Japanese journal of medical electronics and biological engineering
Online ISSN : 2185-5498
Print ISSN : 0021-3292
ISSN-L : 0021-3292
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  • Takahiro TOHYAMA, Itsuro SAITO, Takashi ISOYAMA, Kou IMACHI, Tuneo CHI ...
    2002 Volume 40 Issue 4 Pages 195-200
    Published: 2002
    Released: October 14, 2011
    JOURNALS FREE ACCESS
    For the treatment of patients with allergic diseases, such as atopic dermatitis and asthma, the amount of allergens in the house of an individual patient has to be measured and controlled. Allergen-measuring devices currently in use are too large to bring into a patient's home. Accordingly, we have developed a portable allergen-measuring device that can quickly quantify the amount of Dermatophagoides mite allergens. The new device consists of a reaction tube, secondary antibody reagents, mark reagents, emission-color reagents, emission-color reaction-stoppage reagents, a washer, a photometer, and a timer. The antibody, which specifically binds to the Derf 1 protein in the Dermatophagoides farinae antigen, is attached to the inner surface of the reaction tube. The scattering filter is mounted between the LED and photodetector, and absorption of the specimens in the reaction tube can be measured immediately. The efficiency of the antibody attachment is improved by using a test tube with an uneven inner surface. The measurement of Dermatophagoides mite allergens can be completed in 12min. A Derf 1 concentration from 10 to 100ng/ml can be detected and quantified using this device, and there is a strong correlation between measurements made with our device and those obtained utilizing the conventional ELISA method. In this study, a portable, low-cost device for quantifying the amount of Dermatophagoides farinae antigen was developed. It can measure the amount of allergens in the homes of patients, and consequently contributing to an improvement in patients' living environments and their quality of life. The device can also be used as a tool for maintaining a healthy house environment because early detection of the existence of allergens can help prevent allergenic diseases.
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  • Kazuyoshi FUKUNAGA, Akio FUNAKUBO, Yasuhiro FUKUI
    2002 Volume 40 Issue 4 Pages 201-213
    Published: 2002
    Released: October 14, 2011
    JOURNALS FREE ACCESS
    The electromechanical or electrohydraulic mechanisms conventionally used for driving pulsating ventricular-assist devices (VADs) must use a movement converter. It is this movement converter that is the main item preventing the miniaturization of VADs and improvement the level of reliability. This paper suggests a linear oscillatory actuator (LOA) for VADs that provides reciprocating motion without requiring a converter mechanism. It consists of a stator with a single-winding excitation coil and a mover with two permanent magnets. The mover moves back and forth when forward and reverse electric currents are supplied to the excitation coil. We first propose a newly designed inner stator/outer mover LOA. The structure of the inner stator has led to a reduction in total coil resistance because the winding diameter of the coil is shorter than the outer stator. A large force is required to drive a VAD in the systolic phase; however, a small force is sufficient for the diastolic phase. For this reason, we propose using a non-symmetrical LOA that generates high thrust on one side alone. A magnetic field analysis was applied to examine the proposed configurations and design the prototype LOA. The dimensions of the prototype LOA are 60mm in diameter and 24mm inn thickness, and it has a mass of 465g and a volume of 68mL. In the large-thrust phase, at an input power of 20W, the starting static thrust was approximately 87N and maximum static thrust was approximately 195N. In the small-thrust phase, for the same input of 20W, the starting static thrust was approximately 43N and maximum static thrust was approximately 70N. The static thrust of the large-thrust phase was approximately three times larger than the small-thrust phase with the same electrical power input.
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  • Ayako KATOH, Yasuhiro FUKUI
    2002 Volume 40 Issue 4 Pages 214-221
    Published: 2002
    Released: October 14, 2011
    JOURNALS FREE ACCESS
    Much information is received from facial expressions during communication. Therefore, during the interface between humans and machines, for example, it's important to extract the information from facial images in order to obtain the correct understanding. This paper proposes a new method for extracting information from facial images. The method provides a self-clustering of image features, and has procedures to cluster images input using self-organizing maps (SOMs). A SOM is an artificial neural network consisting of an input layer and an output layer. When the brightness values of an image are input into the input layer, the output layer works as a map layer that clusters the features of the image. This ability is obtained using a process known as “self-training.” This paper discusses the application of the suggested method for analyzing actual facial images. Six fundamental facial expressions (i. e., happiness, anger, sadness, disgust, fear and surprise) were enacted and recorded by digital VTR. First, an image sequence was composed from the recorded film footage, and the eyebrows, eyes and mouth were semiautomatically selected for observation from each image. Next, training for self-clustering was performed to automatically classify all the facial expressions. After training, an analysis of each SOM was done to review its classification ability. The SOMs were able to classify various shapes of eyebrows, eyes and mouth. When an image sequence from a change in facial expression was input, it was reflected in a change in output that described the change in facial expression. Our method may therefore be used to recognize facial expressions and emotions.
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  • Nobuo EZAKI, Kimiyasu KIYOTA, Tasuku KAMEI, Hotaka TAKIZAWA, Shinji YA ...
