• Journal of the Optical Society of Korea
• /
• v.9 no.2
• /
• pp.74-78
• /
• 2005

With the fast Q-tensor method, which can model the defect dynamics in a liquid crystal director field, the nucleation and dynamical behavior of defects is modeled. In order to model the defect, hormeotropic aligned liquid crystal cell with step inhomogeneous electrode which has a height of $1\;{\mu}m$ is used. From the simulation, we can observe the nucleation and line of the defect from surface inhomogeneity and the experiment is performed for confirmation. The experimental result is compared with numerical modeling in order to verify the simulation of the defect nucleation.

• Journal of the Korean Chemical Society
• /
• v.9 no.2
• /
• pp.110-112
• /
• 1965

The surface tension of liquid iodine was measured by differential capillary rise method at various temperatures above the melting point. A paraffin bath with mercury regulator was used to maintain constant temperature. The height of the meniscus of liquid iodine in the capillary tube was measured by a travelling microscope. The measured values of surface tensions at $125.0^{\circ},135.0^{\circ}, 145.0^{\circ}$ and $155.0^{\circ}$ were 36.88, 35.87, 34.83 and 34.04 dyne/cm, respectively. Calculated Eotvos constant from the surface tension, data. experimentally obtained, were consistent through the temperature range.

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

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

• Coupled systems mechanics
• /
• v.6 no.2
• /
• pp.189-206
• /
• 2017

Tanks are used to store a wide variety of liquids such as oil, gasoline and water. It is reported that, a large number of tanks have been damaged during severe earthquakes. Therefore, understanding their behavior under earthquake is an important subject for structural engineers. In this paper, a comprehensive study is presented on dynamic response of tanks. A parametric study has been completed on the rectangular storage tanks with aid of finite element method (FEM). Various parameters are investigated, such as; liquid height, density and earthquake with different peak ground acceleration (PGA). When investigating these parameters, modal and time history method is used. Six different earthquake records are used for time history analysis. The analysis results show that when the PGA increases by 10.7 times, the maximum displacements, stress, sloshing and base shear increase by 11.4, 22.6, 5.46 and 17.8 times, respectively and when the liquid height increases by two times, the absolute maximum values of stress, displacements, base shear and sloshing increase 1.65, 2.04, 2.05 and 1.34. Furthermore, values of sloshing increase with decrease in density.

• Proceedings of the KSME Conference
• /
• 2001.11b
• /
• pp.124-130
• /
• 2001

The heat transfer and flow measurements were made on a cylindrical pedestal mounted on a flat plate with a turbulent impinging air jet. The heat transfer coefficient distributions on the flat plate were measured using the shroud-transient technique and liquid crystal was used to measure the surface temperature. The jet Reynolds number (Re) is 23,000, the dimensionless nozzle-to-surface distance (L/d) from 2 to 10, the dimensionless pedestal diameter-to-height (H/D) from 0 to 1.5, the dimensionless 2nd pedestal diameter-to-height ($H/D_2$) from 0 to 0.4 and the distance from the stagnation point to 2nd pedestal (p/D). The results show that for H/D = 0.5 to 1.5, the Nusselt number distributions on the plate surface exhibit a maximum between $r/d\;{\cong}\;1.0$ and 1.5. The presence of the pedestal appears to cause the flow separation and reattachment on the plate surface, which results in the maximum heal transfer coefficient. Also, for p/D = 2.5 and $H/D_2$ = 0.3, the local Nusselt number in the region corresponding to $r/d\;{\cong}\;1.1$ was increased up to 50% compared to that for $H/D_2=0$.

