• 한국가시화정보학회:학술대회논문집
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• 2002.11a
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• pp.11-14
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• 2002

A new high-definition stereoscopic PTV was constructed using two CCD cameras, stereoscopic photogrammetry based on a 30-PTV principle. The arrangement of the two cameras was based on angular position. The calibration of cameras and the pair-matching of the three-dimensional velocity vectors were based on Genetic Algorithm based 30-PTV technique. The constructed Stereoscopic PTV technique was tested on the standard images of the Impinging jet proposed by VSJ. The results on the turbulent properties of the jet obtained by the constructed system showed a good agreement with the original LES data.

• Kyungpook Mathematical Journal
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• v.61 no.2
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• pp.323-351
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• 2021

The present paper addresses magnetohydrodynamic pulsating flow and heat transfer of two immiscible, incompressible, and conducting couple stress fluids between two permeable beds. The flow between the permeable beds is assumed to be governed by Stokes' [28] couple stress fluid flow equations, whereas the dynamics of permeable beds is determined by Darcy's law. In this study, matching conditions were used at the fluid-fluid interface, whereas the B-J slip boundary condition was employed at the fluid-porous interface. The governing equations were solved analytically, and the expressions for velocity, temperature, mass flux, skin friction, and rate of heat transfer were obtained. The analytical expressions were numerically evaluated, and the results are presented through graphs and tables.

• KIEE International Transactions on Electrophysics and Applications
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• v.11C no.4
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• pp.150-154
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• 2001

In this paper, we presented a novel structure of microstrip directional coupler for realizing the high directivity characteristic and tight coupling. The achievement of the high directivity with microstrip configuration was carried out by matching the even and odd mode effective phase velocities. By using 2-dimensional finite element (FE) calculations, the phase velocity for each mode and design parameters were extracted for given dimensions. Based on the extracted design parameter with phase-matched condition, we designed and fabricated 3dB and 4.7dB directional coupler at 2.0GHz. Experimental results of microstrip coupler show good performance with excellent isolation characteristics.

• The Journal of Korea Robotics Society
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• v.18 no.3
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• pp.260-270
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• 2023

We introduce a novel Visual Inertial Odometry (VIO) algorithm designed to improve the performance of thermal-inertial odometry. Thermal infrared image, though advantageous for feature extraction in low-light conditions, typically suffers from a high noise level and significant information loss during the 8-bit conversion. Our algorithm overcomes these limitations by approximating a 14-bit raw pixel histogram into a Gaussian mixture model. The conversion method effectively emphasizes image regions where texture for visual tracking is abundant while reduces unnecessary background information. We incorporate the robust learning-based feature extraction and matching methods, SuperPoint and SuperGlue, and zero velocity detection module to further reduce the uncertainty of visual odometry. Tested across various datasets, the proposed algorithm shows improved performance compared to other state-of-the-art VIO algorithms, paving the way for robust thermal-inertial odometry.

• Journal of Electrical Engineering and information Science
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• v.1 no.2
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• pp.96-100
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• 1996

This paper describes a concrete method for computing characteristic impedances and effective dielectric constants of the microstrip coupled lines without and with a dielectric overlay. The frequency-independent spectral domain method is used for the analysis of these lines. This method is a powerful, accurate, and numerically efficient approach for planar transmission line structure. For designing the optimal directional coupler, the velocities of even and odd mode must be equal but velocities of these two modes are different in the conventional coupled line which is inhomogeneous. The results show that these two velocities can be almost same according to variations of structural and material parameters in terms of the overlay(superstrate).

