• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2004.04a
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• pp.504-507
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• 2004

Previous studies on the liquid Gallium ion sources used an electro-chemically etched tungsten wire with a coil-type heater. Such a structure requires excessive power consumption in the course of heating the liquid metal. In this work, a new structure is proposed that replaces the coil-type heater. It uses a Gallium reservoir made of six pre-etched 250 $\mu\textrm{m}$ tungsten wires that surround the needle electrode. Gallium loading at the reservoir is observed to be much more stable, resulting in an improved beam stability.

• 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.

• 한국정보디스플레이학회:학술대회논문집
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• 2003.07a
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• pp.595-599
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• 2003

We have studied the phase transition to look for molecular structure by using several different techniques for new banana-shaped liquid crystals shown in Fig. 1. Based on the similarities to recently observed fluro-contaning materials (switching involves layer structure rearrangement, increasing threshold with increasing temperature) for HC sample (where x is H), we assume that the phase C has a triclinic symmetry corresponding to the double tilted $smC_G$ Phase. The observation that the polarization peak appears at lower field ($E_o{\sim}15V/{\mu}m$) than the amplitude of the threshold ($E_{th}$) can be explained assuming a field induced $SmC_G$ - SmCP (or SmAP) transition at $E_{th}$

• Journal of ILASS-Korea
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• v.2 no.4
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• pp.22-28
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• 1997

In this paper an experimental study of a spray created by two impinging jets is presented utilizing a novel two-reference-beam double-pulse holographic technique. Visualization of the overall spray pattern as well as measurements on the size and velocity of the droplets were performed with the special emphasis on the effect of physical properties of liquids. The overall spray pattern clearly revealed the inherent wave nature In the disintegration process of this type of atomization. The structure of liquid elements near the impingement point is indicative of the mechanisms of the disintegration process. Surface tension plays an important role in the droplet size without any noticeable effect on the spray pattern, whereas viscosity affects the structure without any significant effect on the droplet sire. The droplet velocities were not affected by liquid properties.

• Proceedings of the KIEE Conference
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• 2002.07c
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• pp.1933-1935
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• 2002

In this paper, we present a study of the structure and electro-optic behavior of hybrid liquid-crystal-silica sphere composite photonic crystals, formed by filling the (26% by volume) void space of fee (face centered cubic) silica opals infiltrated with a nematic liquid crystal. Three dimensional photonic crystals of visible range were fabricated via a self assembly method of silica spheres of submicron diameter. The expected fee structure was confirmed by scanning electron microscopy (SEM) of the dehydrated crystal with glass removed. The photonic crystal exhibited significant electric-field-induced shift of the optical Bragg reflection peak when the liquid crystal has the long molecular axis oriented parallel to the sphere surfaces.

• Journal of the Korean Society of Safety
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• v.19 no.3 s.67
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• pp.108-117
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• 2004

Dynamic analysis method is Presented for analyzing rectangular liquid storage structures excited by horizontal and vertical ground motions. The irrotational motion of invicid and incompressible ideal fluid in rigid rectangular liquid storage structures subjected to horizontal and vertical ground motions and the motion of fluid induced by structural deformation are expressed by analytic solutions. Analysis methods are obtained by applying analytic solutions of the fluid motion to finite element equation of the structural motion. The fluid-structure interaction effect is reflected into the coupled equation as added fluid mass matrix. The free surface sloshing motion, hydrodynamic pressure acting on the wall and structural behavior due to horizontal and vertical ground motions are obtained by the presented method.

• Journal of ILASS-Korea
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• v.15 no.4
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• pp.182-188
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• 2010

Significant real fluid behaviors including rapid property changes take place where high pressure combustion devices such as rocket engines. The flamelet model is the reliable approach to account for the real fluid effects. In the present study, the flamelet equations are extended to treat the general fluids over transcritical and supercritical states. The real fluid flamelet model is carried out for the gaseous hydrogen and cryogenic liquid oxygen flames at the wide range of thermodynamic conditions. Based on numerical results, the precise discussions are made for effects of real fluid, pressure, and differential diffusion on the local flame structure.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 1997.04a
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• pp.115-127
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• 1997

A study to evaluate the seismic response of $\frac{1}{2}$-scaled liquid storage tank constructed in Hualien, is performed. And this study is to identify the liquid-structure-soil interaction by observed earthquake data ans analyzed results. After the calculation of soil impedance for the test site by SASSI code, 3-dimensional seismic response analysis is performed by BEM-FEM-Impedance Method with the consideration of liquid-structure-soil interaction when the tank is excited by real earthquake. The observed acceleration and hydrodynamic pressure are compared with the numerical results. This comparisons show good agreement in predominant frequency and maximum hydrodynamic pressure. And the free surface sloshing motion due to earthquake loadings is computed in time domain.

• Proceedings of the KSME Conference
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• 2000.04a
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• pp.602-607
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• 2000

Fuel-storage tank is a representative example of liquid-structure interaction systems. In order to prevent the undesired structural failure by a variety of external loads, the reliable analysis of the dynamic response of such structural system is of a great importance. In this paper, we address the analytical study on free vibration of axisymmetric cylindrical fuel-storage tanks together with the parametric investigation of eigen-characteristics with respect to the relative fuel fill-height and the relative tank height. Numerical results illustrating theoretical results are also included.

• Current Optics and Photonics
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• v.7 no.1
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• pp.83-89
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• 2023

This study reports a structure, based on a liquid-crystal (LC) core optical waveguide, for the switchable spatial control of linearly polarized light. The refractive indices of both left and right isotropic claddings in the waveguide are between the two principal-axis indices of the nematic liquid crystal (NLC). Numerical simulations demonstrate that the proposed structure can be operated in transmission mode or as an attenuator by controlling the on and off states of the applied voltage, whether the initial excitation is transverse electric (TE) linearly polarized light or transverse magnetic (TM) linearly polarized light. The design can also be used as an integrated optical polarizer, since only one type of linearly polarized light is always permitted to pass through the core zone of the NLC optical waveguide.