• Journal of Biomedical Engineering Research
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• v.24 no.6 s.81
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• pp.515-522
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• 2003

Pharynx is a system transporting foods by peristaltic motion(contraction and expansion movement! into the esophagus and functioning as airway passages. In this study, structural changes of pharyngeal dysfunction are analyzed by biomechanical model using CT and FEM(finite clement method). Loading condition was assumed that equal pressure was loaded sequentially to inside of pharyngeal tissue. In order to analyze the pharyngeal muscular dysfunction by biomechanical model. the pharyngeal dysfunctions was classified into 3 cases. Taking into account the clinical complication by neuromuscular symptoms such as pharyngeal dysfunction after stroke. we assumed that a change of material property is caused by muscular tissue stiffness. A deformation of cross sectional area of the pharynx is analyzed increasing the stiffness $25\%,\;50\%,\;75\%$ in each case on the basis of stress-strain relationship. Based on three-dimensional reconstruction of pharyngeal structure using limited factor - techniques and the optimization procedure by means of inverse dynamic approach. the biomechanical model of the human pharynx is implemented. The results may be used as clinical index illustrating the degree of pharyngeal muscular dysfunction. This study may be used as useful diagnostic model in discovering early deglutitory impediment caused by physiological or pathological pharyngeal dysfunction.

• Composites Research
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• v.37 no.4
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• pp.343-349
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• 2024

The use of composite materials for structural fasteners is increasingly common, making it crucial to assess the deformation of these fasteners under fatigue behavior. In this study, clamp-type fasteners were manufactured using carbon fiber reinforced composites, and their structural stability and sectional damage rates were evaluated using electrical resistance measurement during fatigue behavior. While clamp-type composite fasteners exhibited minimal deformation in flat sections, significant deformation occurred in the bent sections due to fatigue. It was observed that insufficient angular stability led to concentrated damage in the bent sections. The dynamic fatigue behavior showed that the length change rate of the composite fasteners was within 0.6%, but the angular change rate reached up to 6%, indicating that the bent sections are the most critical areas. By utilizing the self-sensing capability of the composite fasteners, sectional damage behavior was assessed through electrical resistance measurement. Significant damage was noted in the bent sections due to fatigue, and 3D-CT results revealed substantial deformation and interfacial damage when the initial bend angle of the fasteners was less than 90 degrees. These findings highlight the importance of reinforcing the stiffness of the bent sections and establishing systematic angular standards in the development of composite fasteners.

• Journal of Korean Neurosurgical Society
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• v.61 no.2
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• pp.243-250
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• 2018

Objective : To compare the morphometry of subaxial cervical spine between cerebral palsy (CP) and normal control. Methods : We retrospectively analyzed 72 patients with CP, as well as 72 patients from normal population. The two groups were matched for age, sex, and body mass index. Pedicle, lateral mass (LM), and vertebral foramen were evaluated using computed tomography (CT) imaging. Pedicle diameter, LM height, thickness, width and vertebral foramen asymmetry (VFA) were measured and compared between the two groups. Cervical dynamic motion, disc and facet joint degeneration were investigated. Additionally, we compared the morphology of LM between convex side and concave side with cervical scoliotic CP patients. Results : LM height was smaller in CP group. LM thickness and width were larger in CP group at mid-cervical level. In 40 CP patients with cervical scoliosis, there were no height and width differences between convex and concave side. Pedicle outer diameter was not statistically different between two groups. Pedicle inner diameter was significantly smaller in CP group. Pedicle sclerosis was more frequent in CP patients. VFA was larger in CP group at C3, C4, and C5. Disc/facet degeneration grade was higher in the CP group. Cervical motion of CP group was smaller than those of the control group. Conclusion : LM morphology of CP patients was different from normal population. Sclerotic pedicles and vertebral foramen asymmetry were more commonly identified in CP patients. CP patients were more likely to demonstrate progressive disc/facet degeneration. This data may provide useful information on cervical posterior instrumentation in CP patients.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.36 no.2
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• pp.134-140
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• 2010

