• Publications of The Korean Astronomical Society
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• v.32 no.1
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• pp.45-47
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• 2017

The Infrared Camera onboard the AKARI satellite carried out spectroscopic observations with a grism mode named NG, whose wavelength coverage was $2.5-5.0{\mu}m$. We reinvestigate the current flux calibration for the NG grism mode, with which calculated flux density implausibly decreases at $4.9{\mu}m$ especially for red objects due to the second-order light contamination. We perform a new spectral response calibration using blue and red standard objects simultaneously. New response curves which contain both the first-and second-order light are able to separate each contribution consistently and useful for studies of red objects such as CO ro-vibrational absorption in active galactic nuclei.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.7 no.1
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• pp.126-136
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• 1997

6H-SiC UV photodiodes with $p^+$/n/n mesa structure were fabricated. The photocurrents of the photodiodes were measured in the wavelength range of 200~600 nm. The photocurrents were sensitive to ultraviolet radiation of 200~500 nm, and come to the maximum value at 260 nm. The quantum efficiency was calculated by using the diffusion model of minority carriers, and compared with the distribution of the photocurrent measured as a function of wavelength each other. The photocurrents of the 6H-SiC photodiode were explained by the diffusion model of the minority carriers which contained the optical absorption of the depletion region as well as the other layers.

• Journal of Sensor Science and Technology
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• v.23 no.4
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• pp.272-277
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• 2014

At present, the index of chemical oxygen demand (COD) is widely used as an indicator of organic water pollution with biochemical oxygen demand (BOD). But, traditional COD measurement method are not only with various chemical reagents exhausted, but also long time consumed, the operation procedure and the modification are much professional. This paper reported a novel COD measurement system using double-beam and multiple wavelength analysis UV-VIS spectrometries. It consists of pulsed xenon lamp, two-way optical fiber, optical switch, spectrometer and main processor. Proposed COD measurement system obtains any spectral information of water sample (KHP standard sample and two river water and wastewater) and reference sample (distilled water) in the range of 200~520 nm, corresponding to the COD concentration from 0 to 300 mg/L through calculating the UV absorbance. The system show improved precision and can work continuously fast at time interval about 25 seconds.

• Textile Coloration and Finishing
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• v.9 no.3
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• pp.42-49
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• 1997

In order to study the dyeability of reactive dyes fixable at neutral pH, three reactive dyes(DYE-NC, DYE-PC, and DYE-LC) were prepared by the reaction of Cibacron Brilliant Red 3B-A with nicotinic acid, pyridine, and lutidine, respectively. FT-IR and UV/Vis spectrophometry were used to identify the dyes prepared. While the maximum absorption wavelength (&{\lambda}_{max}&) of Cibacron Brilliant Red 3B-A was 515nm, the &{\lambda}_{max}& of DYE-NC, DYE-PC, and DYE-LC were 522nm, 525nm, and 536nm, respectively. The &{\lambda}_{max}& was shifted to the longer wavelength by introducing the electron donating groups to the pyridine ring of Cibacron Brilliant Red 3B-A. All of the reactive dyes synthesized showed good exhaustion and fixation property to cotton fabric at higher temperature and neutral pH condition. It was regarded that the quaternary pyridinium ion functionated as the leaving group instead of the chloride ion. Among them, DYE-NC showed the best dyeability at the above condition. It was considered that the electron withdrawing carboxylic acid group in nicotinic acid enhanced the cationic property of nitrogn in pyridine ring, resulting the good reactivity with OH group in cellulose.

• Journal of Sensor Science and Technology
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• v.17 no.2
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• pp.120-126
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• 2008

Glucose concentrations in the interstitial fluid were measured based on optical spectroscopy. Prediction of glucose concentrations was made using partial least squares regression and accuracy improvement was achieved by data preprocessing as well as by selecting an optimal wavelength region. For this purpose, artificial interstitial fluid samples were prepared where their glucose levels varied between 0 and 10 g/dl. Infrared spectral regions where glucose absorption lies were investigated. A region of 1000 - 1500 $cm^{-1}$ produced the best accuracy among the regions of 1000 - 1500 $cm^{-1}$, 4000 - 4545 $cm^{-1}$1 and 5500 - 6500 $cm^{-1}$. Further accuracy improvement in 1000 - 1500 $cm^{-1}$ was achieved by selecting specific wavelength bands based on a loading vector analysis method. For the samples whose glucose concentrations ranged between 0 and 0.5 g/dl, SEP= 0.0266 g/dl and R =0.9863 were achieved with 1000 - 1500 $cm^{-1}$. However, the loading vector optimized band of 1002 - 1095 $cm^{-1}$ reduced the prediction error up to 47 % (SEP =0.0125 g/dl and R=0.9970).

