• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.9 no.3
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• pp.76-82
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• 2000

It is well known that during the oxygen cutting process residual thermal stresses are produced in weldment. The local non-uniform heating and subsequent cooling which takes place during any welding process causes complex thermal strains and stresses to finally lead to residual stresses exceed to the yield stress. High tensile stresses combined with applied structural load in the region near the welded joint can given rise to distortion brittle fracture change of the fatigue strength and stress corrosion cracking. The appropriate treatment of the welded component which reduces the peak of he welding residual stresses is believed to lower risk of the fracture during the service of the structure. In this study the impact loading in oxygen cutting frame was applied to reduce the residual stress. After applying the impact loading redistribution of resid-ual stress was measured by cutting method and the effect of fatigue was tested.

• Steel and Composite Structures
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• v.17 no.5
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• pp.687-704
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• 2014

A great number of moment-resisting steel structures collapsed due to ductile crack initiation at welded beam-column connections, followed by explosive brittle fracture in the Kobe (Hyogoken-Nanbu) earthquake in 1995. A series of experimental and numerical studies on cracking behaviors of beam-column connections in steel bridge piers were carried out by the authors' team. This paper aims to study the effect of post weld treatment on cracking behaviors of the connections during a strong earthquake event. Experiments of three specimens with different weld finishes, i.e., as-welded, R-finish, and burr grinding, were conducted. The experimental results indicate that the instants of ductile crack initiation are greatly delayed for the specimens with R-finish and burr grinding finishes compared with the as-welded one. The strain concentration effect in the connection is also greatly reduced in the specimens with post weld treatment compared with the as-welded one, which was also verified in the tests.

• Biomedical Science Letters
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• v.16 no.3
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• pp.169-177
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• 2010

Osteoporosis is a disease that increases the fracture rates and a major cause of increased mortality and morbidity in the elderly people. This study is to determine which components of body composition and metabolic syndrome risk factors are important to bone health, we analysed the relationship among bone mineral density (BMD), body composition and metabolic syndrome risk factors in females. Totally 630 females participated in a medical check-up program (mean age 47 years) were selected for this study. Body composition analysis was performed by segmental bioelectrical impedance method, muscle mass, and percent body fat were measured. We also measured metabolic syndrome risk factors including abdominal obesity, HDL-cholesterol, triglyceride, blood pressure and fasting glucose level. Metabolic syndrome was defined by NCEP-ATP III criteria. The lumbar spine and femoral neck BMD were measured using the dual energy X-ray absorptiometry. Osteopenia and osteoporosis were observed in 180 and 51 persons, respectively. Muscle mass and HDL-cholesterol decreased in osteopenia and osteoporosis groups compared to the control group, and the grade was shown progressively by the symptoms. Significant positive correlation between BMD and muscle mass was observed. Multi variable regression analyses showed that % body fat and muscle mass were independent predictors of BMD after adjustment of age, height and weight. In conclusion, the BMD showed negative correlation with the metabolic and body composition was associated with BMD.

• Korean Journal of Adult Nursing
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• v.21 no.2
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• pp.257-267
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• 2009

Purpose: The purpose of this study was to identify risk factors of fall and to examine its results among patients aged 60 and over diagnosed with osteoporosis. Methods: A retrospective descriptive survey was conducted with 91 patients admitted in a university hospital in a city. Data were collected using an interview method with a structured questionnaire, and were analyzed using descriptive statistics and multiple logistic regression. Results: In patients with osteoporosis, the intrinsic risk factors of falls were aging (OR = 3.742), gait disturbance (OR = 12.565), taking one or fewer medicine (OR = 7.873), and having two or more diseases (OR = 5.173). The extrinsic risk factors included the use of a bed (OR = 3.093), slippery floors (OR = 12.130), bathroom mat without anti-slip rubber backing (OR = 3.564), and presence of a night light on the passage from the bedroom to the bathroom (OR = 2.980). Conclusion: For the elderly aged over 70 who are most vulnerable to falls, screening tests such as bone mineral density (BMD) should be conducted in health examinations and the risk of fracture caused by osteoporosis should be communicated to the vulnerable elderly. Besides, development of new exercise programs combining weightbearing exercise is needed to prevent bone loss and increase functional activities.

