Three-dimensional steady and pulsatile flow experiments and numerical simulations have conducted to investigate the flow characteristics in the aortic bifurcation model. In vitro velocity measurements were made using both laser Doppler anemometry and pulsed Doppler ultrasound velocimetry. In this study, flow phenomena in the aortic bifurcation model are discussed extensively and the numerical results are compared with experimental results.

A biomechanical study was made to demonstrate the superior mechanical performance of the newly designed Miniplate staple to the conventional Coventry staple in high tibial osteotomy(HTO). Using twenty fresh porcine tibiae, the fixational strengh of the two different types of staple in HTO was compared. To minimize the error due to the specimen-to-specimen individuality, the bone mineral density of the tibiae was measured with a bone densitometry (Dual photon absorptionometer, Luner, USA) and those with $0.8\;{\sim}\;1.2\;gm/cm^2$ at the proximal tibia was used in the biomechanical test. Testing was performed on a material testing system (Autogram ET-5, Shimatzu, Japan) with aid of a commercial data processor (IBM 80386/ ASYST). Using two differant loading modes, 'pull-out' and 'push-out', the maximum resistant force required to release the staple from the substrate bone was recorded. In the pull-out test, ten non-osteotomized specimens were used and the staple was pullout by subjecting an axial tension on the head of the staple inserted. While in the pull-out test where ten tibiae osteotomized in the usual way of HTO were used, the staple was not directly loaded. In this testing, as a mimic condition of the natural knee, the distal part of the specimen tibia was pushed horizontally in order for the staple to be pulled out while the proximal tibia was fixed. The pull-out strength of Coventry staple and miniplate staple were found to be $27.88\;{\pm}\;5.12\;kgf$ and $182.47\;{\pm}\;32.75\;kgf$, respectively. The push-out strength of Coventry staple and miniplate staple were $18.40\;{\pm}\;4.47\;kgf$ and $119.95\;{\pm}\;19.06\;kgf$, respectively. The result revealed that miniplate staple had the pull-out/ push-out strength at least fivetimes higher than Coventry staple. Based on the measured data, it was believed that the newly designed miniplate staple could provide much better postoperative fixation in HTO. The postoerative application of long leg casting may not be needed after HTO surgery.

The objectives of the present study are 1)to find the effect of the diameter of transpedicular screws on their fixational strength in pedicles under static pull-out loading, 2)to determine the biomechanical correlation between the pedicle diameter and the screw diameter, and 3)to find the effects of other factors in the screw design, such as materials, screw pitch, thread height and shape on their fixational strength. Biomechanical tests (Test I) were performed to evaluate the effect of the screw diameter on pull-out strength by using 60 porcine pedicls and six groups of custom-made pedicle screws with different diameters (the major and the minor diameter of the screws used in the testing varied from 4mm upto 9mm and from 3mm upto 8mm, respectively) while all other factors (materials, screw pitch, thread height and shape etc.) were fixed. In Test II, by using 61 porcine pedicles, the relationship between the ratio of the pedicle diameter and the screw diameter(=aspect ratio) of the custum-made screw and the pull-out strength of the screw was investigated. Test III was performed with 94 porcine pedicles and 8 different types of the commercial screws from 6 major productors in order to determine the effect of the screw diameter, pitch and the thread shape on the pull-out strength of the screw, respectively. The results of Test I showed that the axial pull-out resistance of the screw could be increased prportionaly to the screw diameter(P<0.05). But this increase in the pull-out resistance did not found when the screws of 4mm or 9mm in the diameter were employed. It was found from the results of Test II that the screws had its maximum pull-out resistant force when the aspect ratio ranging 40 - 69% (P<0.05). based on the results for the major diameter against the minor diameter of screw, the maximal pull-out resistance was found at 60-65% (P<0.05). According to these biomechanical testing results, it seems that the screw with a moderately large pitch is more desirable and the buttress-shaped screw can provide stronger fixation than the V-shape one can, if other designal factor and conditions were fixed.

