The “intermediate frequency” electromagnetic fields in the context of protecting human exposure have received public concerns in recent years. This is mainly due to the growing emergence of technology or products using those fields, such as induction heating (IH) cookers and wireless power transfer (WPT) systems. This paper reviews the trend of studies and guidelines for human protection related to safety assessment of human exposure to such fields.

View full abstract

The purpose of this paper is to propose a method to have less-learning-experienced students understand fundamental mathematics. In the Department of Electrical Engineering of Fukuoka Institute of Technology, many of the students with diverse academic histories have neither enough basic academic skills nor sufficient learning experiences. It is not easy for such students to repeat learning until they acquire the fundamentals and basics. A training system is necessary through which they can continue learning with grasping own learning situation. In the fundamental mathematics class “Elementary Mathematical Practice A” for repeaters, the students had to make the following efforts. The first thing was the implementation of self-evaluation of study. The students reflected their own study of one week through the self-evaluation and considered how they should study the next week. The second was the training of making specific questions. Furthermore, they evaluate the level of their questions by themselves. These tasks made clear what they can and cannot understand. It was confirmed that the students increased their awareness of learning and promoted better understanding through the above approaches.

View full abstract

An efficient analysis method in the frequency domain for the extraction of information under the degradation of signal-to-noise ratio is proposed. When the electromagnetic emission from the cryptographic module on the hardware is analyzed, the electromagnetic fields caused by operations on the other modules interfere to the electromagnetic field from the cryptographic module. Therefore, the amount of the measurement data required for the extraction of information under the condition of degraded SNR increases and the analysis for this increase of data needs additional computation time. In order to accelerate the analysis under the degradation of SNR, we focus on only the processing for analysis target data. Furthermore, the signal of information and noises is separated with the analysis on the frequency domain. The proposed method is examined through experiments.

View full abstract

The microplasma jet in an air flow is produced by a pulsed power generator. The microplasma jet using a high voltage DC power source is generated to compare with that using the pulsed power generator. The gas temperature near an exhaust nozzle of microplasma jet using the DC power source is much higher than that using the pulsed power generator. The emission spectrum shows the clear N₂ second positive band and the N₂ first negative band in the case of the DC power source, but those bands are not clear and the broad band is observed between 400 and 700 nm in the case of the pulsed power generator. The emission spectra in the case of DC power source are approaching to those in the case of pulsed power generator, with increasing the value of capacitor added between electrodes. The microplasma ejected from a discharge region mainly emits line spectra from oxygen.

View full abstract

To analyze the pulse interval dependence on fluid behavior in a linear MHD accelerator, we simulated numerically the behavior by using a third-order upwind scheme combined with MmB method. To understand the fluid behavior in the MHD accelerator, we evaluate the temporal-spatial fluid evolutions in the MHD channel. It indicates that the characteristics curve in the MHD channel determines the hydrodynamics behavior. These estimations almost correspond to the timing of the peak incremental thrust. On the other hand, the average incremental thrust is improved with prolonging the interval time. Nevertheless, it is possible to apply the second current pulse with the arbitrary interval time, because the change of the average incremental thrust is small.

View full abstract

The effects of direct current atmospheric-pressure glow discharge on property and structure of acetic acid solution, as well as hydroxyl radical (OH) generation mechanisms were systematically investigated. The emissions depended on OH was mainly observed under atmospheric-pressure glow discharge. The acetic acid solution around anode exhibited acidity, while that around cathode exhibited basicity. The phase-separated structure was observed by plasma electrolysis. In the solution, the OH was observed in cathode side which showed low charged particle density based on electrical potential distribution. However, hydrogen peroxide was formed in anode side with high charged particle density. The electrical potential distribution depended on the chemical reaction at each electrode side. The OH in anode side was observed in the form of emission for the high electronic density. Meanwhile, that in cathode side was observed in the form of dissolved form for the low electronic density.

View full abstract

To establish a simple method for incorporating materials into fertilized medaka eggs by applying electric pulses including nanosecond pulsed electric fields (nsPEFs), we have tested pulse parameters as pulse width, pulse intensity, number of pulses, combination of several pulses, interval of pulses, and polarities of pulses. Improvement in incorporation efficiency was achieved with a new pulse system, named asymmetric burst system, which could generate a short rectangular pulse (from ten to several hundreds nanosecond) with high intensity (several kilovolt) and asymmetric bipolar burst pulses (in a range of microsecond to millisecond) with low intensity (from several volt to several tens volt). To gain the total efficiency for incorporation, it is necessary to investigate other factors in addition to the pulse parameters. In this paper, the effects of solutions that surrounds eggs are investigated. Among the combinations of pulsing and immersed surrounding solutions, we found that the electrical and experimental deleterious effects were strongly reduced under the condition that eggs were pulsed in a 6 mS/cm NaCl solution and kept in the same solution or put into and kept in an isotonic solution for 2 hours. This might be due to an appropriate electrical conductivity and an osmotic pressure difference between the inside of an egg and the surrounding solution. Moreover the adverse effects of cycloheximide on embryogenesis appeared clearly using the same condition.

View full abstract

We studied 3D dielectrophoretic (DEP) effects induced by dielectric pillar arrays fabricated by soft lithography. Polydimethylsiloxane (PDMS) was casted onto a PMMA mold with arrays of high-aspect-ratio holes micromachined by proton beam writing (PBW), which is a novel direct-write lithographic technique using a scanning proton beam. Arrays of PDMS pillars with diameter of ∼3 µm and a height of ∼15 µm, were fabricated using the soft lithography. The 3D-DEP effect was demonstrated using the PDMS pillar arrays incorporated into a channel on a glass substrate by measuring a trapping capability of E. coli. Coupled use of the soft lithgraphy with the PBW enables us to fabricate low-cost 3D-DEP devices with improved throughput.

View full abstract

We prepared tin added phosphate glass, and investigated the effect of tin addition and humidity on transmittance and electrical properties of samples. It was found that improvement of transmittance and moisture proof. Electrical resistance increased by increasing of added amount of tin in samples, and electrical resistance decreased by increase in humidity.

View full abstract

The activated carbon particles made of charcoal were applied to the EDLC electrodes by using an alkaline activation method. The capacitance and internal resistance of the assembled EDLC cell were measured with 34% KOH water Electrolyte. The density of energy was approximately 2.6Wh/L in the EDLC cells. The internal resistance was less than 80mW in the EDLC cell. Outdoor LED lights were assembled by the charcoal EDLCs adding the solar panel, LED light and their control circuits to confirm the operations of its charcoal EDLC. From the obtained results, there is a possibility of the outdoor practical use of EDLC which is made of the activated charcoal particles in low cost.

View full abstract

We found the high exothermicity performance by the experiment that we apply eddy current for a pet film and an aluminum foil containing iron with the state that contacted it each other. This phenomenon does not occur alone each. Therefore, it is thought that an eddy current of the aluminum promotes fever for the contacted surface of PET film.

View full abstract

[in Japanese]

View full abstract