Kazuo Kato

Tohoku Gakuin University · Department of Electronic Engineering

Eye-blinks and eye movements contaminate electroencephalogram (EEG) results mainly in the form of artifacts, as they generate misleading neural activities in the EEG data. To manage this phenomenon, we proposed an identification technique for the optimal independent components (ICs) of electrical noise generated by artifacts. Our technique integrat...

When an electroencephalogram (EEG) is measured, artifacts due to eye blinks and eye movements contaminate the EEG signal. One of the solutions applied to this problem is independent component analysis (ICA), which can separate the artifact components from EEG data. However, the identification of independent components (ICs) related to artifacts, pa...

Spatial frequency may elicit characteristic mental and neural activity in humans, exhibiting a 1/f fluctuation. However, a visual pattern with only spatial frequency information will not necessarily explicitly affect any reaction, but may do so implicitly. We adopted an implicit association test (IAT), which is widely used in the research of implic...

To design novel displays guiding gaze, it is important to know how the visual search affects the perception and cognitive processing of objects. The purpose of this study was to investigate the characteristics of the visual search that are controlled by spatial frequency. We measured the detection time, accuracy rate, and scan path during eye movem...

The purpose of this study was to identify the key variables that determine the quality of the auditory environment, for the purposes of workplace auditory design and assessment. To this end, we characterized changes in oscillatory neural activity in electroencephalographic (EEG) data recorded from subjects who performed an intellectual activity whi...

To clarify the characteristics of visual search that are controlled by spatial frequency, we measured the scan path during eye movement in response to visual stimuli. A target stimulus with the spatial frequency of 1/fβ (where β is the slope of power spectral density of luminance in an image) was embedded in a background stimulus with white (1/f0)...

The spatial frequency contained in visual objects is known to affect human psychophysiology. In our previous study, we showed that event-related potentials are affected by spatial frequency during a simple calculation task. In that study, however, we did not investigate the contribution of oscillatory neural activities. The purpose of the present s...

A very sensitive thin film sensor was developed using a transmission line. The sensor element consists of a coplanar line fabricated from a ceramic substrate and amorphous-CoNbZr film (4 μm in thickness). The ceramic substrate with high permittivity enhanced the phase change in the carrier, and a phase change around 300 degrees/Oe was achieved. A s...

The aim of this study was to characterize the neural activation that was associated with the performance of intellectual activities under the influence of Brownian noises that were similar to environmental noises in real spaces. An N-back task comprising 2 components, i.e., verbal and spatial tasks, was used to study working memory during 4 types o...

Spatial variation in luminance, which is one of the most important attributes of a visual image, may cause characteristic reactions in higher order brain functions. We aim to characterize the event‐related potentials (ERPs) associated with a cognitive task (simple addition) in terms of how they are influenced by the spatial frequencies of the backg...

We have developed a very sensitive thin film sensor using a transmission line. The sensor element consists of a coplanar line fabricated from a ceramic substrate and amorphous-CoNbZr film (4 ?m in thickness). The ceramic substrate with high permittivity enhances the phase change of the carrier, phase change around 7000 degree/Oe being achieved. A s...

It is important to relate the physiological characteristics of the subject to the physical parameters of the image being viewed. In this study, we employed image analysis to extract the spatial frequency characteristics associated with fixation information; this information provides the visual physiological responses of the subjects viewing station...

There are various elements in visual images, such as luminance, edge, color, movement, and shape, that may affect mental activity. In an attempt to explore the neural processes associated with image features, we extracted the edge and spatial frequency characteristics from images of two movies having completely differential features. Using the fMRI...

In the case of sudden valve closure, water hammer creates the most powerful pressure and damage to pipeline systems. The best way to protect the pipeline system is to eliminate water hammer. The main reasons for water hammer occurrence are valve closure, high initial velocity, and static pressure. However, it is difficult to eliminate water hammer....

We developed a very sensitive high-frequency carrier-type thin film sensor with a sub-pT resolution using a transmission line. The sensor element consists of Cu conductor with a meander pattern (20 mm in length, 0.8 mm in width, and 18 μm in thickness), a ground plane, and amorphous CoNbZr film (4 μm in thickness). The amplitude modulation techniqu...

We developed a very sensitive high-frequency carrier-type magnetic-field sensor with a sub-pT resolution using a transmission-line-type sensor. Meander-type sensor elements using amorphous CoNbZr films (4μm in thickness), Cu conductor with a meander pattern (30 mm in length, 1.0 mm in width, 18 μm in thickness), and a ground plane were fabricated....

