• Journal of the Korean Society of Radiology
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• v.4 no.2
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• pp.27-30
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• 2010

A X-ray optical modulator measures x-ray dose using optical transmissivity ratio change of the liquid crystal cell. To apply in this optical modulator, we made photoconductor films and compared electrical properties of this films in this study. Photoconductors are deposited on ITO glass with $200{\mu}m$ using the percipitation method and print method. I-V test was conducted to alalyze electrical properties of this films and measured darkcurrent and SNR was acquired using the measured dark current and sensitivity. As a result of this measurements, $HgI_2$ film made by precipitation method is lower(about 40%) darkcurrent than $HgI_2$ films made by precipitation method and sensitivity is two times greater than print method. And we knew that $HgI_2$ films were also 10~25 times greater SNR at $1v/{\mu}m$ than $PbI_2$, PbO, CdTe film made by precipitation method. This results suggest that $HgI_2$ films made by precipitation method has improved characteristics of x-ray dose meter by applying in x-ray optical modulator.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.2
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• pp.196-200
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• 2004

Using polyimide Langmuir-Blodgett(LB) films as a tunneling harrier, we fabricated Au/Polyimide/1-layer arachidic acid/Pb structure in order to investigate electron transport properties through a junction. It was found that 9-layer polyimide LB films function as a good tunneling harrier in a study of current-voltage(I-V) chararteristics. And several peaks originating in the vibrational modes of the constituent molecules of 1-layer arachidic acid LB films were clearly observed in d$^2$V/dI$^2$- V corves.

• Journal of the Korean Chemical Society
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• v.4 no.1
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• pp.27-37
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• 1957

High-fire stain is influenced by the conditions of glaze, firing atmosphere, etc. On the contrary, low fire stain is not influenced by those conditions but obtainable in arbitrary colors and it is indispensable for pottery decoration. It is difficult for us to study into the color in the sphere of result publication method and expression of color. Looking over the literature on this subject, I have been confronted with much difficulties, accordingly, I made a basic and systematic experiment as to six low-firing stains (blue, green, blue-green, brown black and yellow) and made it proper to be applied in these studies. On pigment, I confirmed the influence of the assistant coloring matter by mixing up the coloring matter and the assistant coloring matter in various proportions. On flux, I measured the melting point by making PbO-$SiO_2$ system and PbO-$B_2O_3-SiO_2$ system and decided the range of usage. Also I checked the coloring by making the pigment on laze with pigment and flux manufactured, and concluded the pigment and flux adaptation to it.

• Bulletin of the Korean Chemical Society
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• v.20 no.3
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• pp.355-361
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• 1999

To improve the volatility and stability of lead complexes, the principle of stabilization by saturating the metal coordination sphere by intramolecular coordination through a β-diketonates with an ethereal group has was tested. Several new lead complexes with alkoxyalkyl-substituted β-diketonates, Pb(R1C(O)CHC(O)(CH2)3OR2)2(Rl=t-Bu, Me, OMe, i-Pr, R2=Me, Et), or carboxylate, Pb(OC(O)(CH2)3OEt)2, were prepared by the reaction between Pb(OAc)2 and corresponding alkoxyalkyl-substituted β-diketonates, and they were found to have a viscous liquid phase. The nature of the head (β-diketonate or carboxylate) or tails and substituents of β-diketonates appeared not to be important for the formation of the liquid phase. It is worth mentioning that Pb(OAc)2, which has limited use due to its low solubility, was successfully adopted as a starting material for the preparation of new lead complexes. Easy hydrolysis, reaction with HCl, and 13C NMR spectra indicated that tail portions were not coordinated to the metal as a copper derivative, Cu(t-BuC(O)CHC(O)(CH2)3OMe)2. All these complexes were not volatile enough for the MOCVD experiments, but a methyl derivative, Pb(MeC(O)CHC(O)(CH2)3OEt)2, showed some sublimation. The methoxy derivative, Pb(MeOC(O)CHC(O)(CH2)3OEt)2, was thermally unstable due to possible equilibrium between species coordinating with a keto oxygen atom and an ethereal atom of a methoxy group, which was confirmed by IR and 13C NMR spectra.

• Electronic Materials Letters
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• v.14 no.6
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• pp.712-717
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• 2018

In this letter, we have introduced copper chloride ($CuCl_2$) as an additive in the $CH_3NH_3PbI_3$ precursor solution to improve the surface morphology and crystallinity of $CH_3NH_3PbI_3$ films in a single solvent system. Our optimized perovskite solar cells (PSCs) with 2.5 mol% $CuCl_2$ additive showed best power conversion efficiency (PCE) of 15.22%. The PCE of the PSCs fabricated by $CuCl_2$ (2.5 mol%) additive engineering was 56% higher than the PSC fabricated with pristine $CH_3NH_3PbI_3$.