A time-dependent large deformation fracture theory is developed for application to soft biological tissues. The theory uses the quasilinear viscoelastic theory of Fung, and particularizes it to constitutive assumptions on polyvinyl-chloride (PVC) (Part I) and cartilage (Part II). This constitutive theory is used in a general viscoelastic theory by Christensen and Naghdi and an energy balance to develop an expression for the fracture toughness of the materials. Experimental methods are developed for measuring the required constitutive parameters and fracture data for the materials. Elastic stress and reduced relaxation functions were determined using tensile and shear tests at high loading rates with rise times of 25-30 msec, and test times of 150 sec. The developed method was validated, using an engineering material, PVC to separate the error in the testing method from the inherent variation of the biological tissues. It was found that the the proposed constitutive modeling can predict the nonlinear stress-strain and the time-dependent behavior of the material. As an approximation method, a pseudo-elastic theory using the J-integral concept, assuming that the material is a time-independent large deformation elastic material, was also developed and compared with the time-dependent fracture theory. For PVC. the predicted fracture toughness is $1.2{\pm}0.41$ and $1.5{\pm}0.23\;kN/m$ for the time-dependent theory and the pseudo-elastic theory, respectively. The methods should be of value in quantifying fracture properties of soft biological tissues. In Part II, an application of the developed method to a biological soft tissue was made by using bovine humeral articular cartilage.

In this paper, we proposed the 2-stage ultrasound liver image classifier which uses the fractal dimensions obtained from the original image and its 1/2 subsampled image, and the Normalized Fourier Power Spectrum. The fractal dimension based on Fractional Brownian Motion (FBM) is calculated from the variance of the same scale pixels instead of the mean of them. Since the actual ultrasound. liver images does not fully match the FBM, to get the fractal dimension, we use the scale vectors which satisfy the FBM model. In 2-stage classifier, we first classified normal and diffuse liver and then classified the fat liver and cirrhosis from the diffuse liver. For the test liver images. 70% of normal liver and 80% of fat liver and 90% of cirrhosis is classified classified with our 2-stage classifier.

The original DANTE sequence and its variations have limitation in excitation profile (a sinc function-like excitation) due to the finite duration of the DANTE pulsetrain. This sinc function-like selection profile excites only a small fraction of the spins in the pixel thereby results in poor signal to noise ratio (only about ${\sim}1%$ of normal MR imaging sequence). Therefore, this poor signal to noise ratio (SNR) has been the main drawback of the original DANTE sequence. To improve the signal to noise ratio, phases of individual RF pulses in the DANTE pulse train were modulated so that more spins in the object were excited ($1{\sim}3$). We have introduced a new FM (Frequency Modulation) DANTE sequence and analyzed the signal intensity and excitation profiles.

Visualization of three dimensional medical images has been studied in many ways. For CT and MRI data, 3D rendering schemes are commercially available and widly used. However visualization of ultrasonic 3D data is not popular yet, even though its potentional in medical diagnosis seems very high. In this paper we try to visualize 3D ultrasonic data. The basic method is adopted from the volume rendering technique. Based on the characteristics of the ultrasonic images, 3D visualization algorithm is developed and applied for the 3D image set of a dog heart.

In this paper, we classify between the chromosome and blood cell, and find the location of chromosome. First, the gray level images be the binary images using the threshold method. Then, the spot noises are removed by the morphological filtering. Features are obtained using the updated Run length(RL) coding and are classified using the Bayes decision rule. The performances of classification are 83.3% in chromosome and 93.3% in blood cell. Because each sub-images ($256{\times}256$) is obtained from the full image($512{\times}512$), we realize the location of chromosome if we get the corrected chromosome classifications.

An implementation scheme of the magnetic nerve stimulator using a switching mode power supply is proposed. By using a switching mode power supply rather than a conventional linear power supply for charging high voltage capacitors, the weight and size of the magnetic nerve stimulator can be considerably reduced. Experimental results of human nerve stimulations using developed stimulator are presented.

The grabber used for the manipulation of single cell is developed by employing the piezo actuator as a source of grabbing force and this system consists of sucking cylinder, XYZ stage and inverted microscopy. With this grabbing system, 2 experiments are performed and they are as follows; 1) the relation between displacement change of piezo actuator and applied voltage was estimated by using sucking cylinder, 2) we grabbed plotoplast of cabbage's leaf-cell with this system. These experiments showed that the proposed grabbing system can be applicable as a single cell handling device in the field of biotechnology and medicine.

