• Journal of the Semiconductor & Display Technology
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• v.3 no.3
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• pp.37-40
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• 2004

This study presents numerical solutions of three-dimensional laminar flow-field formed by photo resist flow in a slit-coater model. We discuss on the governing equations, laminar viscosities and the computational model applied in our numerical calculation and some results. We prove that the structure of tapered-cavity aid to make uniform pressure-field and boundary effect is an important problem to improve coating uniformity. In view of uniformity improvement, it is necessary to study for the structure of cavity and flow path.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.7
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• pp.647-651
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• 2005

We studied the external pressure-stable advanced frnge field switching (FFS) pixel design with 3 slit sructue. In this mode, a patterned pixel slit is partitioned into 3 areas, namely, two edges and a center, where the edge slit angle is larger than the center slit angle. Thus the reverse twist region in the pixel edge is reduced comparing to the conventional FFS mode so that the LC dynamics in this region becomes very stable. And also, when the external pressure is applied to the panel at the high voltage, the disclination lines (DLs) were barely intruded into active area. Therefore, the structure is use for the pen based system such as the tablet personal computer (PC), personal digital asistant (PDA).

• Journal of electromagnetic engineering and science
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• v.10 no.3
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• pp.127-131
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• 2010

In this paper, the problem of electromagnetic transmission via slits in a cavity inside a conducting screen of finite thickness has been considered in the case that the transverse electric(to the slit axis) polarized plane wave is incident on a slit. The problem is solved numerically by the method of moments and the results are compared with those obtained from an equivalent circuit suitable for a case in which the slit width is infinite and the structure is modified to the two partially overlapped conducting planes. It is observed that when the cavity is resonated, the effective slit width reaches its maximum value of $1/\pi$ wavelengths, irrespective of the actual slit width and the incidence angle. When the thickness of the conducting plane is much smaller than the wavelength, the numerical results for the effective slit width(or transmission width) agree well with those obtained from the equivalent circuit, even though the slit is as narrow as the thickness of the conducting plane.

• Journal of Ocean Engineering and Technology
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• v.24 no.1
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• pp.60-67
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• 2010

Recently, there has been an increase in the construction of various types of coastal structures for efficient wave dissipation, seawater exchange, and so on. Among these, a perforated slit caisson has been widely used to reduce the reflected wave energy and the wave pressure on the structure. Therefore, many studies on the wave force on a caisson, as well as the wave reflection from it, have been carried out with laboratory experiments and numerical analyses, considering it as a 2-D problem. However, because a structure like a perforated slit caisson has a variable 3-D shape, waves forces should be considered as a 3-D problem. Therefore, in this paper, a fully-nonlinear 3-D numerical model (LES-WASS-3D) is proposed to examine the reflection characteristics of a perforated slit caisson with two chambers. The numerical model, LES-WASS-3D, was verified in a 3-D wave field by a comparison with existing experimental data for wave reflection coefficients. Then, using the numerical results, the reflection from a perforated slit caisson with two chambers was examined in relation to wave steepness, chamber width, and the shape/porosity of perforated slit.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.3
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• pp.296-302
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• 2009

In this paper, a planar microstrip patch antenna is proposed using the slit on the top layer of a multi-layered structure for GPS application. The proposed antenna has a circular polarization at 1,575.42 MHz. This proposed antenna is fabricated on multi-layered FR4 substrate. The slits embedded on the top plane may yield to lower a resonance frequency and sustain a broad bandwidth. The proposed antenna size is $20{\times}20{\times}4.0\;mm^3$. The measured gain of 0.5 dBi, 10 dB bandwidth(VSWR 2:1) of 70 MHz(4.4 %), and 3 dB axial-ratio bandwidth of 15 MHz(1 %) have been obtained, respectively.

