• Korean Journal of Remote Sensing
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• v.15 no.3
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• pp.167-175
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• 1999

So far, the remote sensing technology has widely been used in a variety of application areas such as military, medical imaging, environment, geology and so forth. The microwave remote sensing uses the wavelengths ranging from around one centimeter up to a few tens of centimeters and is known to be very effective regardless of the weather conditions and the day/night time as compared with the reflective InfraRed (IR) remote sensing or the thermal IR remote sensing. There are three generic modes of synthetic aperture radar imaging systems depending on its application, that is, stripmap mode, spotlight mode, or inverse mode. In this article we focus on the issue of imaging of flying aircrafts for the inverse mode of a ground - based, fixed radar with moving objects. The imaging of flying aircrafts is considered to be an important step for the automatic target recognition systems, and therefore a great deal of efforts have recently been made on the subject. Here we review the three representative methods including the Fourier transform processing, the time - frequency processing, and the reconstruction from the projection. Some relative merits and drawbacks are also discussed.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.21 no.6
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• pp.1-8
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• 2021

The performance of hidden camera cameras is improving day by day due to miniaturization and advanced technology integration according to the speed of technological development of smartphones. As this external networking computing environment is advanced and diversified, exposure to hidden cameras in addition to general safety cameras is also increasing. On the other hand, the technology for detecting and preventing hidden cameras is not keeping up with the development and speed of these hidden cameras. Therefore, in this study, the heat of the hidden camera was detected using infrared thermal detection technology based on general image and thermal image synthesis technology, and the reflectance of each wavelength according to the difference in ambient temperature was analyzed to reduce the false positive rate.

• Journal of the Korean Chemical Society
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• v.67 no.4
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• pp.236-240
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• 2023

Non-concentration quenching EuGa₂S₄ and Eu₂Ga₂S₅ phosphors, in which the concentration of Eu²⁺ activator ion is 100%, were synthesized by a solid state reaction at temperature range from 800 to 1050 ℃. The wavelength of maximum intensity (λ_max) of EuGa₂S₄ and Eu₂Ga₂S₅ phosphors are 546 and 581 nm, respectively. An examination of the X-ray diffraction patterns and photoluminescent properties of EuGa₂S₄ and Eu₂Ga₂S₅ phosphors revealed that EuGa₂S₄ and Eu₂Ga₂S₅ phosphors were formed at lower temperature range (800~900 ℃) and higher temperature range (1000~1050 ℃), respectively.

• Journal of the Korean Society of Radiology
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• v.2 no.3
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• pp.11-18
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• 2008

In this study, the particle properties and luminescence properties of Gd2O3 nano powder with various Eu content were studied. Gd2O3:Eu nano powder was fabricated using special solvent which mixed the alcohol and the distilled water at specific ratio. This solvent by the solution method showed short fabrication time because solution time of Gd and Eu was reduced. From this experiment with Gd2O3:Eu, the particle properties og nano powder phosphor way analysed using SEM (scanning electron microscope) and EDX(Energy Dispersive X-ray). Also the luminescence properties of nano powder was measured using PL(Photoluminescence) and CL (CathodeLuminescence). The size of powder was 30nm~40nm. The magnitude of powder showed the best peak at 620nm. Among 1,3,5wt% of Eu content, the more Eu content was added in powder, the more photons wre generated. Also it shows luminescence efficiency was improved adding 5% of Eu content.

• Journal of the Korean Chemical Society
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• v.44 no.1
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• pp.45-51
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• 2000

The binding mode of anthryl derivatives to synthetic polynucleotides were investigated by various spectroscopic methods. The spectroscopic properties of anthracence with metbylamine and methylethylenediamine side chains, complexed with $poly[d(A-T)_2]$ and $poly[d(G-C)_2]$, can be summarized as a red-shift, with a strong hypochromism in the absortion spectrum, similar induced CD spectra, and a strong negative LD spectrum with an $LD^r$ magnitude comparable to the DNA absorption region. These observations indicate that anthracene moiety is intercalated between the nucleo-bases of $poly[d(A-T)_2]$ and $poly[d(G-C)_2]$. The side chains did not alter the spectroscopic properties, demonstrating that the binding mode was not affected by them. A strong energy transfer was observed from poly[d(A-T),] and $poly[d(I-C)_2]$ but not from $poly[d(G-C)_2]$, as reported by Kumar et al. (J. Am. Chem. Soc.(1993) 115, 8547). Since the binding mode is the same for all the polynucleotides, the amine group of the guanine base, which protrudes into the minor groove of $poly[d(G-C)_2]$, is concluded to disrupt the energy transfer.

