• Proceedings of the KSME Conference
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• 2002.08a
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• pp.11-16
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• 2002

In this paper, we present two successful results from active controls of flows over a circular cylinder and a sphere for drag reduction. The Reynolds number range considered for the flow over a circular cylinder is 40-3900 based on the free-stream velocity and cylinder diameter, whereas for the flow over a sphere it is $10^{5}$ based on the free-stream velocity and sphere diameter. The successful active control methods are a distributed (spatially periodic) forcing and a high-frequency (time periodic) forcing. With these control methods, the mean drag and lift fluctuations decrease and vortical structures are significantly modified. For example, the time-periodic forcing at a high frequency (larger than 20 times the vortex shedding frequency) produces $50{\%}$ drag reduction for the flow over a sphere at $Re=10^{5}$. The distributed forcing applied to the flow over a circular cylinder results in a significant drag reduction at all the Reynolds numbers investigated.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.21 no.2
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• pp.341-351
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• 1991

The purpose of this study was to aid in the evaluation of prognosis of temporomandibular joint after open reduction of fractured mandible. The author studied the bony changes (remodelling) of 116 temporomandibular joints and facial asymmetry in 58 patients. Subjects were divided into 4 Groups according to the follow up periods after open reduction of fractured mandible. The bony changes and facial asymmetry were observed on lateral tomograms and cephalometric posteroanterior skull radiograms. The results were as follows: 1. The bony changes of condyles were observed in 56 cases (38 flattening, 14 osteophyte, 3 erosion, 1 sclerosis). Flattening was observed in 32.8% (Group Ⅰ 27.8%, Group Ⅱ 37.5%, Group Ⅲ 35.7%, Group Ⅳ 32.1%). Osteophyte was observed in 12.1% (Group Ⅰ 11.1%, Group Ⅱ 8.3%, Group Ⅲ 7.1%, Group Ⅳ 21.4%). Erosion and sclerosis were observed in 2.6%, 0.9%, respectively. 2. The bony changes of articular fossa were observed in 18 cases (15.5%). Flattening was observed in 12.1% (Group Ⅰ 2.8%, Group Ⅱ 4.2%, Group Ⅲ 10.7%, Group Ⅳ 17.9%). Sclerosis was observed in 3.4% (Group Ⅰ 5.6%, Group Ⅲ 3.6%, Group Ⅳ 3.6%). 3. The amount of facial asymmetry was 2.81±2.20㎜ (Group Ⅰ 3.06±1.93㎜, Group Ⅱ 2.38±2.44㎜, Group Ⅲ 2.74±1.19㎜, Group Ⅳ 2.93±2.93㎜). There was no significant difference between all groups according to bony changes of temporomandibular joints after open reduction of fractured mandibles (x²-Test, P>0.05).

• Maxillofacial Plastic and Reconstructive Surgery
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• v.16 no.1
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• pp.89-98
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• 1994

This study was based on a series of 213 patients with facial bone fractures treated at college of Medicine, Dong-A university from Mar. 1990 to Jun. 1993. The results obtained were as follows : 1. The ratio of male to female was 8.3 : 1 and 3rd decade(34.3%) was the highest age group in incidence. 2. Monthly incidence was the highest in Jan. & Jun.(10.3%) 3. Onset time and daily incidence was the highest in pm. 9:00-12:00(21.4%), Sunday(18.8%). 4. Traffic acidents(38.5%) were the most frequent etiologic factor. 5. The most common site of fracture was zygoma & zygomatic arch(42.3%) and mandible (37.8%), maxilla (10.9%) and nasal bone(9.0%) were next in order of frequency. 6. In mandible fractures, the most frequent site was symphyseal area(43.0%) and IMF & open reduction was major method of treatment. 7. In zygoma & zygomatic arch fractures, zygoma(62.0%) was the most common fracture site and open reduction was the most frequent treatment method. 8. In maxilla fractures, the major fracture type was Le Fort I type (72.4%) and treatment was done by IMF & open reduction primarily. 9. postoperative complications were mal-union, fibrous-union, infection, osteomyelitis etc.

• Journal of Korean Foot and Ankle Society
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• v.5 no.2
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• pp.156-159
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• 2001

Unicameral bone cysts are benign solitary lesions that occur in the first two decades of life and with a greater frequency in the humerus and femur. The cyst is usually asymptomatic unless a fracture or impending fracture is present. The traditional method of treating unicameral cysts has been curettage with bone graft or steroid injection. Also, pathologic fractures in the calcaneus, unlike in other bones, are reported especially in the children to be nonexistent. In general, closed treatment was recommended for most of the calcaneal fractures in children, but suggested open reduction when joint displacement was severe. We report a case of displaced intraarticular fracture of the calcaneus with unicameral bone cyst in a child treated by classic curettage, allograft and open reduction with screw fixation.

