• Journal of the Korean Society of Radiology
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• v.11 no.4
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• pp.247-252
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• 2017

Radiologists who experience extravasation of the contrast medium even once suffer mentally during testing due to the fear of its reoccurrence. Establishing a plan for preventing it beforehand is necessary above all because patients experience severe physical and mental pain and become distrusting of medical staff and treatment. Therefore, the present study attempts to prevent extravasation, which is the result of damage from pressure applied to the patient's blood vessels, by lowering PSI, and conducted a comparative analysis of PSI changes during contrast medium injection depending on the diameter of the Y-shape connecting tube which connects the automatic injector and the intravenous injection of the patient. In the case of product A in which the diameter of the Y-shape connecting tube is about 2mm, the average PSI for all ages was 98.5 and standard deviation was 9.72. In the case of product B in which the diameter of the Y-shape connecting tube is about 3mm, the average PSI for all ages was 62.0 and standard deviation was 8.59. Product B with its wider diameter decreased in average pressure by 37.05% when compared to product A, and when product B is used with the p-value at 0.00, pressure decreased even more, achieving statistically significant results.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.22 no.3_1spc
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• pp.573-579
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• 2013

Once-through helically coiled steam generator tubes subjected to external pressure are of interest because of their application to advanced small- and medium-sized integral reactors, in which a primary coolant with a relatively higher pressure flows outside the tubes, while secondary water with a relatively lower pressure flows inside the tubes. Another notable point is that the values of the mean radius to thickness ratio of these steam generator tubes are very small, which means that a thick-walled cylinder is employed for these steam generator tubes. In the present paper, the maximum allowable pressure of helically coiled and thick-walled steam generator tubes with through-wall cracks under external pressure is investigated based on a detailed nonlinear three-dimensional finite element analysis. In terms of the crack orientation, either circumferential or axial through-wall cracks are considered. In particular, in order to quantify the effect of the crack location on the maximum external pressure, these cracks are assumed to be located in the intrados, extrados, and flank of helically coiled cylinders. Moreover, an evaluation is also made of how the maximum external pressure is affected by the ovality, which might be inherently induced during the tube coiling process used to fabricate the helically coiled steam generator tubes.

• Biomolecules & Therapeutics
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• v.6 no.4
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• pp.358-363
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• 1998

Intravenous lipid emulsion is used extensively as a major component of parenteral nutrition for patients in the surgical intensive care unit. Abnormal cardiovascular function related to lipid infusion has been reported although conflicting results exist. In the present study, we investigated the effects of intravenous emulsions of long-chain triglyceride (LCT) and medium-chain triglyceride (MCT) on myocardial ischemia/ reperfusion injury and on platelet aggregation in rat. There was no difference between LCT and MCT considering the effects on left ventricular developed pressure (LVDP) and coronary flow rate (CFR) before and after ischemia/reperfusion in isolated rat heart. On the other hand, a difference was found between LCT and MCT with regard to their effects on heart rate (HR) and end diastolic pressure (EDP) after ischemia/reperfusion. After ischemia/reperfusion, HR was significantly (P<0.05) reduced and EDP significantly (P<0.05) inc.eased by LCT (18$\pm$2.0% and 42.8$\pm$8.9%, respectively), but not by MCT Ex vivo platelet aggregation induced by collagen was reduced by LCT infusion, but not by MCT These findings suggest that MCT may have slightly more favorable effect than LCT on the myocardial function after ischemia/reperfusion in rat.

• Structural Engineering and Mechanics
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• v.64 no.6
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• pp.703-721
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• 2017

The experimental study of the behavior of dry medium and loose sandy soil under the action of a single impulsive load is carried out. Different falling masses from different heights were conducted using the falling weight deflectometer (FWD) to provide the single pulse energy. The responses of soils were evaluated at different locations (vertically below the impact plate and horizontally away from it). These responses include; displacements, velocities, and accelerations that are developed due to the impact acting at top and different depth ratios within the soil using the falling weight deflectometer (FWD) and accelerometers (ARH-500A Waterproof, and Low capacity Acceleration Transducer) that are embedded in the soil and then recorded using the multi-recorder TMR-200. The behavior of medium and loose sandy soil was evaluated with different parameters, these are; footing embedment, depth ratios (D/B), diameter of the impact plate (B), and the applied energy. It was found that increasing footing embedment depth results in: amplitude of the force-time history increases by about 10-30%. due to increase in the degree of confinement with the increasing in the embedment, the displacement response of the soil will decrease by about 25-35% for loose sand, 35-40% for medium sand due to increase in the overburden pressure when the embedment depth increased. For surface foundation, the foundation is free to oscillate in vertical, horizontal and rocking modes. But, when embedding a footing, the surrounding soil restricts oscillation due to confinement which leads to increasing the natural frequency, moreover, soil density increases with depth because of compaction, that is, tendency to behave as a solid medium.

