Koji Mukai

A remote monitor of bed patient cardiac vibration, respiration and movement

We have developed a remote system for monitoring heart rate, respiration rate and movement behavior of at-home elderly people who are living alone. The system consists of a 40 kHz ultrasonic transmitter and receiver, linear integrated circuits, a low-power 8-bit single chip microcomputer and an Internet server computer. The 40 kHz ultrasonic transmitter and receiver are installed into a bed mattress. The transmitted signal diffuses into the bed mattress, and the amplitude of the received ultrasonic wave is modulated by the shape of the mattress and parameters such as respiration, cardiac vibration and movement. The modulated ultrasonic signal is received and demodulated by an envelope detection circuit. Low, high and band pass filters separate the respiration, cardiac vibration and movement signals, which are fed into the microcontroller and digitized at a sampling rate of 50 Hz by 8-bit A/D converters. The digitized data are sent to the server computer as a serial signal. This computer stores the data and also creates a graphic chart of the latest hour. The person’s family or caregiver can download this chart via the Internet at any time.

Nondestructive Evaluation of Corrosion Progression on Titanium and Its Alloy Surface by Wetting Method

The corrosion behavior of pure titanium and Ti-6Al-4V alloy in NaF solutions and the wettability of pure water on the specimens after corrosion were investigated. The relation between the change of surface chemistry and roughness of specimens after corrosion and the wettability of pure water droplets on such surfaces were discussed.

Construction of an elementary education system on semiconductor processes for power devices using TCAD

To realize further high performance in semiconductor devices such as power devices in power electronics, the development of efficient processes and a reduction in the number of trial productions are indispensable. Therefore, the orientation of development plans and a reduction in trial production by using TCAD (Technology Computer Aided Design) are expected. Moreover, in relation to global environmental issues, the importance of energy technology is growing more and more, and expectation for power electronics is especially high. In power electronics, power devices play an important role. Thus research on power devices and education relevant to power devices are vital. However, detailed information of the processes, device structure, and circuits in general power devices are not publically disclosed. By using TCAD as a teaching tool in education for power electronics specializing in the semiconductor process of power devices, we can construct an education system that can solve these issues.

Construction of an elementary education system using power devices

Energy saving and efficient power conversion technology are pressing concerns in todays society[1]. In order to use electrical energy efficiently, the technical development of power electronics - or power conversion technology - is urgently needed[2]. In response to this need, our aim is to nurture power electronics engineers. To this end, we have constructed an education system that presents the complete picture to students from the basic structure of power devices through to their application circuits. By performing simulations using TCAD (Technology Computer Aided Design), this education can be provided at low cost because there is no need to create actual functioning devices. The proposed system deepens the understanding of students by clearly showing them the internal structure and impurity concentrations of power devices, something that is difficult to illustrate using real devices. In addition, the system also deepens understanding of circuits by having students design and create circuits using power devices and then having them consider the resultant waveforms.

Producing micro-droplet of dilute sulphuric acid on pure iron surface and observing its corrosion behaviour by atomic force microscopy

A simple method was presented to produce a micro-droplet of sulphuric acid on a pre-selected micro-zone on a pure iron surface with the tip of an AFM cantilever. The three-dimensional shape of the droplet was imaged with the AC non-contact mode of the AFM, and the liquid/solid interface was observed in situ during corrosion using the contact mode. The substrate surface beneath the droplet was lowered by approximately 19 nm after 3.6 ks of adhesion. This method has important implications for experimental studies of micro-zone corrosion or lubrication.