Synovial condromatosis of the temporomandibular joint (TMJ) is characterized by the presence of loose bodies (joint mices). It can be confused with temporomandibular disorder clinically, and be with chondrosarcoma histologically. The purpose of this clinical report was to review the clinical, radiological, arthroscopic findings, histological feature and the results of surgical treatment of TMJ synovial chondromatosis. Four patients presented with pain of TMJ and limited mouth opening. The dynamic magnetic resonance imaging (MRI) disclosed a characteristic morphologic changes and displacement of the meniscus with limited translation of the condyle head. Bone scans showed progressive resorptive changes with hot-uptake of the radioisotope. The synovial loose bodies in the joint spaces were removed and sent to pathology for diagnosis as the synovial chondromatosis. The follow-up examination with computed tomography (CT) and MRI revealed no evidence of recurrence and good in function until postoperative 18 months. Diagnostically, the distension of the lateral capsule and fluid findings in the joint on the MRI are very suggestive tool for this synovial chondromatosis, but they are not always detected on the preoperative MRI. Arthroscopic approaches are very useful to inspect the joint spaces and to remove the loose bodies without interruption of the whole synovial membranes.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.2
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• pp.167-173
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• 2016

This paper proposes ductile failure simulation under high strain rate conditions using finite element (FE) analyses. In order to simulate a cracked component under a high strain rate condition, this paper applies the stress-modified fracture strain model combined with the Johnson/Cook model. The stress-modified fracture strain model determines the incremental damage in terms of stress triaxiality (${\sigma}_m/{\sigma}_e$) and fracture strain (${\varepsilon}_f$) for a dimple fracture using the tensile test results. To validate the stress-modified fracture strain model under dynamic loading conditions, the parameters are calibrated using the tensile test results under various strain rates and the fracture toughness test results under quasi-static conditions. The calibrated damage model predicts the CT test results under a high strain rate. The simulated results were then compared with the experimental data.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.6
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• pp.585-592
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• 2014

In this study, a multibody simulator was developed to analyze the bio-mimetic motion of a lizard robot design. A RecurDyn multibody dynamics model of a lizard was created using a micro-computerized tomography scan and motion capture data. The bio-mimetic motion simulator consisted of a trajectory generator, an inverse kinematics module, and an inverse dynamics module, which were used for various walking motion analyses of the developed lizard model. The trajectory generation module produces spinal movements and gait trajectories based on the lizard's speed. Using the joint angle history from an inverse kinematic analysis, an inverse dynamic analysis can be carried out, and the required joint torques can be obtained for the lizard robot design. In order to investigate the effectiveness of the developed simulator, the required joint torques of the model were calculated using the simulator.

• Journal of Radiopharmaceuticals and Molecular Probes
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• v.7 no.2
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• pp.99-103
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• 2021

In this study, the initial in vivo pharmacokinetic changes according to the routes of drug administration were investigated using bioimaging techniques. The purpose of this study was to quantify the degree of distribution of each major organ in normal mice over time by acquiring Positron Emission Tomography/Computed Tomography images while administering routes F-18 fluorodeoxyglucose such as intravenous, intraperitoneal and per oral, a representative diagnostic radiopharmaceutical. Dynamic Positron Emission Tomography images were acquired for 90 minutes after drug administration. Radioactivity uptake was calculated for major organs using the PMOD program. In the case of intravenous administration, it was confirmed that it spread quickly and evenly to major organs. Compared to intravenous administration, intraperitoneal administration was about three times more absorbed and distributed in the liver and intestine, and it was showed that the amount excreted through the bladder was more than twice. In the case of oral administration, most stayed in the stomach, and it was showed that it spread slowly throughout the body. In comparison with intravenous administration, it was presented that the distribution of kidneys was more than 9 times and the distribution of bladder was 66% lower. Since there is a difference in the initial in vivo distribution and excretion of each administration method, we confirmed that the determination of the administration route is important for in vivo imaging evaluation of new drug candidates.

• Archives of Plastic Surgery
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• v.35 no.6
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• pp.663-668
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• 2008

