• Korean Journal of Materials Research
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• v.9 no.12
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• pp.1155-1159
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• 1999

Thin film solar cells on a glass/$SnO_2$ substrate with p-SiC/i-Si/n-Si heterojunction structures were fabricated using a plasma-enhanced chemical-vapor deposition system. The photovoltaic properties of the solar cells were examined with varying the gas phase composition, x=$CH_4/\;(SiH_4+CH_4)$, during the deposition of the p-SiC layer. In the range of x=0~0.4, the efficiency of solar cell increased because of the increased band gap of the p-SiC window layer. Further increase in the gas phase composition, however, led to a decrease in the cell efficiency probably due to in the increased composition mismatch at the p-SiC/i-Si layers. As a result, the efficiency of a glass/$SnO_2$/p-SiC/i-SiC/i-Si/n-Si/Ag thin film solar cell with $1cm^2$ area was 8.6% ($V_{oc}$=0.85V, $J_{sc}$=16.42mA/$cm^2$, FF=0.615) under 100mW/$cm^2$ light intensity.

• Applied Chemistry for Engineering
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• v.34 no.6
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• pp.590-595
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• 2023

Novel aromatic imine derivatives with yellow were designed and synthesized for their potential application in color filters for image sensors. The synthesized compounds possessed chemical structures using aromatic imine groups. This innovative material was evaluated thoroughly, considering its optical and thermal properties under conditions similar to commercial device manufacturing processes. Following a rigorous performance evaluation, it was found that (E)-3-methyl-4-((3-methyl-5-oxo-1-phenyl-1H-pyrazol-4(5H)-ylidene)methyl)-1-phenyl-1H-pyrazol-5(4H)-one, abbreviated as MOPMPO, exhibited an impressive solubility of 0.5 wt% in propylene glycol monomethyl ether acetate, predominantly utilized as the solvent in the industry. Furthermore, MOPMPO showed exceptional performance as a color filter material for image sensors, having a high decomposition temperature of 290 ℃. These data unequivocally establish MOPMPO as a viable yellow dye additive for coloring materials in image sensor applications.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.27 no.6
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• pp.313-318
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• 2017

The microstructure of a cobalt-base superalloy (ECY768) obtained by an investment casting process was studied. This work focuses on the resulting microstructures arising from different melt and mold temperatures in normal industrial environmental conditions. The characterization of the samples was carried out using optical microscopy, field emission scanning electron microscopy and energy-dispersive spectroscopy. In this study, the as-cast microstructure is an ${\alpha}-Co$ (face-centered cubic) dendritic matrix with the presence of a secondary phase, such as $M_{23}C_6-type$ carbides precipitated at grain boundaries. These precipitates are the main strengthening mechanism in this type of alloy. Other minority phases, such as the MC-type phase, was also detected and their presence could be linked to the manufacturing process and environment.

• Journal of the Korean GEO-environmental Society
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• v.17 no.3
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• pp.21-26
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• 2016

Soil particle shape analysis was conducted with sands from Jumujun, Korea and Ras Al Khair, Saudi Arabia. Two hundred times enlarged digital images of the particles of those two sands were obtained with an optical microscope. The resolution of the digital images was $640{\times}320$. By conducting digital image processing, the coordinates of the soil particle boundary were extracted. After mapping those coordinates to the complex space, Fourier transformation was performed and the coefficients of each trigonometry term were computed. The coefficients reflect the shape characteristics of the sand grains and are invariant to translation. To evaluate the shape itself excluding the size of the soil particle, the coefficient was normalized by the equivalent radius of soil particle; this is called Fourier descriptor. After analyzing the Fourier descriptors, it was found that the major characteristics of Jumunjin and Ras Al Khair sands were elongation and asymmetry. Furthermore, it was found that the particle shapes reflect the self-similar, fractal nature of the textural features. The effects of resolution on soil particle shape analysis was also studied. Regarding this, it was found that the significant Fourier descriptors were not significantly affected by the image resolution investigated in this study, but the descriptors associated with textural features were affected.

