• The Journal of Korean Academy of Prosthodontics
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• v.44 no.5
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• pp.654-664
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• 2006

Statement of problem: There has been a eat interest in the use of titanium for fixed and removable prostheses in recent because of its excellent biocompatibility. However, the melting temperature and chemical reactivity of titanium necessities casting system different from those used in conventional casting. The current titanium casting systems are based on an electric-arc design for melting the metal in an argon atmosphere and its exclusive investment. Despite the new development in Ti casting system, inadequate mold filling and internal porosity are frequently observed casting defects. Purpose : The purposes of this study were to compare the castibility and reaction layer of the casting titanium under the two casting machines and their investment condition. Material and method: coping and machine-milled titanium coping according to the casting methods and the marginal configurations. The total 28 specimens were used, and these are divided into 4 groups according to 2 casting machines and 2 investments. The castings were analyzed using x-ray microanalysis and microhardness testing. The reaction layer between margin of titanium casting and the investments was observed and analyzed with scanning electron microscope. Result: 1. Castabiliy of casting titanium specimen was best in the group of centrifugal casting machine and Selevest $CB^{\circledR}$ and good that of Selevest CB and pressure differential casting machine, Rematitan plus and centrifugal casting machine, Rematitan plus and pressure differential casting machine in order. 2. There was no significanct correlation in titanium castability in respect of casting machine. However ANOVA indicated that Selevest $CB^{\circledR}$ groups had significantly better castability than Rematitan $plus^{\circledR}$ groups.(p<0.05) 3. There was a significant microhardness difference between centrifugal casting machine groups and pressure differential groups.(p<0.05) Titanium castings in centifugal groups had significantly harder than those in pressure differential groups. 4. The addition of zirconia decreased interfacial reactivity. Conclusion: above result revealed that of the castability of titanium casting specimens had little correlation in casting machines and was better in magnesia-based investment contained ZrO2 groups. However in order to practice casting titanium in clininic, its castability should be improved, also there should be more research on factor of castability so that long-span prothesis and removable partial denture metla frame may be casted completly.

• Tuberculosis and Respiratory Diseases
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• v.81 no.4
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• pp.319-329
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• 2018

Background: Bronchoalveolar lavage (BAL) is a necessary procedure for diagnosis of various lung diseases. High-flow nasal cannula (HFNC) oxygen delivery was recently introduced. This study aimed to investigate the safety and effectiveness of HFNC oxygen supply during BAL procedure in patients with acute respiratory failure (ARF). Methods: Patients who underwent BAL while using HFNC at a partial pressure of oxygen in arterial blood/fraction of inspired oxygen ($PaO_2/FiO_2$; PF) ratio of 300 or below among patients who had been admitted from March 2013 to May 2017 were retrospectively investigated. Results: Thirty-three BAL procedures were confirmed. Their baseline PF ratio was $166.1{\pm}46.7$. $FiO_2$ values before, during, and after BAL were $0.45{\pm}0.12$, $0.74{\pm}0.19$, and $0.57{\pm}0.14$, respectively. Flow (L/min) values before, during, and after BAL were $26.5{\pm}20.3$, $49.0{\pm}7.2$, and $40.8{\pm}14.2$, respectively. Both $FiO_2$ and flow during and after the procedure were significantly different from those before the procedure (both p<0.001). Oxygen saturation levels before, during, and after BAL measured by pulse oximeter were $94.8{\pm}2.9$, $94.6{\pm}3.5$, and $95.2{\pm}2.8%$, respectively. There were no significant differences in oxygen saturation among the three groups. Complications of BAL procedure included transient hypoxemia, hypotension, and fever. However, there was no endotracheal intubation within 24 hours. Baseline PF ratio in "without HFNC" group was significantly higher than that in "with HFNC" group. There were no differences in complications between the two groups. Conclusion: The use of HFNC during BAL procedure in ARF patients was effective and safe. However, there were no significant differences in oxygen saturation level and complications comparing "without HFNC" group in mild ARF. More studies are needed for moderate to severe ARF patients.