    2002 Volume 40 Issue 4 Pages 222-230
    Published: 2002
    Released: October 14, 2011
    JOURNALS FREE ACCESS
    We have developed a pen-based Japanese character input system for use by blind people (particularly acquired blind person). Blind persons that are novices to system use can input Japanese characters without prior training, and information displayed on the screen is given to the user via the system's built-in voice synthesizer. The system can recognize 3, 216 characters including JIS Level 1 characters. However, when the system was applied to an E-mail system, many characters having a small number of strokes (such as Hiragana and Katakana) were contained in the mail text, causing a decrease in the recognition rate as the features used for recognizing a character were fewer. This paper describes an improvement made in recognition accuracy by combining the voting method with our previous method and two other conventional recognition methods. Character recognition of a phrase unit was also extended using a tri-gram probable language model. By applying these additional improvement methods, the recognition accuracy has been improved to 97.7% from 66.2%, and we confirmed the validity of the proposed method.
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  • Measurement of the Opening and Closing Behavior of the Björk-Shiley Monoleaflet Mechanical Heart Valve
    Hwansung LEE, Tomonori TSUKIYA, Akihiko HOMMA, Yoshiyuki TAENAKA, Eisu ...
    2002 Volume 40 Issue 4 Pages 231-238
    Published: 2002
    Released: October 14, 2011
    JOURNALS FREE ACCESS
    Several factors such as peak dp/dt of ventricular pressure, maximum closing velocity of the leaflet and squeeze flow have been studied as indices for the cavitation threshold. To study the possibility of the occurrence of cavitation at a 25mm Björk-Shiley monoleaflet, we analyzed the closing behavior of the valves. The closing events of the valves in the mitral and aortic positions were simulated using a fully electro-hydraulic artificial heart. Tests were conducted under physiologic pressures at heart rates of 50, 60, 70 and 80 beats/min with cardiac outputs of 4.8, 5.9, 7.0 and 8.0L/min, respectively. The closing behavior of the valve was measured using a laser displacement sensor. The maximum velocity of the aortic valve ranged from 0.8 to 0.9m/s, and that of the mitral valve ranged from 1.48 to 1.6m/s. In aortic position valves, the maximum closing velocity was lower than the cavitation thresholds reported, but the maximum closing velocity of th mitral valve was similar to the cavitation threshold. Therefore, we suggest that it is possible for cavitation to occur in the mitral valuve of electro-hydraulic artificial hearts.
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  • Tomoaki NAGAOKA, Kiyoko SAKURAI, Etsuo KUNIEDA, Soichi WATANABE, Hiroy ...
    2002 Volume 40 Issue 4 Pages 239-246
    Published: 2002
    Released: October 14, 2011
    JOURNALS FREE ACCESS
    We have developed high-resolution voxel models of the whole body from MR images of Japanese adult male and female volunteers. These models can be used for dosimetry simulation of exposure to radiofrequency electromagnetic fields over 1GHz. The MR images were taken by making a series of scans over several days; that is, a subject was scanned in several blocks. Scan parameters were optimized for head and body, respectively, in order to get practical contrast and to save data acquisition time. An implement was used to keep the position and form of the subject. All of the MR images were converted to TIFF format. The continuities between different blocks of the data were corrected to form a whole body. Furthermore, the resolution of the images was changed into 2×2mm. Male and female models were segmented into 51 tissues and organs. This segmentation was performed manually using popular image-processing software. The developed models consisted of isotropic voxels with a side of 2mm. Although the masses of the skin and small-sized tissues and organs of the models deviated from the averaged values for Japanese due to the limitation of spatial resolution, the masses of the other tissues and organs and the morphometric measures were nearly equivalent to those of the average Japanese. The models are the first voxel models of the average Japanese that can be used for the dosimetry of electromagnetic fields over 1GHz. Furthermore, the female model is the first of its kind in the world. The models can also be used for various numerical simulations related to Japanese human bodies in other fields of research.
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  • Yuichiro HAYASHI, Kensaku MORI, Jun-ichi HASEGAWA, Yasuhito SUENAGA, J ...
    2002 Volume 40 Issue 4 Pages 247-252
    Published: 2002
    Released: October 14, 2011
    JOURNALS FREE ACCESS
    This paper evaluates the performance of an automated fly-through method of virtual colonoscopy based on the rate of undisplayed regions. When performing a diagnosis using a virtual colonoscopy (VC) system, the doctor observes the state of the colonic wall. Automated fly-through is often used to reduce the operation load on the virtual endoscopy system (VES). The system generates automated fly-through paths based on medial axes extracted from colon regions. There are many folds (i. e., “haustra folds”) in the colon, and these folds create blind regions in the images obtained during VC. There have been no studies on the rate of undisplayed regions resulting from occlusion during VC. This paper quantitatively evaluates automated fly-through paths generated during VC based on a method that measures the rate of undisplayed regions over the whole colon area in VES. We generated various fly-through paths and measured the rate of undisplayed regions. Experiments using three abdominal CT images showed that approximately 30% of the colon area was not displayed at all during automated fly-through.
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  • 2002 Volume 40 Issue 4 Pages 253-258
    Published: 2002
    Released: October 14, 2011
    JOURNALS FREE ACCESS
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