In the case of sudden valve closure waterhammer creates the most powerful pressure and damage to pipeline systems. The best way to protect the pipeline system is to eliminate waterhammer. The main reasons of waterhammer occurrence are valve closing, initial velocity, and static pressure. However, it is not always so easy to eliminate waterhammer. M...

We developed a very sensitive high-frequency carrier-type magnetic field sensor with a pT resolution using a transmission-line-type sensor. Meander-type sensor elements using amorphous CoNbZr films were fabricated. We obtained a magnetic field resolution of 3.0 x 10-12 T/Hz1/2 at 1 Hz. The detectable magnetic field was limited by the 1/f noise. We...

本研究では, 視覚情報の差異に着目し, これらが心的な活動にどのような影響を与え, さらに大脳神経活動にどのような変化として発現するのかを調べることを目的に検討を行った. 実験では, 取り扱いが容易であり, 単純で基本的な対象と考えられることからロウソクの火 (炎) に注目し, その視覚的な情報の特徴である炎の動きと色の有無, および実物と画像の差異について大脳神経活動との関連を調べるため, 12名の被験者を対象に自発脳波律動の測定を行った. また, SD法に基づく主観評価も実施した. その結果, 実物と画像間にはα波,β波の減衰, また色の有無についてはθ波の有意な減衰が観測され, これらが視覚刺激間の差異に固有の心的活動を反映すると推察された. さらに, 本研究で用いた自発脳波の周波数帯...

In order to improve the design efficiency of multilayer-type magnetically shielded rooms (MSRs), the magnetic property of mu-metal in low magnetic fields was investigated. The shielding effects (SEs) of multilayered cylinders composed of mu-metal were measured by using a superconducting quantum interference device (SQUID) magnetometer. Then, the in...

A highly practical method for evaluating magnetic disturbance due to adjacent buildings for the design of a magnetic testing site with nearly zero magnetic field was proposed. A modeling technique for complicatedly distributed magnetic materials in buildings was verified by the measurement using an actually constructed building. Moreover, a conveni...

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In order to investigate an effective method for removing the residual magnetization in the steel structure of a building by a demagnetizing coil, a method for estimating the distribution of residual magnetization by means of a three-dimensional nonlinear eddy-current analysis was proposed. The tendency of the result obtained from the proposed metho...

Recently, color change and distortion in CRT television sets due to residual magnetization in steel structure of building has been troublesome in offices, hospitals, and houses. The residual magnetization is caused by welding current and lifting magnet. In order to investigate an effective method of removing the residual magnetization by a demagnet...

We developed a new shielding system composed of shielding panels by means of an active compensation technique for biomagnetic measurements and electron beam lithography system. The new active compensation system has the main advantage that the panels can be assembled in any shape for the various demands because the unit panel is low weight and smal...

The fluctuations of magnetic field (FMF) from automobiles of different shapes and sizes running north to south, and east to west are measured and the characteristics are grasped. The direction of magnetization of the automobile is assumed by the waveform and amplitude of the FMF obtained by the measurements. In this report, the distribution of dist...

MCG (Magnetocardiography) measurement by a SQUID gradiometer was attempted with only active magnetic shielding (active shielding). A three-axis-canceling-coil active shielding system, where three 16-10-16 turns-coil sets were put in the orthogonal directions, produces a homogeneous magnetic field in a considerable volume surrounding the center. Flu...

Magnetically shielded rooms (MSRs) with materials of high permeability and active shield systems have been used to shield magnetic noise for biomagnetic measurements up to now. However, these techniques have various disadvantages. Therefore, we have developed a new shielding system composed of shielding panels using an active compensation technique...

Most of the natural phenomena include a time fluctuating component. Frequency analysis of this time fluctuation component leads to the famous "1/f fluctuation" characteristic that gives mental as well as psychological relaxation effects to human. Because of wide spreading electrical power supply, modern residence removes the combustion utilities an...

This paper describes suitable active shielding (AS) for electron-beam lithography systems (EBLSs). The optimal position of a reference sensor (RS), of which the signal is used to feed a current into a canceling coil (CC), is discussed. Preliminary experiments using an EBLS verification model and three-dimensional (3-D) magnetic field computations w...

In the National Space Development Agency of Japan (NASDA), a nonmagnetic space is required in the Spacecraft Magnetic Test Site (SMTS) to measure mainly magnetic moments of spacecrafts. This is realized by means of the main toil of a three-axis Braunbek system combined with a nonmagnetic noise source space (NMNSS) of which the radius from SMTS is m...

In this paper, experimental investigations using a model of the EBLS and 3-D magnetic field computations were carried out to find out the optimal position of an reference sensor outside the EBLS that can attenuate the magnetic disturbances inside the EBLS effectively and the degree of disturbance of the EB.