• Journal of the korean academy of Pediatric Dentistry
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• v.43 no.3
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• pp.320-326
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• 2016

The fracture of a needle during local anesthesia in dental treatment is rare; however, when it occurs, the needle should be removed without damage to surrounding structures as soon as possible. A fractured needle fragment that is buried in soft tissue would be difficult to remove, and a careful surgical procedure under general anesthesia is recommended in such cases. Children who require dental treatment are often not capable of cooperative behavior, thus unexpected movements can increase the risk of needle fracture. Clinicians can reduce the incidence of needle fracture accidents with a few precautions. In the present case report, we report a case of needle fracture due to abrupt movement during inferior alveolar nerve block anesthesia in a young child, with the purpose of drawing attention to needle fracture incidents. This report describes the possible causes and prevention methods of local anesthetic needle fracture, and the localization methods and surgical procedure for needle fragment removal.

• The Journal of Korean Academy of Prosthodontics
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• v.41 no.2
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• pp.232-242
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• 2003

Statement of problem : Fiber-reinforced posts have lower modulus of elasticity than titanium post or cast post-core. With this similar elasticity to that of dentin, fiber-reinforced posts have been known to have a tendency to reduce the risk of root fracture. However, there were few studies on the teeth restored with fiber-reinforced posts under the condition of reduced periodontal support. Purpose : The purpose of this study was to evaluate the fracture strength and failure mode of endodontically treated teeth restored with fiber-reinforced posts and titanium posts under the condition of reduced periodontal support. Material and method : Extracted human maxillary incisor roots were divided into 3 groups (group 1 carbon fiber post, group 2 : glass fiber post, and group 3 : titanium alloy post). After coronectomy and endodontic treatment, teeth were restored with each post systems and resin core according to the manufacturer's recommendation. Then, teeth with simulated periodontal ligament were embedded in the acrylic resin blocks at the level of 4 mm below the cemento-enamel junction. Each specimen was exposed to $10^5$ load cycles with average 30 N force in $36.5^{\circ}C$ water using a computer-controlled chewing simulator. Loads were applied at $45^{\circ}$ angle to the long axis of the teeth. After cyclic loading, teeth were subjected a compressive load until failure at a crosshead speed of 0.5 mm/min. Fracture strength (N) and failure mode were examined. The fracture strength was analyzed with one-way ANOVA and the Scheffe adjustment at the 95% significance level. Results and conclusion : The results were as follows. 1. There was no statistically significant difference in the mean fracture strength among the groups (P<.05). 2. Carbon fiber post and glass fiber post group showed less root fracture tendency than control group. 3. All specimens with root fractures showed fracture lines above the level of acrylic resin block, except for only one specimen in group 3.

• Journal of the Korean Orthopaedic Association
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• v.54 no.4
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• pp.336-342
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• 2019

Purpose: To examine the relationship between the progression of a kyphotic deformity and the magnetic resonance imaging (MRI) findings in conservatively treated osteoporotic thoracolumbar compression fracture patients. Materials and Methods: This study categorized the patients who underwent conservative treatment among those patients who underwent treatment under the suspicion of a thoracolumbar compression fracture from January 2007 to March 2016. Among them, this retrospective study included eighty-nine patients with osteoporosis and osteopenia with a bone density of less than -2.0 and single vertebral body fracture. This study examined the MRI of anterior longitudinal ligament or posterior longitudinal ligament injury, superior or inferior endplate disruption, superior of inferior intravertebral disc injury, the presence of low signal intensity on T2-weighted images, and bone edema of intravertebral bodies in fractured intravertebral bodies. Results: In cases where the superior endplate was disrupted or the level of bone edema of the intravertebral bodies was high, the kyphotic angle, wedge angle, and anterior vertebral compression showed remarkably progression. In the case of damage to the anterior longitudinal ligament or the superior disc, only the kyphotic angle was markedly prominent. On the T2-weighted images, low signal intensity lesions showed a high wedge angle and high anterior vertebral compression. On the other hand, there were no significant correlations among the posterior longitudinal ligament injury, inferior endplate disruption, inferior disc injury, and the progression of kyphotic deformity and vertebral compression. The risk factors that increase the kyphotic angle by more than 5° include the presence of injuries to the anterior longitudinal ligament, superior endplate disruption, and superior disc injury, and the risk factors were 21.3, 5.1, and 8.5 times higher than those of the uninjured case, and the risk differed according to the level of bone edema. Conclusion: An osteoporotic thoracolumbar compression fracture in osteoporotic or osteopenic patients, anterior longitudinal ligament injury, superior endplate and intravertebral disc injury, and high level of edema in the MRI were critical factors that increases the risk of kyphotic deformity.

