• Journal of the Korean Society for Precision Engineering
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• v.23 no.2 s.179
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• pp.15-20
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• 2006

• Journal of Biomedical Engineering Research
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• v.19 no.5
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• pp.495-502
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• 1998

A mathematical model of viscoelasticity on the material property of human pharyngeal tissue utilizing Y.C. Fung's Quasi-linear viscoelastic theory is proposed based on cyclic load, stress relaxation, incremental load, and uniaxial tensile load tests. The material properties are characterized and compared with other biological materials' results. The mathematical model is proposed by combining two characteristic functions determined from the stress relaxation and uniaxial tensile load tests. The reduced stress relaxation function G(t) and elastic response function S(t) are obtained from stress relaxation test and uniaxial tensile load test results respectively. Then the model describing stress-time history of the tissue is implemented utilizing two functions. The proposed model is evaluated and validated by comparing the model's cyclic behaviour with experimental results. The model data could be utilized as an important information for constructing 3-dimensional biomechanical model of human pharynx using FEM(Finite Element Method).

• Journal of Veterinary Clinics
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• v.28 no.5
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• pp.486-496
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• 2011

A special mesenchymal tissue layer called perichondrium has a chondrogenic capacity and is a candidate tissue for engineering of cartilage. To overcome limited potential for chondrocyte proliferation and re-absorption, we studied a method of cartilage tissue engineering comprising chondrocyte-hydrogel pluronic complex (CPC) and cultured perichondrial cell sheet (cPCs) which entirely cover CPC. For effective cartilage regeneration, cell-sheet engineering technique of high-density culture was used for fabrication of cPCs. Hydrogel pluronic as a biomimetic cell carrier used for stable and maintains the chondrocytes. The human cPCs was cultured as a single layer and entirely covered CPC. The tissue engineered constructs were implanted into the dorsal subcutaneous tissue pocket on nude mice (n = 6). CPC without cPCs were used as a controls (N = 6). Engineered cartilage specimens were harvested at 12 weeks after implantation and evaluated with gross morphology and histological examination. Biological analysis was also performed for glycosaminoglycan (GAG) and type II collagen. Indeed, we performed additional in vivo studies of cartilage regeneration using canine large fullthickness chondrial defect model. The dogs were allocated to the experimental groups as treated chondrocyte sheets with perichondrial cell sheet group (n = 4), and chondrocyte sheets only group (n = 4). The histological and biochemical studies performed 12 weeks later as same manners as nude mouse but additional immunofluorescence study. Grossly, the size of cartilage specimen of cPCs covered group was larger than that of the control. On histological examination, the specimen of cPCs covered group showed typical characteristics of cartilage tissue. The contents of GAG and type II collagen were higher in cPCs covered group than that of the control. These studies demonstrated the potential of such CPC/cPCs constructs to support chondrogenesis in vivo. In conclusion, the method of cartilage tissue engineering using cPCs supposed to be an effective method with higher cartilage tissue gain. We suggest a new method of cartilage tissue engineering using cultured perichondrial cell sheet as a promising strategy for cartilage tissue reconstruction.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.372-377
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• 2007

For more than 2,500 years, surgical teaching has been based on the so called "see one, do one, teach one" paradigm, in which the surgical trainee learns by operating on patients under close supervision of peers and superiors. However, higher demands on the quality of patient care and rising malpractice costs have made it increasingly risky to train on patients. Minimally invasive surgery, in particular, has made it more difficult for an instructor to demonstrate the required manual skills. It has been recognized that, similar to flight simulators for pilots, virtual reality (VR) based surgical simulators promise a safer and more comprehensive way to train manual skills of medical personnel in general and surgeons in particular. One of the major challenges in the development of VR-based surgical trainers is the real-time and realistic simulation of interactions between surgical instruments and biological tissues. It involves multi-disciplinary research areas including soft tissue mechanical behavior, tool-tissue contact mechanics, computer haptics, computer graphics and robotics integrated into VR-based training systems. The research described in this paper addresses the problem of characterizing soft tissue properties for medical virtual environments. A system to measure in vivo mechanical properties of soft tissues was designed, and eleven sets of animal experiments were performed to measure in vivo and in vitro biomechanical properties of porcine intra-abdominal organs. Viscoelastic tissue parameters were then extracted by matching finite element model predictions with the empirical data. Finally, the tissue parameters were combined with geometric organ models segmented from the Visible Human Dataset and integrated into a minimally invasive surgical simulation system consisting of haptic interface devices and a graphic display.