• Journal of Ocean Engineering and Technology
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• v.28 no.3
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• pp.227-235
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• 2014

Using a 3-D numerical scheme (LES-WASS-3D) that considered wave-structure-sandy seabed interactions in a 3-D wave field, we analyzed the wave reflection and hydraulic characteristics inside a slit caisson with two chambers in a 3-D oblique wave field. To verify the 3-D numerical analysis method suggested in this study, we compared the numerical results with existing experimental results and found good agreement. The numerical analysis revealed that a standing wave field is generated on the front side of the slit caisson due to the effect of wave reflection. For incident waves propagating perpendicular to the slit caisson, the nodes and anti-nodes of the standing wave are apparent and symmetrical. However, in an oblique wave field, as the incident wave angle decreases, the nodes and anti-nodes of the standing wave become ambiguous and unsymmetrical. It was also found that the wave reflection coefficient decreases as the incident wave angle decreases. It can be pointed out that as the incident wave angle decreases, the turbulent intensity in the chamber increases. Thereby, the increased wave energy dissipation by the increased turbulent intensity reduces the rate of wave reflection. In addition, a strong turbulent intensity generally occurs in the first chamber.

• Journal of the Korean Society for Precision Engineering
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• v.32 no.6
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• pp.537-542
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• 2015

The measurement of 3D shape is important in inspecting the quality of product. In this paper, we present a 3D shape measurement system of fastener using a camera and a slit laser. Calibration structure with slits is used in the extrinsic calibration of the camera and laser. The pose of the camera and laser is computed under the same world coordinate system in the calibration structure. Reflection of laser light on the metal surface causes many difficulties in the robust detection of them on image. We overcome this difficulty by using color and dynamic programming. Motor stage is used to rotate the fastener to recover the whole 3D shape of the surface of it.

• Structural Engineering and Mechanics
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• v.81 no.6
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• pp.677-689
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• 2022

Generally, the goal of seismic retrofit design of an existing structure using energy dissipation devices is to determine the optimum design parameters of a retrofit device to satisfy a specified limit state with minimum cost. However, the presence of multiple parameters to be optimized and the computational complexity of performing non-linear analysis make it difficult to find the optimal design parameters in the realistic 3D structure. In this study, genetic algorithm-based optimal seismic retrofit methods for determining the required number, yield strength, and location of steel slit dampers are proposed to retrofit an asymmetric soft first-story structure. These methods use a multi-objective and single-objective evolutionary algorithms, each of which varies in computational complexity and incorporates nonlinear time-history analysis to determine seismic performance. Pareto-optimal solutions of the multi-objective optimization are found using a non-dominated sorting genetic algorithm (NSGA-II). It is demonstrated that the developed multi-objective optimization methods can determine the optimum number, yield strength, and location of dampers that satisfy the given limit state of a three-dimensional asymmetric soft first-story structure. It is also shown that the single-objective distribution method based on minimizing plan-wise stiffness eccentricity turns out to produce similar number of dampers in optimum locations without time consuming nonlinear dynamic analysis.

• Proceeding of KASS Symposium
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• 2008.05a
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• pp.145-150
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• 2008

The purpose of this study is to propose damper system which is easy to design, which can ensure against risks, and to verify earthquake response characteristics. For this study, the pseudo dynamic earthquake response tests carried out for steel frames with two types of seismic and vibration control device. As a result, in case of using the slit plate damper as a vibration control device proposed by this study, the damper having higher stiffness than main-structure turned to the state of plasticity by little displacement has been proved to be able to absorb earthquake energy.

• 한국초전도학회:학술대회논문집
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• v.9
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• pp.91-94
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• 1999

A new type of high-T$_c$ superconducting Josephson junctions has been prepared by Ar ion beam etching and electron beam lithography. YBa$_2Cu_3O_{7-x}$ (YBCO) films deposited on (001) SrTiO$_3$ single crystal substrate by pulsed laser deposition were patterned by Ar ion milling with photolithography. The narrow slit with a electroresist mask, about 1000 ${\AA}$ wide, was constructed over a 3 ${\sim}$ 5 ${\mu}$m bridge of a 1200-${\AA}$-thick YBCO film by electron beam lithography. The slit was then etched by the Ar ion beam to form a damaged 600-${\AA}$-thick YBCO. Thus prepared structure forms an S-N-S (YBCO - damaged YBCO - YBCO) type Josephson junctions. Those junctions exhibit RSI-like I-V characteristics at 77 K. The properties of the Josephson junctions such as I$_c$ R$_N$, and J$_c$ were characterized.