• 소성∙가공
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• 제24권4호
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• pp.280-286
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• 2015

Hemming is used to connect two sheet metal components by folding the edge of an outer panel around an inner panel to create a smooth edge. The minimization of hemming defects is critical to the final quality of automobile products because hemming is one of the last operations during fabrication. Designing the hemmed part is not easy and is influenced by the geometry of the bent part. Therefore, the main problem for automotive parts is dimensional accuracy since formed products often deviate geometrically due to large springback. Few numerical approaches using 3-dimensional finite element model have been applied to hemming due to the small element size which is needed to properly capture the bending behavior of the sheet around small die corner and the comparatively big size of automotive opening parts, such as doors, hoods and deck lids. The current study concentrates on the 3-dimensional numerical simulation of hemming for an automotive door. The relationship between the design parameters of the hemming operation and the height difference defect is shown. Quality improvement of the automotive door can be increased through the study of model parameters.

• Journal of Korean Neurosurgical Society
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• 제40권5호
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• pp.346-350
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• 2006

Objective : The ability to induce segmental lordosis has been reported to be marginal with transforaminal lumbar interbody fusion[TLIF]. Therefore, we analyzed the short-term radiological outcomes of TLIF using $8^{\circ}$ wedged cages for isthmic spondylolisthesis. Methods : Twenty-seven patients with isthmic spondylolisthesis who underwent single level TLIF with pedicle screw fixation[PSF] using $8^{\circ}$ wedged cages were retrospectively evaluated. Changes in disc height, degree of anterolisthesis, segmental lumbar lordosis, whole lumbar lordosis and L1 axis S1 distance were evaluated using standing lateral radiographs before surgery, at 6 weeks follow-up and at the final follow-up. Results : The mean age of the patients was 49.9 years [range, 38 to 64 years]. The affected levels were L4-5 in 17 cases and L5-S1 in 10. There were 18 cases of Grade I isthmic spondylolisthesis and 9 cases of Grade II. At a mean follow-up duration of 9.9 months [range, 6 to 18 months], the disc height [p< 0.001] was significantly increased, and the degree of anterolisthesis was significantly reduced [p< 0.001]. Regarding the sagittal balance, the segmental lumbar lordosis was significantly increased [p=0.01], but other parameters were not significantly changed after surgery. Conclusion : TLIF with PSF using $8^{\circ}$ wedged cages significantly increased the segmental lumbar lordosis.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제30권5호
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• pp.495-499
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• 2008

For the successful placement of dental implants, adequate alveolar bone height and width are required. Alveolar distraction osteogenesis is an effective method that resolves insufficient alveolar bone height for dental implant placement, and thus has been clinically applied with satisfactory results. But, minor and major problems may occur during the treatment. In the following report, we studied for such problematic cases. The problems are as follows: 1) sharp edges of the transport segment, 2) infection, 3) soft tissue dehiscence, 4) limitation of distraction, 5) numbness, 6) insufficient bone formation. But, most of them were answered by simple solutions and did not jeopardize the final outcomes. Distraction osteogenesis can be considered a safe and predictable procedure for lengthening the alveolar bone.

• Journal of Periodontal and Implant Science
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• 제44권5호
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• pp.259-264
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• 2014

Purpose: The aim of this case report is to present the longitudinal results of sinus grafting using a new demineralized bovine bone material (DBBM) in human cases. Methods: A patient with a resorbed maxilla was treated by maxillary sinus grafting using a new deproteinized bovine bone material. After a healing period of 6.5 months, three implants were placed and restored. The patient was periodically recalled and followed up for 5 years after restoration. Results: Twelve partially edentulous patients (average age, 55.7 years) were followed up. All patients had insufficient residual height in their maxillary posterior area and underwent maxillary sinus graft surgery to increase the height of their maxilla. In all, 27 fixtures were placed in the augmented bone area. On average, 8.6 months later, implants were loaded using provisional or final restorations. The observation period ranged from 27 to 75 months (average, 43.3 months), and the patients did not show any severe resorption of the graft material or any infection during this time. Conclusions: Our results show that the new DBBM is useful for a maxillary sinus graft procedure. Good healing responses as well as reliable results were obtained for an average follow-up period of 43.3 months.

