近年の電波利用の拡大に伴い，我々の身の回りの電磁環境は複雑化の一途をたどっている。移動通信システムにはいよいよ第5世代システムが導入され，これまで以上の高速化に加え，多数同時接続や超低遅延な通信が可能となる見込みだ。また，そのような技術を用いてSociety 5.0で実現

Electromagnetic fields (EMF) of all frequencies represent one of the most common and fastest growing physical environmental factors being used for individual, industrial and commercial purposes all of the world. All these technologies have succeeded to make our life richer and easier. All populations are now exposed to varying degrees of EMF, and the levels will continue to increase as technology advances. Modern society is inconceivable without powerlines, computers, information communication technologies, mobile communications and television. However; these technologies have brought with them concerns about possible health effects associated with their use. As part of its Charter to protect public health and in response to public concern, the World Health Organization (WHO) established the International EMF Project since 1996 to date to assess the scientific evidence of possible health effects of EMF. The International EMF Project brings together current knowledge and available resources of key international and national agencies and scientific institutions in order to arrive at scientifically-sound recommendations for health risk assessments of exposure to static and time varying electromagnetic fields in the frequency range 0-300 GHz. The author offers outline of activities of the WHO International EMF Project and current trends of WHO health risk assessment on EMF.

This paper introduces research trends and tasks in recent years on electromagnetic compatibility (EMC) problem for medical electronic instruments including wearable devices such as wearable body-area network (WBAN). International standards for medical electronic instruments and wearable devices are also described. As an example, we introduce the result of examining the EMC characteristics of medical electronic instruments based on the results of radiated immunity test and radiated emission measurements for medical electronic instruments. In addition, the result of investigation on the influence of not only narrowband signal but also wideband signal on medical electronics by conducting immunity test extended to microwave band are shown.

Protection of human from exposures to electric and magnetic fields have received public concerns for decades. Methods to assess physical quantities related to the exposure, such as artificially generated electric and magnetic fields, electric fields inside human body caused by the exposures, and contact currents, have been investigated and established in relation to compliance assessment against exposure guidelines. In addition, some of the methods have been standardized internationally to facilitate mutual authentication by standard methods. This paper reviews the methods to assess the human exposure to electric and magnetic fields, mainly focusing of low and intermediate frequencies (approximately below 100 kHz), and the status of their standardization.

Common-mode (CM) noise is a primary interference to biological signal (biosignal) detection systems, but is hardly solved with passive filtering. Conventionally, a driven-right-leg (DRL) circuit is employed to drive down the CM noise level. In this work, We first clarified how much influence an imbalance in the contact resistance could have for three different kinds of circuits, and then proposed a novel design of imbalance cancellation circuit using the digital potentiometer(digiPOT). Simulation evaluations were performed and the results showed that our circuit design can exceed the DRL by more than 20 dB in reducing the CM noise under the same conditions.

When a magnetic levitation rail carrying a superconducting coil moves at high speed, an electromagnetic induction voltage is generated in the surrounding telecommunication line due to Faraday’s electromagnetic induction. This phenomenon is analyzed by AC/DC module of COMSOL Multiphysics. The telecommunication line is modeled for a common mode flowing in a loop between the telecommunication line and the ground. As a result, we devise a method to calculate the induced voltage to the telecommunication line loop by differentiating in position the position dependency of the superconducting coil with respect to the magnetic flux linking the telecommunication line loop. In addition, to confirm the validity of the calculation method in COMSOL, we compare flux linkages for a model on the ground surface and a model in the complete free space, and also compare the results calculated with MATLAB by modeling with a lumped constant circuit and the results calculated with COMSOL.

ICNIRP guidelines describes addition equation for electrical stimulation, relevant for frequencies up to 10 MHz, with respect to simultaneous exposure to magnetic fields with multiple frequencies. However, there is no literature which estimated the threshold of electromagnetic field exposure of multiple frequencies. Therefore, the purpose of this paper is to estimate the threshold of nerve excitation caused by the application of current with multiple frequencies. In this paper, combinations of two kinds of frequencies f₁ and f₂ were investigated for the applying current. The Frankenhaeuser-Huxley model was employed to analyze nerve excitation effects. The ratios of the applied current value to the threshold current value were kept at the same value for each frequency f₁ and f₂, respectively. Consequently, the threshold did not exceed if the philosophy of the addition equation of ICNIRP was satisfied, with any combination of f₁ and f₂ analyzed in this paper. Especially when f₁=2f₂ and f₂=2f₁, the threshold became a high value. By analyzing the amount of the accumulated electric charge, which is a factor causing the action potential, it was demonstrated that it is difficult to accumulate the electric charge when f₁=2f₂ and f₂=2f₁.

