• Journal of Korean Society of Industrial and Systems Engineering
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• v.35 no.4
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• pp.24-32
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• 2012

Of many approaches to reduce motion analysis errors, the compensation method of anatomical landmarks estimates the position of anatomical landmarks during motion. The method models the position of anatomical landmarks with joint angle or skin marker displacement using the data of the so-called dynamic calibration in which anatomical landmark positions are calibrated in ad hoc motions. Then the anatomical landmark positions are calibrated in target motions using the model. This study applies the compensation methods with joint angle and skin marker displacement to three lower extremity motions (walking, sit-to-stand/stand-to-sit, and step up/down) in ten healthy males and compares their performance. To compare the performance of the methods, two sets of kinematic variables were calculated using different two marker clusters, and the difference was obtained. Results showed that the compensation method with skin marker displacement had less differences by 30~60% compared to without compensation. And, it had significantly less difference in some kinematic variables (7 of 18) by 25~40% compared to the compensation method with joint angle. This study supports that compensation with skin marker displacement reduced the motion analysis STA errors more reliably than with joint angle in lower extremity motion analysis.

• Korean Journal of Computational Design and Engineering
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• v.16 no.6
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• pp.458-466
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• 2011

The morphology of a bone is closely associated with its biomechanical response. Thus, much research has been focused on analyzing the effects of variation of bone morphology with subject-specific models. Subject-specific models, which are generally achieved from 3D imaging devices like CT and MRI, incorporate more of the detailed information that makes a model unique. Hence, it may predict individual responses more accurately. Despite these powerful characteristics, specific models are not easily parameterized to the extent possible with statistical models because of their morphologic complexities. Thus, it is still proven challenging to analyze morphologic variations of subject-specific models across changes due to aging or disease. The aim of this article is to propose a generic and robust parametric morphing method for a subject-specific bone structure. We demonstrate this by using the proposed method on a model of a human proximal femur. Automatic segmentation algorithms are also presented to parameterize the specific model efficiently. A total of 48 femur models were evaluated for defining morphing vector fields. Also, several anatomical and mechanical functions of femur were considered as morphing constraints, and the NURBS interpolating technique was applied in the method to guarantee the generality of our morphed results.

• Journal of Biomedical Engineering Research
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• v.27 no.2
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• pp.64-72
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• 2006

The present study introduces a new cortical patch-based source model for EEG/MEG cortical source imaging to consider anatomical constraints more precisely. Conventional source models for EEG/MEG cortical source imaging have used coarse cortical surface mesh or sampled small number of vertices from fine surface mesh, and thus they failed to utilize full anatomical information which nowadays we can get with sub-millimeter modeling accuracy. Conventional ones placed a single dipolar source on each cortical patch and estimated its intensity by means of various inverse algorithms; whereas the suggested cortical patch-based model integrates whole cortical area to construct lead field matrix and estimates current density that is assumed to be constant in each cortical patch. We applied the proposed and conventional models to realistic EEG data and compared the results quantitatively. The quantitative comparisons showed that the proposed model can provide more precise spatial descriptions of neuronal source distribution.

• Journal of Mechanical Science and Technology
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• v.15 no.7
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• pp.982-994
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• 2001

Commercially available software packages permit to position human models of various geometries in practical scenarios while respecting the anatomical constraints of the skeletal joints and of the bulk of the bodies. Beyond such features, the PAM-Comfort(sup)TM software has been conceived to provide direct access to the muscular forces needed by humans to perform physical actions where muscle force is required. The PAM-Comfort(sup)TM human models are made of multi-body linked anatomical skeletons, equipped with finite elements of the relevant skeletal muscles. The hyper-static problem of determination of muscle forces is solved by optimisation technique. Voluntary stiffening of muscles can be added to the basic contraction levels needed to perform a specific task. The calculated muscle forces obey Hills model. The model and software have been applied in several interesting scenarios of various fields of application, such as car industry, handling of equipment and sports activities.

• Journal of Veterinary Clinics
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• v.37 no.4
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• pp.180-184
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• 2020

The purpose of this study was to report the reliability and validity of oblique single-cut rotation osteotomy (OSCRO) in 3D-reconstructed canine bone models with femoral varus and torsional deformities. A healthy adult male beagle was recruited to create a 3D bone model, and this bone model was modified by using a 3D program. Fifteen bone models were constructed for this study. OSCRO simulation was performed in accordance with the plan after printing using a 3D printing machine. The anatomical lateral distal femoral angle (aLDFA), anteversion angle (AA), anatomical caudo-distal femoral angle (aCdDFA), mechanical caudo-distal femoral angle (mCdDFA) and pre- and postoperative bone length were calculated. There were no significant differences between the target values and postoperative values. In addition, the difference between pre- and postoperative bone length was small (p = 0.001). Our findings suggest that OSCRO could be an effective surgical option for MPL with bone deformities in small-breed dogs that often undergo conventional distal femoral osteotomy.

