• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.3
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• pp.638-642
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• 2014

In this study, we investigate on the crystal microstructure and magneto-resistance (MR) change of Bismuth(Bi) thin films for annealing process, in order to apply Bi thin films to the spin electronic devices. As-prepared Bi thin films show the randomly oriented find grains whose size was measured to about 100 nm and the very low MR (4.7 % at room temperature) while careful annealing results in not only grain growth up to ${\sim}2{\mu}m$ but also drastic MR improvement (404 % at room temperature). The drastic change in the MR after applying the annealing process is attributed to the grain growth decreasing grain boundary scattering of electron. Therefore, in this study, we confirm the annealing effect for the grain boundary formation and MR improvement of Bi thin films, and demonstrate the feasibility of spin electronic devices.

• Journal of the Korean Society of Radiology
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• v.15 no.2
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• pp.101-108
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• 2021

The CT can accurately present the anatomical structure of an organ in the human body, and the resolution of the image is excellent. On Brain CT examination, the radiation sensitivity of the orbit is high and it is subject to many exposure effects. To reduce exposure dose of lens, this study compares change of exposure dose and shielding rate about non-shielding and shielding in a way of using two shielding materials, bismuth and tungsten. In this study, we used bismuth and tungsten filament as shielding materials made by 3D printing to measure the exposure dose according to the materials thickness and each of slices. To compare each shielding rate, 1 mm to 5 mm of two materials was measured with the head phantom fixed and the Magicmax universal dosimeter placed on the eye when the shielding material is not placed, and the shielding material is placed on it. In the 1 mm thick filament, the bismuth filament showed 26.8% and the tungsten filament showed 43.1% shielding rate. Therefore, tungsten presents much greater shielding effect than bismuth.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.2
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• pp.137-142
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• 2011

This study was conducted to establish the optimal electrolyte and bismuth concentrations using bismuth film electrode in laboratory and to confirm the possibilities of using this operational condition for heavy metals monitoring in field. In lab test, heavy metal measurement was not accurate more than 600 ppb when heavy metal (Pb, Cd, Zn) range 100~1,000 ppb was measured with bismuth 2,000 ppb. So, bismuth and heavy metal was reacted about 1:1 with ASV method. In electrolyte test, 0.1 M acetate buffer (pH 4.5), 0.1 M chloroacetate buffer (pH 2.0), 0.1 M HCl (pH 2.0), 0.1 M $HNO_3$ (pH 2.0) was tested. As a results, 0.1 M acetate buffer was most suitable in ASV measurement with bismuth film electrode. In field application, Pb, Cd and Zn was measured respectively 36~45 ppb, 84~91 ppb, 90~98 ppb when heavy metal (Pb, Cd, Zn) 100 ppb was spiked in field sample. These results were identified of matrix effect in field sample, So relationship between heavy metal measurement and matrix effects will be studied.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.8
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• pp.1473-1480
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• 2008

Bisumus has a low melting point, making it easier to handle. This allows us to test what type of effect diamagnetism has on electro static and magnetic field shields. However, the actual materials for experimentation have only ever been manufactured cylindrically, and so there have been no recorded cases of measurements to this effect. To understand what kind of effect pure bisumus as diamagnetism has on electro static and magnetic shields in comparison to other materials, bisumus, along with copper, aluminum and iron 스텐도, were used to make a cylinder each. These cylinders were then used to measure and compare the electro static shield and magnetic shield at different bands of frequencies, starting from a low frequency. As shown on the graph/chart/diagram, the best results were recorded for copper and bisumus as diamagnetism in an electro static field. In terms of magnetic shielding, iron provided the best results, as expected, whereas bisumus displayed minimal effect.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.9
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• pp.1132-1137
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• 2020

In order to reduce unnecessary exposure doses generated when mammography is performed using a mammography device, a shielding ratio analysis was performed when a self-made shielding body made of bismuth was applied to the breast opposite to the imaging site. In order to determine the scattering dose of uncompressed breasts during CC and MLO tests when the right and left are compressed, the experiment is divided into when bismuth is not shielded (Not used: NU group) and when shielded (Used: U group). Proceeded. The average dose of the NU group was 9.568μSv, and the average dose of the U group was 1.038μSv. The average measured dose before and after the use of the bismuth shield was reduced by 89.15%. The use of a bismuth shield for mammography can shield scattered radiation and keep exposure to radiation to a minimum.

