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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 24, Issue 6 - Dec 2003
Volume 24, Issue 5 - Oct 2003
Volume 24, Issue 4 - Aug 2003
Volume 24, Issue 3 - Jun 2003
Volume 24, Issue 2 - Apr 2003
Volume 24, Issue 1 - Feb 2003
Selecting the target year
Effects of Cooling Method Followed by Casting on the Interfacial and Mechanical Properties of Dental CP-Ti Casts
Journal of Biomedical Engineering Research, volume 24, issue 5, 2003, Pages 375~380
In this study. we have intended to control the properties of surface reaction zone generated between pure titanium and oxide investment moulds. Commercially pure titanium was centrifugally casted and silica
alumina based phosphate bonded investment was used as the mould material. The effect of cooling methods after casting on the surface reaction zone and mechanical properties of casts were investigated. The resulting casts showed the multilayered surface reaction zone regardless of cooling method. Especially. water cooling method produced the titanium casts with thinner surface reaction zone. weaker strength. and higher elongation properties compared to air cooling. It can thus be known that the resulting casts had satisfactory mechanical properties as dental materials. From these results, the cooling rate dependence of interfacial and mechanical properties can be attributed to the diffusion of oxygen from casting environment, which control the reaction of titanium and mould.
Design of Head Blood Pressure(HBP) Measurement System and Correlativity Extraction of Blood Pressure(BP) and HBP
Journal of Biomedical Engineering Research, volume 24, issue 5, 2003, Pages 381~389
Various adult diseases (cerebral apoplexy, athymiait, etc.) result from hypertension, blood circulation disturbance and increment of HBP. In early diagnosis of these diseases, MRI, X-ray and PET have been used rather aim for treatment than for a prevention of disease. Since. cerebral apoplexy and athymiait could appear to the regular/irregular persons, it is very important to measure HBP which has connection with cerebral blood flow state. HBP has more diagnosis elements than that of BP. So, we can diagnose accurate hypertension by measuring of HBP. But, existing sphygmomanometers and automatic BP monitors can not measure HBP, and can not execute complex function(measuring of BP/HBP, blood flow improvement). Purpose of this paper is to develop a system and algorithm which can measure BP/HBP for accurate diagnosis. Also, we extracted diagnosis factors by correlativity analysis of BP/HBP. Maximum pressure of HBP corresponds to 62% that of BP, Minimum pressure of HBP corresponds to 46% that of BP. Therefore, we developed the multi-function automatic blood pressure monitor which can measure BP/HBP and improve cerebral blood flow state.
Enhancement of Gas Transfer Efficiency in an Intravascular Lung Assist Device using Blood Substitutes
Journal of Biomedical Engineering Research, volume 24, issue 5, 2003, Pages 391~399
Intravascular oxygenation represents an attractive. alternative support modality for therapy originated with acute respiratory distress syndrome(ARDS). However. the clinical study concluded that more gas exchange was needed for intravascular oxygenation to be clinically effective in ARDS treatment. In this study, we tried to enhance gas exchange on the VIVLAD using microencapsulation of hemoglobin and perfluorocarbon emulsion(PFC emulsion). Blood gas measurements were performed by collecting blood samples from the arterial and venous sides of the circuit, and processing them in a blood/gas analyzer. The function of hemosome. blood/hemosome mixed solution. and blood/PFC emulsion mixed solution were tested by an oxygen dissociation curve using a blood/gas analyzer. As a result, it was shown that the oxygen transfer of hemosome and blood/hemosome mixed solution were higher than that of whole blood. Also. it showed that the carbon dioxide transfer of whole blood/PFC emulsion mixed solution was higher than that of others. Therefore, we determined that hemosome and PFC emulsion could increase oxygen transfer and carbon dioxide transfer. respectively.
A Biomechanical Study on a New Surgical Procedure for the Treatment of Intertrochanteric Fractures in relation to Osteoporosis of Varying Degrees
Journal of Biomedical Engineering Research, volume 24, issue 5, 2003, Pages 401~410
This study investigates the biomechanical efficacies of various cement augmentation techniques with or without pressurization for varying degrees of osteoporotic femur. For this study, a biomechanical analysis using a finite element method (FEM) was undertaken to evaluate surgical procedures, Simulated models include the non-cemented(i.e., hip screw only, Type I), the cement-augmented(Type II), and the cemented augmented with pressurization(Type III) models. To simulate the fracture plane and other interfacial regions, 3-D contact elements were used with appropriate friction coefficients. Material properties of the cancellous bone were varied to accommodate varying degrees of osteoporosis(Singh indices, II∼V). For each model. the following items were analyzed to investigate the effect surgical procedures in relation to osteoporosis of varying degrees : (a) von Mises stress distribution within the femoral head in terms of volumetric percentages. (b) Peak von Mises stress(PVMS) within the femoral head and the surgical constructs. (c) Maximum von Mises strain(MVMS) within the femoral head, (d) micromotions at the fracture plane and at the interfacial region between surgical construct and surrounding bone. Type III showed the lowest PVMS and MVMS at the cancellous bone near the bone-construct interface regardless of bone densities. an indication of its least likelihood of construct loosening due to failure of the host bone. Particularly, its efficacy was more prominent when the bone density level was low. Micromotions at the interfacial surgical construct was lowest in Type III. followed by Type I and Type II. They were about 15-20% of other types. which suggested that pressurization was most effective in limiting the interfacial motion. Our results demonstrated the cement augmentation with hip screw could be more effective when used with pressurization technique for the treatment of intertrochanteric fractures. For patients with low bone density. its effectiveness can be more pronounced in limiting construct loosening and promoting bone union.
