• Journal of the Korean Society of Radiology
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• v.7 no.6
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• pp.403-408
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• 2013

This study made a tentative estimation of the shielding rate of barium compound by thickness through monte carlo simulation to apply medical radiation shielding products that can replace existing lead. Barium sulfate($BaSO_4$) was used for the shielding material, and thickness of the shielding material specimen was simulated from 0.1 mm to 5 mm by applying $15{\times}15cm^2$ of specimen area, $4.5g/cm^3$ of density of barium sulfate, and $11.34g/cm^3$ density of lead. Entered source was simulated with 10kVp Step in consecutive X-ray energy spectrum(40 kVp ~ 120 kVp). Absorption probability in 40 kVp ~ 60 kVp showed same shielding rate with lead in 3 mm ~ 5 mm of thickness, but it was identified that under 2 mm, the shielding rate was a bit lower than the existing lead shielding material. Also, the shielding rate in 70 kVp ~ 120 kVp energy band showed similar performance as the existing lead shielding material, but it was tentatively estimated as fairly low shielding rate below 0.5 mm. This study estimated the shielding rate of barium compound as the thickness function of x-ray energy band for medical radiation through monte carlo simulation, and made comparative analysis with existing lead. Also, this study intended to verify application validity of the x-ray shielding material for medical radiation of pure barium sulfate. As a result, it was estimated that the shielding effect was 95% higher than the existing lead 1.5 mm in at least 2 mm thickness of barium compound in medical radiation energy band 70 kVp ~ 120 kVp, and this result is considered valid to be provided as a base data in weight lightening production of radiation shielding product for medical radiation.

• Steel and Composite Structures
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• v.38 no.2
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• pp.189-211
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• 2021

An analytical solution is presented to analyze the thermoelastoplastic response of a rotating thick-walled cylindrical pressure vessel made of functionally graded material (FGM). The analysis is based on Tresca's yield condition, its associated flow rule and linear strain hardening material behaviour. The uncoupled theory of thermoelasticity is used, and the plane strain condition is assumed. The material properties except for Poisson's ratio, are assumed to vary nonlinearly in the radial direction. Elastic, partially plastic, fully plastic, and residual stress states are investigated. The heat conduction equation for the one-dimensional problem in cylindrical coordinates is used to obtain temperature distribution in the vessel. It is assumed that the inner surface is exposed to an airstream and that the outer surface is exposed to a uniform heat flux. Tresca's yield criterion and its associated flow rule are used to formulate six different plastic regions for a linearly hardening condition. All these stages are studied in detail. It is shown that the thermoelastoplastic stress response of a rotating FGM pressure vessel is affected significantly by the nonhomogeneity of the material and temperature gradient. The results are validated with those of other researchers for appropriate values of the system parameters and excellent agreement is observed.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.9
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• pp.4071-4077
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• 2014

Background: The effects of CYP1A1 gene polymorphisms on the risk of bladder cancer (BC) remain controversial. We carried out a meta-analysis to clarify the role of CYP1A1 gene polymorphisms in BC. Material and Methods: A comprehensive literature search was conducted up to November 20, 2013. Odds ratios (ORs) with 95% confidence intervals (CIs) were used to estimate the strength of the association. Meta-regression, subgroup analysis, sensitivity analysis and publication bias were also performed. Results: Eight studies involving 1,059 BC cases and 1,061 controls were included. The meta-analysis showed that there was no significant association between the two common mutations of CYP1A1 and BC risk. For the I1e462Val A/G polymorphism with GG vs. AA the OR was 1.47 (95 % CI= 0.70-3.07, P =0.308). For the MspI T/C polymorphism, though a slight trend was found this was not statistically nonsignificant (CC vs.TT, OR = 1.24, 95 % CI= 0.98-1.58, P =0.078). Subgroup analyses by ethnicity also found no obvious association between CYP1A1 and BC risk. Conclusion: The present meta-analysis suggests that CYP1A1 polymorphism is not associated with bladder cancer risk.

• Korea Journal of Hospital Management
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• v.22 no.2
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• pp.44-57
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• 2017

The objective of this study is to investigate financial integrity strategies for sustainable development of local public medical centers, and particularly focus on seeking ways to enhance its financial efficiency and publicness. The data which was collected from 33 local public medical centers was analyzed by Data Envelopment Analysis to measure its financial efficiency. Then, Matrix Analysis was used to examine the association of financial efficiency and publicness of local public medical centers with related factors. In the aspects of facilities and location, according to the results, the local public medical centers which have larger number of available hospital beds or located in bigger cities were examined to have higher degree of publicness. In the aspect of human resources, greater number of doctors made both financial efficiency and the degree of publicness decreased, whereas higher participation rate of educational program for doctors affects increasing its financial efficiency and publicness. Lastly, in the aspect of costs, higher labor, material, and administrative cost diminished financial efficiency, but enhanced the degree of publicness. Based on these results, this study concluded that enhancing the publicness of local public medical centers should be pursued by increasing the accessibility with better facilities and location, and also concurrently organizing rational expenditure structure with appropriate cost investment to the resources of local public medical centers. Also, it is necessary to enhance both financial efficiency and publicness simultaneously by improving the quality of health care services through the educational programs for medical staffs.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.29 no.6
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• pp.438-443
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• 2003