• Analytical Science and Technology
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• v.11 no.5
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• pp.360-365
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• 1998

We have studied structural characterization, electrical charge and discharge, and impedence properties for the $LiMn_2O_4$ synthesized by solid state reaction. From the X-ray diffraction results, diffraction patterns for compounds of the four kinds of $LiMn_2O_4$ compounds were observed to peaks of (111), (311), (004) and (400). Also, Small similar peaks (110), (222) and (313) were observed for sample C1 and C2. Concerning to new peaks of (113) and (331) for the sample C4, we can found that structural transitions were accompanied from C1 and C2 to C4 via C3 structure. A electrical charge and discharge data showed that efficiency of C1 was very poor state and efficiencies of C2 and C3 were about 60-70% of theoretical capacity. But, the C4 showed good charge and discharge properties of more than 70% of theoretical capacity. From the impedence properties for finding the effect of ions and electrons transfer of battery, C2 and C3 of high frequency of real number showed good electrical impedence properties.

• Polymer(Korea)
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• v.38 no.4
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• pp.535-543
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• 2014

This work, which was about the synthesis of naphthalimidopropyl acrylate and GMA copolymers and their physical properties, investigated the compositions of the copolymer, the reactivity ratios of the monomer, resonance effect (Q), polar effect (e) and fluorescence of naphthalene. Azobisisobutyronitronitryl (AIBN) as an initiator was employed at $60^{\circ}C$ with dimethylformamide (DMF) of solvent for the copolymerization of NIPA. $r_1$ was found to be higher than $r_2$ from the reactivity ratios of the monomer obtained from Fineman-Ross (F-R), Kelen-$T{\ddot{u}}d{\ddot{o}}s$(K-T) methods. NIPA was found to be more copolymerized than GMA. $r_1{\cdot}r_2$ product was lower than 1, copolymerization was maked random-alternating type. The fluorescence spectrum of these polymers showed a weak monomer fluorescence band at 380 nm and a strong excimer fluorescence band at about 460 nm. Fluorescence life time of NIPA monomer showed fluorescence cover with UV 355 nm at room temperature, and life time showed $5.1449{\times}10^{-7}s$.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.19 no.1
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• pp.15-18
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• 2009

To enhance near UV-visible absorption region and to applied phosphor convert-white LEOs (PC-WLEDs), a red phosphor composed of ${Y_2}{SiO_5}:\;EU^{3+}$, $Bi^{3+}$ compounds was prepared by the conventional solid-state reaction. The photoluminescence (PL) shown that samples were excited by near UV light 395 nm for measurement of PL spectra. Emission spectra of samples have shown red emissions at 612 nm ($^5D_0{\to}^7F_2$). The enhanced near $UV{\sim}$ visible excitation spectrum with a broad band centered at 258 nm and 282 nm originated in the transitions toward the charge transfer state (CTS) due to the $Eu^{3+}-Bi^{3+}-O^{2-}$ interaction. The other excitation band at $350\;nm{\sim}480\;nm$, corresponding to the transitions $^7F_0{\to}^5L_9$ (364 nm), $^7F_0{\to}^5G_3$ (381 nm), $^7F_0{\to}^5L_6$ (395 nm), $^7F_0{\to}^5D_3$, (415 nm) and $^7F_0{\to}^5D_2$ (466 nm), occurred due to enhanced the f-f transition increasing $Bi^{3+}$ and $Eu^{3+}$ ions. The PL intensity increased with increased as concentration of $Bi^{3+}$ and the emission intensity becomes with a maximum at 0.125 mol.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.23 no.5
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• pp.230-234
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• 2013

IR cut-off thin films consisted of ATO nanoparticles were successfully fabricated by sol-gel method. The coating solution was synthesized with organic/inorganic hybrid binder and ATO colloidal solution and ATO thin films were coated on a slide glass with the withdrawal speed of 5~40 mm/s. As the withdrawal speed increased from 5 mm/s to 40 mm/s, the thickness of coating thin films also increased from $1.05{\mu}m$ to $4.25{\mu}m$ and the IR cut-off in wavelength of 780~2500 nm increased from 49.5 % to 66.7 %. In addition, the pencil hardness of ATO thin films dried at $80^{\circ}C$ was ca. 5H and the coating films were not removed after a cross cutter tape test because of the hybrid binder synthesized with tetraethylorthosilicate and methyltrimethoxysilane. The surface morphologies, optical properties and film thickness of prepared thin films with a different withdrawal speed were measured by field emission scanning electron microscope (FE-SEM), UV-Vis spectrophotometer, and Dektak.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.16 no.3
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• pp.112-115
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• 2006

The red emission properties of $Bi^{3+}$ co-doped $Y_2O_3:Eu^{3+}$ prepared by the solid-state reaction was investigated, in order to verify its potential to act as the red emitting phosphor of white LEDs. The emission spectrum consisted of a weak band at 581, 587, 5931 and 599 nm, with maximum sharp peaks occurring at about 611 nm due to the $^5D_0{\rightarrow}^7F_2$ transition of $Eu^{3+}$, while the excitation spectrum exhibited a broad band between 290 and 430 mm with peaks occurring in the range of $310{\sim}390nm$. Also, SEM image of the sample containing 0.43 mol% $H_3BO_3$ and 2.08 mol% $BaCl_2{\cdot}2H_2O$ phosphor particles grew to achieve diameters of $700{\sim}800nm$.