전산화폐활량계를 국산화하기 위하여 호흡기류 계측시스템을 개발하였다. 호흡기류를 측정하는 방법으로 Pneumotachography를 적용하였다. 자체 Pneumotachometer를 설계, 제작하였고, 증폭기와 필터를 통하여 0 - 5 V 범위의 기류신호가 출력되도록 하였다. 온도보정을 위하여 기류의 온도를 K-type 열전쌍으로 연속측정하여 보정신호를 역시 0 - 5 V 범위로 제공하도록 제작하였으며 따라서 온도에 따른 측정오차를 근본적으로 제거하였다. 피검자의 감염 가능성을 최소화하기 위하여 환기기구를 사용하였으며 전력소모가 적고 미세균의 제거가 가능하다. 본 시스템의 특성 측정 결과 충분히 우수한 정특성과 동특성을 얻었으며 현재 호흡기류를 정량분석하는 S/W-시스템을 개발중이다.

A low-noise pre-amplifier is developed for use in Topographic Brain Mapping system. It consists of signal generator, signal amplifier with a impedance converter, shield driver, body driver, differential amplifier, and isolation amplifier. Pre-amplifier circuit is designed with the concept of isolation and active body and shield driver. This amplifier shows the good noise behavior, high CMRR, high input impedance, low leakage current and high IMRR.

본 연구에서는 슬라이딩 모드를 전기유압식 심실보조기의 직류모터제어기의 속도와 위치제어에 적용하였다. 슬라이딩 모드 컨트롤은 가변구조시스템(varaiable sturucture system)의 일종으로 적절한 내부스위칭 논리를 갖는 연속적인 부시스템(subsystem)의 모임으로 구성된다는 접에서 고정된 제어구조를 갖는 일반적인 제어시스템과 다르다. 이 시스템은 불연속적인 동적시스템이나 시변적인 요소를 갖는 시스템등에서 사용되고 있다. 이 논문에서는 슬라이딩 모드 제어를 적용하여 좌심실보조기를 제어하는 경우에 넓은 작동범위에서도 시스템이 안정적이며 혈류역학적인 외란에 대해서도 기준입력에 대한 속도의 추종이 잘 이루어지는지의 여부를 실제의 구현에 앞서 컴퓨터모델을 통해 검증하고 문제점들을 조사하였다.

Using electrocardiography is a common method to diagnose heart disease, Modeling and simulation of activation process for the heart system is useful to understand electrocardiography. This paper proposes a two-dimensional cellular automata model for the activation process of the ventricles. The model represents the geometry of the ventricles by the ellipsoidal shape in two dimension. In the model, ventricles are divided into four layers, each of which has a set of cells with preassigned properties. The proposed model takes Into account the local orientation of the myocardial fibers and their distributed velocity, and refractory period. Simulation experiment is performed to measure activation potential for each cell in each layer within the ventricles.

Combined models, specified by two or more modeling formalisms, can represent a wide variety of complex systems. This paper describes a methodology for the development of combined models in two model types of discrete events and continuous process. The methodology is based on transformation of continuous state space into discrete one to homomorphically represent dynamics of continuous processes in discrete events. As an example, a combined model of human heart is developed which Incorporates conventional differential equation formalism with Zeigler's DEVS(Discrete Event Specification System) [4]formalism.

This study investigated the effects of mechanical factors involved in several corneal refractive surgeries on the surgical outcomes. Then we proposed possible new techniques from the mechanical point of a view utilizing finite element method. The models studied are: circumferential keratetomy, combination of excimer laser photorefractive keratectomy and circumferential keratotomy for myopia treatment, arcuate keratotomy for astigmatism treatment. The cornea was assumed to be nonlinear elastic and almost incompressible material as the most soft tissue in the human body. In the circumferential keratotomy the effect of the incision location was investigated. The angle and location of the incision were varied to predict the surgical outcomes in the arcuate keratotomy. The finite element analysis results showed that the location of incision was a critical factor affecting the surgical outcomes in the circumferential keratotomy. In the combination of the excimer laser photorefractive keratectomy and circumferential keratotomy, it was predicted that the circumferential can increase or decrease the refractive power depending on the incision location or it can be used to adjust the overcorrection of undercorrection. In the arcuate keratotomy for astigmatism, the most diopter changes were predicted when the location and the angle of the incision were 3.0mm from the apex and $90^{\circ}$, respectively. In the arcuate keratotomy, the effects of an incision were studied within the incision area as well as outside the incision area. Also, the arcuate keratotomy with two incisions located on the opposite area of the cornea was also studied. As a conclusion, the finite element method is a useful technique in the area of corneal refractive surgeries to develop new techinques.

