• Journal of International Society for Simulation Surgery
• /
• v.3 no.1
• /
• pp.22-27
• /
• 2016

Background Craniosynostosis management using distraction osteogensis represent a challenge for surgeons due to the great variability of the skull deformity even within the same etiology. The ability to apply the simulation surgery for improving the preoperative planning for distraction osteogensis could improve the results.Planning and Simulation 14 patients presented with craniosynostosis had been subjected to simulation surgery prior to real surgery. 3D CT scans was obtained upon patient admission. Adjustment of all skull position to Frankfort horizontal plane was done. 3 different distraction osteogensis plans were done for each patient according to the skull morphology. For each plane, movement for each bone segment was done according to the pre-planned distraction vectors. Also the distances of distractions were pre-determined according to the cephalic index as well as brain volume. Intraoperatively, we choose the most appropriate plan for the patient by the surgeon. At the end of distraction, 3D CT scan was obtained, and was compared to the simulation plan. Also the distance and the direction of distraction was compared to that of the plan. Accordingly, the distance was almost matching that of the simulation surgery, however the vector of distraction was not matched.Conclusion Preoperative stimulation planning for craniosynostosis patient is very valuable tool in the surgical management of craniosynostosis patients.

• Journal of Information Display
• /
• v.6 no.4
• /
• pp.26-34
• /
• 2005

In this paper, a new rectification scheme to transform the uncalibrated stereo image pair into the calibrated one is suggested and its performance is analyzed by applying this scheme to the reconstruction of the intermediate views for multi-view stereoscopic display. In the proposed method, feature points are extracted from the stereo image pair by detecting the comers and similarities between each pixel of the stereo image pair. These detected feature points, are then used to extract moving vectors between the stereo image pair and the epipolar line. Finally, the input stereo image pair is rectified by matching the extracted epipolar line between the stereo image pair in the horizontal direction. Based on some experiments done on the synthesis of the intermediate views by using the calibrated stereo image pairs through the proposed rectification algorithm and the uncalibrated ones for three kinds of stereo image pairs; 'Man', 'Face' and 'Car', it is found that PSNRs of the intermediate views reconstructed from the calibrated images improved by about 2.5${\sim}$3.26 dB than those of the uncalibrated ones.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.6 no.6
• /
• pp.132-141
• /
• 1998

Particle image velocimetry(PIV), a planar measuring technique, is an efficient tool for studying the complicated flow field such as in-cylinder flow, and intake port flow. PIV can be also used for analyzing the integral length scale of turbulence, which is a measure of the size of the large eddies that contain most of the turbulence kinetic energy. In this study, dual color scanning PIV was designed and demonstrated by using a rotating mirror and a beam splitter. This PIV system allowed enlargement of flexibility in the intensity of vectors to be calculated by spatial filtering technique, even in combustion chamber with high velocity gradient and high vorticity$({\sim}1000s^{-1})$. A new color image processing algorithm was developed, which was used to find the direction of particle movement directly from the digital image. These measuring techniques were successfully applied to obtaining the turbulence intensity (~0.1m/s) and the turbulent integral length scale of vorticity(~1mm).

• Journal of The Korean Society of Agricultural Engineers
• /
• v.54 no.5
• /
• pp.79-89
• /
• 2012

The objectives of this paper were to evaluate the wind flow behind the livestock ventilation fan for small-scale wind power generation and to make flow profiles of imaginary ventilation fan for future simulation works. The field experiments using typical 50-inch fan indicated that the wind flow behind the ventilation fan had a good possibility of power generation with its high and steady wind speeds up to a distance of 2 m. The expected electricity yield was almost 101~369 W with a small (0.8 m radius) wind turbine. The decline of ventilation fan performance caused by the obstacle was also not significant with about 4 % from a distance of 2 m. The flow profiles for the computational fluid dynamics (CFD) simulation was created by combining the direction vectors analyzed from tuft visualization test and the flow predicted by the rotating fan modeling. The flow profiles are expected to provide an efficient saving of computational time and cost to design a better wind turbine system in future works.

