• Title/Summary/Keyword: 차폐 효과

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The Shielding Effectiveness Analysis of Power Cables Has Coaxial Structure Using Inductive Coupling Test (유도결합 실험을 통한 동축구조를 갖는 전력케이블의 차폐효과 분석)

  • Song, Euihyun;Lee, Keonbong;Nah, Wansoo
    • Proceedings of the KIEE Conference
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    • 2015.07a
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    • pp.1277-1278
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    • 2015
  • 본 논문에서는 유도결합 실험을 통해 동축 구조를 갖는 전력케이블의 차폐효과에 대해 분석했다. 케이블의 차폐 도체의 재료에 따라 차폐 정도를 비교했고, 또한 주파수의 변화에 따른 차폐 정도를 비교했다. 측정 결과, 주파수가 증가할수록 차폐효과가 감소하는 것을 알 수 있었으며, 차폐 재질에 따라서도 차폐효과가 달라지는 것을 확인 할 수 있었다. 전달 임피던스를 통해 차폐효과를 분석한 실험의 결과와 비교를 통한 실험의 타당성도 보였다.

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Effect of hiding-exposure effect on concentration profile of suspended sediment (하상재료의 차폐효과가 부유사의 농도분포에 미치는 영향)

  • Byun, Jisun;Son, Minwoo
    • Proceedings of the Korea Water Resources Association Conference
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    • 2021.06a
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    • pp.259-259
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    • 2021
  • 하상을 구성하는 사립자들이 흐름에 의해 움직이기 시작하는 상태를 한계운동이라 하며, 한계운동이 시작될 때의 흐름조건을 한계조건이라 한다. 흐름에 부유되어 이동하는 부유사의 농도분포를 정확하게 산정하기 위해서는 하상재료의 침식율을 정확하게 산정하는 것이 필요하다. 특히 하상재료에 다양한 크기의 하상재료가 혼합되어 있을 때에는 차폐효과(Hiding-Exposure Effect)에 대한 고려가 필요하다. 여기서 차폐효과란, 동일한 크기의 사립자들로 구성된 균질 하상에 비해 비균질 하상에서 굵은 사립자가 흐름에 더 많이 노출되어 한계소류력이 감소하고, 잔 사립자의 한계소류력이 굵은 사립자로 인해 증가하는 현상을 의미한다. 하상토의 차폐효과는 Shields (1936)에서 제안된 무차원 한계소류력을 각 사립자의 크기별로 산정 한 후 보정계수를 곱해 고려해주는 것이 일반적이다. 이에 본 연구에서는 하상재료의 차폐효과가 부유사의 연직방향 농도분포에 미치는 영향을 살펴보았다. 연구를 수행하기 위해 하상토의 입도분포를 바탕으로 차폐효과를 고려하고 연직방향으로의 유사농도를 계산하는 유사이동모형을 개발하였다. 수치모형의 검증은 실험실 실험자료와의 비교를 통해 수행되었다. 수치모의 결과로부터 차폐효과를 고려하지 않는 경우에는 하상에서의 침식율이 과다하게 산정되는 것으로 나타났으며, 불균질한 하상재료로 구성된 하천에서 부유사의 연직방향 유사농도를 정확하게 계산하기 위해서는 차폐효과에 대한 고려가 필요하다는 결론이 도출되었다.

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Prediction of Shielding Effectiveness in Honeycomb Structure Using the Modified Design Equation (수정된 설계 방정식을 이용한 허니컴 구조의 차폐 효과 예측)

  • Lee Kyung-Won;Cheong Yeong-Chul;Hong Ic-Pyo;Yook Jong-Gwan
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.16 no.9 s.100
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    • pp.862-871
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    • 2005
  • In this paper, the modified design equation of shielding effectiveness was presented to predict more accurately the shielding effectiveness of honeycomb structure with hexagonal waveguide. The design equation of shielding effectiveness in honeycomb was represented from adding shielding effectiveness of single lattice to shielding effectiveness of infinite array of single lattice. This paper proposed the generalized design equation of shielding effectiveness by analyzing basis lattice of hexagonal waveguide which composes honeycomb structure and infinite array structure of basis lattice. To provide the validity of the modified design equation of shielding effectiveness in this paper, comparison with other available date using 3D EM commercial software is made.

