Effect of the Rotation Angle in Multi-Ring Metallic Meshes on Shielding Effectiveness

2020 ◽  
Vol 30 (7) ◽  
pp. 629-632
Author(s):  
Xieming Xu ◽  
Zhongxi Lin ◽  
Shuaihua Wang ◽  
Shaofan Wu
Author(s):  
H. Hashimoto ◽  
Y. Sugimoto ◽  
Y. Takai ◽  
H. Endoh

As was demonstrated by the present authors that atomic structure of simple crystal can be photographed by the conventional 100 kV electron microscope adjusted at “aberration free focus (AFF)” condition. In order to operate the microscope at AFF condition effectively, highly stabilized electron beams with small energy spread and small beam divergence are necessary. In the present observation, a 120 kV electron microscope with LaB6 electron gun was used. The most of the images were taken with the direct electron optical magnification of 1.3 million times and then magnified photographically.1. Twist boundary of ZnSFig. 1 is the image of wurtzite single crystal with twist boundary grown on the surface of zinc crystal by the reaction of sulphur vapour of 1540 Torr at 500°C. Crystal surface is parallel to (00.1) plane and electron beam is incident along the axis normal to the crystal surface. In the twist boundary there is a dislocation net work between two perfect crystals with a certain rotation angle.


2009 ◽  
Author(s):  
Sue A. Ferguson ◽  
William S. Marras ◽  
W. Gary Allread ◽  
Gregory G. Knapik ◽  
Kimberly A. Vandlen ◽  
...  

2010 ◽  
Vol E93-C (6) ◽  
pp. 929-931 ◽  
Author(s):  
Yeong-Chul CHUNG ◽  
Kyung-Won LEE ◽  
Ic-Pyo HONG ◽  
Kyung-Hyun OH ◽  
Jong-Gwan YOOK

2020 ◽  
Vol 13 (1) ◽  
pp. 16
Author(s):  
Kukjoo Kim ◽  
Kyung-Ryeung Min ◽  
Young-Jun Park

The Korean peninsula is under increasing threat of electromagnetic pulses (EMPs) from neighboring countries; EMP protection facilities are an essential means of ensuring the operational readiness of the military. However, existing EMP protection facilities are manufactured as fixed-weight structures, which limit the mobility of military operations and lead to the misconception of EMP protection as something only required for higher command. The current military and official EMP protection standards require only a uniform shielding effectiveness of 80 dB. Therefore, this study aims to differentiate the existing uniform level of shielding effectiveness of 80 dB into 80 dB, 60 dB, 40 dB, etc. Further, it seeks to derive the factors to be considered when applying various methods, such as shielding rooms, shielding racks, site redundancy, spare equipment, and portable lightweight protective tents, for recovery of failure, instead of the existing protection facilities that rely on shielded rooms by the Delphi analysis. Then, the applicability of lightweight EMP protection is determined after selecting lightweight materials to build a facility. The electromagnetic shielding performance of 21 types of materials was measured in the 30 MHz–1.5 GHz frequency band using ASTM-D-4935-10. The results showed the possibility of developing a lightweight EMP shielding facility, which would save approximately 316,386 tons of concrete, reducing the CO2 emissions by approximately 9,972,489 tons. Assuming that the Korean carbon transaction price is USD 50/ton CO2, the savings are equivalent to USD 49,862,435.


Polymers ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 971
Author(s):  
Young Soo Yu ◽  
Chi Bum Ahn ◽  
Kuk Hui Son ◽  
Jin Woo Lee

A trachea has a structure capable of responding to various movements such as rotation of the neck and relaxation/contraction of the conduit due to the mucous membrane and cartilage tissue. However, current reported tubular implanting structures are difficult to impelement as replacements for original trachea movements. Therefore, in this study, we developed a new trachea implant with similar anatomical structure and mechanical properties to native tissue using 3D printing technology and evaluated its performance. A 250 µm-thick layer composed of polycaprolactone (PCL) nanofibers was fabricated on a rotating beam using electrospinning technology, and a scaffold with C-shaped cartilage grooves that mimics the human airway structure was printed to enable reconstruction of cartilage outside the airway. A cartilage type scaffold had a highest rotational angle (254°) among them and it showed up to 2.8 times compared to human average neck rotation angle. The cartilage type showed a maximum elongation of 8 times higher than that of the bellows type and it showed the elongation of 3 times higher than that of cylinder type. In cartilage type scaffold, gelatin hydrogel printed on the outside of the scaffold was remain 22.2% under the condition where no hydrogel was left in other type scaffolds. In addition, after 2 days of breathing test, the amount of gelatin remaining inside the scaffold was more than twice that of other scaffolds. This novel trachea scaffold with hydrogel inside and outside of the structure was well-preserved under external flow and is expected to be advantageous for soft tissue reconstruction of the trachea.


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