• Proceedings of the IEEK Conference
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• 1999.11a
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• pp.55-58
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• 1999

For the asymmetric digital subscriber line communications, the paper proposes a new echo canceller with the so-called CALAOI(CAscade of LAttice and Orthogonalized IIR) structure, which comprises of a lattice and an orthogonalized IIR structure. Through simulations, the CALAOI echo canceller was verified to have much fewer complexity of computations and has faster convergence speed than conventional FIR echo canceller. The CALAOI echo canceller is predicted to maximize performances of communication services in high speed communications such as VDSL, GIGA bit Ethernet, and so on as well as ADSL.

• Journal of the Korean Society of Combustion
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• v.8 no.3
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• pp.24-30
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• 2003

A convolution algorithm combined with Fourier transformation has been applied to the tomographic reconstruction of asymmetric soot structure to identify the local soot volume fraction distribution. Line-of-sight integrated data from light extinction measurement with multi-angular scanning formed basic information for the deconvolution. Multi-peak following interpolation technique was applied to obtain the effect of increasing number of scanning angles. Height-by-height reconstructed soot volume fraction distribution was compared with laser-induced incandescence signals.

• Transactions of the Korean Society of Automotive Engineers
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• v.4 no.1
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• pp.177-186
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• 1996

A convolution alogorithm combined with Fourier transformation is applied to the tomographic reconstruction of the asymmetric spray structure to identify the local drop size and volume concentration. The line of sight intergrated data from Malvern particle analyzer with multiangular scanning form a basic information for the deconvolution. Linear interpolation is tested to obtain the effect of increasing number of scanning angles. This transformation method predicts well the structure of asymmetric spray. The tehnique can be extended to other line of sight combustion diagnostics.

• 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.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.10 no.2
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• pp.124-129
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• 2011

The thick plate produced by rolling process is used as the basic members of a ship structure. In this paper, we present a setup model to control the asymmetric factors causing plate bending in the upper or lower direction during rolling. A series of finite element analysis are conducted to predict the relationship between various asymmetric factors and plate bending. The setup model is developed by regressing the relationship to the linear equations with several non-dimensional parameters. The setup model is verified by a pilot rolling test and applied to actual rolling conditions. Results show that the model is substantial to predict the asymmetric deformation in the plate rolling process.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.6
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• pp.599-605
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• 2003

A dual-mode asymmetric canonical filter is widely used in an input demultiplexer for satellite transponder. This paper deals with a simple synthesis method fur an asymmetric canonical filter. The coupling matrix of an asymmetric canonical filter is obtained by applying plane rotation technique to the coupling matrix of a symmetric canonical filter. This paper gives a list of pivots and rotation angles to obtain the coupling matrix of asymmetric canonical structure filters. The coupling matrix of 8th and 10th order asymmetric canonical filter is obtained by this proposed method. It is shown that the frequency response of asymmetric canonical filter is identical to that of symmetric canonical filter.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.8
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• pp.87-95
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• 2001

Although asymmetric beams are widely used in industry, few research results are available on the dynamic modeling and analysis of structure including asymmetric beams. Asymmetric beams cause complicated vibration phenomena due to the inherent bending-torsion coupled vibration. In this paper, an exact dynamic element matrix for the bending-torsion coupled vibration of asymmetric beam is derived. The application of the derived exact dynamic element matrix is demonstrated by some illustrative examples wherein the natural frequencies by the proposed modeling method are compared with those available in the literature. Another numerical example is also illustrated which deals with a general beam with joints. The numerical study shows that the exact dynamic element model is useful for the dynamic analysis of asymmetric bending-torsion coupled beams.

• Journal of the Korea Institute of Military Science and Technology
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• v.16 no.5
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• pp.607-612
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• 2013

The effect of the flow actuator on the asymmetric vortex structure around the ogive-cylinder body with fineness ratio of 4 flying at the speed of Mach 0.1 at angle of attack of 50 degree is studied. The ogive-cylinder model is developed with the actuator placed near the nose tip and numerically simulated using the in-house CFD code named KFLOW. The numerical simulation employs two different actuator modeling: one is the boundary condition given by blowing normal to the surface and another shearing on the surface. The numerical simulation reveals that response of the vortex structure to the actuation is dependent on the type of modeling as well as the strength and direction of the actuation.

• Proceedings of the Membrane Society of Korea Conference
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• 1995.09a
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• pp.73-85
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• 1995

The asymmetric hollow fiber membranes were prepared by the wet spining of polyetherimide dope solution and the effect of hollow fiber structures on the permeation characteristics of carbon dioxide and nitrogen gases through these membrane were investigated. As the concentration of the $\gamma$-butyrolactone (GBL) in dope solution, acting as a swelling agent was increased, the structure of hollow fiber was changed from the finger to sponge type. The permeabilities of gases (CO$_{2}$, N$_{2}$) through these membrane were measured over the wide range of pressure under different temperature. The effect of water vapor on the permeabilities of gases was also investigated. The measured permeabilities showed the different characteristics depending on the structure of membranes. It was found that the flow through the pores were dominant over the polymers matrix. Blocking effect by water vapor in the pores of skin layer greatly improved the ideal separation factor of carbon dioxide/nitrogen.

• Korean Membrane Journal
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• v.10 no.1
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• pp.1-7
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• 2008

Polystyrene-co-divinylbenzene (PS-co-DVB) asymmetric membranes were prepared. In order to control their structure and mechanical properties the degree of cross-linking and the composition of casting solution were varied. The rubber added PS-DVB membranes was also prepared to overcome the mechanical limitation of cross-linked membrane, and their mechanical properties were investigated. It was revealed that the concentration of polymer in the casting solution affected the determination of skin formation. When the PS-co-DVB membrane consists of styrene-butadiene (SB) rubber or liquid polybutadiene (PBD), the structures formed showed that the PS content in the PS/DVB system played an important role in determining the porous sublayer structure.