• Journal of the Institute of Convergence Signal Processing
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• v.3 no.3
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• pp.6-13
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• 2002

In this paper, we propose an image processing based method to measure red-time and green-time backward moving shockwave speed automatically at signalized intersections. Shockwave means the discontinuous boundary line between different vehicle traffic flows, and its moving speed is called shockwave speed which is obtain from the slope of boundary line. In this paper, we compose distance-time diagram for measuring shockwave speed automatically. By global vehicle tracking, we draw all of the vehicle moving path on distance-time diagram. We analyze the slope change pattern of curved moving path line, and compute red-time and green-time backward moving shockwave speed. We obtain the measurement result of shockwave speed, when applying above mentioned proposed method to experiment at signalized intersections, Once we can measure the shockwave speed, we could apply the result to highway ramp metering and automatic signal control at intersections effectively since we know the situation of frontal congestion easily.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.12C
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• pp.1138-1146
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• 2009

Digital cameras adopting a single CCD detector collect image color by subsampling in three color planes and successively interpolating the information to reconstruct full-resolution color images. Therefore, to recovery of a full-resolution color image from a color filter array (CFA) like the Bayer pattern is generally considered as an interpolation issue for the unknown color components. In this paper, we first calculate luminance component value by combining R, G, B channel component information which is quite different from the conventional demosaicing algorithm. Because conventional system calculates G channel component followed by computing R and B channel components. Integrating the obtained gradient edge information and the improved weighting function in luminance component, a new edge sensitive demosaicing technique is presented. Based on 24 well known testing images, simulation results proved that our presented high-quality demosaicing technique shows the best image quality performance when compared with several recently presented techniques.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.41 no.6
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• pp.373-380
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• 2017

In this study, we conducted computational fluid dynamics (CFD) simulations for the unsteady hydrodynamic interaction of multiple thrusters by solving Reynolds averaged Navier-Stokes equations. A commercial CFD software, STAR-CCM+ was used for all simulations by employing a ducted thruster model with combination of a propeller and No. 19a duct. A sliding mesh technique was used to treat dynamic motion of propeller rotation and non-conformal hexahedral grid system was considered. Four different combinations in tilting and azimuth angles of the thrusters were considered to investigate the effects on the propulsion performance. We could find that thruster-hull and thruster-thruster interactions has significant effect on propulsion performance and further study will be required for the optimal configurations with the best tilting and relative azimuth angle between thrusters.

• Journal of KIISE:Software and Applications
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• v.37 no.8
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• pp.629-640
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• 2010

The exemplar-based inpainting model is widely used to remove objects from natural images and to restore a damaged region. This paper presents a method which improves the performance of the conventional exemplar-based inpainting model by modifying three major parts in the model: data term, confidence term and patch selection. While the conventional data term is calculated using the local gradient, the proposed method uses 16 compass masks to get the global gradient to make the method robust to noise. To overcome the problem that the confidence term gets negligible in the inside of the eliminated region, a method is proposed which makes the confidence term decrease slowly in the eliminated region. The patch selection procedure is modified so that the closer patch has higher weight. Experiments showed that the proposed method produced more natural images and lower reconstruction error than the conventional exemplar-based inpainting.

• The KIPS Transactions:PartC
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• v.17C no.3
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• pp.259-270
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• 2010

In this paper, a Location Information-based Gradient Routing (LIGR) algorithm is proposed for setting up routing path based on physical location information of sensor nodes in wireless ad-hoc networks. LIGR algorithm reduces the unnecessary data transmission time, route search time, and propagation delay time of packet by determining the transmission direction and search range through the gradient from the source node to sink node using the physical location information. In addition, the low battery nodes are supposed to have the second or third priority in case of forwarding node selection, which reduces the possibility of selecting the low battery nodes. As a result, the low battery node functions as host node rather than router in the wireless sensor networks. The LIGR protocol performed better than the Logical Grid Routing (LGR) protocol in the average receiving rate, delay time, the average residual energy, and the network processing ratio.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.8
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• pp.881-886
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• 2014

The purpose of three-dimensional (3-D) metal printing using 5-axis is to deposit metal powder by changing the orientation of the deposited structure to be built for the overhang or undercut feature on part geometry. This requires a complicated preprocess functionality of providing three dimensionally sliced layers to cover the required part geometry. This study addresses the overhang/undercut problem in 3-D metal printing and discusses a possible solution of providing 3-D layers to be built using the DMT(R) machine.

