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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of Biomedical Engineering Research
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Journal DOI :
The Korea Society of Medical and Biological Engineering
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Volume & Issues
Volume 22, Issue 6 - Dec 2001
Volume 22, Issue 5 - Oct 2001
Volume 22, Issue 4 - Aug 2001
Volume 22, Issue 3 - Jun 2001
Volume 22, Issue 2 - Apr 2001
Volume 22, Issue 1 - Feb 2001
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A Spline-Regularized Sinogram Smoothing Method for Filtered Backprojection Tomographic Reconstruction
Lee, S.J. ; Kim, H.S. ;
Journal of Biomedical Engineering Research, volume 22, issue 4, 2001, Pages 311~319
Statistical reconstruction methods in the context of a Bayesian framework have played an important role in emission tomography since they allow to incorporate a priori information into the reconstruction algorithm. Given the ill-posed nature of tomographic inversion and the poor quality of projection data, the Bayesian approach uses regularizers to stabilize solutions by incorporating suitable prior models. In this work we show that, while the quantitative performance of the standard filtered backprojection (FBP) algorithm is not as good as that of Bayesian methods, the application of spline-regularized smoothing to the sinogram space can make the FBP algorithm improve its performance by inheriting the advantages of using the spline priors in Bayesian methods. We first show how to implement the spline-regularized smoothing filter by deriving mathematical relationship between the regularization and the lowpass filtering. We then compare quantitative performance of our new FBP algorithms using the quantitation of bias/variance and the total squared error (TSE) measured over noise trials. Our numerical results show that the second-order spline filter applied to FBP yields the best results in terms of TSE among the three different spline orders considered in our experiments.
A New Synthetic Aperture Technique Using Linear Wave Fronts
Journal of Biomedical Engineering Research, volume 22, issue 4, 2001, Pages 321~330
In this paper, we propose a new synthetic aperture focusing scheme for improving the lateral resolution which is one of the most important factors determining the quality of ultrasound imaging. The proposed scheme enables full round-trip dynamic focusing with approximately limited property. This properties are obtained through transmitting plane waves of which the traveling angle varies with the receive subaperture position, as opposed to stepping the spherical wave source across an array in other synthetic aperture focusing schemes, and employing dynamic focusing in receive. In this paper, the properties of the proposed scheme is analyzed in which a hypothetical infinite line source is used to transmit the plane waves and verified through computer simulation results. Also, we show that the proposed scheme is realizable with an array transducer with a finite aperture size. In summary, it is shown through comparison between the field contours of the proposed scheme and the conventional scheme that the proposed scheme can improve greatly the lateral resolution of ultrasound imaging.
New Computer Retina Model Reflecting the Mechanism of Amacrine Cell
Journal of Biomedical Engineering Research, volume 22, issue 4, 2001, Pages 331~338
In this paper, we have proposed a new computer retina model reflecting the mechanism of transient amacrine cell on the basis of a conventional computer retina model to understand mechanism of visual information processing. The conventional computer retina model contained most of mechanism for other retina models and it was verified with the physiological data. However, we found that a conventional computer retina model doesn't have the mechanism of amacrine cell that was likely to respond to moving stimulus. In proposed model, therefore, a conventional computer model that considered from photoreceptors to bipolar cells and a new computer model that considered for transient amacrine cell and ganglion cell was combined. As we compared the physiological data with the results of computer simulation of transient amacrine cell about fixed stimulus and moving stimulus, we confirmed that the proposed new computer retina model was normally operated.
A Fast 3D Digital Scan Conversion in Ultrasound Volume Rendering System
Journal of Biomedical Engineering Research, volume 22, issue 4, 2001, Pages 339~347
The proposed ultrasound volume rendering system concists of 3D digital scan conversion (DSC) part and volume rendering (VR) part, which requires large memory space to store 3D data and high computation power to process them. Though there are several methods to reduce the computation amount such as early ray termination in VR, it is very difficult to process 3D DSC in real time. The 3D DSC converts the 3D sampled data in spherical coordinates or cylindrical coordinates into the 3D data in Cartesian coordinates. Since the input data of ultrasound volume rendering system are obtained from 3D
interpolation has to be performed as the 3D DSC algorithm. The 3D
interpolation requires large computation amount. We can reduce the computation amount by applying the fast processing methods of volume rendering and the characteristics of TMS320C6201. Only the part of the data needed to be rendered is converted by the early ray termination and voxel skipping method. And we can move the data between memories efficiently by using the DMA and using the 16-bit data type. This paper proposes a fast technique of 3D DSC algorithm for 3D ultrasound images, which is appropriate for volume rendering
Development and Evaluation of a Novel Electro-mechanical Implantable Ventricular Assist System
Journal of Biomedical Engineering Research, volume 22, issue 4, 2001, Pages 349~358
A novel electro-mechanical implantable ventricular assist system is developed as a bridge to transplantation or recovery for patients with end-stage heart failure. The developed system is composed of an implanted blood pump, an external monitoring system which stores data, and a wearable system including a portable external driver and a portable power supply system. The blood pump is designed to be implanted into the left upper abdominal space and provides blood flow from the left ventricular apex to the aorta. The pulsatile blood flow is generated by a double cylindrical cam. There was mo excessive heat emission from the blood pump into the temperature-controlled chamber in the heat test and no stagnated flow within the blood sac by the observation in the flow visualization test. Animal experiments were performed using sheep and calves. The maximum assist flow rate reached 7.85L/min in the animal experiment. The evaluation results showed that the developed system was feasible for the implantable ventricular assist system. The long-term in vitro durability test and mid-term in vivo experiments are in progress and mow the modified next model is under development.