• Journal of the Korean Society of Radiology
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• v.16 no.2
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• pp.103-113
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• 2022

In this paper, a combined ¹⁸F-FDG(fluorodeoxyglucose) and MNP(magnetic nanoparticles) contrast agent was synthesized using N-(p-maleimidophenyl) isocyanate as the crosslinker for use in simultaneous PET-MRI scans. PET-MRI images were acquired and evaluated before and after injection of the combined contrast imaging agent (¹⁸F-FDG labeled MNP) from a glioma stem cell mouse model. After setting the region of interest (ROI) on each acquired image, the area of the lesion was calculated by segmentation. As a result, the PET image was larger than the MRI. In particular, the simultaneous PET-MRI images showed accurate lesions along with the surrounding soft tissue. The mean and standard deviation values were higher in the MRI images alone than in the PET images or the simultaneous PET-MRI images, regardless of whether the contrast agent was injected. In addition, the simultaneous PET-MRI image values were higher than for the PET images. For PSNR experiments, the original image was PET Image using 18F-FDG, MRI using MNPs, and MRI without contrast medium, and the target image was simultaneous PET-MRI image using 18F-FDG labeled MNPs contrast medium. As a result, all of them appeared significantly, suggesting that the 18F-FDG labeled MNPs contrast medium is useful. Future research is needed to develop an agent that can simultaneously diagnose and treat through SPECT-MRI imaging research that can use various nuclides.

• The Journal of Korean Obstetrics and Gynecology
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• v.33 no.3
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• pp.95-118
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• 2020

Objectives: The objective of this in vivo study is to observe the analgesic effects or improvements of Gyejibokryeong-hwan aqueous extracts (GJBRHe) on the Primary dysmenorrhea (PD) in rats as compared to those of Indomethacin (IND). Methods: The rats were administered with estradiol benzoate for 10 days and oxytocin 1 hour after the last 10th administration of estradiol benzoate to make the primary dysmenorrhea rat model. Gyejibokryeong-hwan aqueous extracts 500, 250 and 125 mg/kg were orally administrated, for 10 days once a day. Then the changes on the body weights and gains during experimental periods, uterine weights and gross inspections, abdominal writhing response for analgesic activities, uterus lipid peroxidation (malondialdehyde (MDA) levels), antioxidant defense system - glutathione (GSH) contents, activities of superoxide dismutase (SOD) and catalase (CAT), Nuclear factor-κB (NF-κB) and Cyclooxygenase (COX)-2 mRNA expressions, were monitored with uterus histopathology and immunohistochemistry for tumor necrosis factor (TNF)-α and inducible nitric oxide synthase (iNOS). The results of Gyejibokryeong-hwan aqueous extracts were compared to those of Indomethacin adminstered rats. Results: As results of estradiol benzoate and oxytocin treatment, noticeable decreases of body weights and gains, uterus GSH contents, SOD and CAT activities, increases of abdominal writhing responses, uterus lipid peroxidation (MDA level), uterus weights, NF-κB and COX-2 mRNA expressions were observed with increases of TNF-α and iNOS immunolabeled cells, inflammatory cell infiltrations, congestion and enlargement of the uterus at gross and histopathological inspections. These means classic inflammatory and oxidative stress mediated primary dysmenorrhea are relatively well induced. However, these signs were favorably and dose-dependently inhibited by administration of three different dosages of Gyejibokryeong-hwan aqueous extracts, but lesser than those of Indomethacin. Conclusions: The results obtained in this study suggest that Gyejibokryeong-hwan aqueous extracts has favorable analgesic and refinement activities dose-dependently on the estradiol benzoate and oxytocin treatment-induced primary dysmenorrhea signs.