• 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.

• Journal of Korean Academy of Nursing
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• v.49 no.4
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• pp.495-504
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• 2019

Purpose: Nursing students experience a high degree of perceived stress during skills training. The resulting academic sentiment is worthy of research. This study examined the learning motivation as a mediator in the association between perceived stress and positive deactivating academic emotions in nursing students undergoing skills training. Methods: A survey was conducted on 386 third-year undergraduate nursing students at a university in Changchun, China, in 2017. The survey included the items on perceived stress, learning motivation during nursing skill training, and general academic emotion. There were 381 valid responses (response rate=98.7%). Based on the results of partial correlation and stepwise multiple regression equations, the study examined the mediation model between perceived stress, learning motivation and positive-deactivating academic emotions using process 2.16 (a plug-in specifically used to test mediation or moderation effect in SPSS). Results: There was a significant negative correlation between students' perceived stress and learning motivation during nursing skills training and positive-deactivating academic emotions. Nervousness, loss of control, and interest in developing reputation had significant predictive effects on positive-deactivating academic emotions. The mediating model was well supported. Conclusion: Learning motivation during nursing skills training lessened the damage of perceived stress on positive-deactivating academic emotions. Improving students' motivation to learn could reduce their perceived stress and build more positive emotions. Positive emotions during learning played an important role in helping nursing students improve skills and enhance their nursing competence.

• Journal of The Korean Society of Emergency Medicine
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• v.29 no.6
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• pp.578-584
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• 2018

Objective: This study examined the initial partial pressure of carbon dioxide ($PCO_2$) as a possible indicator of prehospital ventilation and its association with prehospital i-gel in out-of-hospital cardiac arrest (OHCA) patients. Methods: The demographics and arrest parameters, including i-gel insertion and initial arterial blood gas analysis, of OHCA patients who visited the emergency department were analyzed retrospectively. Linear regression analysis was performed to examine the association between i-gel insertion and the initial $PCO_2$. Results: A total of 106 patients were investigated. Fifty-six patients had prehospital i-gel insertion and 50 patients did not have a prehospital advanced airway. The initial $PCO_2$ was higher in the i-gel group than the no advanced airway group (105.2 mmHg [77.5-134.9] vs. 87.5 mmHg [56.8-115.3], P=0.03). Prehospital i-gel insertion was associated with a higher initial $PCO_2$ level (${\beta}$ coefficient, 20.3; 95% confidence interval, 2.6-37.9; P=0.03). Conclusion: Prehospital insertion of i-gel was associated with higher initial $PCO_2$ values in OHCA patients compared to no advanced airway.

• Archives of Plastic Surgery
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• v.48 no.2
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• pp.219-223
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• 2021

Background A micro-arteriovenous fistula (AVF) is a minute, short shunt between an artery and a vein that does not pass through a capillary. We investigated the association between micro-AVFs and lymphedema using computed tomography angiography (CTA) and venous blood gas analysis. Methods In 95 patients with lower limb lymphedema, the presence or absence of early venous return (EVR) was compared between patients with primary and secondary lymphedema. Furthermore, we investigated the difference in the timing of edema onset in patients with secondary lymphedema with or without EVR using CTA. In 20 patients with lower limb lymphedema with confirmed early EVR in a unilateral lower limb, the partial pressure of oxygen (PO₂) was compared between the lower limb with EVR and the contralateral lower limb. Results Secondary lymphedema with or without EVR occurred at an average of 36.0±59.3 months and 93.5±136.1 months, respectively; however, no significant difference was noted. PO₂ was 57.6±11.7 mmHg and 44.1±16.4 mmHg in the EVR and non-EVR limbs, respectively, which was a significant difference (P=0.005). Conclusions EVR and venous blood gas analysis suggested the presence of micro-AVFs in patients with lower extremity edema. Further research is warranted to examine the cause of micro-AVFs, to advance technology to facilitate the confirmation of micro-AVFs by angiography, and to improve lymphedema by ligation of micro-AVFs.