• Fire Science and Engineering
• /
• v.18 no.3
• /
• pp.39-44
• /
• 2004

This study is intended to understand flame behavior of the pool fire. Liquid fuels were acetone, methanol, hexane and heptane which are used in many industries. Diameter of vessel was varied from 50 mm to 400 mm and the vessel was made by stainless steel and copper. Combustion time, temperature of vessel wall and heat flux of flame were measured, and flame behavior was visualized with video camera. Based on the experiment, it was found that the burning velocity and flame height was increased according to increase of vessel diameter, and vortex shedding frequency was inverse proportion to vessel diameter. And the characteristics of pool fire were affected by physical and chemical properties of liquid fuel and the vessel materials.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2008.03a
• /
• pp.39-44
• /
• 2008

In this paper, heat transfer coefficients were measured in a channel with one side dimpled surface. The sphere type dimples were fabricated and the diameter and depth of dimple was 16mm and 4mm, respectively. Two channel heights of about 0.6 and 1.2 time of the dimple diameter, two dimple configuration were tested. The Reynolds numbers based on the channel hydraulic diameter was varied from 30000 to 50000. The improved hue detection based transient liquid crystal technique was used in the heat transfer measurement. Heat transfer measurement results showed that high heat transfer was induced downstream of dimples due to flow reattachment. Due to the flow recirculation on the upstream side in the dimple, the heat transfer coefficient was very low. As the Reynolds increased, the overall heat transfer coefficients also increased. With same dimple arrangement, the heat transfer coefficients and the thermal performance factor were higher for the lower channel height. As the distance between dimples became smaller, the overall heat transfer coefficient and the thermal performance factor were increased.

• Nuclear Engineering and Technology
• /
• v.52 no.6
• /
• pp.1164-1171
• /
• 2020

T-junction structures play an important role in nuclear power plant systems. Research on liquid entrainment is mostly based on small-scale branch pipes (d/D ≤ 0.2) and attention paid to large-scale branch pipes (0.33 < d/D < 1) is insufficient. Accordingly, this study implements a series of experiments on the liquid entrainment of T-junction with different angles (32.2°,47.9°,62.3°,90°) through a large-scale branch (d/D = 0.675). The onset liquid entrainment is related to the gas phase Froude number Fr_g, the dimensionless gas chamber height h_b/d and the branch pipe angle 𝜃. As Fr_g increases, h_b/d also rises. With a constant h_b/d, the onset liquid entrainment changes from droplets entrainment by the gas phase to that by the rising liquid film. The steady-state liquid entrainment is related to w_3g, h/d and 𝜃. With constant w_3g and h/d, the branch quality grows as the branch angle increases. With a certain h/d, the branch quality increases, as the w_3g number increases.

• Journal of The Korean Society of Grassland and Forage Science
• /
• v.19 no.2
• /
• pp.121-126
• /
• 1999

Manure management is a top priority on both dairy and swine farrns at present. This experiment was carried out to determine the effect of different types and N rates of liquid manure on forage yield and quality of oats(Avena sativa L.) in Suweon, 1997. Seven treatments consisting of chemical fertilizer $120kg\;N\;ha^{-1}$, liquid cattle manure 120, 240 and $360kg\;N\;ha^{-1}$, and liquid swine manure 120, 240 and $360kg\;N\;ha^{-1}$ were arranged in a randomized complete block design with three replications. As increasing N rate of the liquid manure, the plant height was increased, but dry matter content of oats was decreased as increasing liquid manure N rate. There were significant differences in dry matter yield of oats among the liquid manure N rates(P<0.05). Crude protein(CP) content of oats ranged from 14.7 to 24.1% (P<0.05), and CP yield was orderly ranked as liquid swine manure $360kg\;N\;ha^{-1}$>liquid cattle manure $360kg\;N\;ha^{-1}$>liquid swine manure $240kg\;N\;ha^{-1}$(P<0.05). Acid detergent fiber(ADF) content of the liquid cattle manure treatment showed a slightly higher than that of the liquid swine manure treatment(P<0.05). Neutral detergent fiber(NDF) content of the liquid cattle manure treatment was lower than that of the liquid swine manure treatment(P<0.05). Relative feed value(RFV) of the liquid cattle manure treatment decreased with increasing liquid manure N rates compared with that of the liquid swine manure treatment. Based on the results of this experiment, it is indicates that to increase the N rates from liquid manure application could be obtained from the increase of forage yield.