Shielding Effectiveness Analysis of the Digital Module Storage Cabinet for Nuclear Power Plants According to the Internal Structure and the Angle of EM wave Incidence (내부구조와 전파 입사각에 따른 원전용 디지털 모듈 보관 캐비닛의 차폐효과 분석)

  • Youn, Sang-Woon;Jang, Do-Young;Choo, Ho-Sung;Kim, Young-Mi;Lee, Jun-Yong
    • The Journal of the Korea institute of electronic communication sciences
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    • v.16 no.1
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    • pp.1-8
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    • 2021
  • In this paper, the cabinet shielding effectiveness (SE) including digital modules for nuclear power plants is analyzed depending on the internal structure and electromagnetic (EM) wave incidence angle. To analyze the SE, the cabinet and modules are modeled using the FEKO EM simulation tool. The SE is then obtained by comparing the electric field with and without the cabinet. In addition, the cabinet SE is observed by changing various conditions such as the spacing of each digital module, incidence angle, and the polarization of the EM wave at the 2.4 G[Hz frequency. To verify the results, the dipole antenna for SE measurements is fabricated, and the SE is measured in a semi-anechoic chamber. The result demonstrates that the SE by the cabinet structure can be expected to be higher when the polarization of the incident EM wave is horizontal to the ground and the distance between the digital modules is wide.

Establishment of the Electromagnetic Shielding Effectiveness Measurement System (전자파차폐효과 측정시스템의 구현)

  • 정연춘;강태원;정낙삼
    • The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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    • v.4 no.3
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    • pp.45-53
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    • 1993
  • The shielding effectiveness of materials is determined by measuring the ratio of the incident electromagnetic power to that which passes through the material under test. The measurement system is constructed using several test fixtures, tracking generator, spectrum analyzer, step attenuator, RF switches, and amplifiers, etc.. The automation of measurements is completed using a personal computer. Especially, incident power, reflected power, and transmitted power are measured with only one spectrum analyzer using a dual directional coupler and RF switches. Therefore the system is to be used in design of shielding materials, as well as shielding effectiveness measurements. This system has dynamic range of more than 120 dB in the frequency range of 10 MHz to 1 GHz, and it can be used to measure shielding effectiveness of composite materials.

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A Study on Validation of the Shielding Effectiveness Measurement Method of the Concrete Containing Electric Arc Furnace Oxidizing Slag (전기로산화슬래그를 활용한 콘크리트의 차폐효과 측정 방법의 유효성 검증 연구)

  • Jang, Hong-Je;Lee, Han-Hee;Choi, Hyo-Sik;Song, Tae-Seung;Cho, Won-Seo
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.9 no.4
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    • pp.478-482
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    • 2021
  • In this paper, methods for manufacturing shielding concrete by recycling steelmaking slag discarded as industrial waste and measuring the shielding effectiveness of the shielding concrete were studied. By comparing the result of shielding effectiveness measurement of this concrete block with shielding effectiveness measurement of the structure constructed with this concrete, the measurement system for measuring shielding effectiveness of the concrete block was verified. The size of the concrete stru ctu re is 2.9 × 2.9 × 3.4m and the concrete block is 0.3 × 0.3 × 0.2m. The frequ ency band u sed for mesu rement is 600MHz - 2GHz, the types of concrete u sed to measu re the shielding effectiveness are general concrete and concrete containing electric arc furnace oxidizing slag. In the case of the concrete structure, reinforcing rebars are installed at intervals of 15cm for stru ctu ral safety, as the frequ ency increase, the electromagnetic wave properties of rebars gradu ally decreased, there was a slight difference in the measurement results. In conclusion, the measurement result of shielding effectiveness of the concrete block is similar to the result of the concrete structure. It is thought that it can be sufficiently utilized for electromagnetic wave engineering design, and the concrete shielding effectiveness measurement system using standard specimens was verified.