• Journal of Korean Neurosurgical Society
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• v.64 no.4
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• pp.631-643
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• 2021

Objective : Here, we evaluated whether cerebrospinal fluid (CSF) profiles and their changes after intraventricular chemotherapy for leptomeningeal carcinomatosis (LMC) could predict the treatment response or be prognostic for patient overall survival (OS) along with clinical factors. Methods : Paired 1) pretreatment lumbar, 2) pretreatment ventricular, and 3) posttreatment ventricular samples and their CSF profiles were collected retrospectively from 148 LMC patients who received Ommaya reservoir installation and intraventricular chemotherapy. CSF profile changes were assessed by calculating the differences between posttreatment and pretreatment samples from the same ventricular compartment. CSF cell counts were further differentiated into total and other based on clinical laboratory reports. Results : For the treatment response, a decreased CSF 'total' cell count tended to be associated with a 'controlled' increase in intracranial pressure (ICP) (p=0.059), but other profile changes were not associated with either the control of increased ICP or the cytology response. Among the pretreatment CSF profiles, lumbar protein level and ventricular cell count were significantly correlated with OS in univariable analysis, but they were not significant in multi-variable analysis. Among CSF profile changes, a decrease in 'other' cell count showed worse OS than 'no change' or increased groups (p=0.001). The cytological response was significant for OS, but the hazard ratio of partial remission was paradoxically higher than that of 'no response'. Conclusion : A decrease in other cell count of CSF after intraventricular chemotherapy was associated with poor OS in LMC patients. We suggest that more specific CSF biomarkers of cancer cell origin are needed.

• Advances in concrete construction
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• v.11 no.5
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• pp.375-386
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• 2021

In this paper, a study of stability and health of a newly-built railway tunnel is presented. The field test was implemented to monitor the secondary lining due to the significant cracking behaviors influenced the stability and health of the tunnel structure. Surface strain gauges were installed for monitoring the status of crack openings, and the monitoring outputs demonstrated that the cracks were still in the developing stage. Additionally, adjacent tunnel and poor condition of surrounding rock were identified as the causes of the lining cracking by systematically characterizing the crack spatial distribution, tunnel site and surrounding rock conditions. Reconstruction of partial lining and reconstruction of the whole secondary lining were designed as the maintenance projects for different cracking regions based on the construction feasibility. For assessing the health conditions of the reinforced lining, embedded strain gauges were set up to continuously measure the strain and the internal force of the reconstructed structures. For the partially reconstructed lining, the outputs show the maximum tensile elongation is 0.018 mm during 227 days, which means the structure has no obvious deformation after maintenance. The one-year monitoring of full-section was implemented in the other two completely reconstructed cross-sections by embedded strain gauge. The outputs show the reconstructed secondary lining has undertaken the pressure of surrounding rock with the time passing. According to the calculated compressive and tensile safety factors, the completely reconstructed lining has been in reliable and safe condition during the past year after reinforcement. It can conclude that the aforementioned maintenance projects can effectively ensure the stability and health of this tunnel.

• 대한상한금궤의학회지
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• v.13 no.1
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• pp.21-44
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• 2021

Objective : This study aimed to assess the preventive effect of Bupleuri Radix aqueous extracts (BR) and red koji-fermented BR (fBR) in lipopolysaccharide (LPS)-induced acute lung injury in a rat model. Methods : Rats were administered 30, 60, or 120 mg/kg/day of fBR for 28 days before LPS treatments. All rats were sacrificed 5 h after LPS treatment (500 ㎍/head, intratracheal instillation). Body weights, lung weights, pulmonary transcapillary albumin transit, arterial gas parameters (pH, partial pressure [Pa] of O2, PaCO2), bronchoalveolar lavage fluid (BALF) protein, lactate dehydrogenase (LDH), tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), total cell numbers, neutrophil/alveolar macrophage ratios, lung malondialdehyde (MDA), and myeloperoxidase (MPO) were measured. In addition, histopathological changes including the luminal surface of alveoli (LSA), thickness of alveolar septum, and number of polymorphonuclear neutrophils (PMNs) were checked. Results : LPS injection led to increases in lung weights, pulmonary transcapillary albumin transit, BALF protein, LDH, TNF-α and IL-1β contents, total cells, neutrophil and alveolar macrophage ratios, lung MDA, MPO, alveolar septum thickness, and PMNs, and decreases in PaCO2 and pH of arterial blood and LSA. However, these LPS-induced acute lung injuries were inhibited by pretreatment of 30, 60, and 120 mg/kg of fBR. The most favorable effects were seen with 30 mg/kg fBR as compared with 60 mg/kg of α-lipoic acid and BR. Conclusions : fBR showed preventive effects on LPS-induced acute lung injury, which resembles acute respiratory distress syndrome. The mechanisms of action were likely via antioxidant and anti-inflammatory means.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.35 no.3
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• pp.275-280
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• 2022

