• Journal of Korea Multimedia Society
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• v.11 no.12
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• pp.1658-1667
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• 2008

Reconstruction of 3D objects from a single view image is generally an ill-posed problem because of the projection distortion. A monocular vision based 3D object localization method is proposed in this paper, which approximates an object on the ground to a simple bounding solid and works automatically without any prior information about the object. A spherical or cylindrical object determined based on a circularity measure is approximated to a bounding cylinder, while the other general free-shaped objects to a bounding box or a bounding cylinder appropriately. For a general object, its silhouette on the ground is first computed by back-projecting its projected image in image plane onto the ground plane and then a base rectangle on the ground is determined by using the intuition that touched parts of the object on the ground should appear at lower part of the silhouette. The base rectangle is adjusted and extended until a derived bounding box from it can enclose the general object sufficiently. Height of the bounding box is also determined enough to enclose the general object. When the general object looks like a round-shaped object, a bounding cylinder that encloses the bounding box minimally is selected instead of the bounding box. A bounding solid can be utilized to localize a 3D object on the ground and to roughly estimate its volume. Usefulness of our approach is presented with experimental results on real image objects and limitations of our approach are discussed.

• Journal of computational fluids engineering
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• v.15 no.4
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• pp.53-59
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• 2010

Preliminary design of a ground plate, a device installed close to the aircraft model for wind tunnel test to simulate the ground effect, was performed by a numerical simulation. A two-dimensional numerical study was performed initially to decide the optimal leading edge and flap configurations. Then, three-dimensional studies were conducted to decide the optimal flap deflection angle for pressure distribution reduction since the plate and the plate supporting system generate static pressure difference between the upper and lower flow regions. Three-dimensional simulation additionally studied the effect of the clearance between the plate and the wind tunnel side wall. For the efficiency of computation, half model was simulated and a symmetric boundary condition was applied on the center plane. Based on the preliminary design, a ground plate was designed, manufactured and tested at the Korea Aerospace Research Institute(KARI) wind tunnel. The measured pressure differences versus flap deflection angle agreed well with the predicted results.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.2
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• pp.188-193
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• 2010

In this paper, SI(Signal Integrity) characteristic of the 4-layer PCB(Printed Circuit Boards) with a through-hole via was analyzed by impedance mismatching between the through-hole via and the transmission line, and deterioration of clock pulse response characteristic due to the P/G plane resonances which are generated between the power and the ground plane. The minimized impedance mismatching between the through-hole via and the transmission line for the improving of SI characteristic is confirmed by the TDR(Time Domain Reflector) simulation and lumped element modeling of the through-hole via. And the cancellation method of P/G plane resonances for improvement of the SI characteristic is represented by simulation result.

• Geotechnical Engineering
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• v.11 no.4
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• pp.99-110
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• 1995

In this study, friction angles on the surface of vertical rigid ground anchor in normally consolidated dry sand were measured by model pullout tests in laboratory. Friction angles were obtained from the normal and shear stresses measured along depth of the anchor stir face by attaching several 2-dimensional load cells. Model tests were conducted under the plane strain state and axial symmetric state. From the results of tests, it was concluded that the maximum friction angle on the anchor surface coincides nearly with the maximum angle of stress obliquity on the plane of zero-extension direction obtained by plane strain compression test. This result was made with regard to the strength anisotropy and stress dependency of sand. It showed that when angle of shear resistance of the sand is applied to the friction angle of the anchor surface, the design capacity could be less than the applied force, thus making the anchor unsafe.

• International Journal of Naval Architecture and Ocean Engineering
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• v.6 no.2
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• pp.323-332
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• 2014

High-speed marine vehicles can take advantage of aerodynamically supported platforms or air wings to increase maximum speed or transportation efficiency. However, this also results in increased complexity of boat dynamics, especially in the presence of waves and wind gusts. In this study, a mathematical model based on the fully unsteady aerodynamic extreme-ground-effect theory and the hydrodynamic added-mass strip theory is applied for simulating vertical-plane motions of a tunnel hull in a disturbed environment, as well as determining its steady states in calm conditions. Calculated responses of the boat to wind gusts and surface waves are demonstrated. The present model can be used as a supplementary method for preliminary estimations of performance of aerodynamically assisted marine craft.

• ETRI Journal
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• v.30 no.6
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• pp.877-879
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• 2008

A novel differential dual-frequency antenna using proximity coupling is proposed. Dual bands are realized by a slot in the ground plane. The lower resonant frequency is controlled by the slot in the ground plane, and the upper resonant frequency is mainly determined by the dimensions of the radiating patch. Measured results show that the proposed antenna can operate at 2.51 GHz and 5.38 GHz.

• Journal of Navigation and Port Research
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• v.35 no.7
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• pp.563-568
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• 2011

The various properties such as the electric current distribution, resonant frequency and radiation patterns of open-ended meander slot antenna placed on a small ground plane, are investigated to give the help in performing antenna design. Based upon these characteristics, the designed antenna which is only 22mm($0.06{\lambda}_g$) in height and 31mm($0.09{\lambda}_g$) in width can operate at the 433 MHz with the measured radiation efficiency of 8% and end-fire radiation pattern. These properties make the antenna suitable for the handheld device such as the wireless remote controller.

• Journal of information and communication convergence engineering
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• v.10 no.2
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• pp.97-102
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• 2012

The differential global positioning system (DGPS) transmits a GPS enhancement signal using a top-loaded monopole antenna in the medium frequency range. The top-loaded antenna in the medium frequency band can attain a radiation efficiency on the order of 10%. The antenna ground plane characteristics affect the antenna radiation efficiency. To improve the radiation efficiency, it is necessary to install the antenna on a ground plane with large enough physical dimensions and good conductivity. The antenna radiation efficiency is a primary factor in determining the DGPS service area. The service area of the DGPS using a medium frequency band is dominantly affected by the antenna radiation efficiency. To determine antenna radiation efficiencies accurately, the antenna radiation efficiencies of DGPS are deduced from the propagation power in this paper. Based on the deduced antenna radiation efficiencies, the service area for the Korean nationwide-DGPS is analyzed and evaluated.

• Journal of electromagnetic engineering and science
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• v.13 no.3
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• pp.165-172
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• 2013

This paper describes a design for a spiral antenna with a conical wall to obtain the high gain. The gain and the axial ratio of the spiral antenna were improved by a new design that included a conical wall and an optimized Archimedean slit on the ground plane in a conventional antenna with a circular cavity wall and a 4.5-turn slit. A gain improvement of 9.5 dBi higher and a good axial ratio of 1.9 dB lower were measured by the added conical wall and the newly designed slit from the current distribution control on the ground plane, respectively. The measured return loss, gain and axial ratio of the proposed antenna showed a good agreement with the simulated results. The proposed antenna will be applied to a non-linear junction detector system.

• Proceedings of the IEEK Conference
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• 1999.11a
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• pp.845-848
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• 1999

We designed and fabricated partially shorted QMSAs(Quarter-Wavelength Microstrip Antennas) for 850［MHz］band on various Copper-clad Laminates substrates (TACONIC company), where the width of the radiation patch is identical with that of the ground plane and the radiation patch is partially shorted to the ground plane. The resonant frequencies and the return losses according to the electrical thickness were measured by reducing the PSW (Partially Shorted Width) to 0［mm］. As a result, a good characterized antenna with an average 11% reduced resonant length and a return loss -15.86~-30.68［㏈］ was obtained when the total PSW was in the range of 70% of radiated patch width, compared to the conventional QMSA.