Purpose : This study evaluated the usefulness of resorbable plate and screw for treatment of maxillofacial bone fractures. Patients and methods : From july, 2000 to july, 2002, we used resorbable plates and screws($Biosorb^{(R)}$ FX, Bionix Inc, Finland) on 126 patients for treatment of maxillofacial bone fractures. Among them, 80 patients were capable of periodic following up to present season. We evaluated these patients with clinical, radiographic findings and subjective satisfaction. Results : 80 patients composed of 63 men and 17 women. Complication rates are 7.5%(6/80) recorded. 1 of bulging sensation, 3 of infection sign, 2 of the plate detachment were shown. The plates involved in such complications were removed. The other patients(92.5%) were not shown any problems. We could not find complete resorption of screw holes in the mandibular symphysis area even though two years later after surgery. Conclusion : Bioresorbable plates and screws are useful as fixation material at maxillofacial fractures although strength is thought to be weaker than titanium plate. But to reduce the possible complicaions, need to careful clinical and radiographical evaluations.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2016.11a
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• pp.117-117
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• 2016

Total ankle replacement (TAR) is a visible option in the surgical treatment of degenerative or inflammatory diseases of ankle joint. it is attributed to the current TAR which has improvements in surgical technique, uncemented implant fixation and minimally constrained articulation. In the clinical result, they can show promised surgical result when compared to earlier attempts in TAR. However, TAR is still not as successful as total knee replacement (TKR) or total hip replacement (THR), it needs to be note that there are limitations in concerning of long term performance of TAR, the high failure rate still associated with wear of the PE (polyethylene) component that has related with their material property and surface roughness. The aim of this study was to introduce the tribology characteristics of total ankle joint prosthesis with one of TDR model which was fabricated to try multi-axis wear test as a region of motion in ankle joint. The wear specimen of TDR was prepared with Ti-6Al-4V alloy and UHMWPE (ultra-high molecular weight polyethylene) for tibia-talus and bearing component, respectively. A wear test was carried out using a Force 5 (AMTI, Massachusetts, US) wear simulator which can be allowed to move in three axis to flexion-extension ($+3^{\circ}{\sim}-6^{\circ}$), internal-external axial rotation (${\pm}5^{\circ}$), as well as sinusoidal compressive load (1.6 kN, R=10). All tests were performed following standard ISO 14243, wear rate was calculated with weight loss of UHMWPE bearing while the specimen has tested at certain cycles. As based on the preliminary results, wear rate of UHMWPE bearing was $7.9{\times}10^{-6}mg/cycles$ ($R^2=0.86$), calculated loss weight until $10^7cycles$ was 79 mg, respectively.

• The Korean Journal of Emergency Medical Services
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• v.11 no.2
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• pp.19-27
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• 2007

Purpose: By identifying the actual profile of emergency medical personnel's pre-admission infection control practices, this study intended to provide a basic reference material for the improvement and reorientation of pre-admission infection control measures, and thereby help establish an effective plan for pre-admission infection control activities. Methods: Total 119 EMT's working for Jeollabuk-do Provincial Fire Defense HQ were asked to join a structured questionnaire survey from June to August 2006. Results: 1. It was found that 56.1% respondents answered no guideline available on the prevention of infection. Out of our rescue brigade members who knew about relevant guideline available, 34.2% respondents answered that their department conducted quality control program for the guideline. 2. For protective outfit in emergency practice, it was found that most respondents put on gloves or nothing at all(38%), which was followed by sterile gloves(29.2%), disposable mask(26.9%), gown(4.3%) and protective goggle(1.6%). And it was noted that all respondents(100%) washed out any clothing contaminated with somatic secretion on their own. 3. For a question about any experience in emergency activities exposed to infectious diseases, it was found that most of all respondents(77.9%) answered 'No', which was followed by 'Don't Know'(18.6%) and Yes(3.9 %). 4. For a question about any experience in inquiring of patients about infectious diseases, it was found that most respondents(49.4%) answered 'Yes' and 'Sometimes'(9.1%). It was noted that 20.2% respondents had extra medical examination in medical institution in terms of whether they were exposed to infectious diseases, apart from regular medical examination. Conclusions: In order to protect 119 EMT's from infectious diseases, it will be necessary to acquire emergency medical staffs specializing in infection control and organize corresponding personnel training units to keep providing reorientation and evaluation. In addition, it will be also necessary to supply them with a full set personal protection apparatuses and other equipments required for disinfection and sterilization.

