• Bulletin of the Korean Chemical Society
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• 제33권11호
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• pp.3740-3744
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• 2012

We synthesized three different derivatives of bis-spiropyran using simple organic reactions with high yields. BSP1, a derivative of bis-spiropyran having a connection at the position 6' and BSP2, a derivative of bis-spiropyran having a connection at the position 5 and BSP3, a derivative of bis-spiropyran containing a dithienylethene group between two spiropyran moieties were synthesized. The optical properties of BSPs were characterized. UV-Vis spectra showed that BSPs exhibit reversible photo-isomerization and the efficiency of photo-isomerization is highly dependent on the position of nitro group. BSPs having nitro group at para position of hydroxy group showed the higher efficiency of photo-isomerization that the one having nitro group at ortho position. The optical microscope images obtained under ultraviolet or visible light exposure demonstrated that the formation of nanorods can be reversibly controlled by optical signal.

• Journal of Radiation Protection and Research
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• 제41권2호
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• pp.167-171
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• 2016

Background: TlBr is of considerable technological importance for radiation detection applications where detecting high-energy photons such as X-rays and ${\gamma}$-rays are of prime importance. However, there were few reports on investigating optical properties of TlBr itself for deeper understandings of this material and for making better radiation detection devices. Thus, in this paper, we report on the optical characterizations of TlBr single crystals. Spectroscopic ellipsometry (SE) and photoluminescence (PL) measurements at RT were performed for this work. Materials and Methods: A 2-inch TlBr single crystalline ingot was grown by using the vertical Bridgman furnace. SE measurements were performed at RT within the photon energy range from 1.1 to 6.5 eV. PL measurements were performed at RT by using a home-made PL system equipped with a 266 nm-laser and a spectrometer. Results and Discussion: Dielectric responses from SE analysis were shown to be slightly different among the different samples possibly due to the different structural/optical properties. Also from the PL measurements, it was observed that the peak intensities of the middle samples were significantly higher than those of the other two samples. With the given values for permittivity of free space (${\varepsilon}_0=8.854{\times}10^{-12}F{\cdot}m^{-1}$), thickness (d = 1 mm), and area ($A=10{\times}10mm^2$) of the TlBr sample, capacitances of TlBr were 6.9 pF (at $h{\nu}=3eV$) and 4.4 pF (at $h{\nu}=6eV$), respectively. Conclusion: SE and PL measurement and analysis were performed to characterize TlBr samples from the optical perspective. It was observed that dielectric responses of different TlBr samples were slightly different due to the different material properties. PL measurements showed that the middle sample exhibited much stronger PL emission peaks due to the better material quality. From the SE analysis, optical, dielectric constants were extracted, and calculated capacitances were in the few pF range.

• 한국세라믹학회지
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• 제27권1호
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• pp.136-146
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• 1990

Whiskers of SiC were grown from the mixture of silica and graphite powders by Acheson method(direct heating method). The structrua, morphological and chemical characterizations have been performed by X-ray diffractometer(XRD), transmission electron microscopy(TEM), optical microscopy(OM), scanning electron microscopy(SEM), X-ray photoelectron spectroscopy(XPS) and energy dispersive spectrometer(EDS). The growth mechanism of SiC whiskers is also discussed.

• Bulletin of the Korean Chemical Society
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• 제35권4호
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• pp.1077-1081
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• 2014

Polyacrylamide (PAM) -HgS nanocomposites were successfully prepared in polyacrylamide (PAM) matrix. From TEM and XRD characterizations, the synthesized HgS nanocrystals were chain-like spherical in shape with a diameter of about 40-60 nm and high crystalline quality. The quantum-confined effect of HgS nanocrystals was confirmed by UV-vis diffuse reflection spectra. The optical properties of products were investigated by using photoluminescence (PL) spectra, which showed that HgS nanocrystals exhibited good optical properties with maximum emission peak at about 640 and 650 nm at different reaction temperatures. The interaction of HgS nanocrystals with PAM was studied through FT-IR spectroscopy and TG analysis, which suggested that $Hg^{2+}$ could interact with functional groups of PAM. The experimental results indicated that PAM not only induced nucleation, but also inhibited further growth of HgS crystals and play an important role in the formation of PAM/HgS nanocomposites. In addition, the possible mechanism of HgS nanoparticles growth in PAM solution was also discussed.

