• Journal of Biomedical Engineering Research
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• v.23 no.6
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• pp.437-449
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• 2002

Coronary arteries are subjected to very different flow conditions compared to other arteries in systemic blood circulation. We Performed a computational fluid dynamic research to investigate influence of such flow conditions in coronary arteries on development and progress of atherosclerosis in the same. The results showed big differences in the flow field of the coronary artery compared to the abdominal and femoral arteries. The coronary artery showed higher wall shear stresses due to the small vessel diameter. On the other hand, it showed only one vortex distal to the stenosis throat during a whole pulse cycle. However. several vortices were observed in the abdominal and femoral arteries in both proximal and distal sides of the stenosis throat The wall shear stresses and extent of recirculation area were increased with impedance phase angle increasing toward more negative values. Therefore, cardiac contraction and the negative impedance phase angle as large as -110。 may induce a flow field that accelerates atherosclerosis.

• Journal of Biomedical Engineering Research
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• v.23 no.5
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• pp.375-383
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• 2002

Aneurysm embolisation method using coils have been widely used. Micro coils are introduced via a small catheter, and are packed inside of aneurysm sac, which induces intraaneurysmal flow stagnation and thrombus formation. When partial blocking of an aneurysm is inevitable, the location of coils is important since it changes the flow patterns inside the aneurysm, which affect the embolisation process. We measured the flow field inside the partially blocked lateral aneurysm models in vitro, and tried to suggest the effective locations of coils for aneurysm embolisation. Velocity fields are measured using a particle image velocitimeter for different coil locations- proximal neck, distal neck, proximal dome and distal dome. Flow into the aneurysm sac was significantly reduced in the distally blocked models, and coils at distal neck blocked inflow more effectively comparing to those at distal dome. This study suggests that distal neck should be the most effective location for aneurysm embolisation.

• Journal of the Korea Safety Management & Science
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• v.14 no.2
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• pp.41-48
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• 2012

수공구 사용시 과도한 힘은 작업성 근골격계 질환을 일으킬 수 있는 주요 원인중 하나이다. 이와 관련하여, 수공구 파지시 인체 내부에 부과되는 근력과 외적으로 작용된 힘 간의 비율을 이해하는 것이 중요하며, 이는 근육에 부과되는 과도한 힘을 최소화 시키고, 작업에 필요한 힘의 효율성을 극대화 시키는데 필수적이라 할 수 있다. 이러한 비율과 관련하여 많은 연구가 되어 왔으나, 대부분 수리적 인체역학적 모델과 같은 간접적 추정 방법에 의거하고 있는 실정이다. 이러한 인체역학적 모델을 검증하고 개선하기 위하여 해부용 팔 (cadaver)을 활용한 직접적인 근력과 악력 측정이 필수적이다. 본 연구에서는 이러한 해부용 팔을 이용하여 상지 굴근(hand flexor)을 자동으로 제어하고 근력과 함께 악력을 측정할 수 있는 Hand Motion Simulator를 개발하고, 이를 통하여 다양한 사이즈의 손잡이 파지시 요구되는 근력과 외적으로 적용된 악력을 비교함으로써 수공구 손잡이 사이즈에 따른 근력의 효율성에 대하여 측정을 해 보았다. 또한, 적용된 굴근 (FDP & FDS) 간의 힘 비율에 따른 파지법의 차이를 조사해 보았다. 내부에 주어진 근력은 외부로 작용된 악력보다 5.3배 높은 부하가 작용하였으며 이러한 수공구 손잡이 파지시 힘의 효율성 역시 FDP 와 FDS 간의 비율이 3:2 였을 때, 그리고 손잡이 크기가 작을수록 높은 결과를 보였다. 반대로 손잡이의 크기가 커질수록 힘의 효율성은 저하되었다. 또한, 손가락 관절 각도의 경우 FDP와 FDS간의 비율에 따라 상이한 자세를 나타내었다. FDP 굴근의 비율이 높을 경우 손가락 끝마디 관절 (DIP) 의 굴곡을 보였으며, FDS 굴근 비율이 높을 경우 손가락 두 번째 관절(PIP)의 굴곡을 보였다. 본 연구를 통한 결과는 추후 상지작업자에 대한 근골격계 질환 예방 기준안 마련 및 수공구 설계를 위한 기초자료로 활용이 가능할 것으로 보인다.

• Journal of Biomedical Engineering Research
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• v.20 no.3
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• pp.315-321
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• 1999

The purpose of this study is to develop a mathematical model for system identification in order to predIct muscle force based on eledromyographic signal. Therefore, a finding of the relalionship between characteristics of electromyographic signal and the corre spondng muscle force should be necessiiry through dynamic, joint model. To develop the dynamic joint model, the upper limb mcludmg the wrist and elbow joint has been considered. The kinematic and dynamic data, such as joint angular displacement, velocity, deceleration along with the moment of inertla, required to establish the dynamic model has been obtained by electrical flexible goniometer which has two degree-of-frcedoms. ln this model, muscle force can be predicted only electromyographs through the relationship between the integrated lorce and the mtegrated electromyographic signal over the duration of muscle contraclion in this study.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.22 no.6
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• pp.533-539
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• 2009

In this study, the femur, the tibia, the articular cartilage and the menisci are three dimensionally reconstructed using MR images of healthy knee joint in full extension of 26-year-old male. Three dimensional finite element model of the knee joint is fabricated on the reconstructed model. Also, the FE models of ligaments and tendons are attached on the biologically suitable position of the FE model. Bones, articular cartilages and menisci are considered as homogeneous, isotropic and linear elastic materials, and ligaments and tendons are modeled as truss element and nonlinear elastic springs. The numerical results show the contact pressure and the von Mises stress distribution in the soft tissues such as articular cartilages and menisci which can be regarded as important parameters to estimate the failure of the tissues and the pain of the patients.

