• Title/Summary/Keyword: Lead Oxide

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Design of Double Layer Shielding Structure using Eco-friendly Shielding Materials (친환경 차폐물질을 이용한 이중구조 차폐체의 설계)

  • Park, Ji Koon;Choi, Il Hong;Park, Hyung Hoo;Yang, Sung Woo;Kim, Kyo Tae;Kang, Sang Sik
    • Journal of the Korean Society of Radiology
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    • v.10 no.8
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    • pp.559-563
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    • 2016
  • Recently, a barium(Ba) and an iodine(I) being studied as a conventional lead(Pb) alternatives of shielding material has excellent shieding rate, but the characteristic x-ray photons in the energy range near 30 keV line is released. In this study, with bismuth oxide(BiO) coupled barium sulfate($BaSO_4$) double layer, transmitted spectra, shieding rates and relative weighting rates were evaluated to validate the applicability of eco-friendly double layer shieding structure using monte carlo simulations as a prior study. From the evaluation results, in 0.4mm and 0.5mm thickness of BiO layers coupled with top 0.1mm-$BaSO_4$ layer, the shieding rate showed 1.9% and 3.9% higher than 0.6mm thickness of Pb single layer, respectively. In addition, the relative weight also 28% and 34.5% lower than 0.6mm-Pb in 0.4mm and 0.5mm thickness of BiO layers coupled with top 0.1mm-$BaSO_4$ layer.

Effect of Passive Layer to Improve Performance of Digital Dosimeter in Brachytherapy (방사선 근접치료 디지털 선량계의 성능 개선을 위한 Passive Layer의 효과)

  • Han, Moo-Jae;Yang, Seung-Woo;Park, Sung-Kwang
    • Journal of the Korean Society of Radiology
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    • v.15 no.5
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    • pp.715-721
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    • 2021
  • In radiation brachytherapy, the wrong source location may cause excessive dose to normal tissue. Therefore, research on digital dosimeters is being made to replace the analog detection method. Therefore, in this study, a lead (II) oxide (PbO) dosimeter applied with a passive layer (PL) was fabricated as a basic study to improve the dosimeter performance. Afterwards, reproducibility, linearity, and distance dependence were evaluated to analyze the performance of the Ir-192 source under irradiation conditions. The reproducibility of the PL-PbO dosimeter was 0.40%, which satisfies the evaluation criteria of 1.5%, and showed improved results compared to the PbO dosimeter. Linear function R2 showed excellent results as 0.9995, and slope analysis through regression analysis of the linear function was excellent in PL-PbO. The distance dependence of the PL-PbO dosimeter was +0.599 higher than that of PbO when the slope obtained through regression analysis of the power function was compared with the inverse square value. This study presents the effects and measurement variables according to the measurement configuration of the solid-state dosimeter, and can be used in various radiation detection fields.

The Conservation Treatment of the Central Asian Mural Painting(II) -An Investigation on the Pigments for the Mural Painting and of the Plants Used for Making the Original Wall - (중앙아세아벽화(中央亞細亞壁畵) 보존처리(保存處理)(II) - 壁畵(벽화)의 채색(彩色) 안료(顔料) 및 벽체(壁體) 조성(造成)에 사용(使用)된 초재류(草材類) 조사(調査) -)

  • Yi, Yonghee;Yu, Heisun;Kim, Soochul;Kang, Hyungtae;Jo, Yeontae;Aoki, Shigeo;Ohbayashi, Kentaro
    • Conservation Science in Museum
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    • v.4
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    • pp.1-16
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    • 2003
  • For the conservation treatment of the Central Asia mural painting which is to be exhibited in the new museum in Yongsan, we analyzed the pigments used in this mural painting and examined to identify the species of the straw in the wall. We also analyzed the species of the wood of the wooden protective frame and the material of the paper in it, in order to review the material and technique of the conservation treatment performed before the mural painting had been brought to the National Museum of Korea in 1916. The results were as follows: the black pigments of Bon4075 and Bon4078 is carbon(C); the white pigment on the background is gypsum[Ca(SO)4(H2O)2]; the red pigment is lead oxide(Pb3O4) and hematite(Fe2O3) etc. The straw, which had been mixed into the wall to prevent the wall from cracking, was proved to be either wheat straw or oats straw. The wooden protective frame, which protects the mural painting now, was proved to be made of Salix, Populus, Cryptomeria japonica and pine. The paper discovered in the frame was proved to be made of the bark of a mulberry.

