• Journal of Korean Neurosurgical Society
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• v.58 no.2
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• pp.131-136
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• 2015

Objective : To investigate the incidence of corpus callosum injury (CCI) in patients with mild traumatic brain injury (TBI) using brain MRI. We also performed a review of the clinical characteristics associated with this injury. Methods : A total of 356 patients in the study were diagnosed with TBI, with 94 patients classified as having mild TBI. We included patients with mild TBI for further evaluation if they had normal findings via brain computed tomography (CT) scans and also underwent brain MRI in the acute phase following trauma. As assessed by brain MRI, CCI was defined as a high-signal lesion in T2 sagittal images and a corresponding low-signal lesion as determined by axial gradient echo (GRE) imaging. Based on these criteria, we divided patients into two groups for further analysis : Group I (TBI patients with CCI) and Group II (TBI patients without CCI). Results : A total of 56 patients were enrolled in this study (including 16 patients in Group I and 40 patients in Group II). Analysis of clinical symptoms revealed a significant difference in headache severity between groups. Over 50% of patients in Group I experienced prolonged neurological symptoms including dizziness and gait disturbance and were more common in Group I than Group II (dizziness : 37 and 12% in Groups I and II, respectively; gait disturbance : 12 and 0% in Groups I and II, respectively). Conclusion : The incidence of CCI in patients with mild TBI was approximately 29%. We suggest that brain MRI is a useful method to reveal the cause of persistent symptoms and predict clinical prognosis.

• Journal of Korea Foundry Society
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• v.35 no.4
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• pp.80-87
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• 2015

The Al die casting process has been widely used in the manufacturing of automotive parts when the process requires near-net shape casting and a high productive rate. However, porosity arises in the casting process, and this hampers the wider use of this method for the creation of high-durability automotive components. The porosity can be controlled by the shot condition, but, it is critical to set the shot condition in the sleeve, and it remains difficult to optimize the shot condition to avoid air entrapment efficiently. In this study, the 4.5 mm, 2.0 mm plate die castings were fabricated under various shot conditions, such as plunger velocities of 0.7 m/s ~ 3.0 m/s and fast shot set points of the cavity of -25%, 0%, 25%, and 50%. The mold filling behavior of Al melts in the cavity was analyzed by a numerical method. Also, according to the shot conditions, the results of numerical analyses were compared to those of die-casting experiments. The porosity levels of the plate castings were analyzed by X-ray CT images and by density and microstructural analyses. The effects of the porosity on the mechanical properties were analyzed by tensile tests and hardness tests. The simulation results are in good general agreements with the die-casting experimental results. When plunger velocity and fast shot set point are 1.0 m/s and cavity 25% position, castings had optimum condition for good mechanical properties and a low level of porosity.

• Proceedings of the KOSOMBE Conference
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• v.1997 no.05
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• pp.123-126
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• 1997

We present a method for the estimation of 3D solid angle assessment of the acetabular coverage of the femoral head in 3D space. At first, femoral head and acetabulum is segmented from the original CT scan images. The slice thickness is 1.5mm and the number of slices is usually 30-40 to cover the entire acetabulum. The superior half of the femoral head is modeled as part of a sphere. Thus, the axial cross sections of the upper half of the femoral head are also modeled as circles. A set of points from each outline image of femoral head is fitted recursively into a circle by minimizing root-mean-square (RMS) error. With these fitted circles, a center point of the femoral head model is evaluated. This is a reference point for calculating the solid angle of the acetabular inner surface. Next, the tangent lines connecting from a set of points of the acetabular edge to the center of the fitted sphere are obtained. The lines pass through the unit sphere whose center is the same as that of the femoral head. With the points on the unit sphere, we calculate area and estimate the solid angle. Based on this solid angle, the deformity of the acetabulum is analyzed. In case of normal subject, the solid angle is about 4.3 (rad) and acetabular coverage is 68%.

