• Journal of Korea Game Society
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• v.13 no.4
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• pp.25-34
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• 2013

Spatial partitioning trees are needed for processing collision detections efficiently. In order to select split planes for spatial partitioning trees, the tree balance and the number of polygons overlapped with the split plane should be considered. In this paper, the heuristic algorithm controlling weight values of tree build criteria is proposed for spatial partitioning trees of 3D games. As the weight values are changed, tree build time, T-junction elimination time which can cause visual artifacts in splitting polygons overlapped with the split plane, rendering speed (frame per second: FPS) according to tree balance are analysed under 3D game simulations.

• Tribology and Lubricants
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• v.4 no.1
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• pp.36-42
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• 1988

On the basis of the thermally-activated Wear theory, it is well estabilished that the secondary activated energy, which is mainly resulted from the exothermic reaction of hydrogen from thermal decomposition of the hydrocarbons at the high temperature and the high speed, caused catastropic failure. The new additive, viz., DEP was synthesized to reduce or eliminate the hydrogen effect at the contact junction. Through the thermal degrading and the thermodynamic consideration, the synthesized additive, viz., DEP showed the possibiliy as the hydrogen scavenger.

• Journal of Korean Neurosurgical Society
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• v.29 no.4
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• pp.574-579
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• 2000

Chordomas are rare central nervous system tumors that are found predominantly in the sacrococcygeal(50%) and basiosphenoidal region(35%). Most of the remainder are related to the vertebral bodies and only 1 to 2% of them are known to occur in the thoracic vertebrae. A 15-year-old girl was admitted because of paraparesis. Three months prior to admission, she underwent a lumbar laminectomy at other hospital for the treatment of herniated lumbar disc but paraparesis became rather aggravated after the operation. At admission, MRI showed a low signal T1WI, high signal T2WI mass compressing the cord at T2 vertebral body. The tumor was subtotally removed via costotransversectomy but as the tumor was proven to be a chordoma, a second stage operation via anterior route was followed. At second operation, T2 corpectomy and T1-T3 plate fixation with autogeneous ileac bone graft was performed. Shortly after the operation, preoperative paraparesis disappeared completely and no evidence of tumor recurrence was noticed both clinically and radiologically for next 2 years. Spine surgery at cervicothoracic junction may be technically demanding due to anatomical complexity and hindering large vessels. The authers reviewed this case with special emphasis on the surgical procedure in this region.

• The korean journal of orthodontics
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• v.31 no.1 s.84
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• pp.71-83
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• 2001

The purpose of this study was to Prove that the medial edge epithelial cells covering the secondary palatal shelves were removed by apoptosis during palatal fusion. 12 mature female rats (Suprague-Dawley) were mated overnight with male rats and sacrificed on days 15.0, 16.5, 16.75, 17.0 of pregnancy. The embryos were removed from the uterus and the heads were embedded in paraffin. The paraffin blocks were sectioned and the sections were undergone H-E staining for general histologic feature and TdT staining for detection of apoptotic cells. The obtained results were as follows. k. In the section of 16.0 and 16.5 day embryos, the palatal shelves were prior to contact and no apoptotic cells wereobserved in the medial edge epithelium. At the initial contact of Palatal shelves, there was a few apoptotic cells in the fusing epithelium. 2. In the 16.75 day embryos, the samples that epithelial seams did not lost there continuity, apoptotic cells were rarely seen at the midline epithelial seam. In contrast, a lot of apoptotic cells were observed at epithelial triangles and the junction between palatal shelves and nasal septum. 3. In the 16,75 day embryos, the samples that epithelial seams lost their continuity and disrupted to epithelial islands, large number, of apoptotic cells were observed at epithelial islands and epithelial triangles. Some apoptotic cells were also observed at the oral, nasal epithelium near the midline. 4. In the 17.0 day embryos, most of epithelial islands were disappeared and mesenchymal confluence was achieved. Apoptotic cells were rarely observed in the mesenchymal tissue which replaced epithelial islands, but there were some apoptotic cells at the epithelial triangles, oral and nasal epithelium. From the results of the study, it was revealed that medial edge epithelial cells of fusing palate were removed by apoptosis. Apoptotic cells were found mainly in the disappearing midline epithelial seam and the oral and nasal epithelial triangles at some late stages of palatal fusion.

• Journal of Korean Orthopaedic Sports Medicine
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• v.5 no.2
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• pp.155-160
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• 2006

Purpose: To evaluate the results of meniscal repair and partial meniscectomy of lateral meniscus injury associated with tibial plateau fracture. Materials and Methods: Between February 1993 and August 2004, 24 cases (23 patients) of lateral meniscus tear with tibial plateau fracture were evaluated retrospectively. The most frequent type of tear was the longitudinal tear of the meniscocapsular junction (14 cases, 66.7%). All fractures were reduced under the control of arthroscopic and image intensifier. Arthroscopic repair of the longitudinal tear of the lateral meniscus or arthroscopic partial meniscectomy was performed. The final results were evaluated with the Ikeuchi criteria and Lysholm score. Results: At the final follow-up, the outcome was excellent in 12 cases (85.7%), good in 1 case (7.1%) and fair in 1 case (7.1%) among 14 cases of meniscal repair, and the excellent in 4 cases (66.7%) and good in 2 cases (33.3%) among 6 cases of partial meniscectomy according to the Ikeuchi criteria, There was a significant improvement of Lysholm score after surgery, 92.3 postoperatively compared with 56.6 preoperatively (p<0.0001, paired t-test). Conclusion: The fracture of the lateral tibial plateau did not seem to affect on the healing of the meniscus repair and partial meniscectomy.