• Journal of Chest Surgery
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• v.32 no.5
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• pp.413-421
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• 1999

Background: Ischemia reperfusion injury is known to contribute to the major causes of the early graft failure in lung transplantation. Triiodothyronine (T3) has been suggested to ameliorate ischemia reperfusion injury from both in vivo and in vitro experiments of various organs. Prospecting its beneficial effect for pulmonary allograft preservation, we made a new solution by adding T3 into the extracellular type dextran solution. Material and Method: Twelve adult mongrel dogs underwent left lung allotransplantation. Six donor dogs were flushed with the new solution(Group 1, n=6), and the remaining six were flushed with Euro-Collins solution to serve as controls(Group 2, n=6). Allografts were stored in each preservation solution for 20 hours at 4$^{\circ}C$. Left single lung transplantations were performed. The right pulmonary artery and the right main bronchus were clamped at 15 minutes after the reperfusion and maintained throughout the experiment to evaluate the transplanted left lung function. Result: Arterial carbon dioxide tension was better in group 1 than in group 2 throughout the experiment period and the difference was statistically significant at 2 hours after reperfusion(28.0${\pm}$3.0 mmHg and 53.1${\pm}$17.4 mmHg, p<0.05). The differences of arterial oxygen partial pressure, peak airway pressure and pulmonary vascular resistance showed no statistical significance. The malondialdehyde(MDA) level, measured from tissue obtained at 120 minutes after reperfusion showed no statistically significant difference. The tissue wet/dry ratio of group 1(649${\pm}$27 %) was significantly lower than that of group 2(686${\pm}$71 %, p<0.05). The microscopic examination revealed varying degrees of injury represented mainly by findings such as perivascular neutrophil infiltration, capillary hemorrhage and interstitial congestion. These findings were less severe in group 1 than those in group 2. Conclusion: The new solution demonstrated superior allograft preservation after 20 hour ischemia compared to Euro-Collins solution in canine single left lung transplantation model, these results suggest that T3 might be a promising agent for pulmonary allograft preservation.

• Journal of Chest Surgery
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• v.43 no.1
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• pp.104-107
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• 2010

Acute respiratory distress syndrome (ARDS) is difficult to treat and it is often fatal. If the medical treatment for ARDS is not effective, then extracorporeal membrane oxygenation (ECMO) can be applied to the patient. A 22-year-old female who suffered multiple traumatic injuries due to a car accident presented with acute respiratory distress syndrome. Veinarterial extracorporeal membrane oxygenation (VA ECMO) was started to treat her respiratory failure. With the VA ECMO, the systemic oxygen saturation remained at only 84%, and so the ECMO system was switched to V-VA ECMO via an additional venous outflow through the right jugular vein to increase both the systemic and pulmonary oxygen saturation. After conversion to the V-VA type ECMO, the systemic oxygen saturation increased to 94% and the partial pressure of oxygen ($PaO_2$) increased to 65 mmHg. We report here on a successful case of ECMO conversion from the VA type to the V-VA type in a patient with severely hypoxic respiratory failure.

• Korean Journal of Materials Research
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• v.8 no.11
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• pp.977-981
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• 1998

Controlling the wafer temperatures from 200 to$500^{\circ}C$, low resistive tungsten thin films used for VLSI metallization are deposited by PECVD method. Resistivities of plasma deposited tungsten thin films are very sensitive to the $H_2/WF_6 $ partial pressure ratios. Residual stress behaviors of the films as a function of plasma power density were also studied. At the power density under the $0.7W/\textrm{cm}^2$, residual stress of W film is about $2.4\times10^9dyne/\textrm{cm}^2$. When the power density is. however, increased from 1.8 to $2.7W/\textrm{cm}^2$, residual stress is suddenly increased from $8.1\times10^9$ to $1.24\times10^{10}dyne/\textrm{cm}^2$ ue to the ion or radical bombardment at high power density.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.32 no.5
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• pp.371-375
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• 2019

Developing a thin-film transistor with characteristics such as a large area, high mobility, and high reliability are key elements required for the next generation on displays. In this paper, we have investigated the research trends related to improving the reliability of oxide-semiconductor-based thin-film transistors, which are the primary focus of study in the field of optical displays. It has been reported that thermal treatment in a high-pressure oxygen atmosphere reduces the threshold voltage shift from -7.1 V to -1.9 V under NBIS. Additionally, a device with a $SiO_2/Si_3N_4$ dual-structure has a lower threshold voltage (-0.82 V) under NBIS than a single-gate-insulator-based device (-11.6 V). The dual channel structure with different oxygen partial pressures was also confirmed to have a stable threshold voltage under NBIS. These can be considered for further study to improve the NBIS problem.