Extended versions of the residual cutting method, which is a linear iterative solver, are proposed and then applied to the method of moments (MoM) to reduce calculation time. The MoM analyzed electromagnetic fields in lossless cubic cavities on the basis of electric field integral equations. The extended versions employed the BiCGSafe method, which is a type of product-type iterative method, as an inner iterative solver, and they virtually improved the convergence property of the inner solver particularly when the linear systems were ill-conditioned. We increased the cavity side length L from approximately 1 to 37.2 wavelengths (λ) in 0.2-λ increments, and we irregularly increased L above 37.2 λ to as high as 50.8 λ. The average time reduction ratio at around L≒37.2 λ was approximately 50%. The best time reduction ratio of 11.7% was observed when L≒35.2 λ. In addition, we demonstrated that the extended versions could converge the relative residual norms to less than 10^-7 even in a strongly ill-conditioned case at L≒19.0 λ.

In recent years, there are many instruments using time varying magnetic fields up to 100 kHz, for example IH cooker, wireless power transfer systems, and so on. Therefore, it is required to construct the magnetic field (MF) probe with the ability to measure wide band frequency range for evaluating emitted MF from such instruments. The characteristic of MF distributions from these instruments is highly localized in the vicinity of equipments. A prototype of the magneto-optical probe applying the Faraday Effect has been developed to measure and evaluate environmental magnetic fields from the low frequency to the intermediate frequency range. This probe is fabricated with single Faraday rotator by incorporating optical elements, i.e. a polarizer and an analyzer to avoid the fluctuation of measurement value caused by movement of optical fiber cables. Consequently, stable output signal from the developed probe is observed whenever the probe head and optical fibers are moved under applying the sinusoidal magnetic fields with the frequency of up to 500 Hz.

Measurements of radiated electric fields caused by collision electrostatic discharges (ESDs) between charged spherical electrodes with a diameter of 30 mm were previously conducted at charging voltages from 300 V to 600 V by using an optical electric field probe. To reveal that the radiated electric field peaks measured at a distance of 100 mm from the spark point increase with the charging voltages, using an image dipole model combined with Rompe-Weizel spark resistance formula for charged spherical electrodes, we calculate radiated electric fields from the spark lengths that are estimated by the measured electric field peaks when the collision ESD occurs.

The conversion equation to estimate currents induced in a human body exposed to a uniform electric field at power frequency has been proposed based on the measurements. We verify its validation from numerical calculations using multiple numerical homogeneous human models. Furthermore, it is showed that induced electric fields in each part of the body can be estimated from its height.

The separation dependency of the power absorption ratio from the antenna in the millimeterwave band to the human body is analytically obtained by using the theory of a minute antenna and the earth model. The magnitude of the interaction can be estimated by comparing the power absorption ratio when adjacent with that when the antenna is separated enough from the human body. When approaching one wavelength or less for the vertical antenna, the interaction between antenna and human bodies cannot be disregarded. On the other hand, it is permitted up to the quarter wavelength for the horizontal antenna.

This paper discusses about plating thickness sensors with the eddy current for the continuous galvanizing line. We propose that separation index which shows distance between detection signals on the complex plan in order to compare between sensors, and a thickness evaluation method in order to evaluate plating thickness from detection signals. In simulations and experiments, a measurement condition and a best sensor of three sensors was quantitatively selected by using the index. Plating thickness of a test sample was evaluated with the method which use the radial basis function interpolation. These results demonstrate the possibility of making thickness measurements using an eddy current with high and variable liftoff.

TiO₂-V₂O₅ precursor films with a variety of molar ratio of Ti to V (x_m = 0∼35%) were fabricated by metal-organic decomposition (MOD). These precursor films were fired in O₂ atmosphere. It was found that TiO₂ nanoparticles coexisted with V₂O₅ from the measurement of XRD and SEM, and that the obtained films were TiO₂-dispersed V₂O₅ films. Precipitates of TiO₂ were observed on the surfaces of the films for x_m higher than 10%. Atomic ratio of Ti (x_a) dissolved in V₂O₅ grains as TiO₂ nanoparticles increased with increasing x_m and saturated in a range of x_a = 12-13%. For the films fabricated with x_m higher than 10%, TiO₂ precipitated on and/or between the grains. Then, these films were thermally reduced by a heat treatment under a pressure of 1.2 Pa (air). The R-T characteristics of the films indicated the phase transition due to a VO₂(M) phase. The resistance change and the hysteresis loop width decreased with increasing x_m and the suppressed R-T characteristics were obtained.