• Archives of Craniofacial Surgery
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• v.14 no.2
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• pp.96-101
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• 2013

Background: Among facial fractures, nasal bone fracture, zygomatic arch fracture and mandibular subcondyle fracture take a large portion. Among surgical operations for nasal bone fracture, zygomatic arch fracture and mandibular subcondyle fracture, closed reduction has been generally used but, unlike open reduction, there is a problem in evaluating its accuracy of reduction. Methods: An assessment was made from October 2011 until April 2013 prospectively on 37 patients. For all the operations, closed reductions were executed in a conventional way and simultaneously using C-Arm to verify the reduction of fractures. Two images of plain radiography, one taken before operation and another one taken one day after the operation, were compared. After obtaining images of plain radiography using C-Arm immediately after the correction upon operation, they were compared with the images of plain radiography taken one day after the operation. Results: The fracture reductions of 26 patients among 27 nasal fracture patients were satisfactory but one patient showed a marginal overcorrection of less than 1 mm. The fracture reductions of 7 patients among 8 zygomatic arch fracture patients were satisfactory but one patient showed a marginal undercorrection of less than 2 mm. All of two mandibular subcondyle fracture patients showed less than 2 mm undercorrection. Conclusion: Closed reduction guided by C-Arm for nasal bone fracture, zygomatic arch fracture and mandibular subcondyle fracture was clinically useful because it could make a real-time assessment on fractured areas and add immediate corrections during the operation.

• The korean journal of orthodontics
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• v.50 no.1
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• pp.52-62
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• 2020

This case report presents the orthodontic treatment of a 25-year-old patient with skeletal Class II and severe maxillary arch crowding, moderate mandibular arch crowding, anterior crossbite, and a missing lower incisor. He was treated with molar distalization using a modified C-palatal plate and temporary anchorage devices to create sufficient space for retraction. The total treatment duration was 21 months. After treatment, his occlusion and smile esthetics showed significant improvement. The modified C-palatal plate represents a treatment modality that enhances the prospects of non-extraction treatment and reduces the need for extraction.

• Korean Journal of Applied Biomechanics
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• v.25 no.4
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• pp.489-498
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• 2015

Objective : The purpose of this study was to analyze the effects of the windlass mechanism in trail-walking shoe prototypes that can effectively support arches. A study of these effects should help with the development of a first-rate trail-walking shoe development guide for the distribution of quality information to consumers. Methods : The subjects were ten adult males who volunteered to participate in the study. Shoes from three companies, which will be referred to as Company S (Type A), Company M (Type B), and Company P (Type C), were selected for the experiment. The subjects wore these shoes and walked at a speed of 4.2 km/h, and as they tested each shoe, the contact area, maximum pressure average, and surface force were all measured. Results : Shoe Type A showed a contact area of $148.78{\pm}4.31cm^2$, Type B showed an area of $145.74{\pm}4.1cm^2$, and Type C showed an area of $143.37{\pm}4.57cm^2$ (p<.01). Shoe Type A demonstrated a maximum average pressure of $80.80{\pm}9.92kPa$, Type B an average of $85.72{\pm}11.01kPa$, and Type C an average of $89.12{\pm}10.88bkPa$ (p<.05). Shoe Type A showed a ground reaction force of $1.13{\pm}0.06%BW$, Type B a force of $1.16{\pm}0.04%BW$, and Type C a force of $1.16{\pm}0.03%BW$ (p<.05). Conclusion : The Type A trail-walking shoe, which was designed with a wide arch from the center of the forefoot to the front of the rearfoot showed excellent performance, however, more development and analysis of the windlass mechanism for a variety of arch structures is still necessary.