• Applied Chemistry for Engineering
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• v.21 no.3
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• pp.317-322
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• 2010

In this study, poly(methyl methacrylate) (PMMA) was treated with changing mixing ratios of $F_2$ and $O_2$ using oxyfluorination method for hydrophilic modification of PMMA film. For the characterizations of oxyfluorinated PMMA surface, contact angle, surface free energy, X-ray photoelectron spectroscopy (XPS) and optical transmittance (UV-vis) were carried out. After the oxyfluorination, PMMA surface became more hydrophilic showing the decrease of water contact angle from $69^{\circ}$ to $44^{\circ}$. So, surface free energy of oxyfluorinated PMMA film was increased from 46 to $58\;mN\;m^{-1}$. These results are attributed to hydrophilic functional groups such as hydroxyl group formed oxyfluorination method on the PMMA surface. From XPS results, it was confirmed that O/C concentration ratio on the surface of PMMA was increased, the amount of C-OH bonding which shows hydrophilicity was also largely increased from 6.7 to 24.8% with increasing fluorine partial-pressure via the oxyfluorination, The oxyfluorination conditions, room temperature, 1 bar with one mixture ratio of $F_2$ to $O_2$ had little influence on optical transmittance properties of PMMA film but enhanced its surface hydrophilicity. This result suggests that oxyfluorination method could be useful to change hydrophobic PMMA surface to hydrophilic.

• Tuberculosis and Respiratory Diseases
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• v.69 no.4
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• pp.243-249
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• 2010

Background: Chronic obstructive pulmonary disease (COPD) is one of the leading causes of disability and mortality worldwide. The aim of this study was to evaluate the risk factors associated with recurrent hospital admissions for exacerbation of COPD in Korea. Methods: A retrospective study of 77 consecutive patients hospitalized for exacerbation of COPD at Pusan National University Hospital during the time period January 2005 to May 2008 was performed. The information was collected from the hospitalization period: clinical information, spirometric measures, and laboratory variables. In addition, socioeconomic characteristics, co-morbidity, anxiety, and depression were reviewed. Frequent readmission was defined as 2 or more hospitalizations in the year following discharge. Results: During the 1-year period after discharge, 42 patients (54.6%) reported one hospital admission and 35 patients (45.4%) reported 2 or more hospital readmissions. Among the 35 frequent readmission patients, 4 had more than 10 readmissions. Univariate analysis showed that a body mass index (BMI) <$18.5kg/m^2$, duration >36 months, forced expiratory volume in 1 second ($FEV_1$) <50% predicted, arterial $CO_2$ partial pressure ($PaCO_2$) >40 mm Hg, and arterial oxygen saturation ($SaO_2$) <95% at discharge were associated significantly with frequent readmissions. The multivariate analysis revealed that BMI <$18.5kg/m^2$, $PaCO_2$ >40 mm Hg at discharge were independently associated with frequent readmissions for exacerbation of COPD. Conclusion: Frequent readmissions for exacerbation of COPD were associated with low BMI and hypercapnia at discharge.

• The Korean Journal of Pain
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• v.11 no.2
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• pp.220-225
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• 1998

Background: The patients of facial hyperhidrosis have been known that they had much difficulties in interpersonal relationships and social activities due to excessive hidrosis when they were in stress, hot weather, or having meals. Previous drug therapy and stellate ganglion block have only temporary effects. The surgical method, $T_1$ sympathetomy has the risk of Hornor's syndrome. For that reasons, the sympathicotomy of proximal and distal portions of $T_2$ sympathetic ganglion with electroresectoscope used in transurethral resection seemed to be appropriate procedure, and we would like to report the results of our procedure. Method: Under the general anesthesia with semi-sitting position, and the portal was made through the small incision along the upper border of the 4th rib at the crossing point of mid-axillary line. After the partial collapse of lung by insufflation of 300 to 500 ml of $CO_2$, $T_2$ sympathetic ganglion was identified and resected proximally and distally with electro-cauterization. Finally the lung was expanded by limiting flow until the airway pressure reached 30 to 40 cm$H_2O$, and the wound was closed after removal of electroresectoscope. Result: There was no postoperative complication requiring surgical interventions. The facial sweating was stopped immediately after the operation and all the patients appeared to be satisfied. Conclusion: $T_2$ sympathicotomy with TUR electroresectoscope is thought be the minimal invasive and highly successful method in the treatment of facial hyperhidrosis. But longer terms follow-up will be needed to prove this result.

• Resources Recycling
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• v.17 no.3
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• pp.42-47
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• 2008

In this work, the dissolution behavior of Pb from the complex sulphide concentrates containing Galena and Arsenopyrite by alkaline oxidative leaching was studied. The influences of leaching temperature, oxygen partial pressure, leaching time and NaOH concentration of leaching solution were examined at the leaching conditions in the range of $100^{\circ}C{\sim}140^{\circ}C$ temperature, $40psi{\sim}100psi\;PO_2$ and $0.5M{\sim}2M$ NaOH concentration. The optimum result was obtained at the leaching condition of leaching temperature $120^{\circ}C$, 100psi $PO_2$, leaching time 30min. and 2M NaOH concentration of leaching solution.