• Journal of Haehwa Medicine
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• v.10 no.2
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• pp.91-96
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• 2002

We arrived at the following conclusions after we have studied esophagitis through the literatures of oriental and western medicine. 1. The western medical causes of acute esophagitis are corrosiveness chemical material, esophageal or gastric disease, trauma, blister stomatitis, filamentous fungus infection and uremia of chronic patient etc, and the oriental medical causes are qi and blood stagnation, blood stasis and stagnation, stagnant phlegm by coldness, heating, dyspepsia and food poisoning etc. 2. The western medical causes of chronic esophagitis are malfunction of lower esophageal sphincter, esophageal tom chink and hernia, increase of gastric pressure by overeating, fatness, pregnancy and ascites etc, and the oriental medical causes are asthenic cardiac qi, hepatic qi attacking stomach by seven kinds of depression, cold-damp stagnation and insufficiency of gastric qi by overeating, excessive drinking and sexual indulgence etc. 3. The main symptoms of acute esophagitis are severe chest pain, instantly vomiting, swallowing pain etc, and chronic esophagitis are occasionally light chest pain, heart bum, anorexia, dysphagia, dizziness, general body weakness etc. These symptoms are come under thoracic obstruction, acid regurgitation, vomiting and chest pain of oriental medicine. 4. The western medical diagnoses of acute and chronic esophagitis have used radiation test, esophageal endoscopy, esophageal pressure test and biopsy etc, and the oriental medical diagnoses have used syndrome differentiation by four examination of inspection, listening and smelling examination, inquiring, pulse-taking and palpitation. 5. The western medical treatments of acute esophagitis have regarded preservation stability of esophagus as a principle, and the oriental medical treatments mainly have used expelling pathogen of expelling cold and regulating qi, cooling and removing stasis, promoting blood circulation to remove blood stasis, eliminating phlegm and regulating qi. 6. The western medical treatments of chronic esophagitis have regarded decrease flowing backward of gastric juice as a purpose, and the oriental medical treatments mainly have used strengthening body resistance of replenishing and strengthening cardioqi, dispersing stagnated hepatoqi, expelling cold and dehygrosis, invigorating stomach and nourishing qi.

• Progress in Medical Physics
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• v.33 no.4
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• pp.164-171
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• 2022

The number of facilities using radiation generators increases and related regulations are strengthened, the establishment of a shielding management and evaluation technology has become important. The characteristics of the radiation generator used in previous report differ from those of currently available high-frequency radiation generators. This study aimed to manufacture lead, iron, and concrete shielding materials for the re-verification of half-value layers, tenth-value layers, and attenuation curve. For a comparison of attenuation ratio, iron, lead, and concrete shields were manufactured in this study. The initial dose was measured without shielding materials, and doses measured under different types and thicknesses of shielding material were compared with the initial dose to calculate the transmission rate on 50-300 kVp X-ray. All the three shielding materials showed a tendency to require greater shielding thickness for higher energy. The attenuation graph showed an exponential shape as the thickness decreased and a straight line as the thickness increased. The difference between the measurement results and the previous study, except in extrapolated parts, may be due to the differences in the radiation generation characteristics between the generators used in the two studies. The attenuated graph measured in this study better reflects the characteristics of current radiation generators, which would be more effective for shield designing.

• Journal of Chest Surgery
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• v.57 no.4
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• pp.413-417
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• 2024

A 70-year-old man with dilated cardiomyopathy underwent left ventricular assist device (LVAD) implantation, using a HeartWare ventricular assist device, as a bridge to candidacy. After 26 months, computed tomography (CT) angiography indicated stenosis in the LVAD outflow graft; however, the patient was asymptomatic, prompting a decision to manage his condition with close monitoring. Ten months later, the patient presented with dizziness and low-flow alerts. Subsequent CT angiography revealed a critical obstruction involving the entire LVAD outflow graft. The patient underwent emergency surgery, during which an organized seroma causing the graft obstruction was found between a wrapped expanded polytetrafluoroethylene (ePTFE) graft and a Dacron outflow graft. The covering of the outflow graft was removed, along with the organized seroma. Following removal of the ePTFE wrap and decompression of the outflow graft, normal LVAD flow was reestablished. The practice of wrapping the outflow graft with synthetic material, commonly done to facilitate later redo sternotomy, may pose a risk for outflow graft obstruction.