Von Mises stress and compliance distribution was evaluated using a finite element analysis on the anastomosis of an artery with length of 20mm, inner diameter of 4mm, thickness of 0.5mm and a PTFE graft with length of 5.7mm, Inner diameter of 2mm. thickness of 0.2mm. When anastomotic angle was taken as $45^{\circ}$ and inner pressure of $1330\;dyne/mm^2$ was applied inside the 2 conduits. From the analysis results were obtained as follows. (1)Artery diameter increased in both horizontal x and vertical y directions and the magnitude of that in x direction was bigger than in y direction. (2) The compliance was maximum on the anastomosis. especially on that with acute angle. This reduced approaching to the right or left end. (3) The equivalent stress was maximum on top in the y direction and winimum on the nodes around $110^{\circ}$ in circumferential direction from the top. (4) The equivalent stress was maximum in the vicinity of anastomosis with acute angle along the longitudinal direction of the artery. This trend was also observed along the PTFE graft.

The three dimensional, steady flows of blood and blood analogue fluids in the abdominal aortic bifurcation are simulated using the finite volume method. The objective of this investigation is to understand the generation and progression of site-specific atherosclerosis from a hydrodynamic point of view. Due to complexity of blood in conducting experimental study, aqueous polymer solutions are used as the substitutional fluids. For comparison purpose of the flow characteristics of blood and substitutional fluids, rheologically different fluids such as water soluble polymers of Carbopol-934 and Separan AP-273 are employed for the numerical simulation. In order to understand the role of hydrodynamics in the formation and development of atherosclerosis lesions flow velocities, pressures and shear stresses along the vessel are calculated for steady flows.

Steady and physiological flows of a Newtonian fluid and blood in the bifurcated arterial vessel are numerically simulated. Distributions of velocity, pressure and wall shear stress in the bifurcated arterial vessel are calculated to investigate the differences between steady and physiological flows. For the given Reynolds number physiological flow characteristics of a Newtonian fluid and blood in the bifurcated arterial vessel are quite different from those of steady flows. No flow separation or flow reversal in the bifurcated region in the downstream after stenosis appears during the acceleration phase. Also, no recirculation region is seen for steady flows. However, during the deceleration phase the flow began to exhibit flow reversal, which is eventually extended to the entire wall region.

서울대학교 의공학과에서는 부분적인 심부전 판자의 보조 및 치료장비로 전기유압식 좌심실 보조 장치를 개발하고 있다. 이 장비의 경우 인체의 좌심방 및 대동맥에 직접 연결되므로 실제적으로 좌심실 보조 장치의 박출량을 센서를 통하여 알아내는 데에는 여러가지 어려움이 따른다. 이러한 필요성에 비추어 전기유압식 좌심실 보조 장치의 박출량을 시스템을 ARX모델로 모델링하여 RLS(Recursive Least Square) 알고리듬을 이용하여 추정하였다. 그 결과 비교적 높은 정착도로 박출량이 추정됨을 볼 수 있었다. 하지만, ARX모델의 특성상 원래 본 연구의 시작과정에서 분석한 시스템의 동적 특성을 완전하게 반영할 수 없었다. 앞으로 시스템의 파라미터 추정 과정에서 이미 주어진 동적 특성은 고정시키고 나머지 파라미터들만을 추정하는 알고리듬을 개발하는 것도 흥미로운 과제라 할 수 있다.

The purpose of this paper is to improve ultrasound images using motion estimation and recursive filtering. Although averaging without motion correction can make image blurring, the proposed estimation method improves image SNR without motion blurring by recursively averaging images with motion correction. Computer simulation on the proposed method has been performed to improve phantom and ultrasound fish images and the results show the utility of the proposed method.