• Journal of Broadcast Engineering
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• v.28 no.3
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• pp.267-274
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• 2023

There is a problem that the size of the dataset is insufficient due to the limitation of the collection of the medical image public data, so there is a possibility that the existing studies are overfitted to the public dataset. In this paper, we compare the performance of eight (Unet, X-Net, HarDNet, SegNet, PSPNet, SwinUnet, 3D-ResU-Net, UNETR) medical image semantic segmentation models to revalidate the superiority of existing models. Anatomical Tracings of Lesions After Stroke (ATLAS) V1.2, a public dataset for stroke diagnosis, is used to compare the performance of the models and the performance of the models in ATLAS V2.0. Experimental results show that most models have similar performance in V1.2 and V2.0, but X-net and 3D-ResU-Net have higher performance in V1.2 datasets. These results can be interpreted that the models may be overfitted to V1.2.

• Nuclear Engineering and Technology
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• v.54 no.12
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• pp.4698-4707
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• 2022

As part of the ICRP Task Group 103 project, we developed ten thyroid models for the pediatric mesh-type reference computational phantoms (MRCPs). The thyroid is not only a radiosensitive target organ needed for effective dose calculation but an important source region particularly for radioactive iodines. The thyroid models for the pediatric MRCPs were constructed by converting those of the pediatric voxel-type reference computational phantoms (VRCPs) in ICRP Publication 143 to a high-quality mesh format, faithfully maintaining their original topology. At the same time, we improved several anatomical parameters of the thyroid models for the pediatric MRCPs, including the mass, overlying tissue thickness, location, and isthmus dimensions. Absorbed doses to the thyroid for the pediatric MRCPs for photon external exposures were calculated and compared with those of the pediatric VRCPs, finding that the differences between the MRCPs and VRCPs were not significant except for very low energies (<0.03 MeV). Specific absorbed fractions (target ⟵ thyroid) for photon internal exposures were also compared, where significant differences were frequently observed especially for the target organs/tissues close to the thyroid (e.g., a factor of ~1.2-~327 for the thymus as a target) due mainly to anatomical improvement of the MRCP thyroid models.

• Journal of Computational Design and Engineering
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• v.1 no.1
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• pp.1-12
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• 2014

In this paper, we propose a new method of reconstructing the hand models for individuals, which include the link structure models, the homologous skin surface models and the homologous tetrahedral mesh models in a reference posture. As for the link structure model, the local coordinate system related to each link consists of the joint rotation center and the axes of joint rotation, which can be estimated based on the trajectories of optimal markers on the relative skin surface region of the subject obtained from the motion capture system. The skin surface model is defined as a three-dimensional triangular mesh, obtained by deforming a template mesh so as to fit the landmark vertices to the relative marker positions obtained motion capture system. In this process, anatomical dimensions for the subject, manually measured by a caliper, are also used as the deformation constraints.

• Journal of Biomedical Engineering Research
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• v.21 no.5
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• pp.457-467
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• 2000

In this paper, we propose the method to extract the anatomical objects in medical images using active contour models and genetic algorithms. The performance of active contour models is mostly decided by the optimization of active contour model's energy. So, we propose to use genetic algorithms to optimize the energy of active contour models. We experimented our proposed method on the femoral head medical images and proved that our method provides very acceptable results from any initialization of active contour models.

• International Journal of Vascular Biomedical Engineering
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• v.1 no.1
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• pp.32-40
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• 2003

Axillo-bifemoral (Ax-Fem) bypass are now well accepted for bilateral iliac artery occlusion as the second best option. This extra-anatomical (unnatural) bypasses, however, have various hemodynamic liabilities affecting the patency. Hemodynamic conditions of each different type of Ax-Fem bypass were assessed with computer simulation model to determine the hemodynamically more sound type. Simulation models of five different types of Ax-Fem bypass were constructed. Our investigation based on the computer simulation models have shown distinct differences between two most popular Lazy-S type and Inverted-C type on the distribution of flow volume, shear stress and recirculation zone, etc., though both types have shown similar clinical results. Lazy-S type has shown better hemodyanmic status than inverted-C type. The theoretical advantage of "Lazy-S" type has never been adequately proved for its superiority clinically over the inverted-C type. Inverted-C type is now in more favor with clinically better results in spite of many hemodynamic liabilities including retrograde flow to the branching graft. The improvement of over-all long-term patency rate of various extra-anatomical bypasses is still warranted through proper correction of the hemodynamic liability. Even though clinical outcome of the extra-anatomical bypass has been equal regardless of the type of crossover femoral graft configuration, there are distinct differences on the hemodynamic characteristics among various types of configuration. Further hemodynamic study in the pulsatile flow status is warranted to correct hemodynamic defects with proper modification of various hemodynamic factors of each model.