• Journal of Korean Institute of Industrial Engineers
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• v.30 no.1
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• pp.11-16
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• 2004

Oxygen is an essential element for human beings' physical and mental activities, and in particular, plays an important role in brain functions. The present study attempted to investigate the effects of supply of highly concentrated (30%) oxygen on human ability of visuospatial cognition, compared to air of normal oxygen concentration (21%). This study sampled eight male university students (the average age: 23.5) as subjects. An equipment that supplies 21% and 30% oxygen at a constant rate of 8L/min was developed. Two types of questionnaire containing 20 questions were developed to measure the ability of visuospatial cognition, and accuracy and reaction time were calculated from the result of task performance. The average accuracy was $50.63{\pm}8.63$ [%] and $62.50{\pm}9.64$[%] for 21%and 30% oxygen respectively, and a statistically significant difference was found in the accuracy between the two types of oxygen. The average reaction time was $6.60{\pm}O.77$ [sec] and $7.23{\pm}0.69$ [sec] for 21%and 30% oxygen respectively, and a statistically significant difference was not found in the reaction time. The results showed that there is no difference in the average reaction time but the average accuracy rises with the supply of highly concentrated (30%) oxygen, indicating that the supply of highly concentrated oxygen has a partially positive effect on the ability of visuospatial cognition.

• Health Policy and Management
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• v.31 no.4
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• pp.472-478
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• 2021

Background: Early identification of patients who are highly likely to develop severe illness among confirmed cases of coronavirus disease 19 (COVID-19) can be expected to lead to effective treatment. This study therefore aimed to determine whether the presence of nonalcoholic fatty liver disease (NAFLD) has an impact on the exacerbation of COVID-19 symptoms. Methods: The study used the Korean National Health Insurance claim data for treatment of COVID-19 patients in 2020. NAFLD includes nonalcoholic fatty liver (NAFL) and nonalcoholic steatohepatitis (NASH). The outcome variables used were hospitalization and the use of medical devices. Hospitalization was defined by a length of stay exceeding one day and the use of medical devices was defined as one or more uses of a ventilator or extracorporeal membrane oxygenation. Multivariable logistic regression analysis was performed to determine if there was a difference in the hospitalization and use of medical devices of COVID-19 patients depending on the presence of NAFLD. Results: The odds ratio of hospitalization was 1.059, indicating slightly higher odds of hospitalization for patients with NAFL or NASH compared to those without the conditions, but it was not statistically significant (0.969-1.156). On the other hand, the odds ratio of use of medical devices was high at 1.667 and was statistically significant (1.111-2.501). Conclusion: The study results found NAFLD to be a risk factor that can exacerbate symptoms in COVID-19 patients. Accordingly, it is necessary to identify NAFLD patients through preemptive screening and provide them with appropriate treatments.

• Clinical Endoscopy
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• v.56 no.4
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• pp.446-452
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• 2023

Background/Aims: Colonoscopy for screening is associated with unpleasant experiences for patients, and abdominal compression devices have been developed to minimize these problems. However, there is a paucity of data supporting the therapeutic benefits of this strategy. This study examined the effects of using an abdominal compression device during colonoscopy on the cecal intubation time (CIT), abdominal compression, patient comfort, and postural changes. Methods: We searched PubMed and Scopus (from inception to November 2021) for randomized controlled trials that assessed the effects of an abdominal compression device during colonoscopy on CIT, abdominal compression, patient comfort, and postural change. A random-effects meta-analysis was performed. Weighted mean differences (WMDs) and Mantel-Haenszel odds ratios (ORs) were calculated. Results: Our pooled analysis of seven randomized controlled trials revealed that abdominal compression devices significantly reduced CIT (WMD, -0.76 [-1.49 to -0.03] minutes; p=0.04), abdominal compression (OR, 0.52; 95% confidence interval [CI], 0.28-0.94; p=0.03), and postural changes (OR, 0.46; 95% CI, 0.27-0.78; p=0.004) during colonoscopy. However, our results did not show a significant change in patient comfort (WMD, -0.48; 95% CI, -1.05 to 0.08; p=0.09) when using an abdominal compression device. Conclusions: Our findings demonstrate that employing an abdominal compression device may reduce CIT, abdominal compression, and postural change but have no impact on patient comfort.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.11
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• pp.6821-6829
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• 2014

The use of semiconductor devices as a component of eco-friendly motor vehicles has increased and their widespread use as high voltage switches is expected. On the other hand, in the case of high-voltage switches, reliability test equipment is not localized. To test high voltage switches, this paper analyzed the relevant test standards for developing power supplies. In particular, for the automotive semiconductor reliability test, the AEC (Automotive Electronic Council) Q101 was analyzed. Based on that, the standard specifications of the power supply were determined. For the main power circuit, the pull bridge converter was adopted and based on the specification, the circuit parameters were determined and verified by simulation. The interface for the parallel and pattern operation was designed. The characteristics of the power supply were tested.