• Composites Research
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• v.31 no.2
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• pp.51-56
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• 2018

A new study was carried out to utilize a pencil drawing paper sensor (PDPS), which drew a line using a pencil on the paper, as a sensor. The sensing effect on 3 different papers based on the properties of PDPS was compared. The specimens were prepared by drawing 4B pencils on plain (A4), Hwasun, and Han papers. The silver paste was used to give good electrical contacts of the copper wires and the pencil drawn line. The chemical structures of 3 papers for PDPS by FT-IR spectrum analysis were similar and the comparative compact states of each paper were observed by optical microscope. From statistical evaluation of tensile strength using 3 papers, plain paper was chosen to be best for the PDPD. The optimum drawing number of PDPD was determined by changing the thickness of the paper with the drawing number. Electrical resistance (ER) with graphite on 3 different papers were compared. The changes in compression was observed through cyclic compressive test of composite materials, it was possible to predict the degree of strain sensing under compressive test. It leads to expectation of properties.

• Journal of Korean Ophthalmic Optics Society
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• v.13 no.3
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• pp.1-6
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• 2008

Purpose: Plastic optical monomer materials having ultra high refractive index have an income of the whole quantity from advanced nations to domestic companies which are related to plastic optical lens. It is necessary to develop novel plastic optical lens materials in order to overcome a FTA provision and revitalize a stagnating optical lens industry in the interior optical lens industries. The new plastic optical lens materials against the substitution effect of income should be gradually demanded. This work will be synthesized novel super high refractive monomer resin materials of urethane lens series and studied the properties of optical lens using it. Methods: ETS-4 (2-(2-mercaptoethylthio)-3-{2-[3-mercapto-2-(2-mercaptoethylthio)propyl thio]ethylthio}propane -1-thiol), which is optical lens monomer resin having super high refractive index, was synthesized and identified its structure and property by elemental analysis, EI-MS, TGA, FT-IR spectroscopy, $^1H$ and $^{13}C$ NMR spectroscopies. After mixing evenly from mixed monomer resin and diisocyanate series, it was casting in glass mold. After thermal curing, the obtained optical lenses were measured and compared with the refractive index and Abbe number for studies of their optical properties. Results: We have synthesized the novel ultra high refractive index monomer resin, ETS-4, and have identified its structure and property by elemental analysis, EI-MS, TGA, FT-IR spectroscopy, $^1H$ and $^{13}C$ NMR spectroscopies. The existence of three isomers for EST-4 was identified by $^{13}C$ NMR spectroscopy. The refractive index ($N_d$ at $25^{\circ}C$) of monomer resin in liquid state obtained from the Abbe refractometer was 1.647. The refractive indexes of raw plastic optical lenses prepared from the mixed ETS-4 monomer and diisocyanate series were in the range of 1.656~1.680. Conclusions: Novel super high refractive index plastic optical lens monomer was synthesized and analysed, the optical lenses prepared using it were colorless transparency and excellent properties. It is of utility for the industrialization.

• Journal of Conservation Science
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• v.27 no.4
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• pp.371-380
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• 2011

For studying of the characteristics and structures of material in lacquer layer in Joseon Dynasty, 6 types and 7 pieces of sample were observed with the optical microscope and the polarizing microscope. For analyzing, SEM-EDS and FT-IR were used and TOF-SIMS was also used on trial. The former is directly varnished on the iron layer so the sample includes more iron component than the others. In the results of the trial analyzing in TOF-SIMS, it is possible to verify the minerals on the foundation layer with the infinitesimalsample. The analysis results of lacquer layer with FT-IR are compared with previous studies and all the samples have the spectrum of the lacquer. Through the result of the Joseon lacquer layer, there are not many samples, however, when it compared with unified Silla, the period of the Three States, and the previous era, the lacquer layers are simpler than the relics from previous era. It looks to have the relation with the simplification of manufacturing method because of expanding of the using of lacquer wares.