Computer Interface for the Disabled Using Gyro-sensors and Artificial Neural Network
Journal of Biomedical Engineering Research, volume 24, issue 5, 2003, Pages 411~419
This paper aims at developing 'gyro-mouse' which provides decent and comfortable human-computer interface that supports the usage of such software as an internet-browser in PC for the people paralyzed in upper limbs. This interface operates on information collected from head movement to get the cursor control. The interface is composed of two modules. One is hardware module in which the head horizontal and vertical angular velocities are detected and transmitted into PC. The other is a PC software that translates the received data into movement and click signals of the mouse. The ANN (artificial neural network) learns the quick nodding pattern of each user as click input so that it can provide user-friendly interface. The performance of the system was evaluated by three indices that are click recognition rate. error in cursor position control. and click rate of the moving target box. The performance result of the gyro-mouse was compared with that of the optical-mouse to assess the efficiency of the gyro-mouse. The average click recognition rate was 93%, average error in cursor position control was 1.4∼5 times of optical mouse. and the click rate with 50 pixels target box was 40%(30 clicks/min) to that of optical mouse. The click rate increased monotonously with the number of trial from 35% to 44%. The suggested system is expected to provide a new possibility to communicate with the society.
Analysis of Dural-sac Cross Sectional Area Changes According to Vertical Impact rate
Journal of Biomedical Engineering Research, volume 24, issue 5, 2003, Pages 421~425
In this study the occlusion of dural-sac. the outer membrane of spinal cord in the lumbar region. was quantitatively analyzed using one motion segment finite element model. Occlusion was quantified by calculating cross sectional area change of dural-sac for different compressive impact duration (loading rate) due to bony fragment at the posterior wall of the cortical shell in vertebral body. Dural-sac was occluded most highly in the range of 8∼12 msec impact duration by the bony fragment intruding into the spinal canal.
t = 400 msec case 4 % cross sectional area change was calculated. which is the same as the cross sectional area change under 6 kN of static compressive loading.
A Study on Development of ECS for Severly Handicaped
Journal of Biomedical Engineering Research, volume 24, issue 5, 2003, Pages 427~434
In this paper, we present a speech-based Environmental Control System(ECS) and its application. In the concrete, an ECS using the speech recognition and an portable wheelchair lift control system with the speech synthesis are developed through the simulation and the embodiment. The developed system apply to quadriplegic man and we evaluate the result of physical effect and of mental effect. Speech recognition system is constructed by real time modules using HMM model. For the clinical application of the device, we investigate the result applied to 54-years old quadriplegic man during a week through the questionnaires of Beck Depression Inventory and of Activity Pattern Indicator. Also the motor drive control system of potable wheelchair lift is implemented and the mechanical durability is tested by structural analysis. Speech recognition rate results in over 95% through the experiment. The result of the questionnaires shows higher satisfaction and lower nursing loads. In addition, the depression tendency of the subject were decreased. The potable wheelchair lift shows good fatigue life-cycle as the material supporting the upper wheelchair and shows the centroid mobility of safety. In this paper we present an example of ECS which consists of real-time speech recognition system and potable wheelchair lift. Also the experiments shows needs of the ECS for korean environments. This study will be the base of a commercial use.
Balance Recovery Mechanisms Against Anterior Perturbation during Standing
Journal of Biomedical Engineering Research, volume 24, issue 5, 2003, Pages 435~442
In this paper, biomechanical aspects of dynamic대학교postural responses against forward perturbations were experimentally determined simultaneous measurements of joint angles, accelerations. EMG activations, center of pressure(CoP) movements and ground reaction forces(GRF), Thirteen young healthy volunteers, stood on a flat platform, were translated into the forward direction by an AC servo-motor at two separate velocities(0.1m and 0.2m/s). In order to recover postural balance against the forward perturbation, joint motions were observed in the sequence of the ankle dorsiflexion, the knee flexion and then the hip flexion during the later acceleration phase. Both acceleration patterns at the heel and the sacrum were shown the forward acceleration pattern during the later acceleration phase and early of constant velocity phase as increasing platform velocity, respectively. Tibialis anterior(TA) for the ankle dorsiflexion and biceps femoris(BF) for the knee flexion. the primary muscle to recover the forward perturbation, was activated during the half of acceleration phase. Ankle strategy was used for slow-velocity perturbation, but mixed strategy of both ankle and hip used for the fast-velocity perturbation. In addition, parameters of perturbation such as timing and magnitude influenced the postural response against the perturbation.