A Preliminary Study on the Igneous Layering and Concentration of Fe-Ti Oxide Minerals within Amphibolite in Soyeonpyeong Island (소연평도 각섬암 내 화성기원 층상구조와 Fe-Ti 산화광물의 농집에 관한 예비연구)

  • Kim, Eui-Jun
    • Economic and Environmental Geology
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    • v.50 no.5
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    • pp.375-387
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    • 2017
  • Amphibolite-hosted Fe-Ti mineralization at the Soyeonpyeong Island, located in central western part of the Korean Peninsula is a typical orthomagmatic Fe-Ti oxide deposit in South Korea. The amphibolite intruded into NW-SE trending Precambrian metasedimentary rocks. Lower amphibolite is characterized by igneous layering, consisting of feldspar-dominant and amphibole-Fe-Ti oxide-dominant layers. The igneous layering shows complicated and/or sharp contact. In contrast, upper amphibolite has a more complicated lithofacies (garnet-bearing, coarser, and schistose), and massive Fe-Ti oxide ore alternates with schistose amphibolite. NS- and EW-trending fault systems lead to redistribute upper amphibolite-hosted Fe-Ti orebody and igneous layering of lower amphibolite, respectively. The whole-rock compositions of amphibolite and Fe-Ti oxide ore reflect their constituent minerals. Amphibolite shows significantly positive Eu anomalies whereas Fe-Ti oxide ore has weak negative Eu anomalies. Plagioclase (Andesine to oligoclase) and Fe-Ti oxide minerals have constant composition regardless of their distribution. Amphibole has a compositionally variable but it doesn't reflect the chemical evolution. Mineral compositions within individual layers and successive layers are relatively constant not showing any stratigraphic evolution. This suggests that there are no successive injections of Fe-rich magma or assimilation with Fe-rich country rocks. Contrasting Eu anomalies between amphibolite and Fe-Ti oxide ore also suggest that extensive plagioclase fractionation during early crystallization stage cause increase in $Fe_2O_3/FeO$ ratio and overall Fe contents in the residual magma. Thus, Fe-rich residual liquids may migrate at the upper amphibolite by filter pressing mechanism and then produce sheeted massive Fe-Ti mineralization during late fractional crystallization.

The $PbWO_{4}:Nb$ single crystal growth and its optical properties ($PbWO_{4}:Nb$ 단결정의 성장과 그 광학적 특성)

  • 장경동;김도형;양희선;이상걸;박효열;이진호;이동욱;이상윤
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.9 no.2
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    • pp.141-148
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    • 1999
  • High quality pure and Nb-doped $PbWO_{4}$ Single Crystal were grown from a 50 %~50 % mixture of Lead oxide (PbO) and Tungsten oxide $(WO_{3})$ by Czochralski method in Iridium crucible. The stoichiometric deviation correspond to the selective loss of the crystal constituents is found to be responsible for the yellowish coloration of $PbWO_{4}$. Through the X-ray powder diffraction experiment, we have investigated the lattice constant variations of each $PbWO_{4}$ crystals. We also present information on their photoluminescence (PL), optical absoption properties and Raman spectra. The temperature dependence of PL intensity and FWHM (Full Width Half Maximum) were measured in the temperature range 10 K~300 K. One observes a slight temperature dependence in the low temperature region and PL intensity decreases over 200 K by thermal quenching. The activation energy, Huang-Rhys coupling constant and inhomogenious brodenning acquired from their temperature dependence.

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Adsorption Characteristics of Pb(II) by Manganese Oxide Coated Activated Carbon in Fixed Bed Column Study (망간산화물이 코팅된 활성탄의 납 흡착특성에 관한 칼럼 실험)

  • Lee, Myoungeun;Lee, Chaeyoung;Chung, Jaewoo
    • Journal of the Korean GEO-environmental Society
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    • v.15 no.8
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    • pp.39-44
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    • 2014
  • Effects of operating parameters on the breakthrough properties of Pb(II) by $Mn_3O_4$ coated activated carbon prepared by supercritical technique were investigated through fixed-bed column experiments. The mass transfer zone and equilibrium adsorption capacity were enhanced about 2.8 times for Pb(II) by $Mn_3O_4$ coating onto activated carbon. Increase of bed height enhanced the residence time of Pb(II) in adsorption zone, giving the higher breakthrough time, mass transfer zone and equilibrium adsorption capacity. Increase of flow rate reduced the residence time and diffusion of Pb(II) in adsorption zone, therefore decreased the equilibrium adsorption capacity. The higher inlet concentration of Pb(II) decreased the breakthrough time and mass transfer zone through the promotion of Pb(II) transfer onto adsorbent.

Anti-neuroinflammatory Effects of Quercetin-3-O-glucuronide Isolated from the Leaf of Vitis labruscana on LPS-induced Neuroinflammation in BV2 Cells (포도잎으로부터 분리된 Quercetin-3-O-glucuronide의 LPS로 유도된 BV2 미세아교세포에서의 항염증 효과)

  • Yoon, Chi-Su;Kim, Dong-Cheol;Ko, Won-Min;Kim, Kyoung-Su;Lee, Dong-Sung;Kim, Dae-Sung;Cho, Hyoung-Kwon;Seo, Jungwon;Kim, Sung Yeon;Oh, Hyuncheol;Kim, Youn-Chul
    • Korean Journal of Pharmacognosy
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    • v.45 no.1
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    • pp.17-22
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    • 2014
  • Grapes has long been used for food, and reported as containing polyphenol which has antioxidant and anti-cancer effects. Neuroinflammation is chronic inflammation at the brain, lead to neurodegenerative diseases. In this study, quercetin-3-O-glucuronide (QG) isolated from the leaf of Vitis labruscana has anti-neuroinflammatory effects. QG were investigated using MTT assay, western blot, nitric oxide (NO) assay, prostaglandin $E_2$ ($PGE_2$) assay, cytokine assay in lipopolysaccharide (LPS)-induced inflammation in BV2 cells. QG dose-dependently attenuated the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2), accordingly inhibited the production of NO and $PGE_2$. QG decreases the levels of proinflammatory cytokine such as tumor necrosis factor-${\alpha}$ (TNF-${\alpha}$), interlukin-$1{\beta}$ (IL-$1{\beta}$). Thereby, QG may offer therapeutic potential for treatment of neurodegenerative disease related to neuroinflammation.