Chromosome analysis is an important and difficult task for clinical diagnosis, for mutagen dosimetry, and for biological research. It is expensive, time consuming and imprecise when performed manually. Efforts lo automate some or all of the procedures have continued for more than 30 years, with only limited success. An acquiring sample from chromosome group is not solved with automatic method. It is still performed by user. This paper represents the method of an automatic chromosome sample extraction which based on region splitting, and scan converted method.

A three dimensional fractal coding with a perceptually enhanced matching is proposed. Since most of medical images (e.g. computed tomography or magnetic resonance image) have three dimensional character, the searching region is extended to adjacent slices. For perceptually enhanced matching, a high frequency booster filter is used for prefiltering of the original image, and the least mean square error matching is applied to this edge enhanced image rather than the original image. From the simulation with the magnetic resonance images ($255{\times}255$, 8bits/pixel). the proposed algorithm provides excellent image quality with compression rations higher than 10. Compared to existing fractal coding the algorithm also provides better subjective image quality with higher compression ratio.

스크린-필름 X선 유방조영술(Screen-film X-ray mammography)은 유방암 진단을 위한 기준이 되는 방법으로 독보적인 위치를 차지하고 있다. 그러나 현재 사용되는 스크린-필름 방식 유방조영술은 여러 가지 한계점들이 인식되어 왔으며, 만약 유방 X선 사진(mammogram)이 디지탈 형식으로 곧 바로 얻어진다면 영상의 질(image quality)과 방사선량의 감소 가능성 관점에서 향상될 수 있다는 증거가 있다. 본 논문에서는, 디지탈 유방조영술에 대한 논리적 근거가 제시되고, 스크린 대용으로 개발되고 있는 X-선 검출기들과 이들을 사용한 여러가지 디지탈 유방조영술 시스템들을 분석 전망한다. 디지털 유방조영술을 실용화하기 위해 해결되어야 할 문제점들이 논의된다.

완전이식 모터구동형 인공심장과 같은 전기에너지를 사용하는 인공장기를 이식한 환자에게 감염의 위험이 없이 안정적인 파워를 공급하기 위한 위하여 연구되고 있는 무선 에너지 전송 시스템 (Trancutaneous Energy Transmission System, TETS)을 개발하였다. 본 연구팀에 의해 개발된 모터구동형 인공심장용 TFT System의 경우, 인공심장의 안정적인 구동을 위해 평균 40Watt에서 최대 90Watt를 전송하여야 하는데, 시스템의 전송효율이 20-50Watt 전송시에는 77%이상이지만 출력이 그 이상으로 증가하면 효율이 떨어지는 문제점이 있다. 이를 해결하기 위해서는 실제 전송장치의 구동회로 및 회로를 구성하고 있는 각 소자들의 성능개선 등이 시도되어야 하나, 근본적으로는 에너지 전달코일을 포함한 전체 시스템의 동작에 대한 분석이 선행되어야 한다. 본 연구에서는 개발된 TFT시스템에 대한 전자기적인 모델링과 해석을 통하여 고출력에서의 효율 감소 억제 및 전체 효율증가를 이루기 위한 조건을 제시하고, 실험을 통하여 향상된 성능을 확인하였다.

A design method that can easily construct intelligent patient monitoring systems is proposed. To achieve the design method, the SES/MB concept and a discrete event-based logic control formalism based on a set theory is introduced. In this control paradigm the controller expects to receive confirming sensor responses to its control commands within definite time windows determined by DEVS model of the system under control. Because data to be used for rule-based symbolic reasoning are to be abstracted, several AI methods are applied the processes. These methods are applied to intelligent patient monitoring systems so that they facilitate transformation from low level raw data to high level linguistic data. Model-based system representations have advantages of reusability, extensibility, flexsibility, independent testability and encapsulation.

An optimal EEG and artifact classifier is proposed using neural network operating characteristics. The neural network operating characteristics are two dimensional parametric representations of the right and false identification probabilities of the network classifier. Since the EEG and EP signals acquired from multi -channel electrodes placed on the head surface are often interfered by other relatively large physiological signals such as electromyogram (EMG) or electroculogram (EOG), the removal of the artifact-affected EEGs is one of the key elements in neuro-functional mapping. Conventionally this task has been carried out by human experts spending lots of examination time. Using the neural-network based classification, human expert's efforts and time can be substantially reduced. From experiments, the neural-network based classification performs as good as human experts: variation of decisions between the neural network and human expert appears even smaller than that between human experts.

