• Clinical Endoscopy
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• v.56 no.6
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• pp.754-760
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• 2023

Background/Aims: Endoscopic vacuum therapy (EVT) can heal a variety of defects within the gastrointestinal (GI) tract via applying negative pressure, which reduces the defect size, aspirates the infected fluid, and promotes granulation tissue. Here we present our experience with EVT as it relates to both spontaneous and iatrogenic upper GI tract perforations, leaks, and fistulas. Methods: This retrospective study was conducted at four large hospital centers. All patients who underwent EVT between June 2018 and March 2021 were included. Data on multiple variables were collected, including demographics, defect size and location, number and intervals of EVT exchanges, technical success, and hospital length of stay. Student t-test and the chi-squared test were used to analyze the data. Results: Twenty patients underwent EVT. The most common defect cause was spontaneous esophageal perforation (50%). The most common defect location was the distal esophagus (55%). The success rate was 80%. Seven patients were treated with EVT as the primary closure method. The mean number of exchanges was five with a mean interval of 4.3 days between exchanges. The mean length of hospital stay was 55.8 days. Conclusions: EVT is a safe and effective initial management option for esophageal leaks and perforations.

• Steel and Composite Structures
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• v.52 no.2
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• pp.165-182
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• 2024

Grouted sleeve splice (GSS) is an effective type of connection applied in the precast concrete structures as it has the advantages of rapidly assembly and reliable strength. To decrease the weight and cost of vertical rebar connection in precast shear walls, a light-weight sleeve is designed according to the thick-cylinder theory. Mechanical behaviour of the light-weighted GSS is investigated through experimental analysis. Two failure modes, such as rebar fracture failure and rebar pull-out failure, are found. The load-displacement curves exhibit four different stages: elastic stage, yield stage, strengthening stage, and necking stage. The bond strength between the rebar and the grout increases gradually from outer position to inner position of the sleeve, and it reaches the maximum value at the centre of the anchorage length. A finite element model predicting the mechanical properties of the light-weighted GSS is developed based on the Concrete Damage Plasticity (CDP) model and the Brittle Cracking (BC) model. The effect of the rebar anchorage length is significant, while the increase of the thickness of sleeve and the grout strength are not very effective. A model for estimating ultimate load, including factors of inner diameter of sleeves, anchorage length, and rebar diameter, is proposed. The proposed model shows good agreement with various test data.

• Korean Journal of Optics and Photonics
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• v.13 no.3
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• pp.266-271
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• 2002

The finite schematic eye based on spherical aberration and Stiles-Crawford effect is designed by an optimization method. It consists of four aspherical surfaces. The radius of curvature, thickness, asphericity, and spherical aberration are used as constraints in the optimization process. Stiles-Crawford effect in the pupil is considered as a weighting value for optimum design. The designed schematic eye has effective focal length of 20.8169 mm, back focal length of 15.4820 mm, front focal length of -13.8528 mm, and image distance of 15.7150 mm. When the pupil diameter is 4 mm, the diameter of entrance pupil and exit pupil are 4.6919 mm and 4.2395 mm, respectively. From the data of 75 measured Korean emmetropic eyes, this finite schematic eye is designed first in Korea.

• Journal of the Korean Institute of Telematics and Electronics
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• v.20 no.4
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• pp.10-15
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• 1983

In this paper effective methods of demodulation and equalization in a 9600 bps modem have been studied. To reduce the number of multiplications required per symbol in demodula-tion, the method of using a decimation filter is presented. In the equalizer the optimum step size and the steady state mean-squared error (MSE) are obtained from computer simulation results. The performance of the first-order carrier phase tracking loop is compared with that of the second-order loop when carrier frequency offset exists. In addition, the finite word length effects in the equalizer are studied.

