The radio-frequency protection guideline of Japan recommend the limits of contact current for contact hazard due to an ungrounded metallic object under an electromagnetic field in the frequency range from 10 kHz to 15 MHz. To arrange the standard measurement methods of contact current in Japan, the contact body impedance for the Japanese in the frequency range from 75 kHz to 15 MHz is obtained, and the simplified equivalent circuit is determined using nonlinear least squares method. In addition, the human body impedance is obtained from numerical simulation using the impedance method and voxel human model, and compared it with measured one.

The purpose of this study is to provide a new approach for detection using bio-impedance. This impedance is measured by the four-electrode method. As the impedance changes resulting from ankle, knee, and hip movements depended heavily on electrode placement, we determined the optimal electrode configurations for those movements by searching for high correlation coefficients, large impedance changes, and minimum interferences in ten subjects (Age: 204). Our optimal electrode configurations showed very strong relationships between the ankle joint angle and ankle impedance (γ = -0.9130.03), between the knee joint angle and knee impedance (γ = 0.9440.02), and between the hip joint angle and hip impedance (γ = 0.8230.08). This study showed the possibility that lower leg movement could be easily measured by impedance measurement system with two pairs of skin-electrodes.