The objectives of study are to develop a peripheral device on the endoscopic surgery system. These systems are consist of the following units. They are a color monitor of high resolution, light source, computer system and endoscopic camera with a C-mount head, irrigator, color video printer, Super VHS recorder and a system rack. The color monitor is a NTSC monitor for monitoring the image projected of the surgical section. The lightsource is necessary to irradiate the interior of a body via an optic fiber, The light projector will adapt the brightness in accordance with changing distance from the object. A miniature camera using a color CCD chip and computer system is used to capture and control an image of the surgical section[1]. The video printer is a 300 DPI resolution using thermal sublimation methods, which is developed by Samsung Electronics Co., Ltd. The specification of the endoscopic data management system is consist of storage of a captured image and pathological database of patients [2-4].

A quadrature-channel MODEM using amplitude modulation was constructed. To test the MODEM, 6.4 MHz sinusoidal wave 1 KHz triangular wave were modulated, then the modulated signal was fed into the demodulator, to reconstruct the triangular wave.

This paper relates the occidental constitutional theory to the oriental one, concluding their origins to be similar, and demonstrates a new method of constitutional diagnosis by O-Ring Measurement System Of Muscular Meridians and Laser Constitutional Diagnosis. It establishes Laser Constitutional Diagnosis(L.C.D) using laser beams according to the principles of acupuncture and Sa-Sang constitutional physiology under the effect of spatial morphological energy of geometric isomers. Finally, hypothetical theory of L.C.D. was experimented by the O-Ring Measurement Systems of Muscular Meridians(O-R MSMM). O-R MSMM has been specially devised to improve the manual O-Ring Test prevailing to distinguish energetic response by muscle tonicity. Statistically, it has been proved that the constitutional diagnosis with O-R MSMM was highly effective and objective in the clinical experiences.

Although air, water, and noise pollutions have been widely recognized, electromagnetic forces(EMF) hazard has been rarely recognized as a pollution and very little studies has been done in this country. Thus, in this study electromagnetic forces radiated by various home appliances, once machines, and communication equipments were measured and so were several places radiating strong EMF such as subway stations and electric substations. Among the home appliances microwave oven senates lots of magnetic field and microwaves, and electric mattress does strong magnetic field. In video game room strong magnetic and considerable electric fields were measured. It was observed strong magnetic field inside of electric powered train and very strong magnetic and electric fields on some platforms. Hand-phone and car-phone radiate very hazardous level of microwaves to brain and that they rapidly come into wide use. In this study data base for various electric machines and places radiating strong EMFs were constructed and could be used for future epidemiological studies.

We present a visual programming system for signal analysis; it allows the user to construct signal processing algorithms by assembling visually fundamental signal processing blocks, and to observe the processed signals as well as the original signals in detail by magnifying a portion and measuring the time interval and amplitude between two points. Each fundamental signal processing block is implemented as an independent dynamically linked library module. Therefore, the user can expand the system processing capability by simply adding dynamically linked library modules without restructuring the entire system.

This paper performed P wave detection algorithm for diagnosis in according to method of cardiologist's P wave detection. We used correlation pattern matching for prominent P waves and P-P interval estimation for ambiguous P waves. Results of this study indicate that this algorithm has potential for improving P wave detection performance.

체성-교감 반사 유발시 동맥혈압의 조절에 관여한다고 생각되는 상부 복외측 연수 내의 심혈관계 세포를 대상으로 흥분발사의 반응특성을 측정, 분석하였다. 심장 박동주기와 시간적으로 동기되는 흥분발사를 보이는 심혈관계 세포를 찾은 후 체성-교감 반사의 승압반응과 감압반응을 유발시키며 각각에 대해 동일한 세포의 흥분발사의 변화를 측정한 결과 5가지 유형의 반응특성을 얻을 수 있었다. 이들 간에 구성되어 있는 회로망 연결을 설명하고자 2 가지 종류의 특성 세포와 적절한 자극 전달 경로 및 세포간 회로망 연결을 도입하여 본 연구의 실험결과를 모두 설명할 수 있는 가장 간단한 죄소 세포회로망 모델을 구성하였다. 최소 모델의 고찰 결과 고유한 감압경로의 존재가능성이 도출되었다.