Summary form only given. The shielding effect of a magnetically shielded room (MSR) should be designed for biomagnetism by taking into account the S/N ratio of the biomagnetic signals and the environment magnetic field noise (EMFN), (generated by the movement of automobiles), and for semiconductors by the ratio of the noise level required by the in...

Biomagnetic signals such as MEG (magnetoencephalography) and MCG (magnetocardiography) are very weak compared with those of environmental magnetic fields due to trains and motor cars. In Japan, the fluctuation and frequency dependence of the environmental magnetic noises at extremely low frequencies in urban areas are considerably different between...

this paper, the new system was introduced to a low performance MSR in Sophia University which suffers environmental urban noises

this paper, the fluctuations of magnetic fields were measured at three locations near to railroads of dc railcars at Tagajo city, Sendai city and Koto-ku in Tokyo. All railcars use personal tracks. Firstly, the fluctuation characteristics of magnetic fields from the nighttime to the daytime at three locations were discussed to understand that the e...

this paper, the 3-D magnetic field analysis is carried out by using the finite element method taking account of eddy currents [5] to estimate an effective combination of magnetic and conductive layers. The consequences of the analysis can be applied to the optimal design of a MSR in the frequency range from 0.01 Hz to several ten Hz. The numerical...

Biomagnetic signals are very weak compared with those of the environmental magnetic field due to trains and motorcars. Trains, especially direct-current electric railcars, seem to be one of the main urban magnetic noise sources of low frequency in Japan, as indicated by comparing the fluctuation of the magnetic field during the day when there are m...

In order to examine the relationship between volcanic explosions and electromagnetic phenomena, we constructed the continuous extremely low frequency (ELF) band measuring system, which is composed of geoelectric potential differences (GPDs) and geomagnetic fields (GF's) at the foot of Mt. Sakurajima, Kyushu Island, Japan. The results of the measure...

A magnetically shielded room for biomagnetism should be designed taking account of the S/N ratio of the biomagnetic signal to the environmental magnetic noise generated mainly by dc electric railcars at an installed location. This paper describes the characteristics of the fluctuation of magnetic noise and a method of prediction of its amplitude. T...

This paper describes the optimal design of magnetically shielded room used for measurements of extremely weak magnetic fields such as biomagnetic measurements, in which the higher shielding factor is required in the frequency range from 0.01 Hz to several ten Hz at a low cost. The 3D magnetic field analysis is carried out by using the finite elemen...

Biomagnetic signals are very weak compared with those of the environment magnetic field due to train and motor car. The train especially the direct-current electric railcar is seemed to be one of the main urban magnetic noise sources at low frequency in Japan, by comparing the fluctuation of magnetic field at the day when there are many trains with...

This paper describes the optimal design of magnetically shielded room used for measurements of extremely weak magnetic fields such as biomagnetic measurements, in which the higher shielding factor is required in the frequency range from 0.01 Hz to several ten Hz at a low cost. The 3-D magnetic field analysis is carried out by using the finite eleme...

Binocular rivalry (BR) is the process where dissimilar images given to corresponding parts of the left and right eyes are perceived alternately at any moment in time. In an attempt to detect the neural activities related to the endogenous alternation of perceived images in BR, we have studied the potentials elicited by the alternation in six health...

Event-related potentials, as well as reaction time and percent correct of performance, were measured and analyzed in six healthy subjects during the phonemical comparison between Hiragana and Katakana letters (Japanese phonogram) which were visually presented simultaneously. Two different tasks were designed in the experiments. One was the task cal...

In order to investigate neuronal activities related to binocular rivalry (BR), we have studied spatio-temporal characteristics of EEG rhythmic activities and event-related-potentials (ERPs) elicited by the switching from binocular fusion (BF) to BR and vice versa. EEGs were measured and analyzed at 20 electrode positions over the entire head in nin...

Spontaneous EEGs, at 16 electrode positions over the entire head in five healthy subjects, were measured and analyzed while the subjects gazed at a variety of images in binocular vision. A significant difference in the EEG alpha rhythm (8-13 Hz) was observed between the two states of gazing at stationary and moving gratings in binocular fusion (BF)...

Spontaneous EEGs were measured at 12 electrode positions over the entire head when subjects perceived alternately one of two stimuli, that were given separately to the left and right eyes, in binocular rivalry. Upward and downward triangles of the same size were used as the two stimuli. The EEGs when subjects perceived a fused image in binocular fu...

In order to investigate neuronal activities related to binocular rivalry (BR), we have studied spatio-temporal characteristics of EEG rhythmic activities and event-related-potentials (ERPs) elicited by the switching from binocular fusion (BF) to BR and vice versa. EEGs were measured and analyzed at 20 electrode positions over the entire head in nin...