A Study on the Adduction and Abduction Measurement of Children with Spastic Cerebral Palsy for the Development of Multi-axial Lower Extremity Orthosis
Journal of Biomedical Engineering Research, volume 24, issue 5, 2003, Pages 443~446
In the present study. the design of multi-axial lower extremity orthosis was presented with adduction and abduction force data which were measured from three children with cerebral palsy and a normal child. The measurements of adduction and abduction forces were conducted in standing and wolking condition. Adduction and abduction forces were measured by strain gages which were attached on the lateral uprights of lower extremity orthoses. In the standing condition. addcution force of childrens was distributed from 0.11 kgf to 0.26 kgf. During the walking condition. adduction force was reached to 1.56 kgf and abduction force was reached to 1.52 kgf.
Analysis of Bone-Remodeling Process Using Quasi-molecular Dynamics
Journal of Biomedical Engineering Research, volume 24, issue 5, 2003, Pages 447~451
A new method for analyzing the bone-remodeling process using quasi-molecular dynamics was proposed in this study. The effect of pressure due to bone marrow, which could not be considered in previous methods, was also considered in this method. Bone-remodeling response of the 2D vertebral body of lumbar spine to a uniaxial compressive displacement of 1.8564mm. corresponding to approximately 2kN of compressive load, was studied. Converged shape change of the cortical shell and rearrangement of cancellous bone structure matched well with a normal shape of the vertebral body. The calculated responses in the spinal elements also shows closed results compared with experimental results.
Identification of Sound Source Location Generated by Shock Wave for Medical Treatment
Journal of Biomedical Engineering Research, volume 24, issue 5, 2003, Pages 453~458
When the piezoelectric extracorporeal shock wave lithotripter is operated. sounds are generated. In this paper, we present a fact that the sounds are radiated undoubtedly from the object to be hit by the shock waves. For this results. we use the method to identify the sound source location of the radiated sounds by estimating the distance and the bearing from the sound source using one hydrophone. In addition. we investigate the relation between the radiated sounds and the vibrations of the objects using bronze models of disc type with clear vibrating characteristics and present the results of experiments to be analyzed.
Reconstruction of Myocardial Current Distribution Using Magnetocardiogram and its Clinical Use
Journal of Biomedical Engineering Research, volume 24, issue 5, 2003, Pages 459~464
The source current distribution in a heart was reconstructed from the magnetocardiogram (MCG) and its clinical usefulness was demonstrated. MCG was measured using 40-channel superconducting quantum interference device (SQUID) gradiometers for a patient of Wolff-Parkinson-White (WPW) syndrome, which has an accessory pathway between the atria and the ventricles. Reconstruction of source current distribution in a plane below the chest surface was performed using minimum norm estimation (MNE) algorithm and truncated singular value decomposition (SVD), In the simulation, we confirmed that the current distributions. which were computed for the test dipoles, represented well the essential feature of the test current configurations, In the current map of WPW syndrome, we observed abnormal currents that would bypass the atrioventricular junction at a delta wave. However, we could not observe such currents any more after the surgery. These results showed that the obtained current distribution using MCG signals is consistent with the electrical activity in a heart and has clinical usefulness.
Chronic Stress Evaluation using Neuro-Fuzzy
;;;;;;;Hiroko Takeuchi;Haruyuki Minamitani;
Journal of Biomedical Engineering Research, volume 24, issue 5, 2003, Pages 465~471
The purpose of this research was to evaluate chronic stress using physiological parameters. Wistar rats were exposed to the sound stress for 14 days. Biosignals were acquired hourly. To develop a fuzzy inference system which can integrate physiological parameters. the parameters of the system were adjusted by the adaptive neuro-fuzzy inference system. Of the training dataset, input dataset was the physiological parameters from the biosignals and output dataset was the target values from the cortisol production. Physiological parameters were integrated using the fuzzy inference system. then 24-hour results were analyzed by the Cosinor method. Chronic stress was evaluated from the degree of circadian rhythm disturbance. Suppose that the degree of stress for initial rest period is 1. Then. the degree of stress after 14-day sound stress increased to 1.37, and increased to 1.47 after the 7-day recovery period. That is, the rat was exposed to 37%-increased amount of stress by the 14-day sound and did not recover after the 7-day recovery period.
Fast Implementations of Projector-Backprojector Pairs for Iterative Tomographic Reconstruction
Journal of Biomedical Engineering Research, volume 24, issue 5, 2003, Pages 473~480
Iterative reconstruction methods have played a prominent role in emission computed tomography due to their remarkable advantages over the conventional filtered backprojection method. However, since iterative reconstructions typically are comprised of repeatedly projecting and backprojecting the data, the computational load required for reconstructing an image depends highly on the performance of the projector-backprojector pair used in the algorithm. In this work we compare quantitative performance of representative methods for implementing projector-backprojector pairs. To reduce the overall cost for the projection-backprojection operations for each method, we investigate how previously computed results can be reused so that the number of redundant calculations can be minimized. Our experimental results demonstrate that the ray tracing method not only outperforms other methods in computation time, but also provides improved reconstructions with good accuracy.