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The author proposed an immunity prediction technique to electrostatic discharge (ESD) in the early design stage. The immunity prediction technique was applied to the immunity prediction of ICs on printed wiring boards (PWBs). It consists of a conducted immunity measurement of ICs and a circuit simulation. In the conducted immunity measurement, conducted noise from an ESD-gun is directly injected between a power terminal and a ground terminal of ICs and increased up to a malfunction of the IC. The input voltage at the IC terminals is measured when the IC malfunctions. In the circuit simulation, equivalent circuits are created by modeling the structure of the ESD-gun and the PWBs. The equivalent circuits were analyzed by the circuit simulation and calculated induced voltages between a power layer and a ground layer of the PWBs. Finally, threshold failure levels of the ICs on the printed wiring boards to ESD were defined as ratio of the input voltage measured by the conducted immunity measurement and the induced voltage calculated by the circuit simulation. The results of the immunity prediction technique were verified experimentally.

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The International Electro-technical Commission (IEC) prescribes immunity test methods (IEC 61000-4-2) of electronic equipment against electrostatic discharges (ESDs), which also specifies contact discharges of an ESD-gun onto a vertically placed metal plate named vertical coupling plane (VCP) in the vicinity of equipment under test (EUT) to simulate personnel ESDs onto metal objects being close to the EUT. According to IEC 61000-4-2, EUT shall be placed at a distance of 0.1m from the VCP, and the contact discharge of an ESD-gun should be conducted to the centre of a vertical edge of the VCP, while inclinations of an ESD-gun and reference locations of EUT are not specifically determined, which can provide different test results even for the same EUT. In this study, using a simple printed circuit board (PCB) with a trace in lieu of EUT, we measured induced voltages on the trace for contact discharges from an ESD-gun onto a VCP in conformity to IEC 61000-4-2. As a result, we found that peaks of the induced voltages on the PCB arranged at a fixed position change with variability of ±20% for contact discharges of the ESD-gun with different inclinations, while an additional VCP placed at a right angle to the VCP edge reduces the peak variability by 7% or less. It was also found that although different locations of the PCB provide variability from+18% to -14% in the peak voltages for contact discharges of the ESD-gun with a fixed inclination, the additional VCP gives the peak variability from +37% to -11%. The above findings suggest that an additional VCP provides an immunity test method that could be less affected by arrangements of EUT and contact discharges of an ESD-gun, when EUT to be tested is placed away from the additional VCP.

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With a 12-GHz oscilloscope we measured the discharge currents due to the approach of a hand-held metal piece, and thereby derived the resultant discharge voltages through both the inverse Fourier transform and convolution integral. As a result, we found that although the results calculated from the both methods are rigorously different, there is good agreement between the waveforms of the discharge voltages just after a spark occurs. It was also found that the breakdown field is (2-3)×10⁷ [V/m] at a charge voltage of 600 V, which was validated in comparison with other researcher's results including our previous paper.

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Anechoic chamber characteristic is evaluated by SA (Site Attenuation). To optimize an anechoic chamber (its size and absorber), it is necessary to forecast the SA by calculation before constructing anechoic chamber. As for Open test site, the technique which solve impedance matrix of image antenna to calculate the SA has already been shown. However, in order to extend this technique for the anechoic chamber, an efficient algorithm of the mirror image is necessary. In this paper, we showed the algorithm of an imaging method (Ray trace method) that is able to be applied to the anechoic chamber with an arbitrary polygon shape. As a result, it was confirmed that the calculation value by this algorithm and actual measurement value was corresponding well.

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The breakdown field strength and radiated electromagnetic field intensity due to micro gap discharge were examined in experimental study. As a consequence, the radiated electromagnetic field intensity has inverse proportion to discharge voltage below about 800V breakdown. And so, the relationship between radiated electromagnetic field intensity and discharge voltage has indefinite dispersion in the wide gap discharge of about over 0.04mm gap length. It was confirmed that one of cause of the dispersion is an effect of surface condition in the discharge electrode.

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A remote, continuous environmental electromagnetic field monitoring system for use in magnetic confinement fusion test facilities is developed. Using this system, both the static magnetic field and the high frequency electromagnetic field could be measured. The required frequency range of the measurement system is from 25 to 100 MHz for the ICRF (Ion Cyclotron Range of Frequencies) heating system. The outputs from the measurement instruments are measured simultaneously by custom-built software using a laptop-type personal computer connected to a local area network. In this way, the electromagnetic field strength could be monitored from a control room located about 200 m from the fusion device building. Examples of measurement data from the vicinity of a high-frequency generator and amplifier and the leakage static magnetic field from a fusion test device are presented.

