• Maxillofacial Plastic and Reconstructive Surgery
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• v.17 no.4
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• pp.379-388
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• 1995

This study was based on a series of 369 patients with Oral and Maxillofacial injuries treated at Kumi Hospital, College of Medicine, Soon-Chun-Hyang University from Jan. 1992 to Dec. 1994. The results obtained were as follows : 1. The number of male patient was 310 and that of female was 59, leading to 5.3 : 1 of male-female ratio, and the 3rd decade was the highest age group in incidence. 2. Weekly incidence was the highest in Sun. & Sat. and monthly incidence was the highest in Nov.& Oct. 3. Causes as follows : traffic accident 41.9%, slip& fall down 25.4%, human trouble 16.5%, industrial accident 7.5%, sports 6.7%, etc. 4. Site distribution as follows : mandible fracture 32.3%, maxilla fracture 4.8%, zygoma fracture 21.4%, nasal bone fracture 34.1%, orbital& ethmoidal fracture 4.6%. 5. The most common site of mandible was symphysis & angle, and the ratio of OR & CR was 1.3 : 1. 6. The most common site of maxilla was Le Fort 1, 2, and the ratio of OR & CR was 3 : 1. 7. The most common site of zygoma was body, the ratio of OR & CR was 3.3 : 1. 8 . The mean period of intermaxillary fixation was 4.33weeks. 9. Combined injury in facial fracture was 35.8% : The facial fracture were most frequently combind with head & neck(47.0%), upper extremities and abdomen(9.8%). 10. The mean elapsed time from injury to hospital was 1.9days, and that to operation was 5.1days. 11. The mean number of combined teeth injury was 0.6, and percent of combined soft tissue injury of face was 51.3%. 12. Post-operative complication occurred in 4 out of 323 cases. all of that was infection.

• Journal of the Korean Arthroscopy Society
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• v.7 no.1
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• pp.92-95
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• 2003

A 34-year-old man with ACL total rupture due to slip down injury, had received ACL reconstruction using autogenous hamstrings tendon with cross-pin femoral fixation. Postoperative course was as usual. But postoperative 3 months later, he complained posterolateral knee pain, recurrent effusion and mild instability. He was managed repeatitive aspiration and nonsteroid antiinflammatory drugs but was failed to relieve symptoms & signs. In CT scans, perforation of posteromedial femoral cortex of lateral femoral condyle was found. In second look arthroscopy, two pieces of broken femoral cross pin were found in between tibiofemoral Joint which was badly injured cartilage. We considered malposition of pins was the main cause of failure. We propose that femoral tunnel must be made more acute angle and femoral cross-pin guide must be positioned more external rotation 10-20 degree than transepicondylar axis made confirm the cross-pin tunnel position in order to avoid posterior cortex perforation and early failure.

• Journal of Acupuncture Research
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• v.18 no.2
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• pp.237-244
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• 2001

Back pain has plagued humans for many thousands of years. The treatment of back pain is divided into operative treatment and conservative treatment. It is reported that cure rate of conservative treatment is 80~90 percent. Generally, the treatment of oriental medicine is mostly conservative treatment. But, surgery should not be used as a last resort in treatment; it is just one of many treatment options for various spinal conditions. In some instance, it can be to preferred choice; in other situations, alternative therapies may be superior. Selections of the operation in HIVD 1. Acute disc herniations with a protracted significant component af back pain. 2. Chronic disc degeneration with significant back pain and degeneration limited to one or two disc levels. 3. Sugical instability created during decompression. 4. The presence of neural arch defects coincident with disc disease. 5. Symptamatic and radiographically demonstrable segmental instability. Selections of the operation in stenosis 1. If it does not slowly progress in physical therapy and other nonoperative measures, many of these patients may ultimately need surgical decompression. 2. Absolute stenosis in an impression of CT, MRI.(under 10mm) 3. In patients with established symptoms of .neurogenic claudication. 4. In patients with bad influence of neurogenic derangement.(strength, sensory) Selections of the operation in spondylolisthesis 1. Persistence or recurrence of major symptoms for at least one year despite activity modification and physical therapy. 2. Tight hamstrings, persistently abnormal gait, or postural deformities unrelieved by physical therapy. 3. Sciatic scoliosis. 4. Progressive neurologic deficit. 5. Progressive slipping beyond 25 or 50 percent, even when asymptomatic. 6. A high slip angle (40 to 50 degrees) in a growing child, since it is likely to be associated with further progression and deformity. 7. Psychologic problems attributed to shortness of trunk, abnormal gait, and postural deformities characteristic of more severe slips.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.37 no.4
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• pp.693-703
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• 2017

