• Title, Summary, Keyword: Shielding analysis

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Comparison of Striking Distance Formulae and Their Effect on Lightning Shielding Analysis (뇌 차폐 해석에서 뇌격흡인 거리 수식과 영향 비교)

  • Kim, Sung-Sam
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.60 no.4
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    • pp.694-699
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    • 2011
  • This paper compares the performance of lightning shielding analysis methods using the seven striking distance formulae in substation. For comparison, we evaluate the number of expected strikes and exposed area using WinIGS Software. Seven striking distance formulae are compared using the electrogeometric model analysis and the rolling sphere method. Based on the electrogeometric model analysis, the risk of shielding failure in either the whole substation or parts of it is determined. According to the simulation results, one can justify whether the substation satisfies the criterion of shielding design. In particular, according to the rolling sphere method, the exposed areas in substation determine the location of the additional shielding poles or shield wires. Therefore, the installation of the additional shielding poles and shield wires in substation was accepted by shield design at the phase conductors exposed in the larger area.

Shielding effect model and Signal Switching in the multi-layer interconnects (다층 배선에서 차폐효과 모델 및 스위칭에 미치는 영향)

  • 진우진;어영선
    • Proceedings of the IEEK Conference
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    • pp.1145-1148
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    • 1998
  • New capacitance modeling and transient analysis for multi-layer interconnects with shielding effect are presented. The upper layer capacitances with under-layer shielding lines are represented by introducing a filling factor η which can be defined as the ratio of upper-layer line length to the total under-layer line width. The upper-layer effective self capacitances considering two extreme cases which the underlayer metals are assumed as a ground or as a Vdd are modeled. The signal transient analysis with shielding effect model is performed.

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Analysis of Different 500kV HVAC Transmission Lines Lightning Shielding

  • Nayel, Mohamed
    • Journal of the Korea Convergence Society
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    • v.4 no.4
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    • pp.49-57
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    • 2013
  • The lightning shielding of different 500 kV HVAC-TL high voltage AC transmission lines was analyzed. The studied transmission lines were horizontal flat single circuit and double circuit transmission lines. The lightning attractive areas were drawn around power conductors and shielding wires. To draw the attractive areas of the high voltage transmission lines, transmission line power conductors, shielding wires and lightning leader were modeled. Different parameters were considered such as lightningslope, ground slope and wind on lightning attractive areas. From the calculated results, the power conductors voltages affected on attractive areas around power conductors and shielding wires. For negative lightning leader, the attractive area around the transmission line power conductor increased around power conductors stressed by positives voltage and decreased around power conductors stressed by negative voltage. In spite of this, the attractivearea of the transmission line shielding wire increasedaround the shielding wire above the power conductor stressed by the positive voltage and decreased around the shielding wire above the power conductor stressed by negative voltage. The attractive areas around power conductors and shielding wires were affected by the surrounding conditions, such as lightning leader slope, ground slope. The AC voltage of the transmission lines made the shielding areas changing with time.

Analysis of Shielding Effectiveness and Estimation of Shielding Factor in Conductive and Magnetic Shields (도전성 및 자성 차폐체의 차폐효과 해석과 차폐인수 산정)

  • Kang, Dae-Ha
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.27 no.10
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    • pp.30-40
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    • 2013
  • In this study the method based on flux linkage in cell was introduced in calculation of eddy currents by cell method. According to this method eddy current distribution and the loss can be evaluated and since the shielding effectiveness by flux cancelation of eddy current can be analyzed, this method is applicable to design of conductive shield. And also the formula of shielding factor were so deduced as to be applicable to finite-width infinite-length shielding sheets and infinite-length underground cable shield. These formula are adaptable to magnetic materials as well as conductive materials. As the results of calculation in model shields are follows. In case of finite-width infinite-length shielding sheet, shielding effectiveness increases with increasing of conductivity. In case of infinite-length underground cable shield, the effectiveness become higher with increasing of permeability. Especially the effectiveness is very high in materials with both high conductivity and permeability in underground cable shield.

Development of Shielding Analysis System for the Reactor Vessel by $R-{\theta}$ Coordinate Geometry ($R-{\theta}$ 좌표계에 의한 원자로 압력용기 차폐해석체계 개발)

  • Kim, Ha-Yong;Koo, Bon-Seung;Kim, Kyo-Youn;Lee, Chung-Chan;Zee, Sung-Quun
    • Journal of Radiation Protection and Research
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    • v.30 no.1
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    • pp.39-44
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    • 2005
  • A new developing reactor isn't fixed the structure and the materials of reactor components. To perform the shielding analysis for a reactor vessel by $R-\theta$ geometry, it takes much effort and time to modeling of source term according to the change of reactor components every time. Therefore, we developed the shielding analysis system for the reactor vessel by $R-{\theta}$ geometry, which wasn't affected by the reactor core geometry. By using the developed shielding analysis system, we performed the shielding analysis for the reactor vessel of an integral reactor which has the hexagonal geometry of nuclear fuel assemblies in reactor core. We compared the results obtained from the developed system with those obtained from MCNP analysis. Because the results of developed shielding analysis system were more conservative than those of MCNP calculation, it is useful for shielding analysis. As we had developed the new shielding analysis system for a reactor vessel by $R-{\theta}$ geometry, we reduced error of model for reactor core which was formerly designed by hand and saved the time and the effort to design source term model of reactor core.