• Electrical & Electronic Materials
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• v.8 no.4
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• pp.472-477
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• 1995

The degree of the photodoping process in Ag(100[.angs.])/a-Se$_{75}$Ge$_{25}$(1500[.angs.]) films has measured as a function of the photon energy between 1.5[eV] and 2.9[eV] with the exposing time. The "window" characteristics of Ag occur at 3400[.angs.] (3.65[eV]) and Ag is almost transparent in this region. It is shown that transmittance is almost constant (40-50%) for the wavelength ranges of our experiment. It is found that the energy gap of a unexposed a-Se$_{75}$Ge$_{25}$ film is 1.81[eV]. Ag photodoping process results in the photodarkening effect which the absorption edge shifts to the long wavelength. Especially, very large band shift (-0.3[eV]) is obtained by exposing He-Ne laser(6328[.angs.]).. We have obtained "the U-type property" for Ar He-Ne and semiconductor laser. It is associated with the variation of energy gap(E$_{g}$) with photo-dose and substantially is explained by DWP model.l.gap(E$_{g}$) with photo-dose and substantially is explained by DWP model.

• Current Optics and Photonics
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• v.4 no.2
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• pp.134-140
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• 2020

A significant enhancement of the magneto-optical Faraday rotation and extraordinary optical transmission (EOT) in the cascaded double-fishnet (CDF) structure with periodic rectangular apertures is theoretically predicted by using the extended finite difference time domain (FDTD) method. The results demonstrate that the transmittance spectrum of the CDF structure has two EOT resonant peaks in a broad spectrum spanning visible to near-infrared wavebands, one of them coinciding with the enhanced Faraday rotation and large figure of merit (FOM) at the same wavelength. It is most important that the resonant position and intensity of the transmittance, Faraday rotation and FOM can be simply tailored by adjusting the incident wavelength, the thickness of the magnetic layer, and the offset between two metallic rectangular apertures, etc. Furthermore, the intrinsic physical mechanism of the resonance characteristics of the transmittance and Faraday rotation is thoroughly studied by investigating the electromagnetic field distributions at the location of resonance. It is shown that the transmittance resonance is mainly determined by different hybrid modes of surface plasmons (SPs) and plasmonic electromagnetically induced transparency (EIT) behavior, and the enhancement of Faraday rotation is mostly governed by the plasmonic electromagnetically induced absorption (EIA) behavior and the conversion of the transverse magnetic (TM) mode and transverse electric (TE) mode in the magnetic dielectric layer.

• Bulletin of the Korean Chemical Society
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• v.34 no.3
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• pp.907-911
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• 2013

Numbers of matrix- and analyte-derived ions and their sum in matrix-assisted laser desorption ionization (MALDI) of a peptide were measured using 2,5-dihydroxybenzoic acid (DHB) as matrix. As for MALDI with ${\alpha}$-cyano-4-hydroxy cinnamic acid as matrix, the sum was independent of the peptide concentration in the solid sample, or was the same as that of pure DHB. This suggested that the matrix ion was the primary ion and that the peptide ion was generated by matrix-to-peptide proton transfer. Experimental ionization efficiencies of $10^{-5}-10^{-4}$ for peptides and $10^{-8}-10^{-7}$ for matrices are far smaller than $10^{-3}-10^{-1}$ for peptides and $10^{-5}-10^{-3}$ for matrices speculated by Hillenkamp and Karas. Number of gas-phase ions generated by MALDI was unaffected by laser wavelength or pulse energy. This suggests that the main role of photo-absorption in MALDI is not in generating ions via a multi-photon process but in ablating materials in a solid sample to the gas phase.

• Journal of the Korean Ceramic Society
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• v.42 no.7 s.278
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• pp.461-468
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• 2005

Transparent TiO$_{2}$ sols were prepared by hydrothermal synthesis to heat Ti precursor solutions, from Ti hydroxides obtained with neutralizing aqueous TiOCl$_{2}$ solutions having various concentrations of NaCI by aqueous NaOH solution, in the autoclave at 120$^{\circ}C$ The photocatalytic abilities of glass beads coated with the sol for gaseous benzene were evaluated. As a result, it was found that due to the increase of brookite phase in TiO$_{2}$ by controlling the concentration of Na ion the optical absorption of TiO$_{2}$ increases toward long wavelength but that in the area of short wavelength becomes relatively low and consequently the photocatalytic performance of TiO$_{2}$ thin film for benzene gas rather decreases, compared to that of composite film of anatase and brookite phases. These results suggest that in order for coated TiO$_{2}$ thin film to have high dissociation performance for benzene gas it is effective to form anatase and brookite phases compositely in TiO$_{2}$.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.292-295
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• 2003

Moire topography method is a well-known non-contacting 3-D measurement method. the automatic 3-D measurement by moire topography has been required since the method was frequently applied to the engineering and medical fields. 3-D measurement using digital projection moire topography is very attractive because of its high measuring speed and high sensitivity. In this study, digital two-wavelength phase shilling moire is applied to the entertainment fields. recently. as promoting the growth of the VR-Game, display devices which attract public attention such as HMD or Projector are being appeared in order to deliver effectively the absorption sense. this study realized the Auto-calibrating system for arbitrary display surface using digital moire method which satisfied the shape measurement of display surface and the request of FOV(Field of View) output. also when large screen wasn't prepared, this auto-calibrating system was applied to enjoy games or movies at home with a projector and walls