Purpose: Pedicled transverse rectus abdominis myocutaneous(TRAM) flap has been a gold standard for breast reconstruction and one of surgical techniques preferred by many surgeons. The authors examined the course of deep epigastric artery focusing on distance from margins of rectus abdominis to pedicle and location of choke vessels to get minimal muscles during pedicled TRAM flap operation. Methods: Eleven rectus abdominis muscle from nine cadavers were used in this study. Rectus abdominis was separated from the cadavers, deep inferior and superior epigastric artery were isolated and then 8 anatomical landmarks in medial and lateral margins of rectus abdominis were designated. Distance to a pedicle meeting first horizontally was measured and vertical location from umbilicus to choke vessel was determined. In addition, 32 rectus abdominis images of 16 women(average age: 37.2 years old) from 64 channel abdomen dynamic computerized tomography were also examined with the same anatomical landmarks with those of cadavers. Results: Average distance from four landmarks on lateral margin of rectus abdominis to pedicle was 1.9 - 3.4cm and 1.8 - 3.8 cm on medial margin. Choke vessel was located between middle and inferior tendinous intersection in all cases and average distance between two tendinous intersection was 6.7 - 7.0 cm on medial margin and 6.2 cm on lateral margin. Location of inferior tendinous intersection was on umbilicus or superior of it in all cases and its average distance from umbilicus was 1.8 - 5.6 cm on medial margin and 2.7 - 6.2 cm on lateral margin. Conclusion: Distance from medial and lateral margins of rectus abdominis muscle to pedicle was the shortest in inferior tendinous intersection and that was averagely 1.8 cm on medial margin and 1.9 cm in average on lateral margin. All choke vessels were located between middle and inferior tendinous intersection.

• Progress in Medical Physics
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• v.16 no.2
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• pp.82-88
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• 2005

In this study, the physical compensator made with the high density material, Cerrobend, and the electronic compensator realized by the movement of a dynamic multileaf collimator were analyzed in order to verify the properness of a design function in the commercial RTP (radiation treatment planning) system, Eclipse. The CT images of a phantom composed of the regions of five different thickness were acquired and the proper compensator which can make homogeneous dose distribution at the reference depth was designed in the RTP. The frame for the casting of Cerrobend compensator was made with a computerized automatic styrofoam cutting device and the Millennium MLC-120 was used for the electronic compensator. All the dose values and isodose distributions were measured with a radiographic EDR2 film. The deviation of a dose distribution was $\pm0.99 cGy\;and\;\pm1.82cGy$ in each case of a Cerrobend compensator and a electronic compensator compared with a $\pm13.93 cGy$ deviation in an open beam condition. Which showed the proper function of the designed compensators in the view point of a homogeneous dose distribution. When the absolute dose value was analyzed, the Cerrobend compensator showed a $+3.83\%$ error and the electronic compensator showed a $-4.37\%$ error in comparison with a dose value which was calculated in the RTP. These errors can be admtted as an reasonable results that approve the accuracy of the compensator design in the RTP considering the error in the process of the manufacturing of the Cerrobend compensator and the limitation of a film in the absolute dosimetry.

• The Korean Journal of Nuclear Medicine Technology
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• v.12 no.1
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• pp.39-43
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• 2008

Purpose: There are various methods to diagnose hemangioma, such as ultrasonography (US), computed tomography (CT), magnetic resonance imaging (MRI) and nuclear medicine. However, by development of SPECT imaging, the blood-pool scan using $^{99m}Tc$-labeled red blood cell has been used, because it was non-invasive and the most economical method. Therefore, in this study, we proposed that the usefulness of $^{99m}Tc$-RBC scan and SPECT of the head and neck to diagnose unlocated hemangiomas. Materials and Methods: $^{99m}Tc$-RBC scan and SPECT was performed on 6 patients with doubtful hemangioma (4 person, head; 1 person, neck; 1 person, another). We labeled radiopharmaceutical using modified in vivo method and then, centrifuged it to remove plasma. After a bolus injection of tracer, dynamic perfusion flow images were acquired. Then, anterior, posterior, both lateral static blood-pool images were obtained as early and 4 hours delayed. SPECT was progressed 64 projections per 30 seconds. Each image was interpreted by physicians, Nuclear medicine specialist, and technologist blinded to patient's data. Results: In 5 patients of all the radioactivity of doubtful site didn't change in flow images, but, in blood-pool, delayed and SPECT images, it was increased. So, it was a typical hemangioma finding. The size of lesion was over 2 cm, and it could discriminate as comparing to the delayed and SPECT imaging. On the other hand, in 1 patient, the radioactivity was increased in blood-pool images, but, not in delayed and SPECT images, so, it was proved no hemangioma. Conclusion: Using $^{99m}Tc$-RBC Scan and SPECT, we could diagnose the hemangiomas in head and neck, as well as, liver, more non-invasive, economical, and easy. Therefore, it considered that $^{99m}Tc$-RBC scan and SPECT would offer more useful information for diagnosis of hemangioma, rather than otherimaging such as US, CT, MRI.