본 연구에서는 피부전기반사를 이용하여 각성도를 측정하기 위한 측정 시스템을 구성하고 이를 이용하여 피부 전기활동의 변화가 뇌파를 동시에 측정하여 각성수준의 변화에 따른 세 측정 요소간의 상관관계를 검토하고 측정에 따른 문제점들을 분석하여 각성도 측정 및 평가와 모니터 개발 을 위한 기초적인 연구를 하였다. 분석 결과 기존의 피부임피던스 만을 이용한 수면상태 판정은 불완전하며 피부임피던스 반사도 포함하면 더욱 정확한 판정을 할 수 있슴을 밝혔다.

In this paper, we study myoelectric signal variation through kyungrak needle stimulation. The signal are detected from two kyunrak route of arm; before and after stimulation of a needle, and before and after needle rotation. The detected signals are analyzed at frequency domain to search a characteristic parameters. At the rotation method, spectrum denity of the signals varies large but spectrum is not detected before and after rotation. We can not see any relation bet ween spectrum variation and rotational direction. As the results, when the same stimulation method is used at two different kyungrak route respectively, it is found that the variation of the myoelectric signal is not same.

Polymers have been developed and applied in many biomedical areas as well as engineering and industrial fields. The first essential to achieve successful development and applications is that properties of such polymer materials would be investigated. In many cases, such investigations are accomplished by observing polymeric behavior arising from the environmental changes such as pH, temperature, and ionic concentration. It has long been known that NMR is extremely sensitive to many biochemical and physical changes occurring in the polymer samples. In the present study we focus our study on NMR Microimaging, which is one of the important NMR applications, to characterize the swelling effect by observing the time dependent spatial variations of polymer specimens. For the samples three kinds of polyvinyl alcohol (PVA) specimens are prepared with different degrees of cross linking density. $^1H$ NMR microimages are acquired as a function of time to visualize the swelling behavior as well as volumetric changes occurring in the specimens. From the acquired time dependent images, the swelling process is exploited.

This paper attempts to examine an optimal method for the chromosome specific vector extraction. Usually, represented method are used with a line segmentation on a chromosome Image. It is not Inaccurate but also needs a long time for the analysis. This paper purpose to aquire specific vector in the image with a using optimal ellipse estimation method. Normally, shapes of chromosomes are curved and too difficult to analyze automatically. A chromosome has a lot of band which looks like an ellipse. If we can estimate their bands with an ellipse, we can reconstruct the sample Which Is straight and can be analyzed easily. We have rearranged a chromosome Image with above proposed. Result shows a reconstructed sample which Is simple for chromosome analysis.

Tri-planar interpolation of the orthogonal digital brain Atlas is proposed to achieve a higher resolution of a volume-metric atlas. With these expanded dataset, the brain mapping will be accomplished with fewer registration errors.

In this paper, we propose an effective coding method of the angiography by using the scalable structure in the frequency domain for MPACS(Medical Picture Archiving and Communication System). We employed the subband decomposition method and MPEG-2 system which is the international standard coding method of the general moving picture. After the subband decomposition is applied to split an input image into 4 bands in the spatial frequency domain, the motion compensated DPCM coding method of MPEG-2 is carried out for each subband. As a result, an easily controllable coding Structure is accomplished by composing the compound hit stream for each subband group. Follows are the simulation results of the proposed sheme for the angiography. A scalable structure which can be easily controlled for a loss of transmission or the band limit can be accomplisbed in the MPEG-2 stucture by the subband decomposition minimizing the side information. And by reducing the search area of the motion vector between -4 and 3, the processing speed of a codec is enhanced by more than two times without a loss of the picture quality compare with the conventional DCT coefficients decompositon method. And the processing speed is considerably improved in the case of the parallel construction of each subband in the hardware.

