitatively evaluated by free-hang method. ta-C films of different residual stress were deposited on Si-wafer by modifying DC-bias voltage during deposition. The variation of the G-peak position along the etching depth were observed in the free-hangs of 20~30${\mu}{\textrm}{m}$ etching depth. Mathematical result based on Airy stress function, was compared with experimental results. The more reliable analysis excluding stress-induced shift was possible by elimination of the Raman shift due to residual compressiove stress.

• Bulletin of the Korean Chemical Society
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• v.14 no.1
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• pp.127-131
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• 1993

Laser optoacoustic technique has been employed to obtain the gas phase absorption spectra of 1-chloronaphthalene, 3-chlorobiphenyl, and 2,5,2'-trichlorobiphenyl in conjunction with a gas chromatograph and a Helmholtz resonator at the various $CO_2$ laser wavelengths. Raman spectra of 1-chloronaphthalene, 4-chlorobiphenyl, and 4,4'-dichlorobiphenyl in condensed phase have been also obtained. The optoacoustic measurement of the infrared absorption in gas phase has been shown to be of value in monitoring the environmental pollutants.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.8
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• pp.196-202
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• 2013

Basal cell carcinoma (BCC) is the most common skin cancer and its incidence is increasing rapidly. In this paper, we propose a diagnosis method of basal cell carcinoma by Raman spectra of skin tissue using the NMF(non-negative matrix factorization) algorithm. After preprocessing steps, measured Raman spectra is used classification experiments. The weight and the basis can be obtained in a simple matrix operation and a column vector of the matrix decompsed by the NMF. Linear combination of bases and weights, it is possible to approximate the average of Raman spectra. The classification method is to select the class which to minimize the root mean square of the difference of the linear combination and the objective spectrum. According to the experimental results, the proposed method shows the promising results to diagnosis BCC. In addition, it confirmed that the proposed method compared with the previous research result could be effectively applied in the analysis of the Raman spectra.

• Proceedings of the Korea Crystallographic Association Conference
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• 2002.11a
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• pp.15-15
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• 2002

Homogeneous and crack-free potassium lithium niobate (K₃Li/sub 2-x/Nb/sub 5+x/O/sub 15/, 0＜x＜0.5, KLN) single crystals were successfully grown by the Czochralski technique. The KLN single crystals of several different compositions were employed for the investigation of the lattice vibration spectra using infrared Raman spectroscopy. The characteristic Raman spectra of the [NbO/sub 6/]/sup 7-/ octahedral ions were strikingly influenced by the Li ion content. The symmetric stretch vibrational modes V₁, V₂ are broadened, and the symmetric bend vibration mode V/sub 5/ is broadened and even split into three peaks with increasing the Li content, supporting that the bend vibration modes of the [NbO/sub 6/]/sup 7-/ octahedrons are obviously perturbed by Li ions in the C site. Enhanced Raman peak intensities after the post annealing at 900℃ and for 24 h evidenced that a residual stress in as-grown crystals was negligible and only a defect concentration might be reduced.

• Bulletin of the Korean Chemical Society
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• v.22 no.8
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• pp.837-841
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• 2001

The electronic absorption and Raman spectra of $\alpha\omega-diphenylpolyenyl$, anions Ph(CH)nPh- (DPn- , n = 3, 5, 7, 9, and 13), with odd number of carbons at the polyene part, have been studied in the tetrahydrofuran (THF) solutions and in their solid film states, respectively. In the case of Raman spectra for DPn- , the frequencies and relative intensities of some Raman peaks regularly change with the increase of polyene chain length. The spectral patterns of anions (DPn- ) are very similar with those of radical anion (DPn${\cdot}$- ). However, the C=C stretching peaks of DPn- anions are observed in the 25-35 cm-1 higher frequency region than those of DPn${\cdot}$- radical anions. In the case of long chain models such as DP9- and DP13- , the C=C stretching peaks are observed in even higher frequency region than those of the corresponding neutral polyenes such as DP8, DP10, and DP12. The Raman patterns of DPn- anions in the THF solutions are similar with those in their solid film states. On the other hand, their electronic absorption spectra show a considerable difference each other. The n- ${\pi}*$ electronic absorption bands of DPn- anions in the THF solutions have been observed in the 0.27-0.39 eV lower energy region than those in their solid film states due to the solvent effects on polyene anions.