• Title, Summary, Keyword: pulse electromagnetic fields

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Simulation Study for Electromagnetic Pulse by High-Altitude Nuclear Explosion (고고도핵폭발 전자기펄스 피해 분석을 위한 전산모사 연구)

  • Kah, Dong-Ha;Shim, Woosup
    • Journal of the Korea Institute of Military Science and Technology
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    • v.18 no.6
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    • pp.822-828
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    • 2015
  • This paper describes computer simulation program of high-altitude electromagnetic pulse (HEMP). The HEMP is produced by the gamma rays form high-altitude nuclear explosion. The gamma rays generate a current of compton electron that leads to the production of electromagnetic fields. In case of high altitude nuclear burst, the electrical fields at the earth's surface are strong enough to be damaged for electrical and electronic device over a very much larger area. Therefore, national infrastructure will be serious damage such as power grid and communication network. In this paper introduce simulation program for calculation of HEMP and present to simulation study results of high altitude nuclear explosion experiment from U.S. and U.S.S.R.

The Electric Fields Characteristics of Partial Discharges in $SF_6$ ($SF_6$ 가스중 부분방전시 전계 특징)

  • 김해준;박경태;박광서;이현동;김충년;이광식
    • Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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    • pp.145-149
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    • 2001
  • The most of faults in gas insulation of power facilities are caused by partial discharge. Therefore we simulated partial discharge and measured the radiated electromagnetic wave emitted from partial discharge in SF$_{6}$ gas by biconical antenna. This paper describes time delay and electric fields pulse characteristics of radiated electromagnetic waves with distance(1[m], 3[m], 5[m]) between antenna and discharge source.e.

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The Effects of Pulsed Elctromagnetic Fields on Expression of Neurotrophic Factors after Spinal Cord Hemisection in Rats

  • Kang, Ji-Hyuk;Park, Sang-Young;Lee, Yun-Seob
    • Journal of Magnetics
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    • v.16 no.3
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    • pp.253-258
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    • 2011
  • The purpose of this study was to identify the effect of pulsed electromagnetic fields on the expression of neurotrophic factors after spinal cord injury. Sprague-Dawley male rats were given a spinal cord hemisection and randomly divided into 2 groups, the control and experimental groups. The experimental group was administered a fifteen minutes session of pulsed electromagnetic field once a day, five days a week. In order to observe the effect of these pulsed electromagnetic fields, this study observed the BDNF expression in the rat's lumbar spinal cord and the H&E staining in the gastrocnemius at 3, 7, 14, 21 days group after spinal cord hemisection. The results of this showed that the immunoreactivity of the BDNF in the rat's spinal cord gradually increased in each group. At 21 days, there is a significant difference between the control and experimental groups. The morphological shape of the gastrocnemius was gradually changed from 3days to 21days, and the gastrocnemius at 21 days was significantly degraded. However, the experimental group showed a slightly more organized gastrocnemius than the control group at 21days. The Results of this study suggest that pulsed electromagnetic field application decreases the degeneration of a rat's gastrocnemius morphology, and increases the immunoreactivity of the BDNF in the rat's spinal cord after spinal cord hemisection.

Review of magnetic pulse welding

  • Kang, Bong-Yong
    • Journal of Welding and Joining
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    • v.33 no.1
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    • pp.7-13
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    • 2015
  • Magnetic pulse welding(MPW) is a solid state welding process that is accomplished by a magnetic pulse causing a high-velocity impact on two materials, resulting in a true metallurgical bond. One of the great advantages of MPW is that it is suitable for joining dissimilar metals. No heat affected zones are created because of the negligible heating and the clean surfaces formation that is a consequence of the jet and the metal is not degraded. Also, compared to other general welding processes, this process leads to only a low formation of brittle intermetallic compounds However, although this process has many advantages its application to industrial fields has so far been very low. Therefore, in this study we are presenting the principles, apparatus and application of MPW for application the industrial fields.

Vibration Analysis for BLDC Motor by Electromagnetic Exciting Force (전자기 가진력에 의한 BLDC 전동기의 진동 특성 해석)

  • Chung, H.J.;Shin, P.S.;Woo, S.H.
    • Proceedings of the KIEE Conference
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    • pp.118-120
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    • 2007
  • This paper deals with the vibration analysis of characteristics for BLDC motor by electromagnetic exciting force. Vibration analysis of electric machine is mainly divided into mechanical and electrical approach. However, it need to execute coupling analysis of mechanical and electrical computation because the vibration sources have relation to each other. Magnetic fields is calculated from Maxwell stress method with electromagnetic finite element method. And magnetic radial force is calculated from previous magnetic fields. With coupled electromagnetic and structure finite element, the vibratory behavior between the phase commutation advancing technique and pulse-width control is investigated in single phase brushless dc motor.