• Journal of the Korea Computer Industry Society
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• v.8 no.4
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• pp.295-302
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• 2007

Because Mobile computing uses radio transfer communications division carrying along information terminal, internet link computer and information technology of human body effectively, when, where, who, can offer role that is center enemy of available modern technology moving and reconsider new technology to physiological sounding, and reconstruct creatively. Specially, can offer possibility that can intervene in process that motive living body change before military register symptoms are developed of disease on silver society. But, much parameters data processing, standard anger of data of that is vague. same time collection of data can lift difficulty etc.. Therefore, this research excludes time limitation constituent inflecting Mobile computing, and result that analysis experiments because is proper and Mobile nerve mechanical code Tuesday that do with bioelectricity signal method select and embody system by access that become correct analysis, is becomes model of living body signal Mobile analysis device, and person could apply Mobile living body measuring device m-HSS (mobile-Hardware-software system) that measuring is possible by scientific access.

• Journal of Biomedical Engineering Research
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• v.42 no.4
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• pp.167-174
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• 2021

The purpose of this study is to classify TIFF images, PNG images, and JPEG images using deep learning, and to compare the accuracy by verifying the classification performance. The TIFF, PNG, and JPEG images converted from chest X-ray DICOM images were applied to five deep neural network models performed in image recognition and classification to compare classification performance. The data consisted of a total of 4,000 X-ray images, which were converted from DICOM images into 16-bit TIFF images and 8-bit PNG and JPEG images. The learning models are CNN models - VGG16, ResNet50, InceptionV3, DenseNet121, and EfficientNetB0. The accuracy of the five convolutional neural network models of TIFF images is 99.86%, 99.86%, 99.99%, 100%, and 99.89%. The accuracy of PNG images is 99.88%, 100%, 99.97%, 99.87%, and 100%. The accuracy of JPEG images is 100%, 100%, 99.96%, 99.89%, and 100%. Validation of classification performance using test data showed 100% in accuracy, precision, recall and F1 score. Our classification results show that when DICOM images are converted to TIFF, PNG, and JPEG images and learned through preprocessing, the learning works well in all formats. In medical imaging research using deep learning, the classification performance is not affected by converting DICOM images into any format.

• Journal of the Ergonomics Society of Korea
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• v.28 no.3
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• pp.1-6
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• 2009

Recently, importance of the rehabilitation of hand pathologies as well as the development of high-technology hand robot has been increased. The biomechanical model of hand is indispensable due to the difficulty of direct measurement of muscle forces and joint forces in hands. In this study, a three-dimensional biomechanical model of four fingers including three joints and ten muscles in each finger was developed and a mathematical relationship between neural commands and finger forces which represents the enslaving effect and the force deficit effect was proposed. When pressing a plate under the flexed posture, the muscle forces and the joint forces were predicted by the optimization technique. The results showed that the major activated muscles were flexion muscles (flexor digitorum profundus, radial interosseous, and ulnar interosseous). In addition, it was found that the antagonistic muscles were also activated rather than the previous models, which is more realistic phenomenon. The present model has considered the interaction among fingers, thus can be more powerful while developing a robot hand that can totally control the multiple fingers like human.

• Journal of Biomedical Engineering Research
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• v.20 no.5
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• pp.601-608
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• 1999

동맥의 일부분의 팽창하는 동맥류는 높은 사망률을 야기하는 혈관계 질환이다. 동맥류의 발생 및 파열에는 동맥류 내부의 혈류의 유동에 의한 혈관벽 전단 응력 및 압력이 주용한 원인 중 하나로 의심되고 있다. 복부대동맥류 내부의 혈류 유동 특성을 밝히기 위해서 동맥류의 최대 확장부가 복부동맥의 1.5배, 2배인 유리 모델을 제작하였다. 정상류 상태에서 다양한 레이놀즈수에 대해서 속도 및 난동도를 입자영상속도계를 이용하여 측정하였다. 경계층 박리로 인한 재순환 부분이 끝나는 재부착점은 동맥류 최대 확장부 후부에서 발생하였으며, 이 위치는 레이놀즈수의 변화에 따라 바뀌었다. 축방향 속도의 난동은 최대 확장부 후부에서 크게 나타났으며, 이 위치에서 난동에 의한 부가적 응력이 크며 혈관벽 구조변화가 발생하리라 예측된다. 동맥류 내부의 압력분포는 수치해석에 의해 계산되었다. 동맥류 내부 압력은 크기가 증가함에 따라 커졌으며 압력은 동맥류 최대 확장부 후부에서 발생하는 재부착점에서 최대값을 나타내었다. 동맥류 최대확장부 후부는 압력이 최대값을 가지며, 전단력의 변화 및 난동이 큰 지역이므로 동맥류의 파열이 발생하기 쉬운 지역으로 예측된다.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.22 no.6
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• pp.502-508
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• 2012

An analytical model for a human body is important to predict muscle and joint forces. Because it is difficult to estimate muscle or joint forces from a human body, the objective of this study is the development of a reliable analytical model for a human body to evaluate the lower extremity muscle and joint forces. The musculoskeletal system of the human lower extremity is modeled as a multibody system employing the Hill-type muscle model. Muscle forces are determined to minimize energy consumption, and we assume that motion is constrained in the sagittal plane. Muscle forces are calculated through an equilibrium analysis while rising from a seated position. The musculoskeletal model consists of four segments. Each segment is a rigid body and connected by frictionless revolute joints. Muscles of the lower extremity are simplified to seven muscles with those that are not related to the sagittal plane motion are ignored. Muscles that play a similar role are combined together. The results of the present study are compared with experimental results to validate the lower extremity model and the assumptions of the present study.