Analysis of Shielding Effectiveness of Low Conductivity Shield Layers within Near-field Region (근거리장에 놓인 저전도율 차폐막의 차폐 효과 분석)

  • Lee, Won-Seon;Lee, Won-Hui;Hur, Jung
    • The Journal of The Institute of Internet, Broadcasting and Communication
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    • v.19 no.2
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    • pp.59-65
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    • 2019
  • The EMI shielding effectiveness of shielding layers thickness was analyzed when the low conductivity shielding layers was placed in the near field of the noise source. A spiral antenna with broadband characteristics was used as the noise source, and graphite was selected as the low conductivity shielding material. Two spiral antennas were constructed to analyze the transmission coefficient between two antennas, and the distances between the transmitting and receiving antennas were 5 cm and 10 cm. The thickness of the shielding layers was changed from 1 um to 200 um. The frequency was changed from 100 MHz to 6 GHz to obtain a maximum SE(Shielding Effectiveness) of 70 dB. In this simulation, electronic shielding was used due to the nature of graphite, which is a shielding film material. Based on these results, we will study how to improve the shielding performance by implementing magnetic shielding in the future.

Performance Analysis of Low-level Radiation Shielding Sheet with Diamagnetic Nanoparticles

  • Cho, Jae-Hwan;Kim, Myung-Sam
    • Journal of Magnetics
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    • v.20 no.2
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    • pp.103-109
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    • 2015
  • In this study, the authors attempted to produce a medical radiation shielding fiber that can be produced at a nanosize scale and that is, unlike lead, harmless to the human body. The performance of the proposed medical radiation shielding fiber was then evaluated. First, diamagnetic bismuth oxide, an element which, among elements that have a high atomic number and density, is harmless to the human body, was selected as the shielding material. Next, 10-100 nm sized nanoparticles in powder form were prepared by ball milling the bismuth oxide ($Bi_2O_3$), the average particle size of which is $1-500{\mu}m$, for approximately 10 minutes. The manufactured bismuth oxide was formed into a colloidal solution, and the radiation shielding fabric was fabricated by curing after coating the solution on one side or both sides of the fabric. The thicknesses of the shielding sheets prepared with bismuth oxide were 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, and 1.0 mm. An experimental method was used to measure the absorbed dose and irradiation dose by using the lead equivalent test method of X-ray protection goods presented by Korean Industrial Standards; the resultant shielding rate was then calculated. From the results of this study, the X-ray shielding effect of the shielding sheet with 0.1 mm thickness was about 55.37% against 50 keV X-ray, and the X-ray shielding effect in the case of 1.0 mm thickness showed shielding characteristics of about 99.36% against 50 keV X-ray. In conclusion, it is considered that nanosized-bismuth radiation shielding fiber developed in this research will contribute to reducing the effects of primary X-ray and secondary X-ray such as when using a scattering beam at a low level exposure.

Neutron Dose Rate Analysis of PWR Spent Fuel Transport Cask Using Monte Carlo Method

  • Do, Mahnsuck;Kim, Jong-Kyung;Yoon, Jeong-Hyoun
    • Proceedings of the Korean Nuclear Society Conference
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    • pp.847-852
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    • 1995
  • A shielding analysis for KSC-7, the shipping cask for transporting the 7 PWR spent fuel assemblies, has been carried out. Radiation source term has been calculated on spent fuel with burnup of 50,000 MWD/MTU and 1.5 years cooling time by ORIGEN2 code. The shielding calculation for the cask has been made by using MCNP4A code with continuous cross section data library from ENDF/B-V. As a result of neutron dose rate analysis, another shielding calculational model on spent fuel shipping cask was provided which is using the Monte Carlo method.

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An analysis of new IGBT(Insulator Gate Bipolar Transistor) structure having a additional recessedwith E-field shielding layer

  • Yu, Seung-Woo;Lee, Han-Shin;Kang, Ey-Goo;Sung, Man-Young
    • Journal of IKEEE
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    • v.11 no.4
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    • pp.247-251
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    • 2007
  • The recessed gate IGBT has a lower on-state voltage drop compared with the DMOS IGBT, because there is no JFET resistance. But because of the electric field concentration in the corner of the gate edge, the breakdown voltage decreases. This paper is about the new structure to effectively improve the Vce(sat) voltage without breakdown voltage drop in 1700V NPT type recessed gate IGBT with p floating shielding layer. For the fabrication of the recessed gate IGBT with p floating shielding layer, it is necessary to perform the only one implant step for the shielding layer. Analysis on the Breakdown voltage shows the improved values compared to the conventional recessed gate IGBT structures. The result shows the improvement on Breakdown voltage without worsening other characteristics of the device. The electrical characteristics were studied by MEDICI simulation results.

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An Experimental Study on Installation of the Shielding Material to Reduce the Shock Noise of a Gun (화포소음 저감을 위한 차폐재 설치에 관한 실험적 연구)

  • Lee, Haesuk;Hong, Junhee
    • Journal of the Korea Institute of Military Science and Technology
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    • v.19 no.4
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    • pp.453-461
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    • 2016
  • The paper represents the experimental analysis of the shock noise of medium caliber guns when a projectile is passed through the shielding material. In the study, the shielding material was constructed and tested in three separate experiments. The shielding material was not installed for medium caliber gun in Case 1. A medium caliber gun was fully covered with shielding material in Case 2, and another one was put with shielding material near muzzle in Case 3. In each experiment, the experimental data was compared with each other. Results showed the firing shielding material achieved a significant noise reduction in $90^{\circ}$ to the noise source. Case 3 is confirmed to be better effective than Case 2 in the near field. But, the noise reduction in the far field is small in quantity due to the low frequency. The paper is considered that further study is necessary for the shielding material which can absorb a low frequency noise in the future.