• Advances in nano research
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• 제14권6호
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• pp.557-573
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• 2023

The rapid growth of zinc-oxide (ZnO) nanostructures (NSs) on woven carbon fiber (WCF) is reported in this study employing a microwave-aided chemical bath deposition process. The effects of different process parameters such as molar concentration, microwave duration and microwave power on morphologies and growth rate of the ZnO on WCF were studied. Furthermore, an attempt has been taken to study influence of different type of growth solutions on ZnO morphologies and growth rates. The surface functionalization of WCF fabrics is achieved by successful growth of crystalline ZnO on fiber surface in a very short duration through one-step microwave synthesis. The morphological, structural and compositional studies of ZnO-modified WCF are evaluated using field-emission scanning electron microscopy, X-ray diffraction and energy dispersive X-ray spectroscopy respectively. Good amount of zinc and oxygen has been seen in the surface of WCF. The presence of the wurtzite phase of ZnO having crystallite size 30-40 nm calculated using the Debye Scherrer method enhances the surface characteristics of WCF fabrics. The UV-VIS spectroscopy is used to investigate optical properties of ZnO-modified WCF samples by absorbance, transmittance and reflectance spectra. The variation of different parameters such as dielectric constants, optical conductivity, refractive index and extinction coefficient are examined that revealed the enhancement of optical characteristics of carbon fiber for wide applications in optoelectronic devices, carbon fiber composites and photonics.

• Journal of Electrical Engineering and Technology
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• 제2권4호
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• pp.518-524
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• 2007

This paper describes several improved characterizations of the EPIC CCD, which now has modified electrode and channel structures. From a 3-D numerical simulation of the device, its channel doping and potential distributions are then observed for the optimization of the charge transfer. A wavelength-dependence on the device structure is observed in terms of the reflectivity of the incident radiation. The optical properties of ultra-low energy levels, when using an open-electrode structure, are then considered to improve their quantum efficiency.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 춘계학술대회 논문집
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• pp.169-171
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• 2009

We have fabricated CIGS thin film absorber layers by the evaporation of CIGS powders which were synthesized by solutions with different atomic ratio compositions. We found that the polycrystalline structural properties and optical properties of the deposited CIGS thin films were strongly dependent on the CIGS powder synthesis solution compositions. For three different solution compositions, Cu:In:Ga:Se= 4:3:1:8, 8:3:1:8, 12:3:1,8, the deposited thin film crystalline structures were varied form InSe crystalline structure to CIGS chalcopyrite structures. Our results showed that CIGS powder evaporation is potential for the one step fabrication process for CIGS thin film absorber layer deposition.

• 한국감성과학회:학술대회논문집
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• 한국감성과학회 2000년도 춘계 학술대회 및 국제 감성공학 심포지움 논문집 Proceeding of the 2000 Spring Conference of KOSES and International Sensibility Ergonomics Symposium
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• pp.407-411
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• 2000

Color reproduction n CRT monitors needs colorimetric characterization concluding two stages with 3x3 matrix and three TRCs (Tone-Reproduction Characteristics). The 3x3 matrix is based on the additivity of RGB emissions, and the TRC represents the non-linearity between the input digital counts and the output luminance. The objective of this project is to evaluate the accuracy of color reproduction on LCD monitors using conventional CRT model(GOG model). For two different manufacturers, colorimetric characterizations of desktop LCDs have been performed. Because the transfer function for LCD is very differ from TRC of CRT, some researchers had reported that GOG model is inadequate for the colorimetric characterization of LCDs. However in our experiment, the degree of accuracy was dependent on the shape of electro-optical transfer functions of LCD. It has been founded that the GOG model could be applied for LCD monitors having monotonically increased Electro-optical transfer function.

• Elastomers and Composites
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• 제50권1호
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• pp.49-54
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• 2015

Dynamically vulcanized PMMA/ACM (80 wt%/20 wt%) blend using DCP as a curing agent was prepared using internal mixer. The morphology, mechanical properties, optical properties, melt viscosity and die swell were characterized by using FE-SEM, tensile test, Izod impact test, dynamic mechanical analysis, ARES and capillary rheometer, respectively. The blends show a phase-separated morphology in which ACM are dispersed in PMMA matrix. Dynamically vulcanized blend exhibits higher mechanical properties, higher melt viscosity, and die swell as compared to simple blend. And, the dynamically vulcanized blend showed total transmittance of more than 75% and haze of higher than 90%, which enable it to find potential applications to fabricate an optical diffuser by extrusion process.

• 한국광학회지
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• 제12권1호
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• pp.1-4
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• 2001

테라헤르츠 레이다를 이용하여 알루미늄 거울 및 도체와 부도체로 이루어진 각각의 물질에 대한 테라헤르츠 전자기 펄스의 반사특성을 측정하였다. 알루미늄 거울로부터 반사된 테라헤르츠 펄스의 크기변화를 측정하기 위하여 최고 9회까지 테라파를 반사시켜 펄스의 크기에 대한 변화가 없음을 확인하였다. 또한 알루미늄 거울의 반사각도에 대한 테라파의 영향을 측정하였다 알루미늄 거울에 대한 반사파를 reference로 하여 알루미늄 board, 순수실리콘, quartz, 그리고 LDPE 에 대한 테라파의 반사를 측정하여 각각의 물질에 대한 테라헤르츠 영역의 반사계수와 굴절률을 측정하였다. 이러한 측정법은 sample의 두께에 무관한 비접촉 테라헤르츠 분석법의 적용이라할 수 있다.