• The Journal of the Korean dental association
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• v.54 no.12
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• pp.1045-1054
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• 2016

Purpose : Aim of this study is to describe and compare clinical results and complications epending on the surgical approaches for the mandibular subcondyle fracture Materials and methods : The patients who had been diagnosed as the mandibular subcondyle fracture and underwent open reduction and internal fixation from May 2009 to December 2014 were included. They were divided into two groups depending on the surgical approaches; endoscopically assisted transoral approach and retromandibular approach. Association between the preoperative fracture classification and post-operative results was reviewed depending on the surgical approaches. Results : The number of patients selected in this study was 33. Eighteen patients (male 7, female 11) underwent open reduction and internal fixation via retromandibular approach and fifteen patients (male 12, female 3) underwent open reduction and internal fixation via endoscopically assisted transoral approach. The mean age, follow up period, and operation time were $44.29{\pm}15.19years$, $9.97{\pm}7.82months$, and $161{\pm}89.44minutes$. Post-operative results were all "good" state in the retromandibular approach group regardless of the fracture classification but two patients in the endoscopically assisted transoral approach group underwent re-operation due to "poor" results. The fracture types of two were classified as displacement and lateral override at the same time. There was no statistically significant difference between two groups. Three patients in the retromandibular approach group had experienced facial nerve palsy (17%) temporarily. No one showed malocclusion in this study. There was no significant difference on the complications such as temporomandibular disorder, local infection, and condyle resorption depending on the surgical approaches. Conclusion : In this study, there was no significant difference on the complications between the two groups but retromandibular approach has advantage over endoscopically assisted transoral approach in case of the severely displaced subcondyle fracture.

• Transactions of the Korean Society of Automotive Engineers
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• v.18 no.2
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• pp.122-128
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• 2010

To meet the NOx limit without a penalty of fuel consumption, urea-SCR system is currently regarded as promising NOx reduction technology for diesel engines. SCR system has to achieve maximal NOx conversion in combination with minimal $NH_3$ slip. In this study, the performance characteristics of urea-SCR system with open loop control were assessed in the European Transient Cycle(ETC) for heavy duty diesel engine. The SCR inlet temperaure varied in the range of 200 to $340^{\circ}C$ in the ETC cycle. Open loop control calculated the urea flow rate based on the NOx and NSR map which gave for each combination of SCR inlet temperature and space velocity the normalized $NH_3$ to NOx stoichiometric ratio which resulted in a steady-state $NH_3$ slip of 20ppm. During the ETC cycle, the open loop control with the optimized NSR offset achieved NOx reduction of 80% while keeping the average $NH_3$ slip below 10ppm and maximum 20ppm. It was also found that NOx sensor was cross-sensitive to $NH_3$ and a control strategy for cross-sensitivity compensation was required in order to use a NOx sensor as feedback device.

• Journal of Korean Foot and Ankle Society
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• v.13 no.1
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• pp.75-79
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• 2009

Purpose: To evaluate the outcomes of intra-articular calcaneal fractures treated using AO calcaneal plate surgically. Materails and Methods: Total 15 cases of intra-articular calcaneal fracture that treated with open reduction and internal fixation using AO calcaneal plate were evaluated. The patients were followed over a mean period of 19.8 months. The mean age was 41.6 years. By Sanders classification, there were 2 cases of type II, 10 cases of type III, and 3 cases of type IV. We evaluated radiological outcomes by Bohler angle, Gissane angle, calcaneal hight, calcaneal width and clinical outcomes by Creighton-Nebraska health foundation score. Results: All fractures united at a mean duration of 13.3 weeks. Radiologically, the mean preoperative Bohler angle was $8.5^{\circ}$ and restored to $23.3^{\circ}$. The mean preoperative Gissane angle was $118.7^{\circ}$ and restored to $124.2^{\circ}$. The mean preoperative calcaneal hight was 30.8 mm and restored to 38.9 mm. The mean preoperative calcaneal width was 41.3 mm and restored to 35.3 mm. 10 cases had excellent and good clinical outcomes and 5 cases having fair outcome. Conculsion: In our study, open reduction and internal fixation using AO calcaneal plate showed good results with anatomical restoration of articular surface and stable fixation without late collapse.