• Proceeding of EDISON Challenge
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• 2015.03a
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• pp.378-381
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• 2015

To produce low cost and efficient photovoltaic cells, inorganic-organic lead halide perovskite materials appear promising for most suitable solar cells owing to their high power conversion efficiency. Most recent research showes that formamidinium lead iodide ($FAPbI_3$) with methylammonium lead bromide ($MAPbBr_3$) improves the power conversion efficiency of the solar cell to more than 18 per cent under a standard illumination because incorporated $MAPbBr_3$ makes $FAPbI_3$-relatively unstable but comparatively narrow band gap-more stable composition. In respect to first principle study, we investigated band gap of $MAPbI_3$, $FAPbI_3$, $MAPbBr_3$, $(FAPbI_3)_{0.89}-(MAPbBr_3)_{0.11}$ and 0.615(eV), 0.466, 1.197, 0.518 respectively through EDISON DFT software. These results emphasize enhancing structure stability is important factor as well as finding narrow band gap.

• Journal of the Korean Society of Radiology
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• v.3 no.4
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• pp.29-33
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• 2009

Recently, the compound materials(a-Se, $HgI_2$, PbO, CdTe, $PbI_2$, etc.) that are used in flat panel x-ray imager have been studied for digital x-ray imaging. In this paper, the signal detection properties of $HgI_2$ and a-Se conversion layer, are compared. The thick $HgI_2$ film is fabricated by special particle-in-binder method and the conventional vacuum thermal evaporation is used for a deposition of a-Se film. And an electrical characteristic measurements were investigated about leakage current, signal response property and x-ray sensitivity. From the experimental results show that the $HgI_2$ film has a low operation voltage and high signal generation than that of a-Se.

• Economic and Environmental Geology
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• v.27 no.3
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• pp.219-229
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• 1994

The Sangra Pb-Zn deposit is located in the Gampo area. Most Cretaceous sedimentary rocks and Paleogene felsic intrusives in the study area have experienced intense propylitization. Such propylitization and Pb-Zn mineralization in ore veins are involved with the fluid having very low oxygen isotopic composition.Sulfurisotopic equilibrium temperature during the main Pb-Zn mineralization (late stage I) is calculated as $T=275^{\circ}{\sim}295^{\circ}C$. Oxygen and sulfur fugacity in late stage I fluid is estimated as $logfO_2=-34.4{\sim}-29.1$ and $logfS_2=-12.0{\sim}-8.2$ bars. It is inferred that the sulfur isotopic composition oflate stage I fluid was very high such as ${\delta}^{34}S_{{\Sigma}S}=+22.4{\sim}+22.5$‰ and the origin of sulfur was ocean water sulfate. Oxygen and hydrogen isotopic composition of water in ore-forming fluid was gradually increased and more abundantly affected by ocean water from early to late mineralization stage as follows; (late stage I) ${\delta}^{18}O_{H2O}=-7.2{\sim}-1.1$‰, ${\delta}D_{H2O}=-87{\sim}-84$‰, (stage II) ${\delta}^{18}O_{H2O}=-2.4{\sim}-0.8$‰, ${\delta}D_{H2O}=-39{\sim}-21$‰ (stage III) ${\delta}^{18}O_{H2O}=+0.7{\sim}+12.6$‰, ${\delta}D_{H_2O}=-49{\sim}-42$‰. The pH in ore-forming fluid was about 4.7 during late stage I and is thought to have been gradually decreased from late stage I to stage II mineralization.

• Journal of the Korean Society of Radiology
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• v.7 no.1
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• pp.81-84
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• 2013

The use of the dosimetry have been increasingly recognized as high radiation energy and radiation treatment planning(RTP) have rapidly developed in radiotherapy. There are many types of detectors for the dosimetry such as ionization chamber, film, TLD, diode, and etc. Among such detectors, the diode detector uses a photoconductor materials that generate electrical signals by the incident radiation energy. Though many research groups are recently interested in such materials, there is few experimental results except for silicon in the radiation therapy field. In this study, the feasibility of photoconductor materials was verified as a dosimeter through the evaluation of response properties at a high radiation energy. For the fabricated detectors based on $HgI_2$ and $PbI_2$, reproducibility, linearity, and pulse-rate response were analyzed. Such evaluations are essential factors for the use of dosimeter. From results, linearity and reproducibility of the fabricated $HgI_2$ detector indicated about 7% error. The fabricated $PbI_2$ detector showed 1.7% error in linearity, and 12.2% error in reproducibility.

• Korean Journal of Soil Science and Fertilizer
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• v.19 no.2
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• pp.147-151
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• 1986

A study was carried out to investigate yield, yield components, and change of chemical components in rice plants grown under different concentration of lead compound in nutrient solution of sandy culture. The results obtained are as follows. 1. Increasing lead concentration in culture solutions, pb content in the plant was increased and crop yields were decreased. 2. The critical pb concentration at which yield was declined, was 13.6 ppm. 3. As adding higher concentration of lead in nutrient solutions, concentration of lead in rice plant was significantly increased on leaf blade, and brown rice in pb. 4. Yield loss was closely related to pb content in leaf blade.