An all-solid-state electrochromic film was fabricated by laminating tungsten oxide (WO₃) and nickel oxide (NiO) thin films deposited by a reactive DC magnetron sputtering on flexible ITO films. The influence of oxygen partial pressure on the crystal structure, microstructure, optical properties, and electrochromic properties of WO₃ and NiO thin films were investigated. WO₃ and NiO films showed the best electrochromic properties under the flow of Ar:O₂=80:20 and Ar:O₂=90:10, respectively. The EC film fabricated with an optimized WO₃ and NiO films showed a high coloration efficiency, a fast response time, and a stable optical modulation. It is expected that flexible EC window films will pave the way for the next-generation energy-saving windows.

• Journal of Dental Anesthesia and Pain Medicine
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• v.21 no.4
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• pp.357-361
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• 2021

Methemoglobinemia is a blood disorder in which an abnormal amount of methemoglobin is produced, and prilocaine is one of the drugs that can cause this disorder. The maximum recommended dose of prilocaine is 8 mg/kg. We report a case of methemoglobinemia caused by the administration of 4.2 mg/kg of prilocaine without other methemoglobinemia-inducing drugs during general anesthesia. A 17-year-old girl with hyperthyroidism and anemia was scheduled to undergo maxillary sinus floor elevation and tooth extraction. The patient's peripheral oxygen saturation (SpO₂) decreased from 100% at arrival to 95% after receiving prilocaine with felypressin following induction of general anesthesia. However, the fraction of inspired oxygen was 0.6. Blood gas analysis showed that the methemoglobin level was 3.8% (normal level, 1%-2%), fractional oxygen saturation was 93.9%, partial pressure of oxygen was 327 mmHg, and arterial oxygen saturation was 97.6%. After administration of 1 mg/kg of methylene blue, her SpO₂ improved gradually to 99%, and the methemoglobin value decreased to 1.2%. When using prilocaine as a local anesthetic, it is important to be aware that methemoglobinemia may occur even at doses much lower than the maximum recommended dose.

• Advances in aircraft and spacecraft science
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• v.8 no.4
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• pp.345-372
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• 2021

The analysis of nonlinear vibrations, buckling, post-buckling, flutter boundary determination and post-flutter behavior of a homogeneous curved plate assuming cylindrical bending is conducted in this article. Other assumptions include simply-supported boundary conditions, supersonic aerodynamic flow at the top of the plate, constant pressure conditions below the plate, non-viscous flow model (using first- and third-order piston theory), nonlinear structural model with large deformations, and application of mechanical and thermal loads on the curved plate. The analysis is performed with constant environmental indicators (flow density, heat, Reynolds number and Mach number). The material properties (i.e., coefficient of thermal expansion and modulus of elasticity) are temperature-dependent. The equations are derived using the principle of virtual displacement. Furthermore, based on the definitions of virtual work, the potential and kinetic energy of the final relations in the integral form, and the governing nonlinear differential equations are obtained after fractional integration. This problem is solved using two approaches. The frequency analysis and flutter are studied in the first approach by transferring the handle of ordinary differential equations to the state space, calculating the system Jacobin matrix and analyzing the eigenvalue to determine the instability conditions. The second approach discusses the nonlinear frequency analysis and nonlinear flutter using the semi-analytical solution of governing differential equations based on the weighted residual method. The partial differential equations are converted to ordinary differential equations, after which they are solved based on the Runge-Kutta fourth- and fifth-order methods. The comparison between the results of frequency and flutter analysis of curved plate is linearly and nonlinearly performed for the first time. The results show that the plate curvature has a profound impact on the instability boundary of the plate under supersonic aerodynamic loading. The flutter boundary decreases with growing thermal load and increases with growing curvature.