• Journal of radiological science and technology
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• v.37 no.1
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• pp.49-56
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• 2014

Recently with CT developed, various studies for reduction of exposure dose is underway. Study of bismuth shields in these studies is actively underway, and has already been applied in the clinical. However, the application of the PET/CT examination was not activated. Therefore, through this study, depending on the application of bismuth shields in the PET/CT examination, we identify the quality of the image and the impact on the Standard Uptake Value (SUV). In this study, to apply to the shielding of the breast, by using the bismuth shields that contains 0.06 mm Pb ingredients, was applied to the PET/CT GEMINI TF 64 (Philips Healthcare, Cleveland, USA). Phantom experiments using the NEMA IEC Body Phantom, images were acquired according to the presence or absence of bismuth shields apply. Also, When applying, images were obtained by varying the spacing 0, 1, 2 cm each image set to the interest range in the depth of the phantom by using EBW-NM ver.1.0. When image of the PET Emission acquires, the SUV was in increased depending on the use of bismuth shields, difference in the depth to the surface from deep in the phantom increasingly SUV increased (P<0.005). Also, when using shields, as the more gab decreased, SUV is more increased (P<0.005). Through this study, PET/CT examination by using of bismuth shields which is used as purpose of reduction dose. When using shields, the difference of SUV resulting from the application of bismuth shields exist and that difference when gab is decrease and surface is wider. Therefore, setting spacing of shield should be considered, if considering the reduction of the variation of SUV and image quality, disease of deep organs should be a priority rather than superficial organ disease. Use of bismuth shielding factor considering the standard clinical examination, decrease unnecessary exposure can be expected to be considered.

• The Korean Journal of Nuclear Medicine Technology
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• v.17 no.1
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• pp.36-42
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• 2013

Purpose: Recently with CT developed, various studies for reduction of exposure dose is underway. Study of bismuth shields in these studies is actively underway, and has already been applied in the clinical. However, the application of the PET/CT examination was not activated. Therefore, through this study, depending on the application of bismuth shields in the PET/CT examination, we want to identify the quality of the image and the impact on the SUV. Materials and Methods: In this study, to apply to the shielding of the breast, by using the bismuth shields that contains 0.06 mmPb ingredients, was applied to the PET/CT GEMINI TF 64 (Philips Healthcare, Cleveland, USA). Phantom experiments using the NEMA IEC Body Phantom, images were acquired according to the presence or absence of bismuth shields apply. Also, When applying, images were obtained by varying the spacing 0, 1, 2 cm each image set to the interest range in the depth of the phantom by using EBW-NM ver.1.0. Results: When image of the PET Emission acquires, the SUV was in increased depending on the use of bismuth shields, difference in the depth to the surface from deep in the phantom increasingly SUV increased (P<0.005). Also, when using shields, as the more gab decreased, SUV is more increased (P<0.005). Conclusion: Through this study, PET/CT examination by using of bismuth shields which is used as purpose of reduction dose be considered. When using shields, the difference of SUV resulting from the application of bismuth shields exist and that difference is more decreased as gab of shields and surface is wider. Therefore, setting spacing of shield should be considered, if considering the reduction of the variation of SUV and image quality, disease of deep or other organs should be a priority rather than superficial disease. Through this study, when applying identified to clinical examination, the reduction of unnecessary exposure is considered.

• Journal of the Korean Applied Science and Technology
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• v.14 no.2
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• pp.87-91
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• 1997

서로 다른 씨클로펜타디엔 유도체가 ${\pi}$-결합된 최초의 비스무스 화합물인 ${\eta}^5-C_5(CH_3)_5Bi({\eta}^5-C_5H_5)_2$이 디펜타메틸씨클로펜타디에닐 비스무스디메틸아미드 $Cp{\ast}_2BiNMe_2[Cp{\ast}=C_5(CH_3)_5]$와 씨클로펜타디에닐 모노머와의 반응으로 합성되었다. 반응조건은 에테르 용매하에 -78$^{\circ}C$ 반응온도 조건하에서 얻어졌다. 합성된 반응물을 노르말 헥산 용매에서 재결정시킨 결과, 검은색 결정이 60% 수율로 얻어졌다. 그리고 재결정시킨 반응물을 190K에서 X-선 단결정 구조 분석 방법에 의해 그 구조를 밝혔다. 그 결과 결정계의 격자계는 I2/a, a=1756.00 picometer, b=906.00 picometer, c=2211.00 picometer, ${\beta}$=104.04, Z=8로 확인되었다. 여기서 a, b, c는 결정�Ю� 상수이고, ${\beta}$는 결정격자 상수인 b와 c간의 각도이며, Z는 단위 결정 격자당 분자의 갯수이다.

• Journal of the Mineralogical Society of Korea
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• v.32 no.1
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• pp.1-14
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• 2019

This study used microwave-nitric acid leaching with the aim of removing penalty elements such as As and Bi. Moreover, enhanced gold content from the gold concentrate sample. The leaching conditions were changed: leaching time, nitric acid concentrations and solid-liquid ratio; In order to improve the removal of penalty elements. As a result of the experiment; sample weight loss rate, As and Bi removal rate and gold content in the solid-residues have been increased when the nitric acid concentration and leaching time were increased while the solid-liquid ratio was decreased. The leaching conditions for the maximum As and Bi removal and gold content were: leaching with a 6.0 M nitric acid solution doing 5 min. At these, the solid-residue sample weight loss was 87 %. As removal rate was 98.23 % and Bi was completely removed (100 %). Furthermore, gold content increased from 81.36 g/t to 487.32 g/t. The XRD of the solid residue showed that pyrite disappeared as the nitric acid concentration was increased, whereas sulfur peaks was increased, too.

• Ceramist
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• v.20 no.2
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• pp.45-57
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• 2017