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An immunity testing method for electrostatic discharge (ESD) is being specified in the IEC 61000-4-2, in which two types of discharge method, contact and air discharges of an ESD-gun, are given. The ESD-gun is an ESD generator, which simulates ESD events from a charged human body. The IEC recommends the contact discharge method and has specified a typical discharge current waveform. The air discharge is a way applied when the contact discharge cannot be conducted, while the details of the discharge current waveform has not been given. Even in the same test levels, both the above discharges do not necessarily give the same severity for immunity testing. Though the air discharge which accompanies a spark is said to be severer, the severity has not quantitatively been evaluated. At the same time, as a strange phenomenon, it has been widely known in the related industries that in comparison with high voltage ESDs in several kilovolts, low voltage ESDs in several hundred volts generate EM fields having more broadband frequency spectra. The ESD of this kind causes more serious failure in electronic devices, while the mechanism has not yet been elucidated. From this perspective, grasping the characteristics of discharge current waveforms for contact and air discharges of an ESD-gun, we previously conducted both discharges onto a 50-Ω SMA connector, and showed that, at charge voltages below 1kV, air discharge could provide a larger current peak and shorter rise time than contact discharge. In this study, using a 12-GHz digital oscilloscope, we measured discharge currents for air and contact discharges of an ESD-gun onto an IEC calibration target, and obtained maximum rising slopes of discharge currents with respect to charge voltages from 200V to 15kV. As a result, we found that at charge voltages below 5kV, air discharges give higher current rising slopes than contact discharges, and particularly at charge voltages below 1kV, the rising slopes become larger by double figures and also have smaller variation. This means that air discharges at charge voltages below 1kV can provide a severe and reproducible immunity test.

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Although the EMC rule generally regulates the limited field strength in far electric field, the magnetic near field is practically often measured to evaluate the noise source of electric equipment. However, the magnetic near field strength is not always corresponding to the far electric field one by the complex transmission function from the source to the receiving antenna. The authors have been developing the new electromagnetic field measurement system based on the modulated scattering technique (MST) which could map the radiated noise distribution. Instead of a conventional metallic dipole scatterer, a dielectric spherical scatterer is introduced aiming to obtain the lower field invasiveness and the isotropic polarization for the incident wave. In this paper, the detecting process of scattered electric field by the dielectric sphere on the MST system was represented to the theoretical formulation. The numerical estimation by the analyzed equation showed that the dielectric scatterer could generate enough power to be measured, and a result of experimental measurement agreed with the theoretical one. The measurement sensitivity should be controlled by the scatterer's volume, the MST modulation ratio, and the scattering efficiency corresponding to the permittivity of the dielectric.

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Lightning Research Group of Osaka University (LRG-OU) has been developing and improving the VHF broadband digital interferometer (DITF) for thunderstorm observations. It enables us to locate the impulsive VHF radiation sources caused by lightning discharges with extremely high resolutions. As a result of the VHF observations during the 2007-2008 winter season in the Japan Sea coastal area, cloud-to-ground (CG) flashes that neutralize multiple charge regions inside thunderclouds are visualized by the VHF broadband DITF. The first flash is the positive CG flash that neutralizes multiple positive charge regions in a flash. The second flash is the bipolar lightning flash that neutralizes both positive and negative charge inside thunderclouds. In the case of bipolar lightning flashes, some tens millisecond after the return strokes, the subsequent negative breakdowns initiate from the proximities of the initiation points of the preceding negative stepped leaders. It was also found that the altitudes of negative charge regions are lower than 2km. The bipolar lightning flashes observed in this campaign neutralize positive charge after lowering the negative charge to the ground.

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GMR heads, the most electrostatic discharge (ESD/EOS) sensitive device of all electric devices, are used for high density magnetic recording applications. A number of problems related to electrostatic discharge phenomena in GMR heads have been reported, including melting and diffusion caused by the Joule heating by ESD currents, pinning rotation and demagnetization resulting from high magnetic field strength, and dielectric breakdown induced by a high voltage. In recent years, there has been a growing concern about damaging GMR heads from Electro-Magnetic Interference (EMI). In this paper, we studied a relatively easy method for comprehending the basic characteristics of EMI using the instruments that are widely used in conventional ESD evaluation for GMR head manufacturing.

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In this letter, we studied the use of common mode noise reduction technique for in-vehicle electronic equipment, each comprising large-scale integrated circuit (LSI), printed circuit board (PCB), wiring harnesses, and ground plane. We have improved the model circuit of the common mode noise that flows to the wire harness to add the effect of by-pass capacitors located near an LSI.

