• International Journal of Vascular Biomedical Engineering
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• 제3권1호
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• pp.23-29
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• 2005

We developed a three dimensional cardiac tissue model based on human cardiac cell and mono-domain approximation for action potential propagation. The human myocyte model proposed by ten Tusscher et al. (TNNP model) (2004) for cell electrophysiology and a mono-domain method for electric wave propagation are used to simulate the cardiac tissue propagation mechanism using a finite element method. To delineate non-homogeneity across cardiac tissue layer, we used three types of cardiac cell models. Ansiotropic effect of action potential propagation is also considered in this study. In this 3D anisotropic cardiac tissue with three cell layers, we generated a reentrant wave using S1-S2 protocol. Computational results showed that the reentrant wave was affected by the anisotropic properties of the cells. To test the reentrant wave under pathological state, we simulated a hypertopic model with non-excitable fibroblasts in stochastic manner. Compared with normal tissue, the hypertropic tissue result showed another center of reentrant wave, indicating that the wave pattern can be more easily changed from regular with a concentric focus to irregular multi-focused reentrant waves in case of patients with hypertrophy.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.911-914
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• 2005

Soft tissue characterization and modeling based on living tissues has been investigated in order to provide a more realistic behavior in a virtual reality based surgical simulation. In this paper, we characterize the nonlinear viscoelastic properties of intra-abdominal organs using the data from in vivo animal experiments and inverse FE parameter estimation algorithm. In the assumptions of quasi-linear-viscoelastic theory, we estimated the nonlinear material parameters to provide a physically based simulation of tissue deformations. To calibrate the parameters to the experimental results, we developed a three dimensional FE model to simulate the forces at the indenter and an optimization program that updates new parameters and runs the simulation iteratively. The comparison between simulation and experimental behavior of pig intra abdominal soft tissue are presented to provide a validness of the tissue model using our approach.

• 한국생물정보학회:학술대회논문집
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• 한국생물정보시스템생물학회 2006년도 Principles and Practice of Microarray for Biomedical Researchers
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• pp.30-36
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• 2006

Tissue microarray (TMA) is an array-based technology allowing the examination of hundreds of tissue samples on a single slide. To handle, exchange, and disseminate TMA data, we need standard representations of the methods used, of the data generated, and of the clinical and histopathological information related to TMA data analysis. This study aims to create a comprehensive data model with flexibility that supports diverse experimental designs and with expressivity and extensibility that enables an adequate and comprehensive description of new clinical and histopathological data elements. We designed a Tissue Microarray Object Model (TMA-OM). Both the Array Information and the Experimental Procedure models are created by referring to Microarray Gene Expression Object Model, Minimum Information Specification For In Situ Hybridization and Immunohistochemistry Experiments (MISFISHIE), and the TMA Data Exchange Specifications (TMA DES). The Clinical and Histopathological Information model is created by using CAP Cancer Protocols and National Cancer Institute Common Data Elements (NCI CDEs). MGED Ontology, UMLS and the terms extracted from CAP Cancer Protocols and NCI CDEs are used to create a controlled vocabulary for unambiguous annotation. We implemented a web-based application for TMA-OM, supporting data export in XML format conforming to the TMA DES or the DTD derived from TMA-OM. TMA-OM provides a comprehensive data model for storage, analysis and exchange of TMA data and facilitates model-level integration of other biological models.

• 대한전자공학회논문지
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• 제25권6호
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• pp.654-662
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• 1988

A simple and useful model of light distribution for the biologhical tissue to the Gaussian beam is proposed. This model assumes that the incident Gaussian beam broadens into two Gaussian beams, travelling in the opposite directions as the result of both isotropic scattering and absorption in the tissue. With this assumption, two-dimensional light intensity of each flux as well as the equations of both absorption and scattering have been derived, and the validity of modeling has been confirmed experimentally. Consequently, the results paved a way for easy evaluation of the light distribution in the biological tissue.

• Bulletin of the Korean Chemical Society
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• 제32권11호
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• pp.3967-3972
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• 2011

A whole body physiologically based pharmacokinetic (PBPK) model was applied to investigate absorption, distribution, and physiologic variations on pharmacokinetics of imatinib in human body. Previously published pharmacokinetic data of the drug after intravenous (i.v.) infusion and oral administration were simulated by the PBPK model. Oral dose absorption kinetics were analyzed by adopting a compartmental absorption and transit model in gut section. Tissue/plasma partition coefficients of drug after i.v. infusion were also used for oral administration. Sensitivity analysis of the PBPK model was carried out by taking parameters that were commonly subject to variation in human. Drug concentration in adipose tissue was found to be higher than those in other tissues, suggesting that adipose tissue plays a role as a storage tissue for the drug. Variations of metabolism in liver, body weight, and blood/plasma partition coefficient were found to be important factors affecting the plasma concentration profile of drug in human body.

