• 대한전기학회논문지:전기기기및에너지변환시스템부문B
• /
• 제54권12호
• /
• pp.576-585
• /
• 2005

This paper deals with the electromagnetic field analysis of slotless brushless permanent magnet machines with three different magnetization patterns such as Halbach, parallel and radial magnetization. The magnetization modeling of Halbach, parallel and radial magnetization is performed analytically. And then, analytical solutions for open-circuit field distributions, armature reaction field distributions, flux linkages due to PMs and stator windings, torque, back-emf and inductance are derived in terms of magnetic vector potential and two-dimensional (2-d) polar coordinate systems. The analytical results are validated extensively by finite element (FE) analyses. The magnet volume required in order to produce identical flux density is compared with each magnetization. Finally, analytical solutions and derivation procedures of those presented in this paper can be applied to slotless and slotted brushless permanent magnet AC and DC machines.

• 대한의생명과학회지
• /
• 제12권1호
• /
• pp.9-16
• /
• 2006

We investigated the effects of 835-MHz electromagnetic field (EMF), one of the most popular communication frequency band in Korean code-division multiple-access (CDMA) mobile phone system, on cellular signal transduction. For this, we examined the change of intracellular calcium $([Ca^{2+}]_i)$, reactive oxygen species (ROS) and F-actin polymerization after exposure to 835-MHz EMF followed by the treatment of agonists in Rat-2 fibroblast cells. Culture cells were pretreated with serum-tree medium and concomitantly exposed to 835-MHz at specific absorption rate (SAR) of 4.0 W/kg for 24 hr in a specialized designed apparatus based on Transverse Electro Magnetics (TEM) wave theory. Intracellular $Ca^{2+}$ responses to lysophosphatidic acid (LPA) and epidermal growth factor (EGF) in Rat-2 fibroblast after exposure to 835-MHz EMF were shown to be similar pattern as observed in normal cultured cells. However, the LPA-induced calcium spiking was slightly delayed to 7 sec and sustained thereafter to a little higher ground level under 835-MHz EMF radiation compared to unexposed cells. ROS production level by LPA in the exposed cells was not different from that in control. Furthermore, LPA induced the production of stress fibers with no significant difference in the exposed and unexposed cells. These results suggest that mobile phone radiation (835-MHz, SAR 4.0 W/kg) may not be directly related to signal transduction in Rat-2 fibroblasts except the slight effect of calcium spiking in LPA-induced cells but remain to be further elucidated for possible indirect intervention.

• 대한기계학회논문집B
• /
• 제26권11호
• /
• pp.1613-1621
• /
• 2002

An electromagnetic flowmeter(EMF) essentially averages the velocity distribution over the pipe cross- sectional area, and the measured value is dependent on the velocity profiles. In this study, installation effects of 90$^{\circ}$long elbow(KS B 1522, ISO 3419) on the EMF characteristics was investigated. A commercial EMF was adopted and the distribution of magnetic field in the electrodes cross section was measured. In the experiment, the national flow standard system, of which measurement uncertainty was evaluated in accordance with ISO 17025 recommendation, was used fur characterization of EMF. The leading line has 150D long straight pipe to established a fully developed flow before entering into the elbow and the elbow was installed downstream of it. then the flowmeter was tested within 50 D from the elbow. The installation effects of the flowmeter were investigated by varying the mean velocity(Reynolds No.)in pipe section, the locations and the direction of electrodes plane.($\phi$) From the experimental results, we find the optimal conditions to get most accurate measurements. Generally, the deviations from the calibration value were less than 0.5 % in farther than 10D distance from the elbow and the direction of electrode plane. $\phi$ = 90$^{\circ}$yielded the smallest measurement deviation. These characteristics were shown consistently in turbulent region regardless of the mean Reynolds number.

• Journal of Microbiology and Biotechnology
• /
• 제11권5호
• /
• pp.749-755
• /
• 2001

High Electromagnetic Field (EMF) with an intensity of 1 mT (Tesla) inhibited the growth of both human normal lung and immune T cell down to $20-30\%$, compared to that of an unexposed case. The human T-cells, Jurkat, were more severely affected by EMF than the human lung cells, which showed a relatively slow cell growth and substantial releas of $Ca^+2$ (3.5 times higher than the human T-cells). However, the growth of hepatoma carcinoma, Hep3B, was enhanced by twice that of an unexposed case. The EMF intensity and exposure time did not affect the growth of the cancer cells very much, while it significantly affected the growth of normal cells. Accordingly, it is possible that EMFs may play a role in the initiation of cancer. The EMFs disturbed the signal transduction and membrane systems, such that a five times higher amount of PKC-${\alpha}$ was released from the cell membrane than in the control. Extended exposure to EMFs, for more than 48 hours, also led to 1 $90\%$ necrotic death pattern from apoptotic cell death. Finally, EMF at an intensity of 1mT with a 24-T exposure promoted the differentiation of HL-60 cells to monocytes/macrophages, possibly causing potential acute leukemia.

