• Title/Summary/Keyword: 비스무스

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I-V characteristics and contact resistance of jointed BSSCO tapeI (비스무스 초전도 선재의 전류-저항 특성 및 접합 저항 연구)

  • 박수현;장현식;김영순;심성엽;오상준;김형찬;방소희;이형철
    • Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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    • 2002.02a
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    • pp.163-164
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    • 2002
  • We have measured the I-V characteristics and contact resistance of jointed BSSCO tape in the superconducting state. Electrical joint was made by various type of solder. Estimated critical current was about 30 Amp, and the contact resistance of the joint was about 350 nOhm.

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Low temperature solution growth of silicon on foreign substrates (이종기판을 사용한 저온에서의 실리콘 박막 용액 성장법)

  • Soo Hong Lee;Martin A. Green
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.4 no.1
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    • pp.42-45
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    • 1994
  • Deposition of silicon on pretreated sapphire and glass substrates has been investigated by the solution growth method at low temperatures. An average 14 $\mu\textrm{m}$ thickness of silicon was grown over a large area on sapphire substrate originally coated with a much thinner silicon layer [0.5 $\mu\textrm{m}$ (100) Si/(1102) sapphire)] at low temperatures from $380~460^{\cire}C$. Successful results were obtained from surface treated glass substrates in the temperatures range from $420~520^{\circ}C$.

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Shielding Analysis of the material and thickness of syringe shield in diagnostic radiopharmaceutical injection (진단용 방사성 의약품 주사 시 차폐기구의 재질 및 두께 분석)

  • Cho, Yong-In;Kim, Chang-Soo;Kang, Se-Sik;Kim, Jung-Hoon
    • Proceedings of the Korea Contents Association Conference
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    • 2015.05a
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    • pp.175-176
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    • 2015
  • 몬테카를로 기법을 기반으로 한 모의실험을 통해 방사성 핵종별 주사기 차폐기구의 재질 및 두께에 대한 차폐분석 결과, 텅스텐, 납, 비스무스 경우 가장 높은 차폐효과를 보였다. 그러나 $^{18}F$ 선원의 경우, 차폐두께가 낮은 영역에서 저 원자번호 재질보다 더 높은 에너지를 나타냈으나, 이후 증가된 차폐두께에서는 더 낮은 에너지 분포를 나타냈다. 그 외 재질의 경우 구리, 철, 스테인리스 강, 황산바륨의 순서로 에너지가 낮은 분포를 나타냈고, 알루미늄, 플라스틱, 콘크리트, 물의 경우 핵종별로 각기 다른 양상을 나타냈으며, 상대적으로 감마선의 투과의 증가로 인해 전체적으로 차폐효과가 떨어지는 것으로 나타냈다.

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Microstructure and Conduction Characteristics of Bismuth-Based Zinc Oxide Varistors with $Y_2O_3$Additive ($Y_2O_3$가 첨가된 비스무스계 산화아연 바리스터의 미세구조 및 전도특성)

  • 박춘현;남춘우
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 1998.11a
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    • pp.281-285
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    • 1998
  • The microstructure and conduction characteristics of ZnO varistor fabricated in the range of 0.0 ~ 4.0mol% $Y_20_3$ were investigated. With increasing$Y_20_3$ content, distribution of spinel phase decreased, whereas Y-rich phase segregated to the nodal point increased, as a result, the average grain size decreased in the range of $20.0 ~ 4.8{\mu}m$. $Y_20_3$ content showing relatively good conduction characteristics was l.Omol%, then nonlinear exponent and leakage current was 55.3, 0.66mA.respectively.

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Effect of the $SiO_2$ Addition on the Electrical and Degradation Property of Bi based ZnO Varistor (비스무스계 ZnO 바리스타의 $SiO_2$ 첨가에 따른 전기적특성 및 열화특성)

  • Heo, Jong-Cheol;Kim, Hyung-Sik;Park, Tae-Gone
    • Proceedings of the KIEE Conference
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    • 1998.07d
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    • pp.1522-1524
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    • 1998
  • Experimental results on the effect of $SiO_2$ addition to Bi based ZnO varistor show that secondary phases in microstructure and nonlinear coefficient are increased, and that leakage current is decreased with $SiO_2$ additive content. The varistor with 0.1 mol%-$SiO_2$ additive exhibits lower resistive current than other specimen at ($E_{1mA}$ x 0.6) applied voltage and temperature of $115^{\circ}C$ for 350h.

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Reduced Effect of kV-CBCT Dose by Use of Shielding Materials in Radiation Therapy (방사선 치료 시 차폐물질 사용에 따른 kV-CBCT 선량감소 효과)

  • Jo, Hyeonjong;Park, Euntae;Kim, Junghoon
    • Journal of the Korean Society of Radiology
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    • v.12 no.4
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    • pp.467-474
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    • 2018
  • CBCT is useful for improving the accuracy of the treatment site, but Repeated use increases the exposure dose. In this study, we aimed to provide basic data for dose reduction in CBCT implementation by dataization the simulating and dose reduction effect using shielding substance. Material in this study, Analyzation the photon beam by simulate the CBCT Through MCNPX and then calculate the absorption dose of body organ at shooting moment of thoracic abdominal position as target UF-Revise simulated body. At this time. Dose reduction effects at this time were evaluated according to the texture of materials and presence of shielding materials( lead, antimony, barium, sulfate, tungsten, bismuth). When CBCT was taken without shielding, the dose was calculated to be high in the breast and spine, and the dose in the esophagus and lung was calculated to be low. The doses according to the shield material were calculated as barium sulfate, antimony, bismuth, lead, and tungsten. The shielding rate was the highest in the thymus (73.6%) and the breast (59.9%) compared with the dose reduction according to presence or absence of the shield. However, it showed the lowest shielding rate in lung (2.1%) and spine (12.6%).

