• Journal of the Institute of Electronics Engineers of Korea TC
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• v.40 no.5
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• pp.181-186
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• 2003

This paper presents a numerical dispersion relation for the two-dimensional finite-difference time-domain method based on the alternating-direction implicit time-marching scheme(2-D ADI-FDTD), which method has the potential to considerably reduce tile number of time iterations especially in case where the fine spatial lattice relative to the wavelength is used to resolve fine geometrical features. The proposed analytical relation for 2-D ADI-FDTD is compared with those relations in the Previous works. Through numerical tests, the dispersion equation of this work was shown as correct one for 2-D ADI-FDTD.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2003.10a
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• pp.57-60
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• 2003

An axisymmetric compressible flow solver accounting for chemical equilibrium has been developed as an analysis tool exclusively suitable for performance prediction and optimum contour design of LRE thrust chamber. By virtue of several features focusing on user-friendliness and effectiveness including automatical grid generation and iterative calculations with changes in design parameters prescribed through only one keyword-type input file, a design engineer can evaluate very fast and easily the influences of various design inputs such as geometrical parameters and operating conditions on propulsive performance. Validations have been carried out for various aspects by detailed comparisons with the result of CEA code, experimental data of JPL nozzle, actual data for two historical engines, and ReTF data for KSR-III.

• Fibers and Polymers
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• v.5 no.3
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• pp.177-181
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• 2004

Current efforts to establish links between geometrical features and mechanical performance of nonwoven fabrics in general, and of point-bonded (spot-bonded) nonwovens in particular has been made using the measurements of Fiber Orientation Distribution Function (ODF) and tensile modulus which occurs during controlled-deformation experiments. Image analysis technique (using the Fast Fourier Transform) was used to quantify the fiber orientation distribution. The results suggest that, within a typical window of processing conditions, the fiber orientation has a significant influence on the anisotropical behavior of nonwoven. The data also suggest that mechanical anisotropy of thermally point-bonded nonwovens is likely to be governed by different load transfer mechanism according to the applied macroscopic tensile direction.

• 유체기계공업학회:학술대회논문집
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• 2001.11a
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• pp.216-220
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• 2001

Flow analysis was carried out for two vertical pumps. The geometrical difference of two pumps is the adoption of vaned diffuser. Full pump models were used to simulate the velocity fields of the pumps. Pump head and velocity field were compared to obtain the features of diffuser flow. It was shown that the discontinuity of head curve was predicted and reverse flow could be generated at impeller exit even in the rated flow condition.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.233-236
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• 1997

In modem industry, the accuracy and the surface-finish requirements for machined parts have been becoming ever more stringent. Optical method in measurements is playing an important role in vibration measurement, crack and defect detection and surface topography with the advent of opto-mechatronics. In this study, the principle of the general confocal microscope is introduced for surface measurement, and the advanced confocal microscope that has better measuring speed than the traditional confocal microscope is developed. A study on improving the resolution of the advanced confocal microscope is followed. Finally, Software for data acquisition and analysis of various parameters in surface geometrical features has been developed.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.674-677
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• 2003

This work presents a method of point-to-surface assignment for 3D inspection of solder pastes on PCB. A bounding box enclosing the solder paste tightly on all sides is introduced to avoid incorrect point-to-surface assignment. The shape of bounding box for solder paste brick is variable according to geometry of measured points. The surface geometry of the bounding box is obtained by using five peaks selected from the histogram of normalized gradient vectors for measured points. By using the bounding box enclosing the solder paste. the task of point-to-surface assignment is successfully executed. Subsequently, the geometrical features are obtained via surface fitting.

• Steel and Composite Structures
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• v.5 no.1
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• pp.1-15
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• 2005

Important characteristics of the previously proposed reduced stiffness method and a summery of its design curves for the buckling of the axially loaded sandwich cylindrical shells is presented. Comparison of the lower bound obtained with FEM analysis with that from the reduced stiffness analysis shows that the proposed reduced stiffness method can provide safe lower bounds for the buckling of geometrically imperfect, axially loaded sandwich cylindrical shells. One of the attractive features of the reduced stiffness elastic lower bound analysis is that it provides safe estimates of buckling loads that do not depend on the specification of the precise magnitude of the imperfection spectra. As a result, designers can readily apply this method without being worried about possible geometrical imperfections that might be generated during fabrication and construction of sandwich cylindrical shells.

• Proceedings of the IEEK Conference
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• 1999.11a
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• pp.531-535
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• 1999

Automatic human face detection in a complex background is one of the difficult problems. In this paper, we propose an effective and robust automatic face detection approach that can locate the face region in natural scene images when the system is used as a pre-processor of a face recognition system . We use two natural and powerful visual cues, the skin color and the eyes. In the first step of the proposed system, the method based on the human skin color space by selecting flesh tone regions using normalized r-g space in color images. In the next step, we extract eye features by calculating moments and using geometrical face model. Experimental results demonstrate that the approach can efficiently detect human faces and satisfactory deal with the problems caused by bad lighting condition, skew face orientation.

• International Journal of Naval Architecture and Ocean Engineering
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• v.8 no.3
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• pp.228-234
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• 2016

Recent icebreaking ships need to be designed to enhance not only icebreaking capability but also turning ability. For the evaluation of ice resistance induced by an icebreaking hull form, HHI (Hyundai Heavy Industries) has developed the hybrid empirical formulas (Park et al., 2015) by considering the geometrical hull shape features, such as waterline and underwater sections. However, the empirical formulas have inherent limits to the precise estimation of the icebreaking and turning ability because the breaking process and the resulting pattern are ignored. For this reason, numerical calculation in time domain is performed to predict the icebreaking process and pattern. In the simulation, varying crushing stress according to velocity vectors and contact areas between hull and ice is newly introduced. Moreover, the simulation results were verified by comparing them with the model test results for three different bow-first icebreaking models.

• Journal of Institute of Control, Robotics and Systems
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• v.6 no.5
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• pp.383-389
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• 2000

This paper presents a stereo camera system that provides a Pair of stereo images using a Biprism. The equivalent of a stereo Pair of images is formed as the left and right halves of a single CCD image. The system is therefore cheap and extremely easy to calibrate since it requires only one CCD camera. An additional advantage of the geometrical set-up is that corresponding features lie on the same scanline automatically, The single camera and Biprism have led to a simple stereo system for which correspondence is very easy and which is accurate for nearby objects in a small field of view. Since we use only a single lens, calibration of the system is greatly simplified. Given the parameters in the Biprism-stereo camera system, we can reconstruct the 3-D structure using only the disparity between the corresponding points.