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An Analysis of the HEMP Interference Effect in OFDM System (OFDM 시스템에 미치는 HEMP 간섭 영향 분석)

  • Seong, Yun-Hyeon;Chang, Eun-Young;Yoon, Seok-beom
    • The Journal of Advanced Navigation Technology
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    • v.19 no.3
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    • pp.244-249
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    • 2015
  • High-altitude electromagnetic pulse (HEMP) is generated from a nuclear burst at high altitudes above the Earth, the electromagnetic fields reach the ground nearly simultaneously with regard to the operation time of systems. The aim of this analysis is to inquire about HEMP characteristics and to analyze about effect in orthogonal frequency division multiplexing (OFDM) system. Specifically, HEMP characteristics are classified field sources, spatial coverage, time domain behavior, frequency spectrum and field intensities in this study. Bits error rate (BER) of the receiver with the software simulation is confirmed for the HEMP effect. Q-factor made a difference about interference duration by transfer characteristics of system. When Q factor is smaller, the recovery time from HEMP interference is short. To the contrary, if the Q factor is larger, the recovery duration is lasted longer by 300-600%.

Pulsed Ultrasound and Pulsed Electromagnetic Field in the Treatment of Muscle Contusion in Rats

  • Cheon, Song-Hee;Lee, Sun-Min
    • Journal of Magnetics
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    • v.17 no.3
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    • pp.225-228
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    • 2012
  • Muscle contusion usually results from a direct blunt impact and is frequently associated with contact sports. Muscle contusion results from microscopic muscle fiber and capillary disruption causing a microhemorrhage dissecting torn fibers and remaining viable muscle fibers. Recent studies concluded that some physical methods, including pulsed ultrasound (PU) and pulsed electromagnetic field (PEMF) treatment, accelerate and facilitate wound healing, improve scar quality and have beneficial effects on muscle and tendon healing. However, there are few studies on the effects of the early use of physical methods, such as PU and PEMF, on the expression of neurotrophic factors. The objective of this study was to investigate the effects of the early application of PU and PEMF, measured through the expression of BDNF in the muscles (gastrocnemius) and spinal cords of rats after skeletal muscle contusion. In the spinal cords and muscles, there was a significant increase of BDNF expression in the PEMF and PU groups, a greater increase was found in the PEMF group than in the PU group. In conclusion, PEMF is a useful therapeutic method that improves muscle healing after muscle contusion.

The Effect of a Pulsed Electromagnetic Field with Time on Pain in Muscle Crushed Rat Model

  • Kim, Min-Hee;Cheon, Song-Hee
    • Journal of Magnetics
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    • v.17 no.1
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    • pp.68-71
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    • 2012
  • Acute injuries to skeletal muscles can lead to significant pain and disability. Muscle pain results in muscle weakness and range of motion (ROM) decreases. Pulsed electromagnetic fields (PEMF) promote tissue repair, healing rates and reduce musculoskeletal pain. The results of many previous studies suggest that PEMF can contribute to chronic pain reduction, particularly in musculoskeletal injurys. However, we do not have enough information of its effects compared to a placebo. The principal objective of this study was to investigate differences in acute pain induced by the direct destruction of muscle tissue (extensor digitorum) with varying times of the application of PEMF, measured through the expression of c-fos on the spinal cord. Significant reduction of pain was found in groups exposed to PEMF and the group exposed to PEMF immediately after muscle injury showed the most significant differences. In conclusion, PEMF may be a useful strategy in reducing acute pain in muscle injury.

Study of Defect Prevention on Weld Zone of Magnesium Alloy by Pulse Control of Nd:YAG Laser (Nd:YAG 레이저의 펄스 제어에 의한 마그네슘 합금 용접부의 결함 방지에 관한 연구)

  • Kim, Jong-Do;Lee, Jung-Han;Kim, Jang-Soo
    • Journal of the Korean Society for Precision Engineering
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    • v.27 no.1
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    • pp.99-104
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    • 2010
  • Magnesium and magnesium alloys, the lightest structural materials, have been received plenty of global attention recently. These alloys could be applied in various fields, especially the electronics industry, because of their excellent electromagnetic interference shielding. However, the welding technique of magnesium alloys has not been established. This study is related to the welding of AZ31B magnesium alloy by a short-pulsed a Nd:YAG laser. Two types of pulse waves, square pulse and variable pulse, were used to control weld defects. Results show that the crack and porosity, generated in the weld, had not been controlled by general square pulse. But through the application of variable pulse, the defects could be prevented and the good weld zone was obtained.

Coaxial Marx Type Pulse Generator for UWB EM Pulse (UWB 펄스전자파 발생용 원통형 Marx 펄스발생장치개발)

  • Chang, Yong-Moo;Lee, Sang-Wook
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.121-121
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    • 2010
  • As the industrial technology is getting higher, the pulsed power technology is required from various fields such as thermonuclear fusion energy sources, military applications, electric power distribution, and a variety of new specialized needs. This technology deals with the generation of very high power electromagnetic pulses through fast switching. We fabricated a pulsed power generator, named EMD pulse generator, by using Marx circuit with 200 kV high, 50 ns fast rise time. In this paper, we described about an effect of stray capacitance of coaxial Marx generator, EPG-AM200k, and a comparing the results of experiments and circuit analysis.

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