Rover wheel's mobility depends on soil's condition and wheel's design. The purpose of this study is to evaluate the effect of soil conditions, which are Jumunjin sand and Korean lunar soil simulant (KLS-1), on wheel's motion performance. The experiments were performed by using a single wheel testbed with a wheel which grouser height is 15mm on Jumunjin sand and KLS-1, respectively. Also the influence of grouser length to wheel's mobility performance was studied. The experimental results of torque, drawbar pull and sinkage relating to slip ratio were discussed and analyzed to evaluate wheel's motion performance. Results showed wheel moving on KLS-1 has high performance than Jumunjin sand. Wheel's mobility performance was influenced by soil's properties of cohesion and frictional angle. In addition, wheel's performance of drawbar pull and Torque increased with the increasing of grouser length.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.25 no.2
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• pp.471-482
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• 1995

Bony remodeling pattern of condyle fractures in children are different from in adult for growing of condyle, also might affect treatment and prognosis of the condyle fracture. Subjects of this clinical and radiologic study were 26 temporomandibular joints diagnosed as condyle fracture in 23 patients under 15 years old age. They were treated with conservative method at Dental Hospital of Yonsei University from Jan., 1986 to Oct., 1994. Bony remodeling related with fracture pattern was evaluated. The results obtained are as follows: 1. The ratio of male to female in patients with condyle fracture was 1 : 0.9 and the difference of sex ratio was not noted. Comparing with preschool-age group and school-age group, age frequency was higher in preschool-age group(83％). 2. Fallen down(54％) was the most frequent cause of condyle fractures. Traffic accident and slip down were followed. 3. The most common clinical sign of condyle fractures was tenderness to paipation09 cases). Mouth opening limitation07 cases), swelling(7 cases), malocclusion(3 cases) were next in order. 4. According to sites of condyle fractures, unilateral fractures were in 20 patients and bilateral fractures in 3 patients, therefore total 23 patients-26 cases of condyle fracture were observed. According to fracture distribution, condyle fractures were in 10 patients(44％). Condyle fractures with symphysis fracture(9 patients, 39％), condyle fractures with ascending ramus fracture(2 patients, 9％), condyle fracture with mandibular body fracture(1 patient, 4％), and condyle fractures with mandibular angle fracture(1 patient, 4％) were followed. 5. In displacement pattern of fractured fragment of mandibular condyle, dispiacement(17 cases, 66％) was most common. Dislocation(5 cases, 19％) and deviation (4 cases, 15％) were next in order. 6. During the observation period of fractured condyles, remodeling patterns of fracture sites related with articular fossa were observed with usual condylar shape in 23 cases and with prominently different shape in 3 cases.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.10
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• pp.1089-1095
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• 2011

Numerical simulation is performed for nucleate boiling on a micro-finned surface, which has been widely used to enhance heat transfer, by solving the equations governing the conservation of mass, momentum, and energy in the liquid and vapor phases. The bubble motion is determined by a sharp-interface level-set method, which is modified to include the effect of phase change and to treat the no-slip and contact-angle conditions, as well as the evaporative heat flux from the liquid microlayer on immersed solid surfaces such as micro fins and cavities. The numerical results for bubble formation, growth, and departure on a microstructured surface including fins and cavities show that the bubble behavior during nucleate boiling is significantly influenced by the fin-cavity arrangement and the fin-fin spacing.

