• Earthquakes and Structures
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• v.16 no.6
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• pp.727-741
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• 2019

A reinforced concrete water tank is a typical functional liquid storage structure and cracks are the greatest threat to the liquid storage structure. Tanks are readily cracked due to seismic activity, thereby leading to the leakage of the stored liquid and a loss of function. In order to study the effect of cracks on liquid storage tanks, self-healing and leakage tests for bending cracks and through cracks in the walls of a reinforced concrete water tank were conducted. Material performance tests were also performed. The self-healing performance of bending cracks in a lentic environment and through cracks in a lotic environment were tested, thereby the self-healing width of bending micro-cracks in the lentic environment in the short term were determined. The through cracks had the capacity for self-healing in the lotic environment was found. The leakage characteristics of the bending cracks and through cracks were tested with the actual water head on the crack. The effects on liquid leakage of the width of bending cracks, the depth of the compression zone, and the acting head were determined. The relationships between the leakage rate and time with the height of the water head were analyzed. Based on the tests, the relationships between the crack characteristics and self-healing as well as the leakage were obtained. Thereby the references for water tank structure design and grading earthquake damage were provided.

• Structural Engineering and Mechanics
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• v.52 no.5
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• pp.875-887
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• 2014

The aim of the shaking table experiment is to verify the isolation effect of a storage liquid tank with multiple friction pendulum bearings. A 1:20 scale model of a real storage liquid tank that is widely used in the petroleum industry was examined by the shaking table test to compare its anchored base and isolated base. The seismic response of the tank was assessed by employing the time history input. The base acceleration, wave height and tank wall stress were used to evaluate the isolation effect. Finally, the influences of the bearing performance that characterizes the isolated tank, such as the friction force and residual displacement, were discussed.

• Journal of Aerospace System Engineering
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• v.18 no.3
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• pp.8-16
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• 2024

Because hydrogen has very low density, a different storage method is required to store the same amount of energy as fossil fuel. One way to increase the density of hydrogen is through liquefaction. However, since the liquefied temperature of hydrogen is extremely low at -252 ℃, it is easily vaporized by external heat input. When liquid hydrogen is vaporized, a self-pressurizing phenomenon occurs in which the pressure inside the hydrogen tank increases, so when designing the tank, this rising pressure must be carefully predicted. Therefore, in this paper, the internal pressure of a cryogenic liquid fuel tank was predicted according to the liquid hydrogen filling ratio. A one-dimensional thermodynamic model was applied to predict the pressure rise inside the tank. The thermodynamic model considered heat transfer, vaporization of liquid hydrogen, and fuel discharging. Finally, it was confirmed that there was a significant difference in pressure behavior and maximum rise pressure depending on the filling ratio of liquid hydrogen in the fuel tank.

• Earthquakes and Structures
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• v.15 no.5
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• pp.513-528
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• 2018

A typical viable technique to decrease the seismic response of liquid storage tanks is to isolate them at the base. Base-isolation systems are an efficient and feasible solution to reduce the vulnerability of structures in high seismic risk zones. Nevertheless, when liquid storage tanks are under long-period shaking, the base-isolation systems could have different impacts. These kinds of earthquakes can damage the tanks readily. Hence, the seismic behaviour and vibration of cylindrical liquid storage tanks, subjected to earthquakes, is of paramount importance, and it is investigated in this paper. The Finite Element Method is used to evaluate seismic response in addition to the reduction of excessive liquid sloshing in the tank when subjected to the long-period ground motion. The non-linear stress-strain behaviour pertaining to polymers and rubbers is implemented while non-linear contact elements are employed to describe the 3-D surface-to-surface contact. Therefore, Nonlinear Procedures are used to investigate the fluid-structure interactions (FSI) between liquid and the tank wall while there is incompressible liquid. Part I, examines the effect of the flexibility of the isolation system and the tank aspect ratio (height to radius) on the tank wall radial displacements of the tank wall and the liquid sloshing heights. Maximum stress and base shear force for various aspect ratios and different base-isolators, which are subjected to three seismic conditions, will be discussed in Part II. It is shown that the composite-base isolator is much more effective than other isolators due to its high flexibility and strength combined. Moreover, the base isolators may decrease the maximum level pertaining to radial displacement.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.696-699
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• 2004