• 상하수도학회지
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• 제28권5호
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• pp.609-614
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• 2014

Researcher of this study improved conventional circle secondary settling basin, through the way such as extend of inlet pipe length, introduction of device for inducting uniforming of flow, keeping of height of sludge interface. Also, we compared conventional circle settling basin to improved circle settling basin the water treatment efficiency. Result of research, when SVI is average 117, improvement rate of SS and BOD were 51.0%, 37.0% approximately compared to conventional settling basin. And when SVI is average 178, improvement rate of SS and BOD were 22.7%, 36.0% approximately. Also when SVI is average 196, improvement rate of SS and BOD were 24.7%, 30.3% approximately. When it's winter, improvement rate of SS, BOD, COD, TN and TP were 20.6%, 17.9%, 13.9%, 13.5%, 12.4% approximately. Therefore, we can be the judge, this improved settling basin can be used as the final settling basin in the waste water treatment plant.

• 한국의류학회지
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• 제42권6호
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• pp.943-961
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• 2018

This study was to develop an ergonomic Korean male military winter jackets (inner and outer) pattern. First, we developed a prototype pattern and sample jackets based on a previous investigation for fitness and motion suitability of Korean male military winter jackets and evaluated fitness and motion suitability by a wearing test. The evaluation results were positive with an over 3.0 (5.0 Likert scale) for both the inner and outer jacket. However, a relatively low score was shown in the sleeve length and collar front height at the inner jacket and shown in hem circumference, neck circumference, elbow and front neck at the outer jacket. Next, we developed the secondary pattern and sample jacket reflecting the prototype evaluation result and executed expert evaluation. The result showed that the ease amount was appropriate (except for the collar back height) and the appearance was good. Finally, we developed a final pattern that showed good results after evaluation at a Korean military army base.

• Structural Engineering and Mechanics
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• 제86권1호
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• pp.49-68
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• 2023

This study investigates the static and dynamic structural analysis of symmetrical and asymmetrical coupled shear walls using the continuous and modified transfer matrix methods by idealizing the coupled shear wall as a three-field CTB-type replacement beam. The coupled shear wall is modeled as a continuous structure consisting of the parallel coupling of a Timoshenko beam in tension (with axial extensibility in the shear walls) and a shear beam (replacing the beam coupling effect between the shear walls). The variational method using the Hamilton principle is used to obtain the coupled differential equations and the boundary conditions associated with the model. Using the continuous method, closed-form analytical solutions to the differential equation for the coupled shear wall with uniform properties along the height are derived and a numerical solution using the modified transfer matrix is proposed to overcome the difficulty of coupled shear walls with non-uniform properties along height. The computational advantage of the modified transfer matrix method compared to the classical method is shown. The results of the numerical examples and the parametric analysis show that the proposed analytical and numerical model and method is accurate, reliable and involves reduced processing time for generalized static and dynamic structural analysis of coupled shear walls at a preliminary stage and can used as a verification method in the final stage of the project.

• Childhood Kidney Diseases
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• 제10권2호
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• pp.219-227
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• 2006

Purpose : We aim to identify the clinical and demographic characteristics in children who underwent renal transplantation(RTx) and to evaluate the influence on growth of RTx in children. Methods : We reviewed 17 medical records of chronic renal failure patients who underwent RTx from April 1992 and June 2004 at Busan Paik Hospital. Age and sex distribution, cause of disease, donor analysis, patient and graft survival rate, and the status of growth after RTx were analysed by retrospective study. Results : Eighteen RTx were performed in 17 patients(8 boys, 9 girls). The mean age at the time of RTx was $15.8{\pm}3.5$ years and the mean duration of dialysis therapy before RTx was $22.4{\pm}18.0$ months. The 1 year and 5 year patient survival rate were each 100%, and the 1 year and 5 year graft survival rate were 88%, 36% respectively. The most common cause of graft failure was chronic rejection. The mean final height of male patients was $162.8{\pm}10.0$ cm(143.0-172.5 cm) and of female patients was $154.5{\pm}12.1$ cm(135.8-160.0 cm). The mean height standard deviation score(Ht SDS) increased after RTx from -1.95 to -1.53 but the increment rate was not statistically significant. Similar changes were noted in individual patient analysis. Also there was no significant difference between the living-related donors and cadaveric donors. Conclusion : Our data shows that even successful RTx rarely results in full growth rehabilitation. To overcome retarded growth in children with chronic renal failure, appropriate combined management of metabolic and nutritional problems, correction of anemia, proper use of recombinant growth hormone therapy, early renal transplantation and shortening of the duration of dialysis would be necessary.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제39권6호
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• pp.274-282
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• 2013