• Archives of Plastic Surgery
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• v.36 no.1
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• pp.56-60
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• 2009

Purpose: Palatal fracture and mandible fracture result in instability of dental arch. Because they divide the maxillary and mandibular alveolus sagittally and / or transversely and comminute the dentition, they permit rotation of dental alveolar segments and significantly increase the potential for fracture malalignment, complicating fracture treatment. Previous treatment of palatal fracture consisted of palatal splint application and rigid palatal vault stabilization. This procedure result in patient's oral discomfort and removal of palate and screw. Mandible fracture often results in malocclusion due to widening of posterior aspect of dental arch. So we introduce more simple method using intermolar traction wiring, which can protect the widening of dental arch and rotation of dental alveolar segment. Methods: Arch bar and intermolar traction wiring with wire 1 - 0, or 2 - 0 was applied. After exposure of fracture line, neutrooclusion was maintained with intermaxillary fixation. And then open reduction & internal fixation on maxillary fracture line, commonly maxillary buttress, alveolar ridge, pyriform aperture except palatal vault or mandibular fracture line. After 1 week, intermolar traction wiring was removed. We checked occlusion and postoperative radiologic finding. Results: From June of 2007 to October of 2007, 10 patient, who have maxillary fracture with palatal fracture and mandible fracture, underwent open reduction & internal fixation with intermolar traction wiring. All have satisfactory occlusion and there were no complication, like gingiva disease, mouth opening impairment and nonunion. Conclusion: The intermolar traction wiring accompany open reduction and internal fixation can be alternative method for restoration of dental arch in facial bone fracture.

• Clinics in Shoulder and Elbow
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• v.1 no.2
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• pp.198-204
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• 1998

Unstable fractures of the proximal humerus continue to be difficult problems for orthopaedic surgeons. The optimum treatment of these fractures has remained a matter of controversy. We analyzed the clinical results of open reduction and plate fixation underwent for patients of unstable fractures of proximal humerus after minimum 12 months follow up. The purpose of this study is to evaluate the efficacy of open reduction and rigid plate fixation. Twenty-two patients were managed with open reduction and plate fixation. Mean follow up duration was 20.6 months(range, 12 to 28 mon.). Because the age of patient as a maker of degree of osteoporosis was considered the key factor in the success of anatomic reconstruction, we divided into two groups according to age. Group A was comprised of 12 cases with younger than 50 yrs of age. Ten cases of older than 50 yrs of age were Group B. According to Neer's classification, five cases(22%) were two part fracture, 12 cases(64%) were three part fracture, and three cases(14%) were four part fracture. We used the Neer rating system for evaluating the results. In Group A, overall scores were 79.1. In Group B, overall scores were 76.8. Overall scores in two part fracture were 85, overall scores in three part fracture 78.4 and overall scores in three part fracture 68.3. We achieved excellent or good results in nine cases(75%) of Group A and seven cases(70%) of Group B. Also, we obtained excellent or good results in all cases of two part fracture, ten cases(71%) of three fracture and one case(33%) of four part fracture. The complications were three metal loosening, one avascular necrosis of humeral head, one severe stiff shoulder, one superficial wound infection and one ectopic ossification. The results were excellent or good in 16 cases(73%) out of 22 cases. In conclusion, rigid fixation and supervised early exercise would be a good option for unstable fracture of the proximal humerus.

• Journal of Chest Surgery
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• v.49 no.5
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• pp.361-365
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• 2016

Background: Sternal fractures are relatively rare, and caused mainly by blunt anterior chest wall trauma. In most cases, sternal fractures are treated conservatively. However, if the patient exhibits problematic symptoms such as intractable chest wall pain or bony crepitus due to sternal instability, surgical correction is indicated. But no consensus exists regarding the most appropriate surgical method. We analyzed the results of surgical fixation in cases of sternal fracture in order to identify which surgical method led to the best outcomes. Methods: We retrospectively reviewed the medical records of patients with sternal fractures from December 2008 to December 2011, and found 19 patients who underwent open reduction and internal fixation of the sternum with a longitudinal plate (L-group) or a T-shaped plate (T-group). We investigated patients' characteristics, clinical details regarding each case of chest trauma, the presence of other associated injuries, the type of open reduction and fixation, whether a combined operation was performed, and postoperative complications. Results: Of the 19 patients, 10 patients (52.6%) were male, and their average age was 56.8 years (range, 32 to 82 years). Seven patients (36.8%) had isolated sternal fractures, while 12 (63.2%) had other associated injuries. Seven patients (36.8%) were in the L-group and 12 patients (63.2%) were in the T-group. Three patients in the L-group (42.9%) showed a loosening of the fixation. In all patients in the T-group, the fracture exhibited stable alignment. Conclusion: Open reduction and internal fixation with a T-shaped plate in sternal fractures is a safer and more efficient treatment method than treatment with a longitudinal plate, especially in patients with a severely displaced sternum or anterior flail chest, than a longitudinal plate.