• Korean Journal of Remote Sensing
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• v.29 no.1
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• pp.45-55
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• 2013

Campbell Glacier in East Antarctica is one of the major glaciers that flow into Terra Nova Bay. It is necessary to estimate accurate extent and flow velocity of Campbell Glacier which influences the dynamics of mass balance of East Antarctic Ice Sheet. However, few studies on Campbell Glacier have been performed since 1990s. In this study, we obtained a total of 59 COSMO-SkyMed SAR images over Campbell Glacier from June 2010 to January 2012. We estimated variations in the extent of Campbell Glacier Tongue and flow velocity of Campbell Glacier by applying the image digitizing and the offset tracking by image matching. Although the extent of Campbell Glacier Tongue decreased in summertime due to ice calving and increased in wintertime, the variation in the extent was very small. Campbell Glacier Tongue retained mean extent of 75.5 $km^2$. The ice discharge of Campbell Glacier Tongue was estimated to be $0.58{\pm}0.12km^3/yr$, which was bigger than in 1989. The flow velocity over Campbell Glacier Tongue was estimated to be from 181 to 268 m/yr that was faster than in 1988-1989, which contributed to the increase in the ice discharge of the glacier.

• Journal of Korea Water Resources Association
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• v.38 no.10 s.159
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• pp.841-849
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• 2005

Two-phase flows, e.g. sediment-laden flow and bubbly flow, have two different flow profiles; flow velocity and sediment velocity. To measure velocity distributions of two-phase flows, it is necessary to use sophisticated instruments which can separate velocity profiles of two-phases. For bubbly flows, PIV (Particle Image Velocimetry) or PTV (Particle Tracking Velocimetry) has given fairly good velocity profiles of two-phases. However, for sediment-laden flows, the applications of PIV or PTV has not been so successful, because the sediment particles introduced to the flow kept the images from being analyzed. A new algorithm, which consists of several image analysis methods, is proposed to analyze sediment-laden flows. For detection algorithm, threshold method, edge detection method, and thinning method are adapted, and for finding matching pair PIV and PTV routines are combined. The proposed method can (1) detect sediment particles with irregular boundaries, (2) remove reflected images and scattered images, and (3) discriminate tracer particles from reflected images of sediment particles.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.10
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• pp.966-980
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• 2011

Radar receiving echo signal provides target information - range, velocity and position by signal magnitude and Doppler shift, which are determined by target reflection characteristics and target maneuver. Target angle error is extracted from the magnitude ratio of difference channel to sum channel. In this paper, we introduce a radar Return Signal Simulation Equipment(RSSE) which is implemented for the purpose of performance analysis and evaluation of phased array multi-function radar(MFR). It generates multi-target environment with jamming signals using MC-DDS (Multi-Channel Direct Digital Synthesis), and has scalability by using the efficient hardware configuration. The performance of the developed RSSE has been evaluated under various test environments. Especially, we proved that required target detection performance is achieved by RSP(Radar Signal Processor) interfaced RSSE configuration.

• Journal of Energy Engineering
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• v.12 no.4
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• pp.320-327
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• 2003

A CFD (Computational fluid Dynamics) research is conducted for the investigation of the fuel alteration of MBTU (medium-Btu) gas in IGCC gas turbine combustor. The computational analysis method of the gas turbine combustor is constructed by incorporating MBTU gas reaction and fuel NOx models into commercial CFD code. With the use of the present analysis method, comparisons are made on the flow velocity, the chemical species and the temperature distributions, and on the flame shape and behavior of gas turbine combustor firing natural gas and MBTU gases (coal gas, heavy residue oil gas). Furthermore, the NOx formation characteristics and the turbine matching condition of the combustor are analyzed. Based on the computed analysis results, the present study provides the directions for the redesign and the design modification of IGCC gas turbine combustor firing MBTU gas as alternative fuel.

• Journal of the Institute of Convergence Signal Processing
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• v.8 no.1
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• pp.15-21
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• 2007

We propose a 3D modeling method for surface inspection of non-constant velocity moving object. 1'lie laser lines reflect tile surface curvature. We can acquire 3D surface information by analyzing projected laser lines on object. In this paper, we use multi-line laser to improve the single stripe method and high speed of single frame. Binarization and edge extraction of frame image were proposed for robust laser each line extraction. A new labeling method was used for laser line labeling. We acquired some feature points for image matching from the frame data and juxtaposed the frames data to obtain a 3D shape image. We verified the superiority of proposed method by applying it to inspect container's damages.