Naohiro Hozumi

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Ultrasonic has been used since several decades ago. One of ultrasonic application is used in medical field to observe mechanical properties of target, such as speed of sound, density, acoustic impedance, attenuation, etc. Several methods are also available to estimate mechanical property of target. In the previous research, we developed Scanning Acoustic(More)
—Regenerated skin with complete organ structure is desired for the treatment of large burn and for the plastic surgery. High frequency ultrasound is suitable for non-destructive testing of such skin models because it can obtain both morphological and biomechanical information in non-invasive manner. A specially developed acoustic microscope system with the(More)
Antistatic agent is often used for avoiding electrification of polymer films. In some cases, the film has a double-layer structure to improve its adhesive property. As an example, an ethylene-vinylacetate copolymer (EVA) film, in which an antistatistic agent is mixed, is laminated with a low-density polyethylene (LDPE) film. In such a case, there is a(More)
This paper deals with the discharge time lag of partial discharge in insulation-gap-insulation system with different levels of relative humidity. The sample was polymethylmethacrylate (PMMA) plate with 1 mm thickness. The PD patterns and the PD time lag with various levels of relative humidity were measured and discussed. The increasing of relative humidity(More)
This paper presents the structural characterization of treeing phenomena of a micro-composite material, composed of micro-size inorganic silica filler added to epoxy resin. The fractal dimension of the electrical tree and its relationship with filler content was determined. The damaged area of tree in various contents of filler was also estimated.(More)
We have been studying the breakdown characteristic of air-polymer composite insulation under repetitive pulse voltage application using needle-plane electrode system. The purpose of this study is to clarify the effect of heat by discharge on breakdown of air polymer composite insulation. The effect of thermal insulation between low density polyethylene(More)
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