• 한국운동역학회지
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• 제19권2호
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• pp.197-204
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• 2009

It bas been hypothesized that foot ulceration might be internally initiated. Current instruments which merely allow superficial estimate of plantar loading acting on the foot, severely limit the scope of many biomechanical/clinical studies on this issue. Recent studies have suggested that peak plantar pressure may be only 65% specific for the development of ulceration. These limitations are at least partially due to surface pressures not being representative of the complex mechanical stress developed inside the subcutaneous plantar soft-tissue, which are potentially more relevant for tissue breakdown. This study established a three-dimensional and nonlinear finite element model of a human foot complex with comprehensive skeletal and soft-tissue components capable of predicting both the external and internal stresses and deformations of the foot. The model was validated by experimental data of subject-specific plantar foot pressure measures. The stress analysis indicated the internal stresses doses were site-dependent and the observation found a change between 1.5 to 4.5 times the external stresses on the foot plantar surface. The results yielded insights into the internal loading conditions of the plantar soft-tissue, which is important in enhancing our knowledge on the causes of foot ulceration and related stress-induced tissue breakdown in diabetic foot.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제14권2호
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• pp.671-686
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• 2020

Due to the long training time and high training cost of traditional surgical training methods, the emerging virtual surgical training method has gradually replaced it as the mainstream. However, the virtual surgical system suffers from poor authenticity and high computational cost problems. For overcoming the deficiency of these problems, we propose an optimized model for the local compression deformation of soft tissue. This model uses a simulated annealing algorithm to optimize the parameters of the soft tissue model to improve the authenticity of the simulation. Meanwhile, although the soft tissue deformation is divided into local deformation region and non-deformation region, our proposed model only needs to calculate and update the deformation region, which can improve the simulation real-time performance. Besides, we define a compensation strategy for the "superelastic" effect which often occurs with the mass-spring model. To verify the validity of the model, we carry out a compression simulation experiment of abdomen and human foot and compare it with other models. The experimental results indicate the proposed model is realistic and effective in soft tissue compression simulation, and it outperforms other models in accuracy and real-time performance.

• 한국정밀공학회지
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• 제23권2호
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• pp.15-20
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• 2006

• Current Optics and Photonics
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• 제6권1호
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• pp.92-103
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• 2022

The development of midinfrared (mid-IR) quantum cascade lasers (QCLs) has enabled rapid high-contrast measurement of the mid-IR spectra of biological tissues. Several studies have compared the differences between the mid-IR spectra of colon cancer and noncancerous colon tissues. Most mid-IR spectrum classification studies have been proposed as machine-learning-based algorithms, but this results in deviations depending on the initial data and threshold values. We aim to develop a process for classifying colon cancer and noncancerous colon tissues through a deep-learning-based convolutional-neural-network (CNN) model. First, we image the midinfrared spectrum for the CNN model, an image-based deep-learning (DL) algorithm. Then, it is trained with the CNN algorithm and the classification ratio is evaluated using the test data. When the tissue microarray (TMA) and routine pathological slide are tested, the ML-based support-vector-machine (SVM) model produces biased results, whereas we confirm that the CNN model classifies colon cancer and noncancerous colon tissues. These results demonstrate that the CNN model using midinfrared-spectrum images is effective at classifying colon cancer tissue and noncancerous colon tissue, and not only submillimeter-sized TMA but also routine colon cancer tissue samples a few tens of millimeters in size.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.1665-1668
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• 2008

Arrhythmia causes sudden cardiac death. In the past, there were medical limitations in finding the cause of arrhythmia. As an alternative solution for research of arrhythmia, there have been studies to find the causes of arrhythmia by producing a virtual heart model. Medically, arrhythmia has two main causes: abnormal occurrence of action potential and abnormal conduction of action potential. Based on these, the tachycardia, which is one of the arrhythmia, was manifested and the phenomenon of ventricular fibrillation was numerically analyzed in this study. For this purpose, an electrophysiological model of ventricular cells was implemented, which was subsequently applied to the reaction-diffusion partial differential equation to interpret the macroscopic conduction phenomenon in two-dimensional tissues. The ventricular fibrillation refers to a condition where several irregular waves occur in cardiac tissue, whose generation mechanism is pathologically related to the cardiac tissue.