• Journal of Yeungnam Medical Science
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• v.41 no.2
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• pp.96-102
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• 2024

Background: The aim of this study was to compare the early outcomes of octogenarians undergoing minimally invasive right anterior mini-thoracotomy aortic valve replacement (RAT-AVR) with those undergoing transcatheter aortic valve implantation (TAVI) for aortic valve disease. Methods: In this single-center retrospective study, data were collected from octogenarians before and after RAT-AVR and TAVI between January 2021 and July 2022. Short-term outcomes, including the length of hospital stay, in-hospital mortality, all-cause mortality, and other major postoperative complications, were compared and analyzed. Results: There were no significant differences in in-hospital mortality, stroke, acute kidney dysfunction requiring renal replacement therapy, length of intensive care unit stay, or length of hospital stay. However, the TAVI group had a higher incidence of permanent pacemaker insertion (10% vs. 0%, p=0.54) and paravalvular leaks (75% vs. 0%, p<0.001). Conclusion: In the present study on octogenarians, both TAVI and RAT-AVR showed comparable short-term results. Although both procedures were considered safe and effective in the selected group, RAT-AVR had a lower incidence of complete atrioventricular block and paravalvular regurgitation.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.10
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• pp.1271-1277
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• 2018

This paper deals with a voltage sag assessment based on a voltage monitoring program. The voltage sag performance at a specific site can be evaluated by analyzing voltage monitoring data recorded for a long time period. Although an assessment based on voltage monitoring is an effective way to understand voltage sag performance at a measurement site, the statistical confidence of voltage sag frequency estimation heavily depends on the length of monitoring period and the number of recorded events. Short monitoring period and insufficient recorded data can not provide a reliable assessment result. This paper proposes a compensation assessment method by combining a computer simulation approach for in case that monitoring period and data are not enough for a valid assessment.

• Korean Journal of Computational Design and Engineering
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• v.1 no.2
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• pp.150-157
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• 1996

The hob is considered as an effective gear cutting tool for achieving the various gears such as spur gear, helical gear, worm gear and so on. To enhance the productivity and precision of hobs and the competitive ability of domestic CNC hob relieving lathes, a CAM system for CNC hob relieving lathe needs to be realized. In this study, the CAM system is developed based on the personal computer and C language. Besides the automatic generation of CNC data, the developed CAM system has the various capabilities related to the generation of tool path, the cutting simulation for verifying the generated CNC data and forecasting the cutting time, the DNC operation for communicating the CNC data with CNC controller by RS232C port, and the estimation of undercut length for verifying the hob cutting conditions.

• Korean Journal of Agricultural and Forest Meteorology
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• v.6 no.2
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• pp.94-106
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• 2004

Determining those gaps in agricultural and other information to improve agrometeorological analyses for agriculture is a large task. The effective integration of appropriate data systems, including remote sensing systems, with agricultural systems modelling capability is described as a worthy outcome in this endeavour. Data issues, including those associated with data length, quality, maintenance, and archiving remain serious issues to be addressed. The role of remote sensing and geographic information systems in agrometeorology is important and is explored here. The value of simulation models to provide the synthesis for future agrometeorological requirements is further elucidated.

• Journal of Welding and Joining
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• v.27 no.5
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• pp.88-93
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• 2009

While the pinch instability theory (PIT) has been widely employed to analyze the spray transfer mode in the gas metal arc welding (GMAW), it cannot predict the detaching drop size accurately. The PIT is modified in this work to increase the accuracy of prediction and to simulate the molten tip geometry to be more physically acceptable. Since the molten tip becomes a cone shape in the spray mode, the effective wire diameter is formulated that the effective diameter is inversely proportional to current square. Modifications are also made to consider the finite length of the liquid column and current leakage through the arc. While the effective diameter influences drop transfer significantly, the current leakage has negligible effects. The effects of modifications on drop transfer are analyzed, and the predicted drop diameters show good agreements with the experimental data of the steel wire.

• Proceedings of the KWS Conference
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• 2009.11a
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• pp.44-44
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• 2009

While the pinch instability theory (PIT) has been widely employed to analyze the spray transfer mode in the gas metal arc welding (GMAW), it cannot predict the detaching drop size accurately. The PIT is modified in this work to increase the accuracy of prediction and to simulate the molten tip geometry to be more physically acceptable. Since the molten tip becomes a cone shape in the spray mode, the effective wire diameter is formulated that the effective diameter is inversely proportional to current square. Modifications are also made to consider the finite length of the liquid column and current leakage through the arc. While the effective diameter influences drop transfer significantly, the current leakage has negligible effects. The effects of modifications on drop transfer are analyzed, and the predicted drop diameters show good agreements with the experimental data of the steel wire.