• Weed & Turfgrass Science
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• v.6 no.2
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• pp.124-129
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• 2017

The Experiments were conducted by moderate season culture of each of early, medium and late maturing varieties which were considered to be of strong salt tolerance in low and high salty reclaimed areas (0.2% at the May). This study was carried out to investigate the proper nitrogen fertilizer level and seeding rates at reclaimed saline land in Korea. The proper seeding rates were $40kg\;ha^{-1}$ in 0.2% saline land. The dry matter production of barnyard millet was possibly estimated by exponential functions of $Y=0.0098X^2+0.7030X+2.6267$. Effects of nitrogen rate on agronomic characteristics, forage yield, and chemical composition of barnyard millet to reclaimed tidal land are summarized as follows: The proper nitrogen fertilizer level was $200kg\;ha^{-1}$ in 0.2% saline land. N was absorbed actively before the emergence of the barnyard millet but showed relative decrease thereafter. The early growth of the barnyard millet was inhibited, resulting in the favorable late growth, increased panicle weight and ratio of matured grain. These results suggest that barnyard millet is the most forage crops for cultivation on reclaimed tideland in view of the good emergence and forage production.

• The Journal of Engineering Geology
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• v.8 no.1
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• pp.51-73
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• 1998

Hydrogeological systems in a metrnpolitan area can be understood by analyzing the groundwater disturbing factors such as constructions and land applications, the groundwater usage for domestic and industrial purposes, and the groundwater pumpage to lower the groundwater level for the structural safety of subway and underground facilities. This study is part of the study performed to understand the groundwater system in the Seoul area and it is focusing on the hydraulic properties. Groundwater well inventory, barometric efficiency measurements, pumping and slug tests, and long-term groundwater monitoring have been perfonrmed during the last 2 years. The relations between Han River and the groundwater around the river also have been observed. These observations and test data, together with the information on soil distribution, geology, and logging data are used to construct a database and GIS(Geographic Information System) presentation system using ARC/INFO. Barometric efficiencies appeared to have no special trends associated with well depths, which maeans that the degree of confinement of the crystaline rock aquifer of the Seoul area is distributed locally depending on the developrnent of fractures. Hydraulic conductivities exponentialiy decrease with well depth. The stage of Han River fluctuates according to the tidal movement of nearby seawater but the tidal effects attenuate due to the underwater dams. Groundwater levels in the Seoul area seem to have declined for the last two years,but it is not certain that the declination represents the long-term trend.

• Journal of the Korean Society of Marine Environment & Safety
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• v.22 no.7
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• pp.863-868
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• 2016

In this study, the precise shapes of sunken ships and information on seafloor topography were analyzed using data obtained from a multi-beam echo sounder. The state of each sunken ship was analyzed by processing diverse imagery data which was compared with data obtained from past investigations to determine changes in the state and circumjacent seafloor topography. Apparent changes in the seafloor topography around one sunken ship, the "Pacific Friend", were found from stern to bow as a result of continued submarine erosion and sedimentation. In the case of sunken ship "No. 7 Haeseong", the partial collapse of the bow was revealed in the seabed images captured in 2015, though it had still been intact in images captured during the Korea Hydrographic and Oceanographic Agency's investigation in 2011. This partial collapse was presumed to have resulted from the effects of continued tidal currents, the cargo load of the ship and continued corrosion of the ship over a long time on the seabed. Continuous monitoring of residual fuel inside the ship is necessary to avoid leakage and potential marine pollution. By conducting image analysis on these sunken ships, it has been determined that the structural safety of the ships is seriously influenced by tidal currents and seafloor topography, while the hulls will be continuously changed by corrosion. As a result, it can be concluded that the development of prediction and response techniques that take into consideration residual fuel leakage and environmental changes according to the geological characteristics of sunken ships is necessary.

• Korean Journal of Veterinary Research
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• v.45 no.2
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• pp.279-285
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• 2005

One-lung ventilation (OLV) is the isolation and selective ventilation of one lung field. OLV allows the collapse of lung lobes on the side of the thoracic surgical approach to facilitate observation of intrathoracic structures and to achieve lung immobility. OLV be achieved by endotracheal intubation with double lumen tubes or bronchial blockers. In this study, cardiopulmonary consequences of two-lung ventilation (TLV), OLV and Re-TLV (TLV after OLV) were evaluated in 5 dogs. The dogs were anesthetized with mask induction and maintained with isoflurane in oxygen. Tidal volume and respiratory rates were set to maintain end-tidal $CO_2$ at $40{\pm}2mmHg$ during instrumentation. Following instrumentation, the dogs were placed in right lateral recumbency and induced spontaneously respiration state. Effect of TLV on hemodynamic and pulmonary variables were recorded. Then, the left bronchus was obstructed by endotracheal intubation with double lumen endotracheal tube to achieve OLV state and recording was continued. After OLV, double lumen endotracheal tube was extubated, and standard endotracheal tubes was intubated again. In this study, spontaneous OLV caused significant decrease in $PaO_2$, arterial oxygen saturation, mixed-venous oxygen saturation, and increase in $PaCO_2$. Especially, a significant elevation in $PaCO_2$ and respiratory acidosis were remarkable findings. So spontaneous ventilation in OLV affected gas exchange and hemodynamic function.

