• The Korean Journal of Air & Space Law and Policy
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• v.19 no.1
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• pp.79-107
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• 2004

Shielding theory is to allow the construction of a structure that would be shielded by existing permanent structures even thought such structure extends above the height limits prescribed for such zones. This theory is mentioned as recommended practices in ICAO Annex, and is adopted, with modification, in the current Military Airbase Law, amended in August 26th 2002. However, the Military Airbase Law adopts shielding standard allowing 45 meters uniformly, which is a unique standard compared to other countries shielding guideline. The basic principle in applying the shielding theory is, after considering the circumstances of location of shielded structure, whether such structure has physical effect on aeronautical operations. Based upon the basic principle of shielding theory, the uniform application of shielding standard in the Military Airbase Law would undermine the safety of aeronautical operations. This article is to review subsection 2 of section 8 of the Military Airbase Law, which adopts modified shielding theory, and is to suggest better guideline. From a comparative analysis perspective, shielding guidelines of ICAO and other countries will be discussed. Based upon this discussion, the general problems of shielding theory and the specific problems in the Military Airbase Law will be examined. Finally, this article suggests the case-by-case application of shielding theory, considering circumstances of location, for the purpose of ensuring aviation safety.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.2 no.2
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• pp.25-29
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• 1991

In this paper, laminated shielding effectiveness equation is derived from basic shielding theory and this equation is applied to calculate the shielding effectiveness for two typical non-magnetic shielding materials, Aluminium and steel, when they are coated with conductive paint.

• Proceedings of the KIEE Conference
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• 1999.07e
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• pp.2462-2464
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• 1999

All electric and electronic appliances require their own electromagnetic compatibility. So an industrially advanced nations have made many standards for regulation for their profits thus the researches on the electro-magnetic shielding effect(SE) are being increased. But the SE can not proved its effect by a theory alone because of complex-material problems. This study Present the correlation of the SE and immunity of radiated radio frequency of the electromagnetic field. We have analyzed the theory of shielding effect to the shield texture. It has been proved that experimental results showed this effects have intensive relations to the electromagnetic field immunity.

• 전기의세계
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• v.29 no.1
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• pp.65-72
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• 1980

Arstrong-Whitehead theory on effective shielding and shielding failure is extended so that it is applicable to vertical line configuration the existing approaches on back-flash rate calculation are summerized and compared in particular on Model Line, and the usefulness of the whitehead approach is suggested.

• Nuclear Engineering and Technology
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• v.54 no.3
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• pp.1062-1070
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• 2022

In the present communication, pure and stable α-Bismuth Oxide (Bi₂O₃) nanoparticles (NPs) were synthesized by low temperature solution combustion method using urea as a fuel and calcined at 500℃. The synthesized sample was characterized by using powder X-ray Diffraction (PXRD), Scanning Electron Microscopy (SEM), Energy dispersive X-ray analysis (EDAX), Transmission Electron Microscopy (TEM), Fourier Transform Infrared Spectroscopy (FTIR) and UV-Visible absorption spectroscopy. The PXRD pattern confirms the formation of mono-clinic, stable and low temperature phase α-Bi₂O₃. The direct optical energy band gap was estimated by using Wood and Tauc's relation which was found to be 2.81 eV. The characterized sample was studied for X-ray/gamma ray shielding properties in the energy range 0.081-1.332 MeV using NaI (Tl) detector and multi channel analyzer (MCA). The measured shielding parameters agrees well with the theory, whereas, slight deviation up to 20% is observed below 356 keV. This deviation is mainly due to the influence of atomic size of the target medium. Furthermore an accurate theory is necessary to explain the interaction of X-ray/gamma ray with the NPs.The present work opens new window to use this facile, economical, efficient, low temperature method to synthesize nanomaterials for X-ray/gamma ray shielding purpose.

• Journal of Radiation Protection and Research
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• v.21 no.1
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• pp.17-25
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• 1996

In this study, to set-up the calculation method of radiation shielding of the KSC-4 shipping cask which is being used for spent fuel transportation, the pre-existing two calculation methods, deterministic and probabilistic methods were tested. For the first, the DOT4.2 computer code adopting the deterministic theory was applied for the calculation of effective neutron shielding under assumption of continuous wall thickness of the cask. To verify the first results, the probabilistic theory was used as an alternate calculation. In this case MCNP4A computer code adopting the probabilitic theory was used. And same approximation was obtained from the two different shielding calculations. From the results, it could be confirmed that the design and calculation method used for the radiation shielding of the KSC-4 was adequate and sufficiently safe to meet the design and QA requirements of 10CFR71 Appendix H.