• Journal of the Korean Association of Geographic Information Studies
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• v.21 no.1
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• pp.106-114
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• 2018

DEM(Digital Elevation Model) are now easily produced with advancing remote sensing technology. Depending on desired task, UAV can produce high resolution DEM. But high resolution comes with issues of data storage and processing time and cost. To check the effect of DEM resolution, this study compares six geomorphological parameters derived from different resolution DEM in a test area around Chuncheon, Korea. The comparison analysis was based on statistics of each derivatives of slope, curvature, flow direction, flow accumulation, flow length and basin. As a result, it was found that DEM remained unchanged and so did the flow accumulation area. However, slope, curvature, flow length and basin numbers were decreased with the normalization of increasing pixel size. DEM resolution should be carefully selected depending on the precision of application required.

• Journal of the Korean Magnetics Society
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• v.7 no.5
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• pp.225-231
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• 1997

Sulphur Spinel $Co_{0.95}Fe_{0.05}Cr_2S_4$ has been studied with Mossbauer Spectroscopy between 4.2 K and room temperature. The $Fe^{2+}$ ion in a tetrahedral site is the Jahn-Teller active and the dynamic Jahn-Teller distortion starts below the magnetic ordering temperature. The distortion cause a quadrupole shift to appear which increases with decreasing temperature. The magnetic hyperfine field has a maximum at 100 k and then decreases with decreasing temperature. The magnitude of the interaction ratio R between the electric quadrupole and magnetic dipole interaction increases from 0 near the magnetic ordering temperature to 5.4 at 4.2 K. The optimum values of 0, the polar angle of the magnetic hyperfine field with respect to the principle axis of the electric field gradient (EFG) remains zero and the asymmetry of the EFG n is about 0.25. The simulations of Mossbauer spectra coincidence with the experimental results.

• Korean Journal of Microbiology
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• v.25 no.1
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• pp.23-27
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• 1987

Low molecular weight plant ribonucleic acids including viroid-RNA molecules which are soluble in 2M lithium chloride were electrophoresed in the 0M to 8M urea-gradient polyacrylamide gel. Although the linear viroid-RNA molecules migrated at a similarrate across the urea-gradient gel under the denaturing temperature, the circular viroid-RNA molecules moved more rapidly at low urea-gradient region than at high urea-gradient region. Consequently, the migration of the circular viroid-RNA molecules showed a sudden shift across the band of linear forms in the midrange of the urea-gradient gels. Electrophoretic mobilities of the circular viroid-RNA molecules seemed to depend mainly on the concentration of urea in the denaturing urea-gradient gels.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.15 no.1
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• pp.33-38
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• 2003

Turbidity meter calibrations were conducted using bottom sediment and suspended material collected with a vertical array of sediment traps at the coastal water off Gaduk Island. Compared to the bottom sediment comprising sand fraction of approximately 6％, trapped suspended material was composed entirely of silt and clay fractions and showed a tendency to get finer as elevation from the sea-bed increases. Slope parameter of linear regression due to bottom sediment was of minimum value and values of those due to suspended material increased gradually as the height of sediment trap increases (i.e., sediment size decreases). This result shows that turbidity meter calibration using bottom sediment can cause an overestimation error in the calculation of suspended sediment concentration and that the error can reach up to 25% in case of this study. Therefore, it is suggested that the use of a corrected calibration curve based on grain size distribution of suspended material instead of bottom sediment may reduce the measurement error of suspended sediment concentration.