• Journal of Veterinary Clinics
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• v.26 no.1
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• pp.95-100
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• 2009

A 15-year-old, spayed female maltese dog was presented with polydipsia, polyuria, polyphagia, abdominal distention, alopecia and hyperpigmentation. The complete blood counts were in normal range, and the serum biochemistry revealed elevated level of glucose and globulin. Mild hepatomegaly was seen on radiography of abdomen. Abdominal ultrasonography revealed the uniformly enlarged left adrenal gland measured 2.4 cm in diameter. ACTH stimulation test and LDDST revealed hyperadrenocorticism. HDDST revealed pituitary dependent hyperadrenocorticism. On CT images, isodense mass with contrast enhancing was seen in left adrenal gland. Cytologic result is consistent with benign tumor. Adrenal mass was surgically removed and evaluated. Histopathologic examination revealed adenocortical adenoma.

• The korean journal of orthodontics
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• v.42 no.4
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• pp.159-168
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• 2012

Objective: The aims of this study were to investigate mandibular deformation under clenching and to estimate its effect on the stability of orthodontic mini-implants (OMI). Methods: Three finite element models were constructed using computed tomography (CT) images of 3 adults with different mandibular plane angles (A, low; B, average; and C, high). An OMI was placed between #45 and #46 in each model. Mandibular deformation under premolar and molar clenching was simulated. Comparisons were made between peri-orthodontic mini-implant compressive strain (POMI-CSTN) under clenching and orthodontic traction forces (150 g and 200 g). Results: Three models with different mandibular plane angles demonstrated different functional deformation characteristics. The compressive strains around the OMI were distributed mesiodistally rather than occlusogingivally. In model A, the maximum POMI-CSTN under clenching was observed at the mesial aspect of #46 (1,401.75 microstrain [${\mu}E$]), and similar maximum POMI-CSTN was observed under a traction force of 150 g (1,415 ${\mu}E$). Conclusions: The maximum POMI-CSTN developed by clenching failed to exceed the normally allowed compressive cortical bone strains; however, additional orthodontic traction force to the OMI may increase POMI-CSTN to compromise OMI stability.

• Progress in Medical Physics
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• v.19 no.3
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• pp.186-190
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• 2008

In this study, we describe the preliminary application for the delineation of a metal object using cone-beam reconstruction (CBR) based on limited electronic portal imaging device (EPID) projections. A typical Feldkamp, Davis and Kress (FDK) reconstruction algorithm accompanying the edge preserving smoothing filter was used as only a few projections are acquired for reconstruction. In a correlation study of the projection numbers, we found that the size of the seeds and their location depicted by these CBR images were almost identical. Limited views were used for CBR, and our method is inexpensive and competitive for use in clinical applications.

• Journal of Periodontal and Implant Science
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• v.44 no.2
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• pp.50-56
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• 2014

Purpose: The aims of this study were to measure the distance of the intraosseous vascular anastomosis in the anterolateral wall of the maxillary sinus from different reference points, and to correlate the location of the intraosseous vascular anastomosis with the tooth position and the residual bone height of the maxilla. Methods: Computed tomography (CT) images were taken from 283 patients undergoing dental implants placement in the posterior maxilla. Three horizontal lines were drawn at the ridge crest, maxillary sinus floor, and the position of the anastomosis. A vertical second line at the center of each tooth was drawn perpendicular to the horizontal lines. The distance from the ridge crest to the maxillary sinus floor and the distance from the maxillary sinus floor to the bony canal were measured from the intersections of the horizontal and vertical lines. The residual alveolar bone height was used to categorize three groups: group 1,<4 mm; group 2, between 4 and 8 mm; and group 3, >8 mm. Results: The residual bone height values of different tooth positions were significantly different (P=0.0002). The distance from the maxillary sinus floor to the intraosseous vascular anastomosis was significantly different between groups 1 and 3 (P=0.0039). At the molar sites, a moderate negative correlation was found between the residual bone height and the distance from the maxillary sinus floor to the intraosseous anastomosis. The distances of the alveolar ridge crest and the maxillary sinus from the intraosseous vascular anastomosis were not significantly different between sexes. Conclusions: Within the limitations of this study, sites with a higher residual bone height in the molar regions were at a relatively high risk of artery damage during window osteotomy preparation; therefore, we recommend taking more precautions when using a lateral approach for sinus elevation.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.32 no.3
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• pp.282-288
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• 2010

