• Journal of the Korean Ceramic Society
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• v.50 no.6
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• pp.518-522
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• 2013

This study investigatesthe coloration mechanism by identifying the factor that affects thered coloration of copper red glazesin traditional Korean ceramics. The characteristics of the reduction-fired copper red glaze's sections are analyzed using an optical microscope, Raman spectroscopy, scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDX). The sections observed using an optical microscope are divided into domains of surface, red-bubble, and red band. According to the Raman micro spectroscopy analysis results, the major characteristic peak is identified as silicate in all three domains, and the intensity of $Cu_2O$ increases toward the red band. In addition, it is confirmed that the most abundant CuO exists in the glaze bubbles. Moreover, CuO and $Cu_2O$ exist as fine particles in a dispersed state in the surface domain. Thus, Cu combined with oxygen is distributed evenly throughout the copper red glaze, and $Cu_2O$ is more concentrated toward the interface between body and glaze. It is also confirmed that CuO is concentrated around the bubbles. Therefore, it is concluded that the red coloration of the copper red glaze is revealed not only through metallic Cu but also through $Cu_2O$ and CuO.

• The Journal of Natural Sciences
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• v.11 no.1
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• pp.27-31
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• 1999

The Raman scattering was studied from the porous silicons which were made by changing anodization current and time. As the current density was increased, it was observed that Raman peak was red shift and the full width half maximum increased, and was analyzed theoretically.

• ETRI Journal
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• v.24 no.2
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• pp.81-96
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• 2002

This paper describes our design of a hybrid amplifier composed of a distributed Raman amplifier and erbium-doped fiber amplifiers for C- and L-bands. We characterize the distributed Raman amplifier by numerical simulation based on the experimentally measured Raman gain coefficient of an ordinary single mode fiber transmission line. In single channel amplification, the crosstalk caused by double Rayleigh scattering was independent of signal input power and simply given as a function of the Raman gain. The double Rayleigh scattering induced power penalty was less than 0.1 dB after 1000 km if the on-off Raman gain was below 21 dB. For multiple channel amplification, using commercially available pump laser diodes and fiber components, we determined and optimized the conditions of three-wavelength Raman pumping for an amplification bandwidth of 32 nm for C-band and 34 nm for L-band. After analyzing the conventional erbium-doped fiber amplifier analysis in C-band, we estimated the performance of the hybrid amplifier for long haul optical transmission. Compared with erbium-doped fiber amplifiers, the optical signal-to-noise ratio was calculated to be higher by more than 3 dB in the optical link using the designed hybrid amplifier.

• Progress in Superconductivity and Cryogenics
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• v.26 no.1
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• pp.14-19
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• 2024

In this study, we explore the anisotropy of electron-phonon coupling (EPC) constant in epitaxially grown MgB₂ films on c-axis oriented Al₂O₃, examining its correlation with the critical temperature (T_c) and local structural disorder assessed through polarized Raman scattering. Analysis of the polarized Raman spectra reveals angle-dependent variations in the intensity of the phonon spectra. The Raman active mode originating from the boron plane, along with two additional phonon modes from the phonon density of states (PDOS) induced by lattice distortion, was distinctly observed. Persistent impurity scattering, likely attributed to oxygen diffusion, was noted at consistent frequencies across all measurement angles. The EPC values derived from the primary Raman active phonon do not significantly vary with changing observation angles, followed by that the T_c values calculated using the Allen and Dynes formula remain relatively constant across all polarization angles. Although the E_2g phonon mode plays a crucial role in the EPC mechanism, the determination of T_c values in MgB₂ involves not only electron-E_2g coupling but also contributions from other phonon modes.