• Journal of the Korean GEO-environmental Society
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• v.16 no.5
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• pp.55-66
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• 2015

Big tidal differences, which range from 3.0 m to 8.0 m, exist with regional locations at south and west shores of Korea. Under this ocean circumstance, since a large scour may occur due to multi-directional tidal current and transverse stress of the wind, the scour surrounding the wind turbine structure can make instability of the system due to unexpected system vibration. The hydraulic resistance capacity of soils consolidated under different pressures are evaluated by Erosion Function Apparatus (EFA) under unidirectional and bi-directional flows in this study. It was found that the flow direction change affects significantly on the sour rate and critical shear stress, regardless of soil types while the consolidation pressure affects mainly cohesive soil. Among geotechnical parameters, the undrained shear strength can be well-correlated with the hydraulic resistance capacity, regardless soil type while the shear wave velocity shows the proportional relationships with the hydraulic resistance capacities of fine grained soil and coarse grained soil, respectively.

• Ocean Systems Engineering
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• v.6 no.1
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• pp.61-97
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• 2016

This is the second of two papers on the 3D numerical modeling of nearshore hydro- and morphodynamics. In Part I, the focus was on surf and swash zone hydrodynamics in the cross-shore and longshore directions. Here, we consider nearshore processes with an emphasis on the effects of oceanic forcing and beach characteristics on sediment transport in the cross- and longshore directions, as well as on foreshore bathymetry changes. The Delft3D and XBeach models were used with four turbulence closures (viz., ${\kappa}-{\varepsilon}$, ${\kappa}-L$, ATM and H-LES) to solve the 3D Navier-Stokes equations for incompressible flow as well as the beach morphology. The sediment transport module simulates both bed load and suspended load transport of non-cohesive sediments. Twenty sets of numerical experiments combining nine control parameters under a range of bed characteristics and incident wave and tidal conditions were simulated. For each case, the general morphological response in shore-normal and shore-parallel directions was presented. Numerical results showed that the ${\kappa}-{\varepsilon}$ and H-LES closure models yield similar results that are in better agreement with existing morphodynamic observations than the results of the other turbulence models. The simulations showed that wave forcing drives a sediment circulation pattern that results in bar and berm formation. However, together with wave forcing, tides modulate the predicted nearshore sediment dynamics. The combination of tides and wave action has a notable effect on longshore suspended sediment transport fluxes, relative to wave action alone. The model's ability to predict sediment transport under propagation of obliquely incident wave conditions underscores its potential for understanding the evolution of beach morphology at field scale. For example, the results of the model confirmed that the wave characteristics have a considerable effect on the cumulative erosion/deposition, cross-shore distribution of longshore sediment transport and transport rate across and along the beach face. In addition, for the same type of oceanic forcing, the beach morphology exhibits different erosive characteristics depending on grain size (e.g., foreshore profile evolution is erosive or accretive on fine or coarse sand beaches, respectively). Decreasing wave height increases the proportion of onshore to offshore fluxes, almost reaching a neutral net balance. The sediment movement increases with wave height, which is the dominant factor controlling the beach face shape.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.27 no.6
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• pp.373-381
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• 2015

As offshore structures such as offshore wind and offshore platforms have been installed frequently in ocean, scour effects are considered important. To test the scour effect, numerical simulation of scour has been carried out. However, the test was usually conducted under the uni-directional flow without bi-directional current flow in western sea of Korea. Thus, in this paper, numerical simulations of scour around offshore jacket substructure of HeMOSU-1 installed in western sea of Korea are conducted using FLOW-3D. The conditions are uni-directional and bi-directional flow considering tidal current. And these results are compared to measured data. The analysis results for 10,000 sec show that under uni-directional conditions, maximum scour depth was about 1.32 m and under bidirectional conditions, about 1.44 m maximum scour depth occurred around the structure. Meanwhile, about 1.5~2.0 m scour depths occurred in field observation and the result of field test is similar to result under bi-directional conditions.