• Journal of the Korean Dietetic Association
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• v.25 no.2
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• pp.83-104
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• 2019

Elevated high-sensitivity C reactive protein (hs-CRP) levels and metabolic syndrome are considered important predictors of cardiovascular mortality. This study examined the influence of the alcohol consumption level on the hs-CRP level and the prevalence of metabolic syndrome in South Koreans. The study subjects were 3,884 participants (${\geq}19$ years) from the KNHANES in 2015. The subjects were divided into four groups according to their alcohol consumption; None (none-alcohol consumption), Low (less than 15 g/day), Medium (15~29.9 g/day), and High (over than 30 g/day). The odds ratio for high-risk hs-CRP of men was significantly lower in the Low or Medium groups compared to the None group. In women, the odds ratio for high-risk hs-CRP was not decreased in the Low or Medium groups but was significantly higher in the High group than in the None group. Compared to nondrinkers, the prevalence of metabolic syndrome was lower in the Low group and Medium group in both men and women, whereas it was significantly higher in the High group in men only. In particular, the prevalence of low HDL-cholesterol was lower in all drinking groups. When the confounding factors were adjusted, the odds ratio for low HDL-cholesterol appeared to decline in the Low groups in both men and women. On the other hand, in the Medium group, women showed an elevated odds ratios of high blood pressure (HBP) and high fasting plasma glucose but men showed an elevated odds ratios of HBP and high triglyceride levels. The overall results suggest that low alcohol consumption is more appropriate than medium alcohol consumption. Nevertheless, more study will be needed to evaluate the appropriate alcohol consumption level.

• Coupled systems mechanics
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• v.7 no.6
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• pp.649-668
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• 2018

In this paper, we present a numerical model for fluid-structure interaction between structure built of porous media and acoustic fluid, which provides both pore pressure inside porous media and hydrodynamic pressures and hydrodynamic forces exerted on the upstream face of the structure in an unified manner and simplifies fluid-structure interaction problems. The first original feature of the proposed model concerns the structure built of saturated porous medium whose response is obtained with coupled discrete beam lattice model, which is based on Voronoi cell representation with cohesive links as linear elastic Timoshenko beam finite elements. The motion of the pore fluid is governed by Darcy's law, and the coupling between the solid phase and the pore fluid is introduced in the model through Biot's porous media theory. The pore pressure field is discretized with CST (Constant Strain Triangle) finite elements, which coincide with Delaunay triangles. By exploiting Hammer quadrature rule for numerical integration on CST elements, and duality property between Voronoi diagram and Delaunay triangulation, the numerical implementation of the coupling results with an additional pore pressure degree of freedom placed at each node of a Timoshenko beam finite element. The second original point of the model concerns the motion of the outside fluid which is modeled with mixed displacement/pressure based formulation. The chosen finite element representations of the structure response and the outside fluid motion ensures for the structure and fluid finite elements to be connected directly at the common nodes at the fluid-structure interface, because they share both the displacement and the pressure degrees of freedom. Numerical simulations presented in this paper show an excellent agreement between the numerically obtained results and the analytical solutions.

• Structural Monitoring and Maintenance
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• v.8 no.4
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• pp.345-360
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• 2021

