• Journal of the Korean Society for Heat Treatment
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• v.24 no.3
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• pp.133-139
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• 2011

This study has been investigated for tensile properties with lead-free brass containing 1 wt.% of Bi. And also characteristic of corrosion resistance was analyzed by polarization test. An increase of tempering temperature was found to tend to decrease tensile strength, and percentage of elongation was shown to be the lowest value at $300^{\circ}C$. On the other hand, the elongation was increased with an increase of tempering temperature after $300^{\circ}C$. The change of mechanical properties was closely related with the content and shape of acicular Witmanst$\ddot{a}$tten ${\alpha}$ formed at the interface of ${\beta}$ phase as well as in ${\beta}$ phase. Tensile strength had a tendency to be decreased with an increase of test temperature. The elongation was shown to be the lowest value at around $300^{\circ}C$, while it began to increase as test temperature rose after $300^{\circ}C$. It might be speculated that the reason that elongation was decreased was found to form bismuth film at the interface of ${\alpha}/{\beta}$ phase leading to be easily brittle when loaded by tensile stress. The lead-free brass containing 1 wt.% of Bi had similar characteristic of corrosion resistance with a free-cutting brass with 3.4 wt. % of Pb in spite of higher fraction of ${\beta}$ phase.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.03a
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• pp.37-37
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• 2003

Ferroelectric random acess memories (FeRAMs) 재료로 주목받고 있는 강유전 물질은 이미 여러 해 전부터 많은 물질들에 대해 연구가 진행되어 왔다. 그 중 낮은 공정 온도를 가지며 큰 remanent polarization 값을 갖는 lead zirconium titanate (PZT) 박막에 대해 많은 연구가 진행되고 있다. 하지만 Pt 기판위에 증착된 PZT 박막은 높은 피로 현상을 보이는 문제가 있다. 최근 Pulsed laser deposition이나 metal-organic vapor phase epitaxy (MOVPE) 등의 방법에 의해 epitaxial substituted-$Bi_4Ti_3O_{12}$ (La, Nd) 박막에 대해 보고가 되고 있다. 본 연구에서는 높은 remanent polarization 값을 갖는 $(Bi,Ce)_4Ti_3O_{12}$ (BCT) 박막을 pulsed laser deposition 방법을 사용하여 증착하였다. 또한 Bismuth의 양을 변화시켜 Bismuth의 양에 따른 remanent polarization의 변화를 확인하여 보았다. 사용된 기판은 Pt/$TiO_2$/$SiO_2$/Si 기판을 사용하였다.

• Electrical & Electronic Materials
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• v.24 no.7
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• pp.10-17
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• 2011

현재 개발 중인 Chalcogenide계 열전재료 중에서, 이방성 재료인 Thallium chalcogenide, Alkalimetal bismuth chalcogenide, Bismuth telluride와 등방성 재료인 Lead telluride, Silver antimony telluride, TAGS, LAST 및 SALT를 소개하였고, 이 재료들에 대한 연구 동향을 살펴보았다. Chalcogenide는 S, Se, Te 및 다른 원소와의 다양한 조합에 의해, 넓은 온도범위에서 열전재료로 응용하기 위한 밴드갭 에너지의 조절이 가능하다. 또한 합성공정에 따른 상변태, 석출 등 구조변화에 따른 열전특성의 변화를 기대할 수 있어 열전재료 개발 초기부터 활발한 연구가 진행되어 왔다. 과거의 전통적인 Chalcogenide계 열전재료뿐만 아니라, Chalcogenide계 열전 신소재에 대해서도 살펴보았다. Chalcogenide는 전자적, 광학적, 열적 성질 등 특성이 독특하고 변화가 무궁무진하여 아주 매력적이기 때문에, 앞으로도 계속 열전재료로서 각광받는 물질군으로 판단된다. 그림 11에 현재까지 ZT의 최댓값이 1이 넘는다고 보고된 열전재료의 성능지수를 요약하였다.

• Proceedings of the Korean Society Of Semiconductor Equipment Technology
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• 2006.05a
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• pp.194-197
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• 2006

Lead-free bismuth-layered perovskite ferroelectric europium-substituted $Bi_{4}Ti_{3}O_{12}(BTO)$ thin films have been successfully deposited on Pt/Ti/$SiO_2$/Si substrate by a sol-gel spin-coating process. $Bi(TMHD)_3,\;Eu(THMD)_3,\;Ti(OiPr)_4$ were used as the precursors, which were dissolved in 2-methoxyethanol. The thin films were annealed at various temperatures from $600^{\circ}\;to\;720^{\circ}C$ in oxygen ambient for 1 hr, which was followed by post-annealed for 1 hr after depositing a Pt electrode to enhance the electrical properties. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to analyze the crystallinity and surface morphology of layered perovskite phase, respectively. The remanent polarization value of the BET thin films annealed at $720^{\circ}C\;was\;25.95{\mu}C/cm^2$ at an applied voltage of 5 V.

• Journal of the Korean Society of Radiology
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• v.9 no.5
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• pp.279-285
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• 2015

The eye of human is a radiation sensitive organ and this organ should be shielded from radiation exposure during brain CT procedures. In the brain CT procedures, bismuth protector using to reduce the radiation exposure dose for eye. But protecting the bismuth always accompanies problem of the image quality reduction including artifact. This study aim is the eye radiation exposure dose and image quality evaluation of the new tube current modulation such as new organ based-tube current modulation, longitudinal-TCM, angular-TCM between shielding scan technique using bismuth and lead glasses. As a result, radiation dose of eye is reduced 25.88% in new OB TCM technique then reference scan technique and SNR new OB TCM is 6.05 higher than bismuth shielding scan technique and lower than reference scan technique. In clinical brain CT, new OB TCM technique will contribute to reduction of radiation dose for eye without decrease of image quality.

