• International Journal of Naval Architecture and Ocean Engineering
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• v.6 no.1
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• pp.132-150
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• 2014

In this study, the inertial properties of fully filled liquid in a tank were studied based on the potential theory. The analytic solution was obtained for the rectangular tank, and the numerical solutions using Green's 2nd identity were obtained for other shapes. The inertia of liquid behaves like solid in recti-linear acceleration. But under rotational acceleration, the moment of inertia of liquid becomes small compared to that of solid. The shapes of tank investigated in this study were ellipse, rectangle, hexagon, and octagon with various aspect ratios. The numerical solutions were compared with analytic solution, and an ad hoc semi-analytical approximate formula is proposed herein and this formula gives very good predictions for the moment of inertia of the liquid in a tank of several different geometrical shapes. The results of this study will be useful in analyzing of the motion of LNG/LPG tanker, liquid cargo ship, and damaged ship.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.31-37
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• 2011

Detail flow structure in a large solid rocket motor with two inhibitors has been investigated using 3D Large Eddy Simulation and Proper Orthogonal Decomposition(POD) analysis. Vortex shedding frequencies periodically occurred by inhibitors are coupled with flow acoustics induced by the impinging of vorticity on nozzle head. As a result of 3D analysis, it was observed that the nozzle exit flow causes roll-torques from the vortex being decomposed in unbalanced shape for the impinging of vorticity on the nozzle head.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.11
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• pp.3454-3462
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• 1996

Compared to a full three dimensional FEM, the Slab-FEM hybrid method reduces the required computation time distinctly and it can be applied to the analysis of a shape rolling process. However, the method is somewhat approximate and predictions by the method contain certain inaccuracies. In the present investigation a parameter called T-factor was introduced to compensate the inaccuracies of the method and proper values of the parameter were estimated for different widths of bars and reduction ratios. Then, the method was applied to analyze cold and hot rollings of rectangular bars and predicted results were compared to those of experiments. Nonuniform distributions of temperature in the bars were predicted by utilizing the temperature equation obtained for a semi-infinite solid under radiation and convection boundary conditions. It was found out that accuracies of spread and roll separating force predictions could be enhanced by using proper values of the T-factor.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.11a
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• pp.181-185
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• 2010

The behavior of combustion-induced internal flow of SRM equipped with fin-slot grain and submerged nozzle is very complex and diverse. Cold air-flow test for 2D and 3D scale models of SRM has been done in order to specify the visualization method to analyze particular internal flow patterns such as roll-torque inducing flow. Swirl flow induced by asymmetric vortical tube also has been visualized through employing various light source and recording directions.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.6
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• pp.152-157
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• 2012

This study investigates compressive strength of ice pellet strip which is potential medium for Natural Gas Hydrate(NGH) extruded from die holes of Twin-roll Press for Continuous Pelletizing(TPCP). Recently, the prototype of TPCP is newly developed where ice powder is continuously fed and extruded into strip-type pellet between twin rolls. The system is specifically designed for future expansion towards mass-production of ice pellet strips or solid form of natural gas hydrate. It is shown that the compressive strength of pellet strip heavily depends on factors in extrusion process such as disk size, surface smoothness, ring size, taper shape, feeding mechanism, and rotational speed. Here, the mechanism of TPCP, along with compressive strength of pellets is discussed in terms of its feasibility for producing NGH pellets in the future.

• International Journal of Naval Architecture and Ocean Engineering
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• v.9 no.1
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• pp.114-125
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• 2017

This paper addresses a study of inner-tank sloshing effect on motion responses of a Floating Liquefied Natural Gas (FLNG) system, through experimental analysis and numerical modeling. To investigate hydrodynamic characteristics of FLNG under the conditions of with and without LNG-tank sloshing, a series of numerical simulations were carried out using potential flow solver SESAM. To validate the numerical simulations, model tests on the FLNG system was conducted in both liquid and solid ballast conditions with 75% tank filling level in height. Good correlations were observed between the measured and predicted results, proving the feasibility of the numerical modeling technique. On the verified numerical model, Response Amplitude Operators (RAOs) of the FLNG with 25% and 50% tank filling levels were calculated in six degrees of freedom. The influence of tank sloshing with varying tank filling levels on the RAOs has been presented and analyzed. The results showed that LNG-tank sloshing has a noticeable impact on the roll motion response of the FLNG and a moderate tank filling level is less helpful in reducing the roll motion response.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.5
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• pp.426-432
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• 2020

Music with the development of the media since the 20th century marks a change into an era where the live performance and music of the masses, which were hard to imagine in previous times, are shared. Based on this cultural trend, teenage music, which has been completely alienated from existing culture, is in line with the birth of Rock 'n' Roll, an event that has entered the mainstream, and the emergence of the guitar, especially the solid body electric guitar. The Fender Stratocaster, which is referred to as the epitome of this electric guitar, has joined the history of popular music for rock 'n' roll. To this day, the immense influence, which still encompasses many followers and generations, has served as a bridge that continues to be reproduced, even in the historical trend of popular music and the status of electric guitars. In addition, even in the rapid development of popular music and media, we will always be able to give true meaning and value to the vitality with the times. This paper examines the features and marks of these Fender Stratocasters.

• International Journal of Air-Conditioning and Refrigeration
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• v.11 no.2
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• pp.61-66
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• 2003

In order to prevent roll-over and a rapid boil-off of LNG in tanks, the phase equilibria of carbon dioxide in liquefied natural gas components as binary mixtures at cryogenic temperatures have been experimentally measured using Fourier transform infrared spectroscopy in conjunction with a specially designed variable pressure/temperature cryostat cell (pathlength 2 mm; pressures up to 30 bar). Solid carbon dioxide has been found to be comparatively soluble in liquid nitrogen (3.25$\times$${10}^{-6}$ mole fraction), liquid methane (1.04$\times$${10}^{-4}$ mole fraction), liquid ethane (3.1$\times$${10}^{-2}$ mole fraction) and liquid propane (6.11$\times$${10}^{-2}$ mole fraction) at their normal boiling temperatures. The solubilities of carbon dioxide in various cryogens, which increased with increasing temperature, are much lower than those obtained by others using gas chromatography. The differences are attributed to infrared spectroscopy selectively measuring dissolved solute in situ whereas gas chromatography measures microscopic particulate solid in addition to dissolved solute.

• Journal of Aerospace System Engineering
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• v.8 no.3
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• pp.1-5
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• 2014

An inner flow of a porous cylinder with partial slots was visualized to study fluidic phenomena in a solid rocket motor. A high-pressure chamber and an air supply system for high flow rate were used. In order to visualize the inner flow, the smoke generator with a cam-driven pump and heaters and high speed camera were adopted. The results of the cylinder type and the partial slot type were compared. As a result, the injected smoke flow in the partial slot type had circumferential fluctuations unlike the cylinder type. It was found that the circumferential flow induced from the partial slots could be the cause of combustion instability and roll torque.

• Journal of the Korean Society of Propulsion Engineers
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• v.15 no.3
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• pp.31-39
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• 2011

The flowfield in a solid rocket motor was simulated at the wall-injection test model, which has a fin-slot grain and submerged nozzle, and visualized by a smoke-wire. The high speed CCD camera captured the visualized images around the nozzle inlet through the grain center port. The vortical tube structure and circumferential flow patterns at the nozzle throat were visualized. The radial momentum transfer caused by the shear-interactions of slot-outlet flow, fin-base flow and grain port flow from upstream worked as the source of these phenomena.