• Journal of Trauma and Injury
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• v.24 no.1
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• pp.12-17
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• 2011

Purpose: A rib fracture secondary to blunt thoracic trauma continues to be an important injury with significant complications. Unfortunately, there are no definite treatment guidelines for severe multiple rib fractures. The purpose of this study was to evaluate the result of early operative stabilization and to find the risk factors of surgical fixation in patients with bilateral multiple rib fractures or flail segments. Methods: From December 2005 to December 2008, the medical records of all patients who underwent operative stabilization of ribs for severe multiple rib fractures were reviewed. We investigated patients' demographics, preoperative comorbidities, underlying lung disease, chest trauma, other associated injuries, number of surgical rib fixation, combined operations, perioperative ventilator support, and postoperative complications to find the factors affecting the mortality after surgical treatment. Results: The mean age of the 96 patients who underwent surgical stabilization for bilateral multiple rib fractures or flail segments was 56.7 years (range: 22 to 82 years), and the male-to-female ratio was 3.6:1. Among the 96 patients, 16 patients (16.7%) underwent reoperation under general or epidural anesthesia due to remaining fracture with severe displacement. The surgical mortality of severe multiple rib fractures was 8.3% (8/96), 7 of those 8 patients (87.5%) dying from acute respiratory distress syndrome or sepsis. And the other one patient expired from acute myocardial infarction. The risk factors affecting mortality were liver cirrhosis, chronic obstructive pulmonary disease, concomitant severe head or abdominal injuries, perioperative ventilator care, postoperative bleeding or pneumonia, and tracheostomy. However, age, number of fractured ribs, lung parenchymal injury, pulmonary contusion and combined operations were not significantly related to mortality. Conclusion: In the present study, surgical fixation of ribs could be carried out as a first-line therapeutic option for bilateral rib fractures or flail segments without significant complications if the risk factors associated with mortality were carefully considered. Furthermore, with a view of restoring pulmonary function, as well as chest wall configuration, early operative stabilization of the ribs is more helpful than conventional treatment for patients with severe multiple rib fractures.

• The Journal of the Korea Contents Association
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• v.17 no.2
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• pp.105-112
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• 2017

This study recognizes it as a social problem that can be prevented by basic research on safety security design for the elderly, and aims to clearly analyze risk factors for injury. For this study, raw data from the 6th Korean National Health and Nutrition Survey were employed and analyzed. Their social characteristics were classified with standards including gender, education, EuroQoL(human locomotion, normal activity and pain uncomfortableness), the quality of life(PHQ-(1)(2)(4)), recognition on stress, activity restriction status and associated causes(bone fracture and joint injury). Their epidemiological traits were chronic diseases, 'diabetes and hip-joint pain', and health-behavioral traits were 'smoking, breakfast frequency and high-level physical activity status.' In conclusion, it can be found that damage risk of elderly rose in case of female, lower education, inconvenience or limitation, pain or discomfort in locomotion and daily activities, higher recognition of stress, lower interest in work, feeling of depression, despair, and weariness, restriction in activity caused by bone fracture and joint injury, having diabetes and hip-joint pain, smoking, low frequency in having breakfast and high-level physical activities. Based on this study, we envision that an effective solution for injury risk factors caused by the organic relation can be reached in the near future.

• Journal of Trauma and Injury
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• v.33 no.1
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• pp.18-22
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• 2020

Purpose: Damage control laparotomy has contributed to improved survival rates for severe abdominal injuries. A large part of severe abdominal injury occurs with a concomitant pelvic bone fracture. The safety and effectiveness of internal fixation of pelvic bone fracture(s) has not been established. The aim of the present study was to evaluate infection risk in the pelvic surgical site in patients who underwent emergent abdominal surgery. Methods: This single-center retrospective observational study was based on data collected from a prospectively maintained registry between January 2015 and June 2019. Patients who underwent laparotomy and pelvic internal fixation were included. Individuals <18 and ≥80 years of age, those with no microbiological investigations, and those who underwent one-stage abdominal surgery were excluded. Comprehensive statistical comparative analysis was not performed due to the small number of enrolled patients. Results: A total of six patients met the inclusion criteria, and the most common injury mechanism was anterior-posterior compression (67%). The average duration of open abdomen was 98 hours (range, 44-98), and the time interval between abdominal closure and pelvic surgery was 98 hours. One patient (16.7%) died due to multi-organ dysfunction syndrome. Micro-organisms were identified in the abdominal surgical site in five patients (83%), with no micro-organisms in pelvic surgical sites. There was no unplanned implant removal. Conclusions: Internal fixation of pelvic bone fracture(s) could be performed in the state of open abdomen, and the advantages of early fixation may countervail the risks for cross contamination.