• Journal of Computational Design and Engineering
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• v.2 no.4
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• pp.206-217
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• 2015

This paper presents a complete S-shape feed rate scheduling approach (CSFA) with confined jerk, acceleration and command feed rate for parametric tool path. For a Non-Uniform Rational B-Spline (NURBS) tool path, the critical points of the tool path where the radius of curvature reaches extreme values are found firstly. Then, the NURBS curve is split into several NURBS sub-curves or blocks by the critical points. A bidirectional scanning strategy with the limitations of chord error, normal/tangential acceleration/jerk and command feed rate is employed to make the feed rate at the junctions between different NURBS blocks continuous. To improve the efficiency of the feed rate scheduling, the NURBS block is classified into three types: short block, medium block and long block. The feed rate profile corresponding to each NURBS block is generated according to the start/end feed rates and the arc length of the block and the limitations of tangential acceleration/jerk. In addition, two compensation strategies are proposed to make the feed rate more continuous and the arc increment more precise. Once the feed rate profile is determined, a second-order Taylor's expansion interpolation method is applied to generate the position commands. Finally, experiments with two free-form NURBS curves are conducted to verify the applicability and accuracy of the proposed method.

• International Journal of Naval Architecture and Ocean Engineering
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• v.8 no.4
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• pp.301-311
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• 2016

This paper describes the whole procedures to determine ice-induced global loads on the ship using measured full-scale data in accordance with the method proposed by the Canadian Hydraulics Centre of the National Research Council of Canada. Ship motions of 6 degrees of freedom (dof) are found by processing the commercial sensor signals named Motion Pak II under the assumption of rigid body motion. Linear accelerations as well as angular rates were measured by Motion Pak II data. To eliminate the noise of the measured data and the staircase signals due to the resolution of the sensor, a band pass filter that passes frequencies between 0.001 and 0.6 Hz and cubic spline interpolation resampling had been applied. 6 dof motions were computed by the integrating and/or differentiating the filtered signals. Added mass and damping force of the ship had been computed by the 3-dimensional panel method under the assumption of zero frequency. Once the coefficients of hydrodynamic and hydrostatic data as well as all the 6 dof motion data had been obtained, global ice loads can be computed by solving the fully coupled 6 dof equations of motion. Full-scale data were acquired while the ARAON rammed old ice floes in the high Arctic. Estimated ice impact forces for two representative events showed 7e15 MN when ship operated in heavy ice conditions.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.36S no.7
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• pp.71-80
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• 1999

Sign-language communication can be a useful way of exchanging message between people who using different languages. In this paper, we report an experimental survey on the construction of a Korean-Japanese sign-language communication system using 3D model. For real-time communication, we introduced an intelligent communication method and built the system as a client-server architecture on the Internet. A character model is stored previously in the clients and a series of animation parameters are sent instead of real image data. The input-sentence is converted into a series of parameters of Korean sign language or Japanese sign language at server. The parameters are transmitted to clients and used for generating the animation. We also employ the emotional expressions, variable frames allocation method, and a cubic spline interpolation for the purpose of enhancing the reality of animation. The proposed system is implemented with Visual $C^{++}$ and Open Inventor library on Windows platform. Experimental results show a possibility that the system could be used as a non-verbal communication means beyond the linguistic barrier.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.5
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• pp.2113-2120
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• 2013

In this study, an efficient machine vision based inspection system is developed for the in-line measurement of phosphor resin dispensing shapes on LED chip package. Since the phosphor resin (target material) has semitransparent characteristics, illuminated light beam is reflected from the bottom of the chip as well as from the surface. Since such phenomenon can deteriorate inspection reliability, a white LED and a 635nm laser slit beams are experimentally tested to decide suitable illumination optics. Also, specular and diffuse reflection methods are tested to decide suitable optical triangulation. As a result, it can be known that the combination of a white slit beam source and specular reflection method show the best inspection results. The Catmull-Rom spline interpolation is applied to the obtained data to form smoother surface. From the results, it can be conclude that the developed system can be sucessfully applied to the in-line inspection of LED chip packaging process.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.7
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• pp.618-626
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• 2011

In order to complete missions in a complicated terrain or highly dangerous area, an unmanned aerial vehicle(UAV) needs a fine controller to precisely follow the desired path. A PID controller used for the path following feeds forward path curvature information to the control input to improve the path following performance. High gain for PID controller is necessary to follow path tightly. However the high gain could cause instability or performance degradation when the vehicle has slow dynamics. We present PID controller design method which considers response delay of vehicle as well as path curvature. In order to obtain path curvature the desired path is described as a 3rd order polynomial by applying cubic spline interpolation. We apply the proposed controller to the path following of a UAV which is operated in high altitude and has very slow lateral dynamics. The lateral dynamics are modelled as a first order delayed system in the controller design. Nonlinear simulation shows the UAV with proposed controller follows an arbitrary path very tightly.

