• 제목/요약/키워드: electromagnetic waves

검색결과 559건 처리시간 0.027초

전자파 차단 보호복의 온열쾌적성 평가 (Thermal Comfort Evaluation of Protective Clothing for Shielding Electromagnetic Waves)

  • 최정화;김명주;박준희;김도희
    • 한국지역사회생활과학회지
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    • 제21권4호
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    • pp.595-603
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    • 2010
  • The present study was performed on humans to investigate the physiological strain of wearing protective clothing for shielding electromagnetic waves and to compare control clothing that are currently on the market and new clothing that are developed for improving thermal comfort and material weight. Experiments were conducted in a climatic chamber of $28.8{\pm}0.6^{\circ}C$, $37{\pm}5%$RH under three differed experimental clothing conditions: None, Control, New. The results were as follows. Mean skin temperature and rectal temperature in New were significantly lower than that in None and Control (p<.05). The temperature and humidity inside clothing were lower in None (p<.05). Total weight loss was lower in New. Thermal sensation and thermal comfort were less hot and more comfortable in New than those in Control. It was concluded that wearing the protective clothing for shielding electromagnetic waves affects physiological responses such as distribution of body temperature, sweat rate, etc.

대기중과 절연체 갭에서 방사되는 방사전자파의 전파특성 (The Propagation Characteristics of Electromagnetic Wave Radiated at Gap in Air and Insulator)

  • 김충년;이현동;박광서;박원주;이광식;이동인
    • 조명전기설비학회논문지
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    • 제15권1호
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    • pp.104-111
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    • 2001
  • 본 연구에서는 대기중 두가지 형태의 전극부에서 부분방전(partial discharge : PD)시 방사되는 VHF(30∼230 [MHz])대역의 방사전자파를 측정하고, 그 스펙트럼의 특이한 패턴을 나타냈다. 또한 PD에 의해 방사되는 방사전자파에 대한 거리 및 편파특성에 관하여 연구하였다. 에폭시절연체를 삽입한 경우, 방사전자파의 잡음레벨은 90 [MHz] 대역 이하에서 대기중에 비하여 0.6∼6.2 [db] 높게 나타났다. 방사전자파의 스펙트럼 분포는 안테나 엘리먼트 배치에 따라 전주파수 영역에서 차이를 나타내고 있다.

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Prediction of Electromagnetic Wave Propagation in Space Environments Based on Geometrical Optics

  • Kim, Changseong;Park, Yong Bae
    • Journal of electromagnetic engineering and science
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    • 제17권3호
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    • pp.165-167
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    • 2017
  • We predict the electromagnetic wave propagation in space environments using geometrical optics. The effective indices of the troposphere, stratosphere, and ionosphere are computed, and the reflection, refraction, and attenuation of electromagnetic waves in space environments are calculated based on the ray tracing technique and geometrical optics. The influence of the refractive index and loss of atmosphere and the incident angle of the antenna on electromagnetic wave propagation is discussed.

PIC simulation study of the turbulence of the Alfven ion-cyclotron waves induced by electromagnetic ion-cyclotron instability

  • Kaang, Helen H.;Ryu, Chang-Mo;Mok, Chinook;Rha, Ki-Cheol
    • 한국우주과학회:학술대회논문집(한국우주과학회보)
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    • 한국우주과학회 2011년도 한국우주과학회보 제20권1호
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    • pp.29.3-29.3
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    • 2011
  • The turbulence in the nonlinear regime of the electromagnetic ion-cyclotron (EMIC) instability are investigated via a particle-in-cell (PIC) simulation. EMIC instability arises from anisotropic ion temperature and excites the Alfven ion-cyclotron (AIC) waves. The excited AIC waves undergo inverse-cascade via the nonlinear wave interaction of two AIC and one ion density modes. Induced ion density modes are the normal and second harmonic ion-acoustic (IA) waves. They have the same group velocity, but the second harmonic IA mode only generates the longitudinal electric field.

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Beam Efficiency of Wireless Power Transmission via Radio Waves from Short Range to Long Range

  • Shinohara, Naoki
    • Journal of electromagnetic engineering and science
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    • 제10권4호
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    • pp.224-230
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    • 2010
  • Wireless power transmission (WPT) is useful technology in near future. There are some kinds of the WPT technologies, WPT via radio waves, resonance coupling, and inductive. Especially the WPT via radio waves is used for multi-purposes from short range to long range application. However, unfortunately it is misunderstood that it is low efficiency and low power. In this paper, I show the theory of beam efficiency between transmitting antennas and receiving antennas and also show some high efficient applications of the WPT via radio waves. Especially, I pick up a wireless power charging system of an electric vehicle and show the experimental results. I show difference between the theory of beam efficiency and the experimental results of short range WPT. I indicate that reasons of poor beam efficiency in the experiment are (1) change of impedance caused by mutual coupling between transmitting antennas and receiving antennas, (2) oblique direction of microwave power to receiving antennas caused by short distance.

Development of parked vehicles searching system

  • Lim, Do-Hyung;Seo, Chang-Jun
    • 제어로봇시스템학회:학술대회논문집
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    • 제어로봇시스템학회 2005년도 ICCAS
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    • pp.1464-1467
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    • 2005
  • In this research, we developed a system, which can find the location of vehicle when people park their cars in a big parking lot or large area. People can find their cars readily through this simple device and they can save their time and effort. This is the purpose of this research. Performing this, detection of electromagnetic wave's direction is needed and we used shielding effectiveness of electromagnetic waves for the method of it. An absolute coordinate indicates four directions (E, W, S, N) by using an electronic compass module, and it is needed for the localization. The device can check the received count of the electromagnetic waves coming from all other directions through the system, which is installed in the vehicle. The direction recorded the least received count would be the location of the parked vehicles. We can add on the function of this research by using the same frequency of cars alarm goods. Also, it is useful in the huge indoor parking lot.

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접선과 법선 전자파 경계조건의 등가성 (Equivalence of tangential and normal boundary conditions for electromagnetic waves)

  • 조용희
    • 한국콘텐츠학회:학술대회논문집
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    • 한국콘텐츠학회 2010년도 춘계 종합학술대회 논문집
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    • pp.381-383
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    • 2010
  • 전자기파 경계치 문제를 효율적으로 해결하기 위해 접선과 법선 경계조건의 등가성을 증명한다. 4개의 맥스웰 방정식을 모두 이용하여 접선과 법선 경계조건이 등가성을 이루기 위한 조건을 유도한다. 본 연구에서 제안된 등가성을 위한 조건을 이용하여 전자기파 경계치 문제를 풀기 위한 연립식을 얻을 수 있을 것이다.

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Novel Compact Bandpass Filter Based on Folded Half Mode Substrate Integrated Waveguide Cavities

  • Gong, Ke;Hong, Wei;Chen, Jixin;Tang, Hongjun;Hou, Debin;Zhang, Yan
    • Journal of electromagnetic engineering and science
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    • 제10권3호
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    • pp.179-182
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    • 2010
  • This paper proposed a novel compact bandpass filter with folded half mode substrate integrated waveguide (FHMSIW) cavities using two-layer printed circuit board(PCB) process. The area of the FHMSIW filter is reduced by nearly 50 % and 75 % compared with half mode substrate integrated waveguide(HMSIW) filter and substrate integrated waveguide(SIW) filter, respectively. A four-pole Chebyshev FHMSIW bandpass filter at C-band has been designed, simulated and fabricated. Measured results are presented and found to agree with the full-wave simulated results by using Ansoft HFSS. The filter shows good performance and compact size.