• Korean Journal of Agricultural Science
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• v.46 no.1
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• pp.183-194
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• 2019

Adulteration of argan oil with some other cheaper oils with similar chemical compositions has resulted in increasing demands for authenticity assurance and quality control. Fast and simple analytical techniques are thus needed for authenticity analysis of high-priced argan oil. Raman spectroscopy is a potent technique and has been extensively used for quality control and safety determination for food products In this study, Raman spectroscopy in combination with a net analyte signal (NAS)-based methodology, i.e., hybrid linear analysis method developed by Goicoechea and Olivieri in 1999 (HLA/GO), was used to predict the different concentrations of olive oil (0 - 20%) added to argan oil. Raman spectra of 90 samples were collected in a spectral range of $400-400cm^{-1}$, and calibration and validation sets were designed to evaluate the performance of the multivariate method. The results revealed a high coefficient of determination ($R^2$) value of 0.98 and a low root-mean-square error (RMSE) value of 0.41% for the calibration set, and an $R^2$ of 0.97 and RMSE of 0.36% for the validation set. Additionally, the figures of merit such as sensitivity, selectivity, limit of detection, and limit of quantification were used for further validation. The high $R^2$ and low RMSE values validate the detection ability and accuracy of the developed method and demonstrate its potential for quantitative determination of oil adulteration.

• 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.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2013.05a
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• pp.1425-1426
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• 2013

• Journal of the Optical Society of Korea
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• v.18 no.5
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• pp.442-448
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• 2014

For the first time, a novel analytical model of the net gain for a Raman-EDFA hybrid optical amplifier (HOA) is proposed and its various parameters optimized using a genetic algorithm. Our method has been shown to be robust in the simultaneous analysis of multiple parameters (Raman length, EDFA length, and pump powers) to obtain large gain. The optimized HOA is further investigated at the system level for the scenario of a 50-channel DWDM system with 0.2-nm channel spacing. With an optimized HOA, a flat gain of >17 dB is obtained over the effective ITU-T wavelength grid with a variation of less than 1.5 dB, without using any gain-flattening technique. The obtained noise figure is also the lowest value ever reported for a Raman-EDFA HOA at reduced channel spacing.

• Bulletin of the Korean Chemical Society
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• v.34 no.1
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• pp.237-242
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• 2013

This experiment was conducted for the purpose of developing such a sensor that can quickly sense dopamine concentration by using chitosan-gold nanoshell. Chitosan nano particles were reacted with gold nano particles so as to synthesize chitosan-gold nanoshell, and the size of the synthesized product was about 150 nm. When dopamine was reacted with chitosan-gold nanoshell, the size of it was not definitely changed, but dopamine was well reacted with chitosan-gold nanoshell, and it generated SERS (surface-enhanced Raman scattering), which led to a clear difference in the intensity of Raman scattering within the range of dopamine concentration (1 mM-10 mM). When Raman scattering was intensity marked on chitosan-gold nanoshell by employing a calibration curve according to dopamine concentration, a straight line whose margin of error was narrow was earned.

• Journal of the Korean Ceramic Society
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• v.56 no.4
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• pp.374-386
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• 2019

A process for nitrogen doping of TiO₂ ceramics was developed, whereby polycrystalline titania particles were prepared at 450-1000℃ with variation of the firing schedule under N₂ atmosphere. The effect of nitrogen doping on the polycrystallites was investigated by X-ray diffraction (XRD) and Raman analysis. The microstructure of the TiO₂ ceramics changed with variation of the firing temperature and the firing atmosphere (N₂ or O₂). The microstructural changes in the nitrogen-doped TiO₂ ceramics were closely related to changes in the Raman spectra. Within the evaluated temperature range, the nitrogen-doped titania ceramics comprised anatase and/or rutile phases, similar to those of titania ceramics fired in air. Infiltration of nitrogen gas into the titania ceramics was analyzed by Raman spectroscopy and XRD analysis, showing a considerable change in the profiles of the N₂-doped TiO₂ ceramics compared with those of the TiO₂ ceramics fired under O₂ atmosphere. The nitrogen doping in the anatase phase may produce active sites for photocatalysis in the visible and ultraviolet regions.