• Korean Journal of Materials Research
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• v.15 no.1
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• pp.25-30
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• 2005

The microstructural changes by hot extrusion of AZ31B magnesium alloy were observed, and the relation to the tensile property was examined. The tensile properties as oriented longitudinal(L), half transverse(HT) and long transverse(LT) to the extrusion direction were investigated at $20^{\circ}C,\;100^{\circ}C,\;200^{\circ}C,\;300^{\circ}C\;and\;400^{\circ}C$, respectively. As the results, many recrystallized small grains distributed uniformly in large banded microstructures formed along the extrusion direction. The grain size of as-extruded specimen was around $30\~150\;{\mu}m$. As increasing the test temperature the tensile and yield strength with respect to the angle between the axis of the tensile and the longitudinal direction in extrusion was decreased, but their elongation were increased and their deviation between L and LT specimens have disappeared from $300^{\circ}C$. This mechanical anisotropy was reduced at elevated temperatures and almost disappeared at $400^{\circ}C$. It was considered that the homogenization was occured by the recrystallization and the change of slip system was occurred during tensile test process in elevated temperatures.

• Tribology and Lubricants
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• v.35 no.1
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• pp.59-64
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• 2019

When slipping occurs between two materials, the coefficients of friction must be considered because these values determine the overall efficiency of the machine or slip characteristics. Therefore, it is important to find the coefficient of friction between two materials. This paper focuses on obtaining the coefficient of friction between an aiming bolt and a retainer located in the headlamps of a vehicle. This bolt supports the headlamp, and if the bolt is loosened by external vibration, the angle of the light will change and block the vision of pedestrians or other drivers. In order to study these situations, the coefficient of friction between aiming bolts and retainers needs to be measured. In addition, the coefficient of friction of materials used in the headlamp should be obtained. To determine these two factors, a new device is designed for two cases: surface-surface contact and surface-line contact. To increase reliability of the results, the device is designed using an air-bearing stage which uses compressed air as lubricant to eliminate the friction of the stage itself. Experiments were carried out by applying various vertical forces, and the results show that the coefficient of friction can be measured consistently. The procedure for designing the device and the results are discussed.

• Steel and Composite Structures
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• v.43 no.2
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• pp.139-152
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• 2022

Steel-reinforced concrete (SRC) L-shaped column is the vertical load-bearing member with high spatial adaptability. The seismic behavior of SRC L-shaped column is complex because of their irregular cross sections. In this study, the hysteretic performance of six steel truss reinforced concrete L-shaped columns specimens under the combined loading of compression, bending, shear, and torsion was tested. There were two parameters, i.e., the moment ratio of torsion to bending (γ) and the aspect ratio (column length-to-depth ratio (φ)). The failure process, torsion-displacement hysteresis curves, and bending-displacement hysteresis curves of specimens were obtained, and the failure patterns, hysteresis curves, rigidity degradation, ductility, and energy dissipation were analyzed. The experimental research indicates that the failure mode of the specimen changes from bending failure to bending-shear failure and finally bending-torsion failure with the increase of γ. The torsion-displacement hysteresis curves were pinched in the middle, formed a slip platform, and the phenomenon of "load drop" occurred after the peak load. The bending-displacement hysteresis curves were plump, which shows that the bending capacity of the specimen is better than torsion capacity. The results show that the steel truss reinforced concrete L-shaped columns have good collapse resistance, and the ultimate interstory drift ratio more than that of the Chinese Code of Seismic Design of Building (GB50011-2014), which is sufficient. The average value of displacement ductility coefficient is larger than rotation angle ductility coefficient, indicating that the specimen has a better bending deformation resistance. The specimen that has a more regular section with a small φ has better potential to bear bending moment and torsion evenly and consume more energy under a combined action.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.4A
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• pp.267-279
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• 2009

A numerical model that can simulate the nonlinear behavior of ultra high strength fiber reinforced concrete (UHSFRC) structures subjected to monotonic loading is introduced. The material properties of UHSFRC, such as compressive and tensile strength or elastic modulus, are different from normal strength reinforced concrete. The uniaxial compressive stress-strain relationship of UHSFRC is designed on the basis of experimental result, and the equivalent uniaxial stress-strain relationship is introduced for proper estimation of UHSFRC structures. The steel is uniformly distributed over the concrete matrix with particular orientation angle. In advance, this paper introduces a numerical model that can simulate the tension-stiffening behavior of tension part of the axial member on the basis of the bond-slip relationship. The reaction of steel fiber is considered for the numerical model after cracks of the concrete matrix with steel fibers are formed. Finally, the introduced numerical model is validated by comparison with test results for idealized UHSFRC beams.