An experimental investigation was performed under steady flow condition to assess hydrodynamic performance of floating-type monoleaflet polymer valves (MLPV) with different leaflet thickness. The St. Jude Medical valve (SJMV) was also used for comparison tests. Pressure drops of MLPVs are larger than those for other types of polymer valves and mechanical valves. Furthermore, the thicker is the leaflet thickness of a polymer valve, the larger arc the corresponding press drop. The velocity profiles for MLPV reveal a large reversed flow region downward to the valve position. The maximum wall shear stresses of MLPVs at a flow rate of 30 l/min are in the range $54-130\;dyn/cm^2$, and the corresponding maximum. Reynolds shear stresses are in the range of $100-500\;dyn/cm^2$, respectively. Both arc beyond the allowable limit clinically. In contrast, floating-type monoleaflet polymer valves show better hydrodynamic performance in leakage volume. From the designing point of view, it can be concluded that the optimum thickness of leaflet for better hydrodynamic performance is one of the important parameters.

The purpose of this paper is to develop diaphragm-type pneumatic ventricular assist device(VAD) for clinical application and to evaluate its performance through the mock circulation system. The blood housing and diaphragm are made by coating pellethane on the metallic mold and the back plate is made by machining process. The relations of cardiac output(CO) vs. beat rate and CO vs. systolic-to-diastolic rate was estimated through the mock test and hemodynamic waves are recorded for the evaluation of VAD. As a result, the volume of blood pump is 70 ml, maximum CO is 5 L/min and CO has a close relation to the input resistance of blood pump. The hemodynamic data and waves showed this system can be applicable to the animal experiment.

전기 유압식 좌심실 보조기에 있어서 현재 가장 큰 문제점 중의 하나로 지적되고 있는 것은 이완기에 좌심방의 혈액 유입상황을 고려하지 않은 과도한 밀판 당김 속도로 인해 생기는 좌심방의 함몰현상이다. 논문에서는 좌심방의 함몰현상을 구체적으로 정의하고, 좌심방의 함몰여부를 가늠하기 위해 외부에서 관측가능한 요소들과 좌심방의 상태와의 상관관계들을 고찰해 본 다음 이러한 함몰현상을 방지할 수 있도록 이완기 밀판 속도와 이동거리를 능동적으로 변화시키는 방식들을 구성하여 실험을 통해 그 효용성을 검증하였다.

In this study, we present a training method of radial basis function networks based on recursive modified Gram-Schmidt algorithm for single step prediction of chaotic time series. With single step predictions of Mackey-Glass time series and alpha-rhythm EEG which has chaotic characteristics, the radial basis function network trained by this method is compared with one trained by a classical non-recursive method and the radial basis function model proposed by X.D. He and A. Lapedes. The results show the effectiveness of the training method.

중앙 집중식 태아 전자감시 시스템은 태아의 안녕을 판정하는 중요한 평가방법이다. 그러나, 태아감시 시스템은 입력 신호의 장기간의 변동 추이를 검사해야 하며, 따라서 해석하는 사람의 집중력이 쉽게 저하될 수 있다. 컴퓨터를 이용한 태아 감시장치 신호의 자동해석은 분만장의 의사 및 간호사의 업무를 한층 부담없고 손쉽게 할 수 있다. 본 연구에서는 중앙 집중식 태아감시 시스템에서 간단하고 효율적으로 적용할 수 있는 신호 해석 알고리듬을 제시하고, 그에 따른 고속 프로그램을 구현하여 실제 시스템에 적용해 봄으로써 신호 해석 알고리듬의 실효성을 검토해 보고자 한다.

This paper describes a real time QRS detection algorithm. The proposed algorithm detects QRS complex using characteristics of the 2-dimensional phase portrait which is reconstructed from 1-demensional scalar time series. We observe the phase portrait of ECG signal has special trejectory when QRS complex occurs and apply it to detect QRS complexes. In order to evaluate the performance of the proposed algorithm, we use MIT/BIH arrhythmia database. As a result, the proposed algorithm correctly detects 99.3% of the QRS complexes.

This paper describes a complexity measure algorithm based on nonlinear dynamics(chaos theory). In order to quantify complexity or regularity of biomedical signal, this paper proposed fractal dimension-1 and fractal dimension-2 algorithm with digital filter. Approximate entropy algorithm which measure a system regularity are also compared. In this paper investigate what we quantify of biomedical signal. These quantified complexity measure may be a useful information about human physiology.