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A Web-Learning system was developed for medical engineering which is one of the required subjects of the medical technologist's examination for specialist. The system helps students' self-learning to acquire the essential knowledge by the explanation of questions chosen from the past examination. We discussed its learning effect on the basis of experimental results presented at the lecture and practice. The students evaluated that the learning system was practical method for more knowledge of important points in the concerning subjects. Thus, the present method is regarded effective for learning medical engineering, while most students are reluctant to make an effort for its study.

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This paper proposes a simple technique for measuring the radiation efficiency of broadband antennas by using a tunable spherical Wheeler cap made of brass with an inner diameter of 70 mm. The proposed method utilizes a multimode tuner designed as an adjustable brass stub with a ring to compensate the undesirable reductions of the measured efficiency caused by both TM and TE mode resonances of the cap. The required tuning levels for minimizing the undesirable reduction will depend on the Q factors of the cap resonances. The experimental results of a UWB slot antenna, performed at the frequency range of 3 to 10 GHz, show that the efficiency reduction can be minimized by enveloping over all maxima of efficiency curves measured for five different tuner positions.

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Fluid mechanical properties of microwave discharge jet for argon and helium plasmas at atmospheric gas pressure is investigated. Kelvin-Helmholtz (K-H) instability due to shear flow of working gas with surrounding air is seen to reflect on the plasma structure. Pulsation phenomenon for helium plasma jet is found not to have a counterpart in gas fluid behavior. Flickering phenomenon is shared in both jet diffusion flame and plasma jet. Ascending flow due to buoyancy effect and convection surrounding air to be followed by vortex formation originated from K-H instability would be the physical mechanism for the flickering.

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In this research, the chaotic motion of magnetic domain wall is controlled by using Delayed-Feedback-Control (DFC) with automatic gain-adjustment, modified by Nakajima and Ueda in 1995. The method of automatic gain-adjustment is newly applied to Extended-DFC (E-DFC) for more highly performance. It is clearly confirmed that the control-gain was automatically adjusted on each results. But, in this case, the response of E-DFC has not been improved. It is found that the delayed time has strongly influenced on the response. The selective E-DFC is proposed and the response was best.

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The purpose of this research is to automate geological surveys using imaging analysis. In this paper, we discuss an imaging analysis method for quantitative evaluation of weathering. We took pictures of core samples gathered from a boring hole with a color CCD camera. Subsequently, the relation between (I1, I2, I3) color space information in these images in the color space and the weathering characteristics was discussed. Imaging analysis revealed that Inter Quartile Range and Median are closely related to degree of rock weathering. Effective parameters depending on rock types were selected based on this information, and then the degree of rock weathering was evaluated with Support Vector Regression. Using this method degree of rock weathering was correctly identified within a range of ±0.5 from the true value in 90% in the various rock types studied. The above results confirmed the validity of the quantitative evaluation method, suggesting its usefulness in automation of geological surveys.

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Partial discharges (PDs), which occur at coupling points of tension insulators or binding spots of insulated wire of distribution lines, might cause television interference or ground fault. A technique for location of the sources of PDs using time differences in arrival of electromagnetic pulses radiated from PDs has been investigated recently, because it is difficult to find the sources by visual inspection from the ground. However, the technique requires a large and expensive apparatus such as digital storage oscilloscope able to record waveforms of the electromagnetic pulses very fast. We investigate a new technique to estimate the direction of arrival (DOA) of the electromagnetic pulses using analogue signal processing. The experimental analogue circuits for measurement of the time (phase) differences are composed of general purpose modules, i.e., amplifiers, filters, local oscillator, dividers, mixers, etc, and the DOA of the electromagnetic pulse is indicated using a circular symbol superimposed onto the photo image taken with a CCD camera. From the results of the experiments on the DOA estimation, it was proved that the new technique is available for high accuracy DOA estimation of the electromagnetic pulses radiated from PDs in air.

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For the preparation of this paper, we visited a junior high school to give lectures to the eighth grade students regarding energy environment using the fuel cell as a material. As a result of a questionnaire to them, we found that they are very interested in the problem of energy depletion. Also they are interested in solar cell energy generation based on the regionality of Miyazaki.

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A nanoporous titanium oxide (TiO₂) electrode of dye-sensitized solar cells (DSCs) is treated using pulsed corona discharge in room air condition. When the treatment time is 10 min with the discharge voltage of 30 kV, the short-circuit current and the energy conversion efficiency of the treated DSC are 10% higher than those of untreated DSC. This result indicates that the treatment of TiO₂ electrode using a pulsed corona discharge in room air condition can enhance the energy conversion efficiency of DSCs.

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