• 한국안전학회지
• /
• 제32권1호
• /
• pp.33-40
• /
• 2017

This paper addresses the assessment methods used to evaluate the magnetic exposure of a human to ELF EMF (Extremely Low Frequency Electromagnetic Field) which is caused by the process of power delivery from 60 Hz commercial power. These days the main concern is primarily focused on the magnetic field. For the exposure assessment, both numerical studies and laboratory experiments were studied and the results of the two compared for methodological suitability. The numerical analyses employ the Impedance Method (IM), Boundary Element Method (BEM), and Finite Element Method (FEM) and the laboratory experiments used various human phantom models made with conductivities congruent to human organs and then exposed to uniform/non-uniform magnetic fields to produce eddy currents. Under these conditions a number of examples have been evaluated and the reliability assessed to present the pros and cons of each methodology.

• Journal of electromagnetic engineering and science
• /
• 제9권4호
• /
• pp.175-181
• /
• 2009

The measurements were performed to verify experimentally that the voltage arising on a telecommunication line by a power line is due to the induction phenomena because there has been an opinion that the arising voltage on a telecommunication line is not by induction, but by other causality. The voltage appeared on the telecommunication line by way of an electric field or magnetic field generated by the source apparatus that had been artificially made to provide intentional constant high-voltage or current in ELF, that is, 60 Hz as an emulated commercial power.

• Journal of electromagnetic engineering and science
• /
• 제11권3호
• /
• pp.174-182
• /
• 2011

The On-line Electric Vehicle (OLEV) is an electric transport system in which the vehicle's power is transferred wirelessly from power lines underneath the surface of the road. Advantages of the OLEV include reducing battery size and cost to about 20 percent of that of conventional battery-powered electric vehicles, thereby minimizing the vehicle's weight and price, as well as the cost of charging the system. In this paper, we introduce a wireless power transfer mechanism to maximize the electrical performance of the power transfer system. Power transfer capacity, power transfer efficiency, and magnitude of leakage in the electromagnetic field (EMF) are analyzed, and the optimization methodology of the design parameters is discussed.

• 한국전자파학회논문지
• /
• 제20권6호
• /
• pp.526-534
• /
• 2009

본 논문은 전력공급설비 중 변전설비에서 발생하는 극저주파에 의한 자계의 실태를 조사하고 자계의 특성에 관한 이해증진 방안을 제시하는데 그 목적이 있다. 본고에서는 수도권 25개 변전설비를 중심으로 변전소 주변과 감사실 내부의 자계 수준을 IEC에서 제시하는 CISPR의 측정 방법(IEC/TC106 PT 62110)에 의거하여 변전설비에서 발생하는 자계를 측정하였다. 아울러 전력설비와 관련된 자계의 속성에 대한 정확한 이해를 위해 전자계 인증표시제와 같은 객관적이고 신뢰성 높은 정책적 접근방안을 제시한다.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2012년도 추계학술대회 논문집
• /
• pp.627-628
• /
• 2012

• 예술인문사회 융합 멀티미디어 논문지
• /
• 제9권6호
• /
• pp.711-718
• /
• 2019

전자파 측정기와 스펙트럼 분석기를 통하여 가정에서 사용되고 있는 여러 종류의 가전제품에서 발생하는 전자파 발생 거동을 조사하였다. 전자레인지 동작 중에 30cm 떨어진 지점에서 측정된 전자파 전력은 8~11mW/㎡ 범위로 측정되었고 저주파 자기장의 강도는 60~80mG, 전기장 강도는 150~160V/m로 측정되었다. 스마트폰 무선 충전 패드의 경우 10cm 떨어진 지점에서 전자파 전력 0.4mW/㎡, 전기장 160V/m, 자기장 1mG로 측정되었다. 전자레인지 및 무선 충전 패드의 경우 10cm 이내로 근접하여 사용할 경우 전기장 크기가 인체 보호 기준을 초과하는 큰 값으로 측정되었으며 인체 유해성이 우려된다. 한편 TV, 헤어드라이어, 냉장고 등의 가전제품은 전자파, 전기장, 자기장 모두 매우 낮은 수준으로 나타났으며 인체 유해성은 없는 것으로 보인다. 전자파 차폐재의 경우 금속 재질의 Cu 패브릭과 메탈 포일은 높은 수준의 전자파 차단 성능을 나타내었으나, 폴리머 필름의 경우는 전자파 차단 특성이 낮은 수준으로 나타났다.