• 제목/요약/키워드: Shielding performance

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Feasibility study on the inductive fault current limiting cable

  • Lee, Sang Yoon;Choi, Jongho;Kim, Dong Min;Sim, Kideok;Cho, Jeonwook;Kim, Seokho
    • Progress in Superconductivity and Cryogenics
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    • v.15 no.3
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    • pp.24-28
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    • 2013
  • Fault current limiting (FCL) cable is a kind of superconducting cable which has a function of limiting the fault current at the fault of power grid. The superconducting cable detours the fault current through its stabilizer to keep the temperature as low as possible. On the other hands, the FCL cable permits the temperature rise within some acceptable limit and the fault current is limited by the consequent increase of the resistance of superconducting cable. This kind of FCL cable is called 'resistive FCL cable' because it uses resistive impedance to limit the fault current. In this paper, we suggest a novel concept of FCL cable, which is named as 'inductive FCL cable'. The inductive FCL cable is similar as the magnetic shielding fault current limiter in its operating mechanism. The magnetic field of superconducting cable is almost perfectly shielded by the induced current at the shielding layer during its normal operation. However, at the fault condition, quench occurs at the shielding layer by the induced current higher than its critical current and the magnetic field is spread out of the shielding layer. It will induce additional inductive impedance to the superconducting cable and the inductive impedance can be increased more by installing some material with high magnetic susceptibility around the superconducting cable. We examined the feasibility of inductive FCL cable with simple elemental experiments. The current limiting performance of inductive FCL cable was estimated considering an arbitrary power grid and its fault condition.

Construction and Performance of Magnetically Shielded Room for Biomagnetic Applications (생체자기계측을 위한 자기차폐실의 설치 및 특성)

  • 이용호;권혁찬;김진목;임청무;이상길;박용기;박종철
    • Journal of the Korean Magnetics Society
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    • v.6 no.4
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    • pp.264-271
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    • 1996
  • A magnetically shielded room has been constructed for biomagnetic applications. The room has internal dimensions of $2\;m(length){\times}2\;m(width){\times}2.5\;m(height)$ and it consists of high permeability Mumetal and high conductivity alummum, utilizing ferromagnetic shielding and eddy current shielding. The de shielding factor around the center of the room is above 60 dB, and the ac shielding factors at 1 and 10 Hz are larger than 60 and 80 dB, respectively. The internal magnetic field noise at 1 Hz is $500\;fT/{\sqrt}Hz$ and at 10 Hz is $100\;fT/{\sqrt}Hz$, and the field gradient noise at 1 Hz is below $7\;fT/cm{\sqrt}Hz$. Successful measurements of cardiomagnetic fields usmg SQUID magnetometer and neuromagnetic fields using SQUID gradiometer have been done.

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Preparation and characteristics of a flexible neutron and γ-ray shielding and radiation-resistant material reinforced by benzophenone

  • Gong, Pin;Ni, Minxuan;Chai, Hao;Chen, Feida;Tang, Xiaobin
    • Nuclear Engineering and Technology
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    • v.50 no.3
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    • pp.470-477
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    • 2018
  • With a highly functional methyl vinyl silicone rubber (VMQ) matrix and filler materials of $B_4C$, PbO, and benzophenone (BP) and through powder surface modification, silicone rubber mixing, and vulcanized molding, a flexible radiation shielding and resistant composite was prepared in the study. The dispersion property of the powder in the matrix filler was improved by powder surface modification. BP was added into the matrix to enhance the radiation resistance performance of the composites. After irradiation, the tensile strength, elongation, and tear strength of the composites decreased, while the Shore hardness of the composites and the crosslinking density of the VMQ matrix increased. Moreover, the composites with BP showed better mechanical properties and smaller crosslinking density than those without BP after irradiation. The initial degradation temperatures of the composites containing BP before and after irradiation were $323.6^{\circ}C$ and $335.3^{\circ}C$, respectively. The transmission of neutrons for a 2-mm thick sample was only 0.12 for an Am-Be neutron source. The transmission of ${\gamma}$-rays with energies of 0.662, 1.173, and 1.332 MeV for 2-cm thick samples were 0.7, 0.782, and 0.795, respectively.

Evaluation of the Shield Performance of Lead and Tungsten Based Radiation Shields (납과 텅스텐 기반 차폐체의 성능 비교 평가)

  • Jeong-Hwan Park;Hyeon-Seong Lee;Eun-Seo Lee;Hyo-Jeong Han;Yun-Hee Heo;Jae-Ho Choi
    • Journal of radiological science and technology
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    • v.46 no.6
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    • pp.519-526
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    • 2023
  • This study was intended to evaluate the shielding rate of radiation shields manufactured using 3D printers that have recently been used in various fields by comparing them with existing shields made of lead, and to find out their applicability through experiments. A 3D printer shield made of tungsten filament 1 mm, 2 mm, 4 mm shield, RNS-TX (nanotungsten) 1.1 mm, lead 0.2 mmPb, and 1mmPb were exposed to 99mTc, 18F, and 201TI for 15, 30, 45 minutes, and 60 minutes after measuring cumulative dose three times. Based on this, the shielding rate of each shield was calculated based on the dose in the absence of the shield. In addition, 99mTc, 18F, and 201TI were located 100 cm away from the phantom in which the OSLD nano Dot device was inserted, and if there was no shield for 60 minutes, the dose of thyroid was measured using 1.0 mm of lead shield, 1.1 mm of RNS-TX shield, and 2 mm of tungsten shield made by 3D printer. The use of shields during radiation shielding emitted from open radiation sources all resulted in a reduction in dose. The radiation dose emitted from the radionuclides under the experiment was all reduced when the shield was used. This study has been confirmed that tungsten is a material that can replace lead due to its excellent performance and efficiency as shield, and that it even shows the possibility of manufacturing a customized shield using 3D printer.