Generally, the time history analysis among seismic response analyses of a structure needs more times than static analysis. Therefore the mechanical model of a structure has been used as a simple lumped parameter model in time history analysis. For the most cases, the simple mechanical model shows the similar results to that of detailed finite element model. so it is reasonable to use the simple mode] in preliminary analysis. In seismic design of liquid storage tank, such as LNG storage tank, the lumped parameter mode] also is being used in preliminary analysis, however sometimes shows the differences to the results of detailed finite element model. Therefore in this study, the dynamic characteristics between lumped parameter model and detailed finite model is compared for the variables such as height/diameter of liquid-storage tank and thickness of wall, then the applicability of beam mode] to the seismic response analysis are evaluated for some liquid storage tanks.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.745-749
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• 2011

Two-dimemsional liquid-solid multiphase fluid dynamics was used to analyze the suspension and mix of liquid fuel and solid particles in fuel tank installed mixing impeller. In this paper, the multiphase flow was modeled using Eulerian Grandular Multiphase model. Experimental measurements of the axial distribution of solids concentration in stirred tanks under 12vol% solid loading were used for comparison with the CFD simulation. Four cases for the impeller location and flow pumping direction also were reviewed under 10.5% solids loading and 700rpm in fuel mix tank. The result of quality of suspension was compared with each cases and the impeller location and operation of mixing fuel tank was established.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.9
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• pp.1018-1024
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• 2011

Liquid sloshing occurs when a partially filled liquid tank is subjected to undesirable external forces or acceleration/deceleration for positioning control. Installation of baffles is still the most popular way to suppress the sloshing, but recent successes of input shaping in reducing structural vibrations may give a possible alternative. We aim at investigating the applicability of input shaping to sloshing suppression by numerically solving fluid motions in a rectangular tank. The tank is partially filled with water and it is suddenly put into a sequence of horizontal motions of acceleration and constant speed. The flow is assumed to be two-dimensional, incompressible, and in viscid, and a VOF two-phase model is used to capture the free surface. Results show that the sloshing can be successfully suppressed by shaping the input, i.e., the velocity or acceleration profile of tank. Three different input shapers (ZII, ZVD, and two-mode convolved ZV shapers) are tested and compared in this study Among them, the convolved ZV shaper shows a best performance to eliminate the sloshing almost completely.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.17 no.1
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• pp.1-8
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• 2009

In this paper, reorientation based on angular momentum exchange is applied for a bias momentum stabilized satellite, which is equipped with a spherical fuel tank, and the effect of liquid slosh on the attitude properties such as inertia tensor and angular rate is investigated. In order to represent the slosh motion of liquid an equivalent mechanical model is adopted and full nonlinear equations of motion for three-body system are derived. Computer simulations are performed for several cases, which use the viscosity of liquid and the center location of the tank as input parameters, mainly in order to observe how the viscosity of liquid and the center location of the tank influence the spacecraft’s attitude. The investigation includes observing time-variations of the inertia tensor, especially presence of components of product of inertia during the maneuver.

• Earthquakes and Structures
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• v.12 no.5
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• pp.583-589
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• 2017

In this study, result of a field investigation of railway traffic-induced vibrations is provided to examine acceptability levels of ground vibration and to evaluate the serviceability of a liquid-storage tank. Free field attenuation of the amplitudes as a function of distance is derived by six accelerometers and compared with a well-known half-space Bornitz's analytical solution which considers the loss of the amplitude of waves due to geometrical damping and material damping of Rayleigh. Bornitz's solution tends to overlap vertical free field vibration compared with in-situ measured records. The vibrations of the liquid-storage tank were compared with the USA, Federal Transportation Railroad Administration (FTA) criteria for acceptable ground-borne vibrations and with the criteria in DIN 4150-3 German standard. Comparing the thresholds stated in DIN 4150-3, absolute peak particle velocities are within the safe limits, however according to FTA velocity level at the top of the water tank exceeds the allowable limits. Furthermore, it is intended to indicate experimentally the effect of the kinematic interaction caused by the foundation of the structure on the free-field vibrations.

• Journal of Power System Engineering
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• v.21 no.5
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• pp.71-78
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• 2017

The purpose of this study is to propose the basic data for the development of a sensor capable of simultaneously measuring the liquid-level, concentration and temperature of a urea tank using ultrasonic and electrical conductivity sensors for diesel vehicles with a urea-SCR system. It was found that the liquid-level of the urea tank using the ultrasonic sensor showed a good linearity with the actual liquid-level, and the urea concentration maintained good linearity in the range of 32.5 wt% to 10 wt%. It was an effective measurement of urea concentration to use the electrical conductivity sensor in the temperature range of $-10{\sim}22^{\circ}C$ and to use the ultrasonic sensor at $22^{\circ}C$ or more. Simultaneous measurement of concentration, liquid-level and temperature of the urea tank will be possible by attaching the electrical conductivity sensor and the ultrasonic sensor (split-type) to one sensor together.