• Title/Summary/Keyword: Shield Materials

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Impact Damage of Honeycomb Sandwich Antenna Structures (통신 안테나용 허니콤 샌드위치 구조물의 충격 손상에 관한 연구)

  • 조성재;김차겸;박현철;황운봉
    • Proceedings of the Korean Society For Composite Materials Conference
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    • 2001.05a
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    • pp.74-77
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    • 2001
  • The impact response and damage of CLAS panel was investigated experimentally. The facesheet material used was RO4003 woven-glass hydrocarbon/ceramic and the core material was Nomex honeycomb with a cell size of 3.2mm and a density of 96 kg/$\textrm{m}^{3}$. The shield plane used was RO4003 and 2024-T3 aluminum. Static indentation and impact test was conducted to characterize the type and extent of the damage observed in two CLAS panels, and the performance of antenna used in a wireless LAN system. Correlation of peak contact force, residual indentation and the delamination area shows impact damage of the panel with an aluminum shield plane is larger than that of the panel with RO4003 shield plane, although tile former is more penetration resistant. The damage was observed by naked eye, ultrasonic inspection and cross sectioning. The shape and size of delamination was estimated by ultrasonic inspection, and the area of delamination linearly increases as impact energy increases. The performance of impact damaged antenna was estimated by measuring return loss and radiation pattern.

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Study on the design and experimental verification of multilayer radiation shield against mixed neutrons and γ-rays

  • Hu, Guang;Hu, Huasi;Yang, Quanzhan;Yu, Bo;Sun, Weiqiang
    • Nuclear Engineering and Technology
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    • v.52 no.1
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    • pp.178-184
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    • 2020
  • The traditional methods for radiation shield design always only focus on either the structure or the components of the shields rather than both of them at the same time, which largely affects the shielding performance of the facilities, so in this paper, a novel method for designing the structure and components of shields simultaneously is put forward to enhance the shielding ability. The method is developed by using the genetic algorithm (GA) and the MCNP software. In the research, six types of shielding materials with different combinations of elements such as polyethylene (PE), lead (Pb) and Boron compounds are applied to the radiation shield design, and the performance of each material is analyzed and compared. Then two typical materials are selected based on the experiment result of the six samples, which are later verified by the Compact Accelerator Neutron Source (CANS) facility. By using this method, the optimal result can be reached rapidly, and since the design progress is semi-automatic for most procedures are completed by computer, the method saves time and improves accuracy.

Radiological Safety Assessment for a Near-Surface Disposal Facility Using RESRAD-ONSITE Code

  • Jang, Jiseon;Kim, Tae-Man;Cho, Chun-Hyung;Lee, Dae Sung
    • Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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    • v.19 no.1
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    • pp.123-132
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    • 2021
  • Radiological impact analyses were carried out for a near-surface radioactive waste repository at Gyeongju in South Korea. The RESRAD-ONSITE code was applied for the estimation of maximum exposure doses by considering various exposure pathways based on a land area of 2,500 ㎡ with a 0.15 m thick contamination zone. Typical influencing input parameters such as shield depth, shield materials' density, and shield erosion rate were examined for a sensitivity analysis. Then both residential farmer and industrial worker scenarios were used for the estimation of maximum exposure doses depending on exposure duration. The radiation dose evaluation results showed that 60Co, 137Cs, and 63Ni were major contributors to the total exposure dose compared with other radionuclides. Furthermore, the total exposure dose from ingestion (plant, meat, and milk) of the contaminated plants was more significant than those assessed for inhalation, with maximum values of 5.5×10-4 mSv·yr-1 for the plant ingestion. Thus the results of this study can be applied for determining near-surface radioactive waste repository conditions and providing quantitative analysis methods using RESRAD-ONSITE code for the safety assessment of disposing radioactive materials including decommissioning wastes to protect human health and the environment.

Computational analysis of sandwich shield with free boundary inserted fabric at hypervelocity impact (비구속 삽입된 직물 섬유를 이용한 샌드위치 쉴드의 초고속 충격 해석)

  • Moon, Jin-Bum;Park, Yu-Rim;Son, Gil-Sang;Kim, Chun-Gon
    • Composites Research
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    • v.24 no.3
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    • pp.31-38
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    • 2011
  • In this paper, a novel hybrid composite shield to protect space structures from hypervelocity impact of micrometeoroid and space debris is proposed. The finite element model of the proposed shield was constructed and finite element analysis was conducted to approximate the energy absorption rate. Before the final model analysis, analysis of each component including the aluminum plate, PMMA plate, and intermediate layer of fabric was performed, verifying the finite element model of each component. The material properties used in the analyses were predicted material property values for high strain rates. The analysis results showed that, other than the fabric, the energy absorption rate of each component was in agreement. Afterwards, the finite element model of the hybrid composite shield was constructed, where it was analyzed for the restrained and unrestrained fabric boundary condition cases. Through the finite element analysis, the fiber pullout mechanism was realized for the hybrid shield with free boundary inserted fabric, and it was observed that this mechanism led to energy absorption increase.