• Nuclear Engineering and Technology
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• v.55 no.5
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• pp.1519-1526
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• 2023

For the first time Aluminium-BariumeZinc oxide nanocomposite (ZABONC) was synthesized by solution combustion method where calcination was carried out at low temperatures (600℃) to study the electromagnetic (EM) (X/γ) radiation shielding properties. Further for characterization purpose standard techniques like PXRD, SEM, UV-VISIBLE, FTIR were used to find phase purity, functional groups, surface morphology, and to do structural analysis and energy band gap determination. The PXRD pattern shows (hkl) planes corresponding to spinel cubic phase of ZnAl₂O4, cubic Ba(NO₃)₂, α and γ phase of Al₂O₃ which clearly confirms the formation of complex nano composite. From SEM histogram mean size of nano particles was calculated and is in the order of 17 nm. Wood and Tauc's relation direct energy band gap calculation gives energy gap of 2.9 eV. In addition, EM (X/γ) shielding properties were measured and compared with the theoretical ones using standard procedures (NaI (Tl) detector and multi channel analyzer MCA). For energy above 356 keV the measured shielding parameters agree well with the theory, while below this value slight deviation is observed, due to the influence of atomic/crystallite size of the ZABONC. Hence synthesized ZABONC can be used as a shielding material in EM (X/γ) radiation shielding.

• Nuclear Engineering and Technology
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• v.55 no.7
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• pp.2613-2620
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• 2023

Excellent thermal neutron absorption performance of boron expands the potential use of boron rich slag to prepare epoxy resin matrix nuclear shielding composites. However, shielding attenuation behaviors and mechanism of the composites against gamma rays are unclear. Based on the radiation protection theory, Phy-X/PSD, XCOM, and ⁶⁰Co gamma ray source were integrated to obtain the shielding parameters of boron rich slag/epoxy resin composites at 0.015-15 MeV, which include mass attenuation coefficient (µ_t), linear attenuation coefficient (µ), half value thickness layer (HVL), electron density (N_eff), effective atomic number (Z_eff), exposure buildup factor (EBF) and exposure absorption buildup factor (EABF).µ_t, µ, HVL, N_eff, Z_eff, EBF and EABF are 0.02-7 cm²/g, 0.04-17 cm^-1, 0.045-20 cm, 5-14, 3 × 10²³-8 × 10²³ electron/g, 0-2000, and 0-3500. Shielding performance is BS4, BS3, BS3, BS1 in descending order, but worse than ordinary concrete. µ and HVL of BS1-BS4 for ⁶⁰Co gamma ray is 0.095-0.110 cm^-1 and 6.3-7.2 cm. Shielding mechanism is main interactions for attenuation gamma ray by BS1-BS4 are elements with higher content or higher atomic number via Photoelectric Absorption at low energy range, and elements with higher content via Compton Scattering and Pair Production in Nuclear Field at middle and higher energy range.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2003.10a
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• pp.33-36
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• 2003

AC and DC conductivity of the MWNT(Multi walled nanotubes)/polyurethane composites were investigated with respect to the various oxidative conditions, where these means acid concentration, treatment temperature, and treatment time. We suppose that the conditions of oxidation of the MWNTS have a certain influence on the degree of functionalization, damages, and dispersion of the MWNT themselves. Futhermore, the electrical properties of the resulting composites strongly depend on the oxidative conditions of MWNTS. The conductivity of the composites produced by using the optimal condition was measured as a function of frequency with volume content of MWNTS. These experimental results were analyzed using percolation theory Electromagnetic interference shielding effectiveness (SE) of the mixtures of polyurethane (PU), optimized MWNTs, and silver (Ag) is measured in the frequency range from 10 MHz to 6 ㎓ by using ASTM D4935-89. The measured SEs of the mixtures could be controlled from about 55 dB to 85 dB with the compositions of Ag/MWNT and compounding methods(C1, C2).

• Korean Journal of Materials Research
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• v.9 no.9
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• pp.913-918
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• 1999

As an alternative evaluation method of electromagnetic shielding properties, the material parameters are considered in determining the qualitative value of shielding effectiveness. The specimens are metallized nylon fabrics with the thickness of about 0.1 mm and the electrical conductivities in the range from 6.4$\times$10~2.4$\times$10(sup)5 mhos/m. On the basis of shielding theory, the shielding effectiveness (which is a sum of reflection loss and absorption loss) has been determined from the material parameters of the barrier sheets. For the conductive fabrics, the dominant shield mechanism is predicted to be reflection loss, which shows an increasing function of electrical conductivity. Comparing these theoretical value with the directly measured surface impedances, the error range is found to be within 10 dB, which demonstrates that the proposed material-parameters method can be a convenient way to determine the electromagnetic shielding properties.