• Journal of Korea Multimedia Society
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• v.8 no.2
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• pp.164-173
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• 2005

Painterly rendering may bring various results through the parameters that determine the characteristics of brush strokes such as, color, orientation, size, and shape. In this paper, we propose the most adaptive brush stroke generation for source images, using reference data. Our algorithm used Colors formed by actual palette colors from artists. To create the palette, we have referred mostly to colors used in Van Gogh's works and determined the color of brush strokes by transferring it to the most similar one, through comparing colors used in source images and the palette colors. Also, In order to emulate a brush stroke with dynamic properties like Van Gogh styles we have applied a brush stroke orientation that surrounds the edges by referring to the edge orientation of source images. The sizes were determined depending on the different sizes of the objects from wide to narrow brushes. Finally, we applied spline curve shapes to simulate curves and swirls like Van Gogh styles. The brush strokes created in such method, were applied separately according to its segmented images, and composed after rendering.

• Journal of Biomedical Engineering Research
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• v.23 no.6
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• pp.485-489
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• 2002

In this study. respiratory efforts were monitored by the change of pulse transit time (PTT) which is related with the arterial pressure PTT is the time interval between the peak of R wave in ECG and the maximal slope point of photoplethysmogram(PPG). Biosignals, ECG and finger photoplethysmogram(PPG), were converted to digital data, and PTT was evaluated in personal computer with every heart beat. Results were presented as a graph using spline interpolation. The software was implemented in C$\^$++/ as a window-based application program. PTT was periodically changed according to airflow in resting respiration. In the resting respiration, PTT was changed according to the respiratory cycle. The amplitude of PTT fluctuation was increased by deep respiration, and increased by partial airway obstruction. These results suggest that PTT is responsible to respiratory effort which could be evaluated by the pattern of PTT change. And it is expected that PTT could be applied in the monitoring of respiratory effort by noninvasive methods, and is very useful method for the evaluation of respiratory distress.

• Journal of KIISE:Computing Practices and Letters
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• v.15 no.9
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• pp.695-699
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• 2009

In this paper, we propose an automatic prostate segmentation technique using image intensity and gradient information. Our method is composed of four steps. First, rays at regular intervals are generated. To minimize the effect of noise, the start and end positions of the ray are calculated. Second, the profiles on each ray are sorted based on the gradient. And priorities are applied to the sorted gradient in the profile. Third, boundary points are extracted by using gradient priority and intensity distribution. Finally, to reduce the error, the extracted boundary points are corrected by using B-spline interpolation. For accuracy evaluation, the average distance differences and overlapping region ratio between results of manual and automatic segmentations are calculated. As the experimental results, the average distance difference error and standard deviation were 1.09mm $\pm0.20mm$. And the overlapping region ratio was 92%.

• Journal of Navigation and Port Research
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• v.46 no.6
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• pp.471-482
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• 2022

This study aims to investigate the characteristics of wave generation in a deep ocean engineering basin and to develop a meta-model of the transfer function of the wavemaker that reflects the geometric characteristics of the deep ocean engineering basin. To this end, the two-dimensional frequency domain boundary element method was applied to achieve an efficient analysis that reflects the geometric characteristics of the deep ocean engineering basin. The developed numerical method was validated through comparison with the analytical solution. Numerical analyses were conducted for the boundary value problem of the wavemaker according to various periods and the positions of the movable bottom. The numerical results were used to investigate the effect of the geometric characteristics of the deep ocean engineering basin on the transfer function of the wavemaker, and the effect of depth on wave generation was checked by changing the position of the movable bottom. To efficiently utilize the various results of the boundary element method, a meta-model, an approximate model of the transfer function of the wave maker, was developed using a thin plate spline interpolation model. The validity of the developed meta-model was confirmed through a comparison of the results of the model tests.

• Journal of KIISE:Software and Applications
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• v.37 no.4
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• pp.273-281
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• 2010

In this paper, we propose an automatic segmentation method of the endo- and epicardial boundary by using ray-casting profile based on intensity distribution and gradient information in CT images. First, endo-cardial boundary points are detected by using adaptive thresholding and seeded region growing. To include papillary muscles inside the boundary, the endo-cardial boundary points are refined by using ray-casting based profile. Second, epi-cardial boundary points which have both a myocardial intensity value and a maximum gradient are detected by using ray-casting based adaptive gradient profile. Finally, to preserve an elliptical or circular shape, the endo- and epi-cardial boundary points are refined by using elliptical interpolation and B-spline curve fitting. Then, curvature-based contour fitting is performed to overcome problems associated with heterogeneity of the myocardium intensity and lack of clear delineation between myocardium and adjacent anatomic structures. To evaluate our method, we performed visual inspection, accuracy and processing time. For accuracy evaluation, average distance difference and overalpping region ratio between automatic segmentation and manual segmentation are calculated. Experimental results show that the average distnace difference was $0.56{\pm}0.24mm$. The overlapping region ratio was $82{\pm}4.2%$ on average. In all experimental datasets, the whole process of our method was finished within 1 second.