Surgery with the computer navigation system can make it possible to identify important anatomical structures which are difficult to be confirmed with the naked eye in the operation, and has extended their applications in various surgical fields. The head and neck surgery especially requires detailed anatomical knowledges and these knowledges have influences on postoperative functions and esthetics of a patient. In the orthognathic surgery, we should take osteotomies in the precise locations of the jawbones and move segments to the intended positions. There are so many important anatomical structures around the osteotomy-sites in the orthognathic surgery that the prevention of damage to these structures to obtain satisfactory results without any complication. There are vessels of the pterygoid plexus posterior to the pterygoid plate in the maxilla and the mandibular nerve enters the mandibluar foramen in the mandibular ramus. These locations should be confirmed perioperatively to avoid any injury to these structures. The navigation-assisted surgery may be helpful for this purpose. We performed navigational orthognathic surgeries with preoperative CT images and obtained satisfactory results. The osteotomy was performed in the proper location and damaging the surrounding important anatomical structures was avoided by keeping the saw away from them with the real-time navigation. It may be required to develop proper devices and protocols for the navigation-assisted orthognathic surgery.

• The korean journal of orthodontics
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• v.43 no.5
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• pp.218-224
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• 2013

Objective: To examine the effect of bite force on the displacement and stress distribution of orthodontic mini-implants (OMIs) in the molar region according to placement site, insertion angle, and loading direction. Methods: Five finite element models were created using micro-computed tomography (microCT) images of the maxilla and mandible. OMIs were placed at one maxillary and two mandibular positions: between the maxillary second premolar and first molar, between the mandibular second premolar and first molar, and between the mandibular first and second molars. The OMIs were inserted at angles of $45^{\circ}$ and $90^{\circ}$ to the buccal surface of the cortical bone. A bite force of 25 kg was applied to the 10 occlusal contact points of the second premolar, first molar, and second molar. The loading directions were $0^{\circ}$, $5^{\circ}$, and $10^{\circ}$ to the long axis of the tooth. Results: With regard to placement site, the displacement and stress were greatest for the OMI placed between the mandibular first molar and second molar, and smallest for the OMI placed between the maxillary second premolar and first molar. In the mandibular molar region, the angled OMI showed slightly less displacement than the OMI placed at $90^{\circ}$. The maximum Von Mises stress increased with the inclination of the loading direction. Conclusions: These results suggest that placement of OMIs between the second premolar and first molar at $45^{\circ}$ to the cortical bone reduces the effect of bite force on OMIs.

• Imaging Science in Dentistry
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• v.32 no.2
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• pp.81-87
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• 2002

Purpose : To investigate the diagnostic significance of cortical changes in the bone of diseased jaws utilizing computed tomography (CT). Materials and Methods: Computed tomographic images of 91 patients, consisting of 7 osteomyelitis, 46 cysts, 18 benign tumors, and 20 malignant tumors, were analyzed. The pattern of cortical expansion was classified into three types: no expansion (N), buccal or lingual expansion (B/L), and buccolingual expansion (B & L). The pattern of cortical destruction was classified into four types: no destruction (N), point destruction (PO), gross destruction (GR), and permeative destruction (PE). The pattern of periosteal reaction was classified into four types: parallel, irregular, spicule, and Codmans triangle. The relationship between the pattern of cortical bone changes and diseases of the jaws was assessed. Results: When the pattern of cortical expansion was compared to diseases of the jaw, N-type was most prevalent in cases of osteomyelitis and malignant tumors, B/L-type with cysts, and B&L-types with benign tumors. Comparison between the pattern of cortical bone destruction with diseases of the jaw showed strong correlations between PO and PE-types to osteomyelitis, N-type with cysts, N and GR-types with benign tumors, and GR-type with malignant tumors. Finally, the relationship between the pattern of periosteal reaction to diseases of the jaw showed a strong correlation between parallel-type to osteomyelitis and spicule-type to malignant tumors. Conclusion : The pattern of cortical expansion and cortical destruction is useful in differentiating diseases of the jaws.