• Journal of the Microelectronics and Packaging Society
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• v.9 no.1
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• pp.21-28
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• 2002

Bismuth and Indium added Sn-Cu-Ni solder alloy was investigated for a new lead free solder. The thermal, electrical and mechanical properties were characterized for the Sn-0.7%(Cu+Ni) solder alloy by adding 2~5% Bi and 2~ 10% In. The melting point of solder alloy was in range of 200 to $222^{\circ}C$ and the mushy zone was in range of 20 to $37^{\circ}C$. This alloys could be adapted to middle and high temperature solder materials. A new solder alloy composition. Sn-0.7%(Cu+Ni) -3.5%Bi-2%In is very promising with high performance and effective cost. The melting point was $220^{\circ}C$, the mushy zone range was $25^{\circ}C$, and mechanical, electrical and wetting properties were competitive with those of other lead-free solder except the lower elongation value.

• Nuclear Engineering and Technology
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• v.55 no.5
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• pp.1734-1741
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• 2023

This work presents the synthesis and preparation of a new glass system described by the equation of (70-x) B₂O₃-5TeO₂ -20SrCO₃-5ZnO -xBi₂O₃, x = 0, 1, 5, 10, and 15 mol. %, using the melt quenching technique at a melting temperature of 1100 ℃. The photon-shielding characteristics mainly the linear attenuation coefficient (LAC) of the prepared glass samples were evaluated using Monte Carlo (MC) simulation N-particle transport code (MCNP-5) at gamma-ray energy extended from 59 keV to 1408 keV emitted by the radioisotopes Am-241, Ba-133, Cs-137, Co-60, Na-22, and Eu-152. Furthermore, we observed that the Bi₂O₃ content of the glasses had a significantly stronger impact on the LAC at 59 and 356 keV. The study of the lead equivalent thickness shows that the performance of fabricated glass sample with 15 mol.% of Bi₂O₃ is four times less than the performance of pure lead at low gamma photon energy while it is enhanced and became two times lower the perforce of pure lead at high energy. Therefore, the fabricated glasses special sample with 15 mol.% of Bi₂O₃ has good shielding properties in low, intermediate, and high energy intervals.

• Proceedings of the Korean Society for Applied Microbiology Conference
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• 1979.04a
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• pp.115.3-115
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• 1979

중금속을 함유한 13종의 질산염을 명 농도별로 첨가하여 주정효모 Saccharomyces cerevisine의 주정생산과 발효작용에 미치는 영향을 조사하였다. 1. 일반적으로 중금속을 함유한 질산염은 그 첨가량이 0.0001mo1. 보다 고농도일수록 Saccharo-myces cerevisiae의 발효작용을 점차 억제하였다. 2. Nickel nitrate, chromium nitrate들의 0.0001 moi.의 첨가는 Saccharomyces cerevisiae의 alcohol 발효작용을 약간촉진시켰다. 3. Cadmium nitrate 0.001mo1. 이상, cupric nit-rate, nickel nitrate, cobalt nitrate 0.01mo1. 이상, 그리고 silver nitrate, mercurous nitrate, manganese nitrate, zinc nitrate, lead nitrate, chromiun nitrate, ferric nitrate, bismuth nitrate 0.1mol. 의 농도에서 Saccharomyces cerevisiae 의 발효작용은 완전히 조지되었다.

• Journal of the Korea Convergence Society
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• v.9 no.7
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• pp.87-93
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• 2018

In this study, $^{99m}Tc$, $^{123}I$, $^{201}Tl$, $^{18}F$, and $^{131}I$, which are widely used in nuclear medicine, were transmitted through a bismuth shield. We investigated the shielding rates according to the type of radioisotope and the distance of measurement. For the experiment, 6 sheets of lead equivalent 0.25 mm Pb of bismuth shielding material were stacked one by one up to 1.50 mm as the thickness increased. The distance was 30 cm, 50 cm, and 100 cm, and the transmission dose was measured. As a result, the shielding rates was measured as the thickness increased, and the measured value decreased as the distance increased. The shielding rate of $^{123}I$ and $^{201}Tl$ was higher than $^{99m}Tc$, $^{18}F$ and $^{131}I$ showed lower shielding effect when there is a shielding material than when there is no shielding material due to high energy and ${\beta}$ rays. Based on the results of experiments, it would be helpful to reduce the exposure of nuclear medicine workers and to manage the exposure if bismuth shields are used depending on the type of radioisotope.

• Transactions on Electrical and Electronic Materials
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• v.12 no.5
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• pp.193-196
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• 2011

Lead zirconate titanate (PZT)/ bismuth ferrite (BFO) multilayer thin films have been fabricated by the spin-coating method on Pt(200 nm)/Ti(10 nm)/$SiO_2$(100 nm)/p-Si(100) substrates using $BiFeO_3$ and $Pb(Zr_{0.52}Ti_{0.48})O_3$ metal alkoxide solutions. The PZT/BFO multilayer thin films show a uniform and void-free grain structure, and the grain size is smaller than that of PZT single films. The reason for this is assumed to be that the lower BFO layers play an important role as a nucleation site or seed layer for the formation of homogeneous and uniform upper PZT layers. The dielectric constant and dielectric losses decreased with increasing number of coatings, and the six-layer PZT/BFO thin film has good properties of 162 (dielectric constant) and 0.017 (dielectric losses) at 1 kHz. The remnant polarization and coercive field of three-layer PZT/BFO thin films were 13.86 ${\mu}C/cm^2$ and 37 kV/cm respectively.