• The korean journal of orthodontics
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• v.48 no.3
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• pp.153-162
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• 2018

Objective: The aim of this trial was to compare the alignment efficiency and intermaxillary arch dimension changes of nickel-titanium (NiTi) or copper-nickel-titanium (CuNiTi) round archwires with increasing diameters applied sequentially to the mandibular arch. Methods: The initial alignment phase of fixed orthodontic treatment with NiTi or CuNiTi round archwires was studied in a randomly allocated sample of 66 patients. The NiTi group comprised 26 women, 10 men, and the CuNiTi ($27^{\circ}C$) group comprised 20 women, 10 men. The eligibility criteria were as follows: anterior mandibular crowding of minimum 6 mm according to Little's Irregularity Index (LII), treatment requiring no extraction of premolars, 12 to 18 years of age, permanent dentition, skeletal and dental Class I malocclusion. The main outcome measure was the alignment of the mandibular anterior dentition; the secondary outcome measure was the change in mandibular dental arch dimensions during 12 weeks. Simple randomization (allocation ratio 1:1) was used in this single-blind study. LII and mandibular arch dimensions were measured on three-dimensional digital dental models at 2-week intervals. Results: No statistically significant difference was observed between NiTi and CuNiTi according to LII (p > 0.05). Intercanine and intermolar arch perimeters increased in the CuNiTi group (p < 0.001). Inter-first premolar width showed a statistically significant interaction in week ${\times}$ diameter ${\times}$ application (p < 0.05). Conclusions: The effects of NiTi and CuNiTi round archwires were similar in terms of their alignment efficiency. However, the intercanine and intermolar arch perimeters, and the inter-first premolar width changes differed between groups.

• KCI Concrete Journal
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• v.11 no.3
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• pp.191-199
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• 1999

A Precast frame system with hybrid beam-column connections was proposed in this study. An analytical study evaluated the system under seismic loadings. Four buildings with different heights were modeled in which each building had three types of joint details (A. B, C). Thus, twelve buildings were examined with variables such as building height and joint detail. Four earthquake records were applied to the buildings as input ground motions. All the records were normalized to the intensity of 0.25g to assess behavior under the same intensity of seismic excitation. All the joint types showed almost identical results except for the Mexico earthquake which was scaled up from 0. 1g to 0.25g. Buildings with the type C joint exhibited the largest deflection for the Mexico earthquake. It was concluded that type B joint could be used in a high seismic zone and the type C joint could possibly be used in the regions of low to medium seismic activity.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.10a
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• pp.629-634
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• 2000

In this study, 9 reinforced concrete(RC) continuous beams were tested to investigate the arch action. By measuring longitudinal steel strains during the whole loading stages up to failure, the development of arch action is evaluated. Variables included are span length, longitudinal steel ratio and the presence of stirrups. As a result, it was known that measured steel tension in the span is substantially higher than the conventionally calculated values, and it was appeared that near the middle of the shear span the measured values exceeded the calculated values by factors of up to 1.4 or more.

• Computers and Concrete
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• v.14 no.5
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• pp.599-612
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• 2014

This paper presents the effects of the construction stages using time dependent material properties on the structural behaviour of concrete arch dams. For this purpose, a double curvature Type-5 arch dam suggested in "Arch Dams" symposium in England in 1968 is selected as a numerical example. Finite element models of Type-5 arch dam are modelled using SAP2000 program. Geometric nonlinearity is taken into consideration in the construction stage analysis using P-Delta plus large displacement criterion. In addition, the time dependent material strength variations and geometric variations are included in the analysis. Elasticity modulus, creep and shrinkage are computed for different stages of the construction process. In the construction stage analyses, a total of 64 construction stages are included. Each stage has generally $6000m^3$ concrete volume. Total duration is taken into account as 1280 days. Maximum total step and maximum iteration for each step are selected as 200 and 50, respectively. The structural behaviour of the arch dam at different construction stages has been examined. Two different finite element analyses cases are performed. In the first case, construction stages using time dependent material properties are considered. In the second case, only linear static analysis (not considered construction stages) is taken into account. Variation of the displacements and stresses are obtained from the both analyses. It is highlighted that construction stage analysis using time dependent material strength variations and geometric variations has an important effect on the structural behaviour of arch dams. The maximum longitudinal, transverse and vertical displacements obtained from construction stages and static analyses are 1.35 mm and 0 mm; -8.44 and 6.68 mm; -4.00 and -9.90 mm, respectively. In addition, vertical displacements increase from the base to crest of the dam for both analyses. The maximum S11, S22 and S33 stresses are obtained as 1.60MPa and 2.84MPa; 1.39MPa and 2.43MPa; 0.60MPa and 0.50MPa, respectively. The differences between maximum longitudinal, transverse, and vertical stresses obtained from construction stage and static analyses are 78%, 75%, and %17, respectively. On the other hand, there is averagely 12% difference between minimum stresses for all three directions.

• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.5
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• pp.45-52
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• 2020

An open-spandrel arch bridges, which consists of slab deck, arch rib, and vertical members, shows a various level of moment and axial forces according to the supporting boundary condition of arch rib and vehicle speeds. Also, the definition of impact factor accepts any kind of response parameters, not only displacement response at slab deck. The present study considers concrete open-spandrel arch bridges constrained with fixed conditions at the ends of arch rib and investigates the impact factor variation due to moving load speeds, response parameters, measuring locations, and vertical member spacing ratio of the bridges. The results of Reference model show that the impact factor is biggest when the reactive moment resulted at the vehicle-inducing opposite end of the arch rib is applied. The peak impact factor is a similar level obtained for the middle of the span adjacent to the slab deck center, but it is 19% higher than the peak impact factor calculated using the axial force developed at the same location. Reducing the spacing ratio of the vertical members as half as the reference model whose ratio is 1/9.375 produces a similar level of the moment-based peak impact factor compared to the reference model. However, when the spacing ratio is doubled, the peak impact factor is 4.4 times greater than the reference model.

• Archives of Plastic Surgery
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• v.37 no.1
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• pp.91-94
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• 2010

Purpose: The purpose of this study is to describe the usefulness of intraoperative mobile CT scans in the reduction of zygomatic arch fracture. Method: Two patients with zygomatic arch fractures were selected who were indications of closed reduction by Gilles' approach. After the reduction was done in the operating room with zygomatic arch elevator, intraoperative CT scan was done to check the extent of reduction. Additional reduction was performed according to the obtained images from the intraoperative mobile CT scan. Examination of the preoperative CT, intraoperative CT after the reduction, and postoperative plain X-ray films were done for documentation and analysis. Results: Reduction was carried out successfully to the patients without any complications. Both patients were satisfied with the postoperative cosmetic and functional outcome. Revisional surgery was not necessary during the 6 months follow up. Conclusion: The advantage of this method is that it is easier to obtain three dimensional relationships of the fracture site. Furthermore, the operator is less exposed to radiation hazards compared to other methods that obtain intraoperative images such as the C-arm. In conclusion, intraoperative mobile CT scan can be a useful surgical aid in the reduction of zygomatic arch fractures.

• The korean journal of orthodontics
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• v.22 no.4 s.39
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• pp.823-836
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• 1992

Guiding a tooth along an arch wire results in a counteracting frictional force among arch wires, bracket and ligature. This frictional forces should be eliminated or minimized when orthodontic teeth movement is being planned. The purpose of this study was to evaluate the changes of width, cross-sectional forms and surface morphologies of stainless steel wire and $Elgiloy^{\circledR}$ wire after electropolising. Experimental variables included in this experiment were arch wire materials, current, electrolyte temperature and polishing time. Wire widths were measured by micrometer and cross-sectional forms and surface morphologies were examined with optical microscope and scanning electron microcope. The results were as follows: 1. The mean and standard deviation of widths of stainless steel wire and $Elgiloy^{\circledR}$ wire varying polishing time with condition of $249A/dm^2$ and $20^{\circ}C,\;249A/dm^2$ and, $332A/dm^2$ and $20^{\circ}C$ and $332A/dm^2$ and $250^{\circ}C$ were obtained. 2. With increasing polishing time, the widths of stainless steel wire and $Elgiloy^{\circledR}$ wire became decreased proportionally 3. The changes of widths of stainless steel wire and $Elgiloy^{\circledR}$ wire were statistically insignificant between $20^{\circ}C$ group and $25^{\circ}C$ group, but significant between $249A/dm^2$ group and $332A/dm^2$ group. 4 The cross-sectional forms of wire after electropolishing were not changed in stainless steel wire, and while it were changed to rounded corners in $Elgiloy^{\circledR}$ wire. 5. The surface morphologies of wire after electropolishing were scratch-absent and more smoothened both in stainless steel wire and $Elgiloy^{\circledR}$ wire.