Research on Dose Reduction During Computed Tomography Scanning by CARE kV System and Bismuth (전산화 단층검사 시 Bismuth와 CARE kV System을 이용한 선량 저감화에 대한 연구)

  • Kwak, Yeong-Gon;Kim, Chong-Yeal;Jeong, Seong-Pyo
    • The Journal of the Korea Contents Association
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    • v.14 no.8
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    • pp.233-242
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    • 2014
  • The purpose of this study is to compare the reduction of the dose radioactivity by CARE kV with that of the Bismuth shielding. First, CT was performed with transparent materials, including a Bismuth shielder which is a well-known material for decreasing the dose of radiation. Moreover, we have estimated and compared the affects of the reduction of dose on eye lens, thyroid, breast and genitals. These steps aim to compare reactions with and without the application of the Rando phantom with PLD as well as with CARE kV or not. As a result, during the Brain angio scan, the dose of CARE kV set inspection test methods showed the least dose. Depending on whether we use CARE kV, which showed the effect of dose reduction by 63%. During the Carotid angio scan, the dose was increased by 13% by how to set CARE kV+Bismuth. During the Cardiac angio scan, which showed the effect of dose reduction by 31% by how to set CARE kV+Bismuth. During the Lower extremity angio scan, the dose was measured least by how to set up the whole Bismuth. Compared with CARE kV set of test methods, which showed the effect of dose reduction by 9%.

Field Evaluation of Particulate Control Efficiency of Electrostatic Precipitator in Thermoelectric Power Plant Associated with Addition of Triethyl Amino(TEA) (트리에틸아민 첨가에 따른 열병합발전소 전기집진장치의 집진효율 특성의 현장 평가)

  • Jo, Wan-Kuen;Jeon, Ok-Sang
    • Journal of Korean Society of Environmental Engineers
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    • v.27 no.4
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    • pp.445-449
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    • 2005
  • Present study was designed to evaluate the practical application of triethyl amine(TEA) injection for improving the collection efficiency of electrostatic precipitator(ESP) connected to a real operating plant. The major fuels used at the domestic power stations were bituminous coals imported from Australia, China, South Africa, and USA. Although the values of the electric resistance would be more or less different according to the type of the coals used, the unique electric resistance values of fly ash from the coals were mostly higher than $1{\times}10^{12}\;{\Omega}-cm$ and therefore, back corona problems were always expected to occur in the electrostatic precipitator. The particulates concentrations, smoke concentrations and their electric resistivity measured at the outlet of ESP, and the inspection of collection indicated that the injection of TEA improved the collection efficiency of particulate at collection plates of ESP. The electric resistance for, fly ash with the injection concentration of TEA 15 ppm(Purity 99.7%) was lowered to $2.1{\times}10^{11}\;{\Omega}-cm$ after injection from $1.9{\times}10^{12}\;{\Omega}-cm$ before injection. Under this condition, the dust emission content at the stack was reduced to approximately 80%, lowering the average outlet concentrations of particulates from $70\;mg/Sm^3$ to $14\;mg/Sm^3$.

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.

A Study on the Operating Characteristics by Heat Flow Analysis of HYPER Beam Window (HYPER 빔창의 열수력 해석에 의한 운전특성에 관한 연구)

  • Song, Min-Geun;Choi, Jin-Ho;Ju, Eun-Sun;Song, Tae-Young
    • Proceedings of the KSME Conference
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    • 2001.06d
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    • pp.915-920
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    • 2001
  • A spent fuel problem has prevented the nuclear power from claiming to be a completely clean energy source. The nuclear transmutation technology to incinerate the long lived radioactive nuclides and produce energy during the incineration process is believed to be one or the best solutions. HYPER(Hybrid Power Extraction Reactor) is the accelerator driven transmutation system which is being developed by KAERI(Korea Atomic Energy Research Institute). Some major feature of HYPER have been developed and employed. On-power fueling concepts are employed to keep system power constant with minimum variation of accelerator power. A hollow cylinder-type metal fuel is designed for the on-line refueling concept. Lead-bismuth(Pb-Bi) is adopted as a coolant and Spallation target material. HYPER is a subcritical reactor which needs an external neutron source. 1GeV proton beam is irradiated to Lead-bismuth(Pb-Bi) target inside HYPER, and spallation neutrons are produced. When proton beams are irradiated, much heat is also deposited in the Pb-Bi target and beam window which separates Pb-Bi and accelerator vacuum. Therfore, an effective cooling is needed for HYPER target. In this paper, we performed the thermal-hydraulic analysis of HYPER target using FLUENT code, and also calculated thermal and mechanical stress of the beam window using ANSYS code.

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