• Applied Chemistry for Engineering
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• v.18 no.5
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• pp.438-443
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• 2007

Titanium oxide films were deposited by the HCP (hollow cathode plasma) reactor at room temperature. With results of simulation about HCP reactor, the temperature profile is uniform on substrate regardless of the heat generation at cathode. The velocity profile on the surface of substrate is more uniform with increasing the gap between cathode and substrate, and surface roughness was decreased with increasing the gap between cathode and substrate. We could confirm that the composition of oxide increased with RF-power, and the ratio of O to Ti in the films was about 2 : 1 at RF-power of 240 watt and distance between cathode and substrate of 3 cm.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.14 no.2
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• pp.36-42
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• 2000

This paper presents the characteristics analysis of electromagnetic pump using linear induction motors. The electromagnetic pump is designed to transfer the molten metals by the electromagnetic force of linear induction motors. The characteristics f a linear induction motor are analysed by the equivalent circuit method considering the end effects. For the verification of the analysis method, the locked test and load test with molten tin were made. The test results of locked test were compared with the simulations, and the velocity of the load test with molten zinc showed 0.24[m/x] with air gap 30[gap] which is sufficient for transferring molten tin.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2001.05a
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• pp.135-139
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• 2001

This experimental study investigates the wake flow behind a pair of cylinders displaced normal to a free stream. In this experiment, the principal aim is to investigate the transition mechanism of the large vortex generating process in the wake having unique vortex shedding pattern. associated with the gap difference between the cylinders. The detailed visualization is carried out using the PIV measurement. The transition mechanism of the large generating vortex is clarified by showing the streak lines. the vorticity and the statistical fluctuating velocity distributions.

• The Bulletin of The Korean Astronomical Society
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• v.44 no.2
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• pp.63.2-63.2
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• 2019

Recent submillimeter observations of ALMA reveal that many protoplanetary disks contain substructures like gaps or rings. The disk-planet interaction is believed to be the most likely gap formation scenario, and most previous numerical work attempted to constrain the planet mass using the density profiles of gas in the gaps. Since the dust and gas distributions likely differ from each other in protoplanetary disks, however, perturbed rotational velocities that directly probe the gas would give a more reliable estimate to the planet mass. In this work, we run two-dimensional hydrodynamic simulations to measure the amplitudes and widths of rotational velocity perturbations induced by planets with different mass. We present the parametric relations of the gap widths and depths as functions of the planet mass and disk properties. We also apply our relations to HD 163296 to infer the masses of embedded planets.

• Nuclear Engineering and Technology
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• v.56 no.4
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• pp.1407-1424
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• 2024

In Pressurized Water Reactors, most of the failed fuel rods are often observed at the periphery of the fuel assembly, especially near the core baffle. The rod vibration-induced fretting wear is a significant failure mechanism strongly correlated with the coolant and support conditions. This paper presents a coupled vibration model of double-rod to predict the grid-to-rod fretting (GTRF) wear. A motion-dependent fluid force model is used to simulate the coolant cross flow, the gap constraints with asymmetric stiffness between spring and dimple on the vibration form, and the fretting wear are discussed. The results show the effect of the coupled vibration on the deterioration of wear, providing a sound theoretical explanation of some failure phenomena observed in the previous experiment. Exploratively, we analyze the impact of the baffle jet on the GTRF wear, which indicates that the high-velocity cross-flow will significantly affect the vibration forms while sharply changing the wear behavior.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.12 no.1
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• pp.1-6
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• 2016

Characteristics of exhaust from chimney of electricity generator are analyzed based on CFD when Waveguide-Below-Cutoff (WBC) array is installed in order to achieve the certain level of electromagnetic pulse (EMP) shielding. The main purpose is prediction of average and maximum velocity of exhaust. The results reveal that: 1) When the specification of waveguide is given as 80-diameter, 400-length, and the gap of 20 mm, the shielding effectiveness (SE) is 140dB. The average and maximum velocity of exhaust in the chimney with WBC Array can be represented as exponential functions. 2) As the number of WBC increases, the velocity in the chimney dwindles. 3) Under the situation that WBC with 80 mm diameter is located at intervals of 20 mm, the average velocity can be approximated by $25.5344{\times}e^{(-0.0098{\times}N_{WBC})}$ with input velocity of 15 m/s. In addition, the determination coefficient is 0.915, which is sufficiently high.

• Tribology and Lubricants
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• v.19 no.3
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• pp.167-177
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• 2003

The study deals with the development of a thermohydrodynamic (THD) computational procedure for evaluating the pressure, temperature and velocity distributions in fluid films with very rough geometry. A parametric investigation is performed to predict the bearing behaviors in the lubricating film having the absorbed layers and their interfaces determined by the rough surfaces with Gaussian distribution. The layers are expressed as functions of the standard deviations of each surface to characterize flow patterns between both the rough sur-faces. The velocity variations and the heat generation are assumed to occur in the central (shear) zone with the same bearing length and width. The coupled effect of surface roughness and shear zone dependency on hydrodynamic pressure and temperature has been found in non-contact mode. The procedure confirms the numerically determined relationship between the pressure and film gap on condition that its roughness magnitude is smaller than the fluid film thickness.

• Journal of Korean Society for Atmospheric Environment
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• v.30 no.4
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• pp.339-349
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• 2014

$CO_2$ emission has been gradually increased due to rising fossil fuel use. A gliding arc plasma scrubber (GAPS) was proposed to destruct $CO_2$. For optimum design of GAPS, a CFD analysis has been conducted in different configuration for the system. The parameters considered included gas injection velocity at the nozzle and gas flow rate to gap between electrodes. The reactor configuration affected velocity fields which caused changes in the mixture fraction and the retention time. The mixing effect of $CO_2$ and supplied gas ($CH_4$ and steam) was enhanced by installing a orifice baffle. This revealed that the orifice baffle is effective in $CO_2$ conversion by positioning the reactants in the gas into the center of plasma discharge.

• Journal of Advanced Marine Engineering and Technology
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• v.35 no.7
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• pp.921-929
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• 2011

We measured experimentally the properties of fluid dynamics, velocity fields, and the pressure, around stenotic obstruction located inside a circular channel structure. Particle image velocimetry system was employed to obtain velocity fields at the central section of the circular channel in the streamwise direction. The stenosis model used was made of acrylic material with different stenotic aspect ratios. The working fluid was water and it was returned by a centrifugal pump system. Pressure measurements were carried out to validate the effect of a narrow passageway. Results showed that the acceleration of gap flow through stenotic obstruction and the pressure drop in the recirculation regime behind the stenosis model can be observed.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.800-804
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• 2005

In this paper, the radiated sound pressure induced by low velocity impact is obtained by solving the Rayleigh integral equation. For structurally radiated noise, the sound field is directly coupled to the structural motion. Therefore the impact response should be analyzed. It is well known that the presence of the delamination in a composite laminate introduces a local flexibility which changes the dynamic characteristic of the structure. The 2-D simplified delamination model is used to analyze the impact response. And the 3-D non-linear finite element model is developed using gap element to avoid the overlap and penetration between the upper and lower sub-laminates at delamination region. Predicted impact response using 2-D equivalent delamination model are compared with the numerical ones from the 3-D non-linear finite element model.