• Journal of the Korean Vacuum Society
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• v.22 no.3
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• pp.156-161
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• 2013

We fabricated transparent conductive electrodes with silver (Ag) nanofibers by electrospinning process. Ag nanofibers have high aspect ratio and fused junctions which result in low sheet resistance. Electrospinning is a fast and efficient process to fabricate continuous one-dimensional (1D) nanofibers. Ag/polymer ink were prepared in polymer matrix solution by a sol-gel method. Then, Ag/polymer nanofibers precursors are heated at $200{\sim}500^{\circ}C$ in air for 2 h to eliminate partially the polymers. The topographical features of the Ag nanofibers were characterized by FE-SEM, and the electrical property was analyzed through I-V measurement system. Finally, optical property was measured using UV/VIS spectroscopy. The transparent conductive electrodes with Ag nanofibers exhibited a sheet resistance (Rs) of $250{\Omega}/sq$ at a transparency (T) of 83%. Transparent conductive films, contain the Ag nanofibers as conductive materials, have good electrical, optical, and mechanical properties. Therefore, it is expected to be useful for the application of flexible display in the future.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.8 no.1
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• pp.31-40
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• 2005

Purpose: This study aimed to provide, as a basic material, the experiences of endoscopy in diagnosis and treatment of tumorous conditions in the upper gastrointestinal tract in children. Methods: The objects were 26 patients diagnosed as having tumorous conditions in the upper gastrointestinal tract among 1,283 patients who underwent upper gastrointestinal endoscopic examination at the Department of Pediatrics, Pusan National University Hospital, from January 1994 to July 2004 retrospectively. The characteristics of patients, the chief complaints for endoscopic examination, the sorts of tumors diagnosed, the endoscopic findings of tumors, and the treatment of tumors were analysed. Results: 1) Eleven male and fifteen female were included, whose mean age was $6.93{\pm}4.02years$. 2) The chief complaints for endoscopic examination were abdominal pain (80.7%), vomiting or nausea (30.8%), and gastrointestinal beeding (30.7%) in order. 3) Six cases of ectopic pancreas, five cases of sentinel polyp, three cases of papilloma and vallecular cyst, two cases of Brunner's gland hyperplasia and gastric submucosal tumor, one case of gastrointestinal stromal tumor, duodenal intramural hematoma, T cell lymphoma, lipoma, and Peutz-Jeghers syndrome were diagnosed by endoscopy with or without biopsy. 4) The location of tumors was in the pharynx (19.2%), esophagus (7.7%), gastro-esophageal junction (23.0%), stomach (30.7%) and duodeneum (26.9%). 5) The size of tumors was less than 10 mm in 53.8%, 10~20 mm in 26.9%, more than 20 mm 19.2%. 6) Treatments for tumors included resection by laser, surgical resection, endoscopic polypectomy with a forcep or snare, and observation 7) There was no significant complication. Conclusion: Various and not a few tumors were found in the upper gastrointestinal tract. The endoscopy was accurate, effective, and safe means for diagnosis and treatment of those lesions in children.

• Journal of the Korean Electrochemical Society
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• v.10 no.1
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• pp.25-30
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• 2007

Proton exchange membrane fuel cell(PEMFC) performance could be affected by various factors such as cell temperature, total pressure, partial pressure of reactants and relative humidity. Hydrogen ion is combined with water to form hydronium ion [$H_3O^+$] and pass through membrane resulting electricity generation. Cooling system is needed to remove heat and other uses on large scale fuel cell. In case that collant conductivity is increased, fuel cell performance could be decreased because produced electricity could be leaked through coolant. In this study, triple distilled water(TDW) and antifreeze solution containing ethylene glycol was used to observe resistance change. Resistance of TDW was taken 28 days to reach preset value, and effect on fuel cell operation was not observed. Resistance of antifreeze solution was not reached to preset value up to 48 days, but performance failure occurred presumably caused by bipolar plate junction resulting stoppage resistance experiment. Generally PEMFC humidification is performed near-saturated operating conditions at various temperatures and pressures, but non-humidifying condition could be applied in small scale fuel cell to improve efficiency and reduce system cost. However, it was difficult to operate large scale fuel cell without humidifying, especially higher than $50{\sim}60^{\circ}C$. In case of small flux such as 0.78 L/min, temperature difference between inlet and outlet was occurred larger than other cases resulting performance decrease. Non-humidifying performance experiments were done at various cell temperature. When both of anode and cathode humidification were removed, cell performance was strongly depended on cell operating temperature.