Novel Polyurethane Binder for Propellant based on Hydroxyl-terminated Copolyether (폴리에테르 공중합체 디올(HTPE)을 사용한 새로운 추진제용 폴리우레탄 바인더)

  • Song Jong-Kwon;Pan Xiao;Lee Bum-Jae;Jeon Jun-Pyo;Hwang Gab-Sung
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2005.11a
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    • pp.417-421
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    • 2005
  • Novel two synthetic technics using cationic ring-opening copolymerization of tetrahydrofuran (THF) and ethylene oxide (EO), or just polymerized EO on Poly-THF, could lead to random hydroxyl-terminated poly(EO-ran-THF) or tri-block PEG-PTHF-PEC, respectively. These reactions were carried out using $BF_3O(C_2H_5)_2$ as catalyst, 1,4-butanediol or PTHF as diol initiator. Copolymer structures were controlled by monomer feed ratio, or initial PTHF and EO monomer added amount. The molecular weight of polymer was merely dependant on the ratio of [monomer]/[diol], but not on catalyst. Well-defined random and block hydroxyl-terminated copolyether was found to be as the prepolymer for the propellant binder from the experiment to polyurethane with them.

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Materials Chemical Point of View for Durability Issues in Solid Oxide Fuel Cells

  • Yokokawa, Harumi;Horita, Teruhisa;Yamaji, Katsuhiko;Kishimoto, Haruo;Brito, M.E.
    • Journal of the Korean Ceramic Society
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    • v.47 no.1
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    • pp.26-38
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    • 2010
  • Degradation in Solid Oxide Fuel Cell performance can be ascribed to the following fundamental processes from the materials chemical point of view; that is, diffusion in solids and reaction with gaseous impurities. For SOFC materials, diffusion in solids is usually slow in operation temperatures $800\sim1000^{\circ}C$. Even at $800^{\circ}C$, however, a few processes are rapid enough to lead to some degradations; namely, Sr diffusion in doped ceria, cation diffusion in cathode materials, diffusion related with metal corrosion, and sintering of nickel anodes. For gaseous impurities, chromium containing vapors are important to know how the chemical stability of cathode materials is related with degradation of performance. For LSM as the most stable cathode among the perovskite-type cathodes, electrochemical reduction reaction of $CrO_3$(g) at the electrochemically active sites is crucial, whereas the rest of the cathodes have the $SrCrO_4$ formation at the point where cathodes meet with the gases, leading to rather complicated processes to the degradations, depending on the amount and distribution of reacted Cr component. These features can be easily generalized to other impurities in air or to the reaction of nickel anodes with gaseous impurities in anode atmosphere.

Synthesis of NiTi Alloy Powder by the Reaction of NiO-TiH2 Mixing Powders (NiO-TiH2 혼합분말의 반응을 이용한 NiTi 합금분말 제조)

  • Jeon, Ki Cheol;Lee, Han-Eol;Yim, Da-Mi;Oh, Sung-Tag
    • Journal of Powder Materials
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    • v.22 no.4
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    • pp.266-270
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    • 2015
  • The synthesis of NiTi alloy powders by hydrogen reduction and dehydrogenation process of NiO and $TiH_2$ powder mixtures is investigated. Mixtures of NiO and $TiH_2$ powders are prepared by simple mixing for 1 h or ball milling for 24 h. Simple-mixed mixture shows that fine NiO particles are homogeneously coated on the surface of $TiH_2$ powders, whereas ball milled one exhibits the morphology with mixing of fine NiO and $TiH_2$ particles. Thermogravimetric analysis in hydrogen atmosphere reveals that the NiO and $TiH_2$ phase are changed to metallic Ni and Ti in the temperature range of 260 to $290^{\circ}C$ and 553 to $639^{\circ}C$, respectively. In the simple-mixed powders by heat-up to $700^{\circ}C$, agglomerates with solid particles and solidified liquid phase are observed, and the size of agglomerates is increased at $1000^{\circ}C$. From the XRD analysis, the presence of liquid phase is explained by the formation and melting of $NiTi_2$ inter-metallic compound due to an exothermic reaction between Ni and Ti. The simple-mixed powders, heated to $1000^{\circ}C$, lead to the formation of NiTi phase but additional Ni-, Ti-rich and Ti-oxide phases. In contrast, the microstructure of ball-milled powders is characterized by the neck-grown particles, forming $Ni_3Ti$, Ti-oxide and unreacted Ni phase.