• Economic and Environmental Geology
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• v.29 no.2
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• pp.129-138
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• 1996

The ores of the Bobae mine are mainly composed of sericite and quartz, and with appreciable amount of some other minerals such as andalusite. pyrophyllite, and albite, etc.. Sericite occurs in various a1teration zones having different crystal size and habit. Sericites can be c1assified into two types based on the crystal size; fine-grained and coarse-grained sericite. Fine-grained sericite occurs as an aggregate. Mineralogical characterizations of both types of sericites have been studied with various methods. Lattice parameters of two types of sericites occurred in various alteration zones are almost identical. but b parameter of coarse-grained sericite appears to be slight1y bigger than that of fine-grained aggregates. Average structural formula of fine- and coarse-grained sericite is $K_{1.44}Al_{3.86}(Si_{6.35}Al_{1.65})O_{20}(OH)_4$ and $K_{1.71}Al_{3.82}(Si_{6.20}Al_{1.80})O_{20}(OH)_4$, respectively. Structural formulae of coarse-grained sericites are close to that of muscovite. Infrared spectra show that there is slight distinction between sericites occurred in andalusite-pyrophyllite zone and other subzones. IR spectra of sericites due to Si-O vibration ($540{\sim}530cm^{-1}$) tend to shift to smaller wavenumber side from center to outer alteration zone. All samples have litt1e or no interstratified minerals. and this is demonstrated by Ir and DTA-TG results. It indicates that the Bobae mine is formed at relatively high temperature. That the ratio of quartz to sericite in ores varies greatly indicates that several discontinuous hydrothermal alteration processes have been involved.

• Journal of the Korean Vacuum Society
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• v.22 no.2
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• pp.79-85
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• 2013

Rare earth ions, either $Eu^{3+}$ or $Dy^{3+}$-doped $CaMoO_4$ phosphors were synthesized by using the solid-state reaction method. The crystalline structure of all the phosphor powders, irrespective of the type and concentration of activator ions, was found to be a tetragonal system with the main diffraction peak at (112) plane. For $Eu^{3+}$-doped $CaMoO_4$ phosphors, the grain particles showed an increasing tendency and the pebble-like patterns with a very homogeneous size distribution in the range of 0.01~0.10 mol of $Eu^{3+}$ ions concentration, and the excitation spectra were composed of a broad band centered at 311 nm and weak multiline peaked in the range of 360~470 nm. The dominant emission spectrum was the strong red emission centered at 618 nm due to the $^5D_0{\rightarrow}^7F_2$ transition of $Eu^{3+}$ ions. For $Dy^{3+}$-doped $CaMoO_4$ powders, excitation spectra showed a charge transfer band centered at 303 nm and relatively weak bands resulting from the transitions of $Dy^{3+}$ ions and the main yellow emission spectrum was observed at 578 nm, which was assigned to the $^4F_{9/2}{\rightarrow}^7H_{13/2}$ transition of $Dy^{3+}$ ions.

• New Physics: Sae Mulli
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• v.68 no.12
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• pp.1281-1287
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• 2018

In this study, $Al_xGa_{1-x}N$ films were grown on (0001) sapphire substrates by using metal-organic chemical vapor deposition (MOCVD). The crystallinity of the grown films was examined with X-ray diffraction (XRD) patterns. The surfaces and the chemical properties of the $Al_xGa_{1-x}N$ films were investigated using atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS), respectively. The optical properties of the $Al_xGa_{1-x}N$ film were studied in a wide photon energy range between 2.0 ~ 8.7 eV by using spectroscopic ellipsometry (SE) at room temperature. The data obtained by using SE were analyzed to find the critical points of the pseudodielectric function spectra, $<{\varepsilon}(E)>=<{\varepsilon}_1(E)>+i<{\varepsilon}_2(E)>$. In addition, the second derivative spectra, $d^2<{\varepsilon}(E)>/dE^2$, of the pseudodielectric function for the $Al_xGa_{1-x}N$ films were numerically calculated to determine the critical points (CPs), such as the $E_0$, $E_1$, and $E_2$ structure. For the four samples (x = 0.18, 0.21, 0.25, 0.29) between a composition of x = 0.18 and x = 0.29, changes in the critical points (blue-shifts) with increasing Al composition at 300 K for the $Al_xGa_{1-x}N$ film were observed via ellipsometric measurements for the first time.