Transmission Dose Measurement of Gamma-ray Using Tungsten Shield (텅스텐 차폐체의 감마선 투과선량 측정)

  • Han, Sang-Hyun;Koo, Bon-Yeoul
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.19 no.9
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    • pp.124-129
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    • 2018
  • This study was conducted to investigate the penetration dose and shielding rates of tungsten shields used in apron material by changing the type of source used in the nuclear medicine department, thickness of shielding material and distance between the source and detector. For the experiment, the source, shield, and detector were arranged in a straight line and measured with an inspector at a height of 100 cm. The highest shielding effect of tungsten was measured for $^{201}Tl$, while $^{123}I$ showed a higher shielding effect than $^{99m}Tc$. For the sources used in the experiment, the penetration dose decreased with distance and the shielding rate was measured with thicker thickness. However, the shielding rate of $^{13}1I$ and $^{18}F$ sources was found to be lower than when there was no shielding at 0.25 mmPb shield. Therefore, even if the radiation shielding effect of tungsten is high, considering the characteristics according to the type of source and the thickness of the shielding material, it may be helpful to reduce the exposure.

Magnetic Shielding Effect of Amorphous Strips in Low Frequency Field (비정질 연자성재료를 이용한 복층 차폐체의 저주파 자기장 차폐효과)

  • Kim, S.G.;Hur, J.;Park, P.G.;Chung, Y.C.;Kim, Y.B.;Kim, T.K.
    • Journal of the Korean Magnetics Society
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    • v.8 no.6
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    • pp.341-345
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    • 1998
  • Magnetic shielding effect of cylinderical ahields made of commericial amorphous ribbons has been studied. The shell-arrangement-order of double shell shield has been found to show a striking differencein shielding factor. In low applied field region, a 2605CO-2705M-shield (outer shell: 2605CO, inner shell: 2705M) yields two times higher shielding factor than a 2705M-2605CO-shield (outer shell: 2705M, inner shell: 2605CO). The reasons are as follows: In case of 2605CO-2705M-shield, the outer shell is not easily saturated and effectively shields the applied field. In addition, the inner shell shows high shielding factor in the field shielded by the outer shell. In case of 2705M-2605CO-shield, the outer shell is saturated at very low-field as well as the inner shell shows low shielding factor in the field shielded by the outer shell.

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Analysis for shielding effectiveness of a satellite electronic equipment enclosure with a dielectric-backed aperture (유전체로 막힌 개구를 갖는 위성 전자 장비 함체의 차폐 효과 해석)

  • Kim, Su-Han;Lee, Jae-Hyun
    • Journal of Satellite, Information and Communications
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    • v.3 no.1
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    • pp.35-40
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    • 2008
  • In this paper, a new analytical formulation is presented for calculating shielding effectiveness (SE) of shielding enclosure including satellite electronic components and equipments. The shielding enclosure has a dielectric-backed aperture. The SE may be a function of frequency, dielectric constant, and position within the enclosure. And, the formulation has been extended for calculation of the SE of the structure where the one side of dielectric is partially backed by conductor. Our simulation results give that the dielectric material lowers the Q factor, and the further the observation point is from the aperture, the more SE increases.

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Development of Radiation Shielding Sheet with Environmentally-Friendly Materials; II: Evaluation of Barum, Tourmaline, Silicon Polymers in the Radiation Shielding Sheet (친환경 소재의 의료 방사선 차폐 시트 개발; II: 바륨, 토르말린의 실리콘 폴리머 차폐 시트의 성능 평가)

  • Kim, Seon-Chil;Park, Myeong-Hwan
    • Journal of radiological science and technology
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    • v.34 no.2
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    • pp.141-147
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    • 2011
  • We developed an alternative radiation shielding material which is economical and has high protection efficiency. We validated the material in the form of sheet to make an apron. We increased the rate of barium and mixed tourmaline into silicon to improve the flexibility and protection rate of the sheet. The results showed that the shielding effect at low radiation energy is good enough with both 5 mm and 7 mm thickness. In the future, we will perform a quantitative evaluation of the reproducibility, volumetric efficiency, and porosity in mixing the ingredients.