• Journal of Chest Surgery
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• v.34 no.6
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• pp.441-446
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• 2001

Background: Electrical breathing pacing has many advantages over mechanical ventilation. However, clinically permanent diaphragmatic pacing has been applied to limited patients and few temporary pacing has been reported. Our purpose is to investigate the feasibility of temporary electrical diaphragm pacing in explothoracotomy canine cases. Methods: Five dogs were studied under the general anesthesia. Left 5th intercostal space was opened. Self designed temporary pacing leads were placed around the left phrenic nerve and connected to the myostimulator. Chest wall was closed after tube insertion with underwater drainage. Millar catheter was introduced to the aorta and right atrium. Swan-Ganz catheter was introduced to the pulmonary artery. When the self respiration was shallow with deep anesthesia, hemodynamic and tidal volume were measured with the stimulator on. Results: Tidal volume increased from 143.3$\pm$51.3 ml to 272.3$\pm$87.4 ml(p=0.004). Right atrial diastolic pressure decreased from 0.7$\pm$4.0 mmHg to -10.5$\pm$4.7 mmHg(p=0.005). Pulmonary arterial diastolic pressure decreased from 6.1+2.5 mmHg to 1.2$\pm$4.8 mmHg(p<0.001). The height of water level in chest tube to show intrathoracic pressure change was from 10.3$\pm$6.7cmH$_{2}$O to 20.0$\pm$5.3 cmH$_{2}$O. Conclusion: Temporary electrical diaphragmatic pacing is a simple method to assist respiration in explothoracotomy canine cases. Self designed pacing lead is implantable and removable. Negative pressure ventilation has favorable effects on the circulatory system. Therefore, clinical application of temporary breathing pacing is feasible in thoracotomy patients to assist cardiorespiratory function.

• Journal of Yeungnam Medical Science
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• v.35 no.2
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• pp.165-170
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• 2018

Background: The purpose of this study was to investigate whether tidal volume (TV) of 8 mL/kg without positive end-expiratory pressure (PEEP) and TV of 6 mL/kg with or without PEEP in pressure-controlled ventilation-volume guaranteed (PCV-VG) mode can maintain arterial oxygenation and decrease inspiratory airway pressure effectively during one-lung ventilation (OLV). Methods: The study enrolled 27 patients undergoing thoracic surgery. All patients were ventilated with PCV-VG mode. During OLV, patients were initially ventilated with TV 8 mL/kg (group TV8) without PEEP. Ventilation was subsequently changed to TV 6 mL/kg with PEEP ($5cmH_2O$; group TV6+PEEP) or without (group TV6) in random sequence. Peak inspiratory pressure ($P_{peak}$), mean airway pressure ($P_{mean}$), and arterial blood gas analysis were measured 30 min after changing ventilator settings. Ventilation was then changed once more to add or eliminate PEEP ($5cmH_2O$), while maintaining TV 6 mL/kg. Thirty min after changing ventilator settings, the same parameters were measured once more. Results: The $P_{peak}$ was significantly lower in group TV6 ($19.3{\pm}3.3cmH_2O$) than in group TV8 ($21.8{\pm}3.1cmH_2O$) and group TV6+PEEP ($20.1{\pm}3.4cmH_2O$). $PaO_2$ was significantly higher in group TV8 ($242.5{\pm}111.4mmHg$) than in group TV6 ($202.1{\pm}101.3mmHg$) (p=0.044). There was no significant difference in $PaO_2$ between group TV8 and group TV6+PEEP ($226.8{\pm}121.1mmHg$). However, three patients in group TV6 were dropped from the study because $PaO_2$ was lower than 80 mmHg after ventilation. Conclusion: It is postulated that TV 8 mL/kg without PEEP or TV 6 mL/kg with $5cmH_2O$ PEEP in PCV-VG mode during OLV can safely maintain adequate oxygenation.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.29 no.3
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• pp.139-152
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• 2024

This study conducted various sensitivity experiments to assess and improve the performance of low-resolution global ocean circulation models. The MOM6 (Modular Ocean Model Version 6), developed by the Geophysical Fluid Dynamics Laboratory, was utilized. We focused on analyzing the effects of implementing the ePBL (energetics based planetary boundary layer) mixed layer scheme, including tidal simulation, and applying hybrid vertical coordinate system on the simulation accuracy of ocean circulation. The results revealed that the ePBL scheme effectively mitigated excessive mixed layer thickness and high temperature biases in the equatorial Pacific, while tidal simulations contributed to improving the oceanic structures in the Yellow Sea and the East Sea. Additionally, the hybrid vertical coordinate system enabled more accurate simulations of the vertical structure of temperature and salinity, enhancing model performance. This study proposes specific approaches to enhance the accuracy of ocean circulation models, contributing to global ocean and climate modeling efforts.