Development of the Automatic Knee Joint Control System for a Knee-Ankle-Foot Orthosis Using an Electromechanical Clutch
Journal of Biomedical Engineering Research, volume 22, issue 4, 2001, Pages 359~368
A new knee-ankle-foot-orthosis(KAFO) which uses an automatically-controlled electromechanical wrap spring clutch for the knee joint was developed in the present study. It was found that the output voltage from the foot switches of the developed KAFO was proportionally increased with respect to the applied load. The output voltage from the infrared sensor also decreased as the knee flexion angle increased. The knee joint system for the new KAFO weighs only 780g lighter than any other commercially available developed system. In addition, the solenoid reduces the reaction time for the automatic control of the knee joint. The static torque of the clutch was measured for three persons, and it satisfied the normal knee extension moment during the pre-swing. Three-dimensional gait analyses for three different gait patterns (normal gait, locked-knee gait, controlled-knee gait) from five normal subjects were conducted. Controlled-knee gait showed the maximum knee flexion angle of 40.56
and the maximum knee flexion moment of 0.20
0.07Nm/kg at similar periods in the normal gait. Our KAFO system satisfies both stability during stance phase and free knee flexion during the swing phase at the proper period during the gait cycle. Therefore, our KAFO system would be very useful in various low extremity orthotic applications.
A comparison of Multilayer Perceptron with Logistic Regression for the Risk Factor Analysis of Type 2 Diabetes Mellitus
Journal of Biomedical Engineering Research, volume 22, issue 4, 2001, Pages 369~375
The statistical regression model is one of the most frequently used clinical analysis methods. It has basic assumption of linearity, additivity and normal distribution of data. However, most of biological data in medical field are nonlinear and unevenly distributed. To overcome the discrepancy between the basic assumption of statistical model and actual biological data, we propose a new analytical method based on artificial neural network. The newly developed multilayer perceptron(MLP) is trained with 120 data set (60 normal, 60 patient). On applying test data, it shows the discrimination power of 0.76. The diabetic risk factors were also identified from the MLP neural network model and the logistic regression model. The signigicant risk factors identified by MLP model were post prandial glucose level(PP2), sex(male), fasting blood sugar(FBS) level, age, SBP, AC and WHR. Those from the regression model are sex(male), PP2, age and FBS. The combined risk factors can be identified using the MLP model. Those are total cholesterol and body weight, which is consistent with the result of other clinical studies. From this experiment we have learned that MLP can be applied to the combined risk factor analysis of biological data which can not be provided by the conventional statistical method.
Remote Patient Monitoring through the Internet
Journal of Biomedical Engineering Research, volume 22, issue 4, 2001, Pages 377~383
In this paper, we present an intensive patient monitoring service through the Internet, which enables medical doctors to watch their patients in a remote site, to monitor their vital signs and to give them some advices for first-aid treatment. The service consists of three service objects: Monitoring Information Service(MIS), Vital Sign Monitoring Service(VSMS) and Multimedia Consulting (MCS). Through the MIS, medical doctors can get information about the patients currently under monitoring, including their names, ages, genders, symptoms, current main complaints and current locations. The VSMS enables medical doctors to monitor in real-time patients' vital signs such as electrocardiogram (ECG), respiration, temperature, blood oxygen saturation (SpO
), invasive blood pressure (IBP), and non-invasive blood pressure (NIBP). It also generates alarms when the patients are likely to be in a critical situation. The MCS provides a real-time multimedia desktop conferencing facility for watching patients and instructing attendants to administer some first-aid treatment. We carried out some experiments according to two different scenarios. The intensive patient monitoring service was functioning well in a 100Base-T Ethernet LAN environment.