Experimental Study of Emissivity with the Variation of Temperature and Shape Factor Using the Radiation Apparatus (복사 장치를 이용한 온도와 형상계수의 변화에 따른 방사율에 관한 실험적 연구)

  • Kim, Chung-Rae;Jeong, Byung-Cheol;Kang, Hyung-Suk
    • Journal of Industrial Technology
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    • v.25 no.B
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    • pp.135-140
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    • 2005
  • Voltage of radiometer is measured experimentally using the radiation apparatus in each case of iron- and copper-plates as specimen heating device. The length between radiometer and conical shield and the temperature of specimen heating device are considered as variables. The length between radiometer and conical shield controls the amount of radiation from the specimen heating device. Emissivity for both iron-and copper-plates are calculated by using Stefan-Boltzmann equation. One of results shows that emissivity for both materials increases as the length between radiometer and conical shield increases.

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Application of Shield Property on Radiation Noise (Radiation Noise의 Shield를 위한 Paint 특성)

  • Lee, Seong-Jae;Kim, Cheol-Soo
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2006.11a
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    • pp.341-342
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    • 2006
  • A physical model for reduction of Electromagnetic Interference(EMI) or its predecessors, Radio Noise, Electrical Noise, or Radio-Frequency-Interference(RFI), is a rapidly expanding digital technology. It covers the frequency spectrum from DC to about 3 GHz EMI is the poisoner which does not allow radio, TV, radar, navigation, and a lot of electrical, electro-mechanical, and electronic and communication devices, apparatus and systems to operate compatibly in a common frequency spectrum environment EMI can result in a jammed radio, heart pacer failures, navigation errors and many other either nuisance or catastrophic events. Therefore, it follows that this spectrum pollution problem has reached international levels of concern and must be dealt with m proportion to the safety and economic impact Involved.

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Nuclear Energy Depositions in the Primary End Shields and Side Primary Shield Systems (월성 2호기 종단 및 측면 차폐체에의 핵에너지축적 해석)

  • Kim, Kyo-Youn;Kim, Jong-Kyung
    • Journal of Radiation Protection and Research
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    • v.17 no.2
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    • pp.37-48
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    • 1992
  • It was carried out to analyze the nuclear energy deposition rates for the bulk shield components including materials of the primary end shield and side primary systems of Wolsong 2 during steady state operations at 100% full power using ANISN code. This paper has been prepared to support system design of Wolsong 2.

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The reduction methods of operator's radiation dose for portable dental X-ray machines

  • Cho, Jeong-Yeon;Han, Won-Jeong
    • Restorative Dentistry and Endodontics
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    • v.37 no.3
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    • pp.160-164
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    • 2012
  • Objectives: This study was aimed to investigate the methods to reduce operator's radiation dose when taking intraoral radiographs with portable dental X-ray machines. Materials and Methods: Two kinds of portable dental X-ray machines (DX3000, Dexcowin and Rextar, Posdion) were used. Operator's radiation dose was measured with an 1,800 cc ionization chamber (RadCal Corp.) at the hand level of X-ray tubehead and at the operator's chest and waist levels with and without the backscatter shield. The operator's radiation dose at the hand level was measured with and without lead gloves and with long and short cones. Results: The backscatter shield reduced operator's radiation dose at the hand level of X-ray tubehead to 23 - 32%, the lead gloves to 26 - 31%, and long cone to 48 - 52%. And the backscatter shield reduced operator's radiation dose at the operator's chest and waist levels to 0.1 - 37%. Conclusions: When portable dental X-ray systems are used, it is recommended to select X-ray machine attached with a backscatter shield and a long cone and to wear the lead gloves.

The characteristics of bead welding on steel with process parameter during the laser-arc hybrid welding(I) - Effect of flow rate of shield gas and distance between laser and arc - (강의 레이저-아크 하이브리드 용접시 공정변수에 따른 비드용접특성 (I) - 보호가스 유량 및 레이저 아크간 거리의 영향 -)

  • Kim, Jong-Do;Myung, Gi-Hoon;Song, Moo-Keun;Oh, Jae-Hwan;Suh, Jeong
    • Journal of Welding and Joining
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    • v.33 no.2
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    • pp.85-90
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    • 2015
  • Recently many studies for improvement of productivity and automation of process are in progress, and among others, laser-arc hybrid welding that combined laser and arc has attracted much attention. Since parameters by interactions as well as the parameters of each heat source should be considered, There are a lot of hardship in actual application, even though many researches have been done so far. Therefore in this study, bead welding was done to examine the effects of the flow rate of shield gas and the distance between laser and arc during laser-arc hybrid welding. As for hybrid heat source, disk laser and MIG were used. As experiment result, sound bead and weld with no defect were formed when the flow rate of front and rear shield gas were respectively 20 l/min and 15 l/min, and deep penetration was done at DLA=3 mm.