Lead-free inorganic metal perovskites beyond photovoltaics: Photon, charged particles and neutron shielding applications

  • Srilakshmi Prabhu;Dhanya Y. Bharadwaj;S.G. Bubbly;S.B. Gudennavar
    • Nuclear Engineering and Technology
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    • v.55 no.3
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    • pp.1061-1070
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    • 2023
  • Over the last few years, lead-free inorganic metal perovskites have gained impressive ground in empowering satellites in space exploration owing to their material stability and performance evolution under extreme space environments. The present work has examined the versatility of eight such perovskites as space radiation shielding materials by computing their photon, charged particles and neutron interaction parameters. Photon interaction parameters were calculated for a wide energy range using PAGEX software. The ranges of heavy charged particles (H, He, C, N, O, Ne, Mg, Si and Fe ions) in these perovskites were estimated using SRIM software in the energy range 1 keV-10 GeV, and that of electrons was computed using ESTAR NIST software in the energy range 0.01 MeV-1 GeV. Further, the macroscopic fast neutron removal cross-sections were also calculated to estimate the neutron shielding efficiencies. The examined shielding parameters of the perovskites varied depending on the radiation type and energy. Among the selected perovskites, Cs2TiI6 and Ba2AgIO6 displayed superior photon attenuation properties. A 3.5 cm thick Ba2AgIO6-based shield could reduce the incident radiation intensity to half its initial value, a thickness even lesser than that of Pb-glass. Besides, CsSnBr3 and La0.8Ca0.2Ni0.5Ti0.5O3 displayed the highest and lowest range values, respectively, for all heavy charged particles. Ba2AgIO6 showed electron stopping power (on par with Kovar) better than that of other examined materials. Interestingly, La0.8Ca0.2Ni0.5Ti0.5O3 demonstrated neutron removal cross-section values greater than that of standard neutron shielding materials - aluminium and polyethylene. On the whole, the present study not only demonstrates the employment prospects of eco-friendly perovskites for shielding space radiations but also suggests future prospects for research in this direction.

A Study on Performance Improvement of TDMA Noise in a GSM Mobile Phone using the Noise Measure Method (잡음 대책법을 이용한 GSM 방식 이동전화기의 TDMA 잡음 개선에 관한 연구)

  • Oh, Se-Kab;Choi, Jae-Myeong;Kang, Heau-Jo
    • Journal of Advanced Navigation Technology
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    • v.13 no.3
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    • pp.406-411
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    • 2009
  • In this paper, we study the method of noise analysis for analysing TDMA noise in a GSM mobile phone and describe the cause of TDMA noise. And we reduced noise by 9dB, 3.5dB, 6dB, using MIC shielding, equipped bead or capacitance, connected PCB ground based on the difference analysis method, which is one of common noise analysis methods.

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Detailed Analysis of the KAERI nTOF Facility

  • Kim, Jong Woon;Lee, Young-Ouk
    • Journal of Radiation Protection and Research
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    • v.41 no.2
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    • pp.141-147
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    • 2016
  • Background: A project for building a neutron time-of-flight (nTOF) facility is progressing. We expect that the construction will start in early 2016. Before that, a detailed simulation based on the current architectural drawings was performed to optimize the performance of our facility. Materials and Methods: Currently, several parts had been modified or changed from the original design to reflect requirements such as the layout of the electron beam line, shape of the vacuum chamber producing a neutron beam, and the underground layout of the nTOF facility. Detailed analysis for these modifications has been done with MCNP simulation. Results and Discussion: An overview of our photo-neutron source and KAERI nTOF facility were introduced. The numerical simulations for heat deposition, source term, and radiation shielding of KAERI nTOF facility were performed and the results are discussed. Conclusion: We are expecting that the construction of the KAERI nTOF facility will start in early 2016, and these results will be used as basic data.

A Study on the Strength Properties of Mortar with the Graphite (흑연을 혼입한 모르타르의 강도 특성에 관한 연구)

  • Kwack, Jael-Hoon;Kim, Sang-Heon;Ji, Suk-Wonn;Seo, Chee-Ho
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2008.11a
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    • pp.79-83
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    • 2008
  • With excellent mechanical properties and durability of concrete and construction materials so far because, as has been the most widely used. However, existing in the electrical conductivity of the concrete material is given the characteristics of the concrete can not expand a lot of applications. For example, the cathode material of a parameter, ground resistance materials, electromagnetic shielding materials, sense of self-diagnostic materials, and anti-static materials are available. Currently, research on the electromagnetic shielding and absorbing mortar is incomplete. And Japan, the United States is part of the research in research institutions. Therefore, this research rate in the mouth in a different mix of conductive graphite particle the physical properties of cement mortar about the basic performance characteristics of the robbery was to figure out.

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Surface Modification of Ag Coated Cu Conductive Metal Powder for Conductive Silicone Sealant Gasket Paste

  • Park, Seong-Yong;Yoon, Tae-Won;Lee, Chung-Ho;Jeong, In-Bum;Hyun, Sang-Hoon
    • Proceedings of the Korean Powder Metallurgy Institute Conference
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    • 2006.09b
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    • pp.1076-1077
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    • 2006
  • Conductive pastes consist of conductive fillers( Au, Ag, Ni, Cu etc.), organic binders, solvents and additives. Meanwhile, there are some metal powders such as copper, nickel etc that are used for pastes which have serious surface corrosion problems. This problem leads to change of the color and decrease in conductivity and affect storage stability of conductive pastes. By using silane coupling agent and dispersion agent, we can ensure both the corrosion stability and long term storage stability, and enhance the high performance electrical and mechanical properties of EMI shielding silicone sealant.

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