Objectives: The posterior maxillary region often provides a limited bone volume for dental implants. Maxillary sinus elevation via inserting a bone graft through a window opened in the lateral sinus wall has become the most common surgical procedure for increasing the alveolar bone height in place of dental implants in the posterior maxillary region. The purpose of this article is to assess the change of bone volume and the clinical effects of dental implant placement in sites with maxillary sinus floor elevation and autogenous bone graft through the lateral window approach. Materials and Methods: In this article, the analysis data were collected from 64 dental implants that were placed in 24 patients with 29 lacks of the bone volume posterior maxillary region from June 2004 to April 2011, at the Department of Oral and Maxillofacial Surgery, Inha University Hospital. Panoramic views were taken before the surgery, after the surgery, 6 months after the surgery, and at the time of the final follow-up. The influence of the factors on the grafted bone material resorption rate was evaluated according to the patient characteristics (age and gender), graft material, implant installation stage, implant size, implant placement region, local infection, surgical complication, and residual alveolar bone height. Results: The bone graft resorption rate of male patients at the final follow-up was significantly higher than the rate of female patients. The single autogenous bone-grafted site was significantly more resorbed than the autogenous bone combined with the Bio-Oss grafted site. The implant installation stage and residual alveolar height showed a significant correlation with the resorption rate of maxillary sinus bone graft material. The success rate and survival rate of the implant were 92.2% and 100%, respectively. Conclusion: Maxillary sinus elevation procedure with autogenous bone graft or autogenous bone in combination with Bio-Oss is a predictable treatment method for implant rehabilitation.

• Journal of Korean Neurosurgical Society
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• 제48권6호
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• pp.490-495
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• 2010

Objective : Bone cement augmentation procedures such as percutaneous vertebroplasty and balloon kyphoplasty have been shown to be effective treatment for acute or subacute osteoporotic vertebral compression fractures. The purpose of this study was to determine the efficacy of bone cement augmentation procedures for long standing osteoporotic vertebral compression fracture with late vertebral collapse and persistent back pain. Methods : Among 278 single level osteoporotic vertebral compression fractures that were treated by vertebral augmentation procedures at our institute, 18 consecutive patients were included in this study. Study inclusion was limited to initially, minimal compression fractures, but showing a poor prognosis due to late vertebral collapse, intravertebral vacuum clefts and continuous back pain despite conservative treatment for more than one year. The subjects included three men and 15 women. The mean age was 70.7 with a range from 64 to 85 years of age. After postural reduction for two days, bone cement augmentation procedures following intraoperative pressure reduction were performed. Imaging and clinical findings, including the level of the vertebra involved, vertebral height restoration, injected cement volume, local kyphosis, clinical outcome and complications were analyzed. Results : The mean follow-up period after bone cement augmentation procedures was 14.3 months (range 12-27 months). The mean injected cement volume was 4.1 mL (range 2.4-5.9 mL). The unipedicular approach was possible in 15 patients. The mean pain score (visual analogue scale) prior to surgery was 7.1, which decreased to 3.1 at 7 days after the procedure. The pain relief was maintained at the final follow up. The kyphotic angle improved significantly from $21.2{\pm}4.9^{\circ}$ before surgery to $10.4{\pm}3.8^{\circ}$ after surgery. The fraction of vertebral height increased from 30% to 60% after bone cement augmentation, and the restored vertebral height was maintained at the final follow up. There were no serious complications related to cement leakage. Conclusion : In the management of even long-standing osteoporotic vertebral compression fracture for over one year, bone cement augmentation procedures following postural reduction were considered safe and effective treatment in cases of non-healing evidence.