This paper presents an analytical approach to calculate the buckling load of the cylindrical ring structures subjected to both hydrostatic and hydrodynamic pressures. Based on the conservative law of energy and Timoshenko beam theory, a theoretical formula, which can be used to evaluate the critical pressure of buckling, is first derived for the simplified cylindrical ring structures. It is assumed that the hydrodynamic pressure can be treated as an equivalent hydrostatic pressure as a cosine function along the perimeter while the thickness ratio is limited to 0.2. Note that this paper limits the deformed shape of the cylindrical ring structures to an elliptical shape. The proposed analytical solutions are then compared with the numerical simulations. The critical pressure is evaluated in this study considering two possible failure modes: ultimate failure and buckling failure. The results show that the proposed analytical solutions can correctly predict the critical pressure for both failure modes. However, it is not recommended to be used when the hydrostatic pressure is low or medium (less than 80% of the critical pressure) as the analytical solutions underestimate the critical pressure especially when the ultimate failure mode occurs. This implies that the proposed solutions can still be used properly when the subsea vehicles are located in the deep parts of the ocean where the hydrostatic pressure is high. The finding will further help improve the geometric design of subsea vehicles against both hydrostatic and hydrodynamic pressures to enhance its strength and stability when it moves underwater. It will also help to control the speed of the subsea vehicles especially they move close to the sea bottom to prevent a catastrophic failure.

• Journal of the Korean Society of Propulsion Engineers
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• v.2 no.2
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• pp.47-55
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• 1998

Steady-state and transient performance for the medium scale civil aircraft turbofan engine was analyzed. Steady-state performance was analyzed on maximum take-off condition, maximum climb condition, and cruise condition. At 90％RPM of the low pressure compressor, the partload performance was economized. The transient performance was analyzed with cases of the step increase, the ramp increase, the ramp decrease, and the step increase and ramp decrease for the input fuel flow. For the transient performance analysis, work matching between compressor and turbine was needed. Modified Euler method was used the integration of residual torque in work matching equation. At all flight condition, the overshoot of the high pressure turbine inlet temperature was appeared in the step and ramp increase case, and the surge of high pressure compressor was appeared in the step increase case and the ramp increase case within 5.5 seconds of maximum climb condition.

• Journal of Advanced Marine Engineering and Technology
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• v.40 no.6
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• pp.468-475
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• 2016

The purpose of this study is to investigate the acoustic problems of the conventional heat recovery ventilator and to suggest the methods of noise reduction from a heat recovery ventilator according to the installed location. The noise level, in this study, was measured and discussed as the parameters of size, wind volume and sound absorbing duct length for a heat recovery ventilator based on domestic and international related standards. It is found, as a result, that almost all of noise levels from the small and medium heat recovery ventilators without the sound absorbing duct in the anechoic chamber were higher than the noise standard value of 50 dB(A) regardless of the wind volume, and the noise levels went down when a sound absorbing duct was installed. In addition, the sound pressure level relative to frequency bands according to the length of sound absorbing duct was generally decreased, as the length of sound absorbing duct in the small and medium heat recovery ventilators was big, and the sound pressure level was generally increased, as the wind volume was great.

• Journal of the Mineralogical Society of Korea
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• v.31 no.3
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• pp.161-172
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• 2018

Multi-anvil press (MAP) is one of the high pressure apparatuses and often generates the pressure-conditions ranging from 5 to 25 GPa and temperature-conditions up to $2,300^{\circ}C$. The MAP is, therefore, suitable to explore the pressure-induced structural changes in diverse earth materials from Earth's mantle and the bottom of the mantle transition zone (~660 km). In this study, we present the experimental results for pressure-load calibration of the 1,100-ton multi-anvil press equipped in the authors' laboratory. The pressure-load calibration experiments were performed for the 14/8 step, 14/8 G2, 14/8 HT, and 18/12 assembly sets. The high pressure experiments using ${\alpha}$-quartz, wollastonitestructure of $CaGeO_3$, and forsterite as starting materials were analyzed by powder X-ray diffraction spectroscopy. The phase transition of each mineral indicates the specific pressure that is loaded to a sample at $1,200^{\circ}C$: a transition of ${\alpha}$-quartz to coesite at 3.1 GPa, that of garnet-structure of $CaGeO_3$ to perovskite-structure at 5.9 GPa, that of coesite to stishovite at 9.2 GPa, and that of forsterite to wadsleyite at 13.6 GPa. While the estimated pressure-load calibration curve is generally consistent with those obtained in other laboratories, the deviation up to 50 tons is observed at high pressure above 10 GPa. This is partly because of the loss of oil pressure at high pressure resulting from the differences in a sample chamber, and the frictional force between pressure medium and second anvil. We also report the ${\sim}200^{\circ}C/mm$ of thermal gradient in the vertical direction of the sample chamber of 14/8 HT assembly. The pressure-load calibration curve and the observed thermal gradient within the sample chamber can be applied to explain the structural changes and the relevant macroscopic properties of diverse crystalline and amorphous earth materials in the mantle.