• Clinical Endoscopy
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• v.57 no.1
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• pp.96-104
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• 2024

Background/Aims: Selective bile duct or pancreatic duct cannulation remains a significant initial hurdle in endoscopic retrograde cholangiopancreatography (ERCP) despite advances in endoscopy and accessories. This study evaluated our experience with a rotatable sphincterotome in cases of difficult cannulation. Methods: We retrospectively reviewed ERCP cases using TRUEtome, a rotatable sphincterotome, as a rescue device for cannulation at a cancer institute in Japan from October 2014 to December 2021. Results: TRUEtome was used in 88 patients. Duodenoscopes were used for 51 patients, while single-balloon enteroscopes (SBE) were used for 37 patients. TRUEtome was used for biliary and pancreatic duct cannulation (84.1%), intrahepatic bile duct selection (12.5%), and strictures of the afferent limb (3.4%). Cannulation success rates were similar in the duodenoscope and SBE groups (86.3% vs. 75.7%, p=0.213). TRUEtome was more commonly used in cases with steep cannulation angles in the duodenoscope group and in cases requiring cannulation in different directions in the SBE group. There were no significant differences in adverse events between the two groups. Conclusions: The cannulation sphincterotome was useful for difficult cannulations in both unaltered and surgically altered anatomies. It may be an option to consider before high-risk procedures such as precut and endoscopic ultrasound-guided rendezvous techniques.

• Convergence Security Journal
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• v.18 no.3
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• pp.133-140
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• 2018

As the core technology of the 4th Industrial Revolution is applied to drone, the potential for growth in the field of unmanned aerial vehicles is very large, and the utilization of civilian & military fields in the domestic & foreign is increasing rapidly. Because application areas of drone in the civilian field is various, it is excellent in terms of cost effectiveness and high value in utilization when it is used for military operation support mission. Especially, in the case of the Air Force, it is expected that military usage effectiveness will be high if drone replaces various air operations support missions such as aircraft inspection, supply of military supplies, base security. We find out the missions that can utilize drones for military operations support and propose the recommendation and data management plan accordingly. We recommend the most suitable drones and equipment that perform similar missions in the private sector and propose the data modeling of relational database.

• Journal of Aerospace System Engineering
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• v.17 no.6
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• pp.144-148
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• 2023

Aircraft battery is the core equipment of an aircraft that supplies engine starting power and emergency power, and it must be charged to ensure sufficient capacity at all times and maintain high reliability to ensure stable power supply. The battery of the T-50 series aircraft is designed to enable the engine to start up to two times in temperatures as low as -18℃ and above. However, intermittent failures in engine starting have been observed during winter. In this paper, we analyze the failure phenomena occurring during low-temperature charging of the battery and improve the charging algorithm based on the analysis and test. Additionally, the results of start simulation tests show that the battery charging defects at low temperatures are resolved, and an improvement in the charging performance is confirmed; thus, validating the effectiveness of the new algorithm.

• Clinical Endoscopy
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• v.55 no.6
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• pp.767-774
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• 2022

Background/Aims: Few studies have compared the performances of endoscopic knives. This study aimed to compare the therapeutic outcomes of a novel core knife and the conventional IT knife 2 for endoscopic submucosal dissection (ESD) of gastric mucosal lesions. Methods: This prospective, non-inferiority trial included patients diagnosed with gastric adenoma or early-stage adenocarcinoma at Keimyung University Dongsan Hospital between June and November 2020. The patients were randomly assigned to either the core knife or the IT knife 2 group. The operators and assistants scored the knives' grip convenience and cutting abilities. Results: A total of 39 patients were enrolled (core knife group, 20 patients; IT knife 2 group, 19 patients). There were no significant between-group differences in operator-assessed grip convenience (9.600 vs. 9.526, p=0.753), cutting ability (9.600 vs. 9.105, p=0.158), or assistant-assessed grip convenience (9.500 vs. 9.368, p=0.574). Conclusions: The core knife achieved therapeutic outcomes that were comparable to those of the IT knife 2 for ESD of gastric mucosal lesions.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.8
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• pp.36-41
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• 2006

Computer Loads can be found in all of modern society. The switching mode power supplies used in personal computers are major sources of harmonic currents. Harmonic currents can cause lots of harmonic problems such as disruption in computer performance. A series resonant filter is very effective in harmonic reduction for personal computer loads. Voltage sags are short duration reductions in rms voltage. The main causes of voltage sags at faults, motor starting, and transformer energizing. Personal computers are another example of devices sensitive to voltage sags. A serious voltage sag at the terminals way lead mis-operation of the equipment. This paper presents an in depth analysis to evaluate the effect of harmonics reduction based on the IEC 61000-3-2 and the effect of voltage sag using ITI curve by applying a series resonant filter for personal computer loads.

• Journal of the Korean Institute of Gas
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• v.28 no.1
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• pp.27-34
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• 2024

In accordance with the clean hydrogen-centered hydrogen industry development plan, technology development and demonstration operation of water electrolysis devices are being actively carried out. Risk assessments are performed on newly developed hydrogen-using facilities and supplies to identify potential hazard factors. However, in general, most industrial accidents are caused by operator's human error or incorrect work practices. Additionally, the possibility of accidents occurring during operation control, maintenance, and inspection increases. For this reason, for equipment developed for demonstration operation, the correct work methods for the main jobs of operator must be reviewed and work procedures must be prepared. Accordingly, in this study, we conducted a job safety analysis (JSA) on major jobs in the operation of water electrolysis facilities to study safe work methods and necessary measures.