• 한국가시화정보학회:학술대회논문집
• /
• 2002.11a
• /
• pp.105-108
• /
• 2002

Highly swept leading edge extension(LEX) applied to delta wings has greatly improved the subsonic maneuverability of contemporary fighters. In this study, systematic approach by PIV experimental method within a circulating water channel was adopted to study the fundamental characteristics of induced vortex generation, development and its breakdown appearing on a delta wing model with or without LEX in terms of four angles of attack$(15^{\circ},\;20^{\circ},\;25^{\circ},\;30^{\circ})$ and six measuring sections$(30\%,\;40\%,\;50\%,\;60\%,\;70\%,\;80\%)$ of chord length. Distributions of time-averaged velocity vectors and vorticities over the delta wing model were compared along the chord length direction. High-speed CCD camera which made it possible to acquire serial images is able to get the detailed information about the flow characteristics occurred on the delta wing. Especially quantitative comparison of the maximum vorticity featuring the induced pressure distribution were also conducted to clarity the significance of the LEX existence.

• Journal of Internet Computing and Services
• /
• v.11 no.1
• /
• pp.129-141
• /
• 2010

In this paper, we present a wearable intelligent device based on multi-sensor for monitoring human activity. In order to recognize multiple activities, we developed activity recognition algorithms utilizing an image sensor and a 3-axis accelerometer sensor. We proposed a grid?based optical flow method and used a SVM classifier to analyze data acquired from multi-sensor. We used the direction and the magnitude of motion vectors extracted from the image sensor. We computed the correlation between axes and the magnitude of the FFT with data extracted from the 3-axis accelerometer sensor. In the experimental results, we showed that the accuracy of activity recognition based on the only image sensor, the only 3-axis accelerometer sensor, and the proposed multi-sensor method was 55.57%, 89.97%, and 89.97% respectively.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.3 no.2
• /
• pp.59-70
• /
• 1998

Two-dimensional trend-vector model of sediment transport is first tested in the tidal flat of Garolim Bay, mid-western coast of the Korean Peninsula. Three major parameters of surface sediment, i.e., mean grain size, sorting and skewness, are used for defining the best-fitting transport trend-vector on the sand ridge and muddy sand flat. These trend vectors are compared with the real transport directions determined from morphology, field observation and bedforms. The 15 possible cases of trend vectors are calculated from total sediments. In order to find the role of coarse sediments, trend vectors from sediments coarser than < 4.5 ${\phi}$, (sand size) are separately calculated from those of total sediments. As compared with the real directions, the best-fitting transport-vector model is the "case M" of coarse sediments which is the combined trend vectors of two cases: (1) finer, better sorted and more negatively skewed and (2) coarser, better sorted and more positively skewed. This indicates sand-size grains are formed by simpler hydrodynamic processes than total sediments. Transported sediment grains are better sorted than the source sediment grains. This indicates that consistent hydrodynamic energy can make sediment grains better sorted, regardless of complicated mechanisms of sediment transport. Consequently, both transported vector model and real transported direction show that the source of sediments are located outside of bay (offshore Yellow Sea) and in the baymouth. These source sediments are transported through the East Main Tidal Channel adjacent the baymouth. Some are transported from the subtidal zone to the upper tidal flat, but others are transported farther to the south, reaching the south tidal channel in the study area. Also, coarse sediment grains on the sand ridge are originally from the baymouth, and transported through the subtidal zone to the south tidal channel. These coarse sediments are moved to the northeast, but could not pass the small north tidal channel. It is interpreted that the great amount of coarse sediments is returned back to the outside of the bay (Yellow Sea) again through the baymouth during the ebb tide. The distribution of muddy sand in the northeastern part of study area may result from the mixing of two sediment transport mechanisms, i.e., suspension and bedload processes. The landward movement of sand ridge and the formation of the north tidal channel are formed either by the supply of coarse sediments originating from the baymouth and outside of the bay (subaqueous sand ridges including Jang-An-Tae) or by the recent relative sea-level rise.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.31 no.6B
• /
• pp.531-539
• /
• 2011

It has been widely acknowledged that climate system associated with extreme rainfall events was difficult to understand and extreme rainfall simulation in climate model was more difficult. This study developed a new model for extracting rainfall filed associated with extreme events as a way to characterize large scale climate system. Main interests are to derive location, size and direction of the rainfall field and this study developed an algorithm to extract the above characteristics from global climate data set. This study mainly utilized specific humidity and wind vectors driven by NCEP reanalysis data to define the rainfall field. Geometric first and second moments have been extensively employed in defining the rainfall field in selected zone, and an ellipsoid based model were finally introduced. The proposed geometric moments based ellipsoid model works equally well with regularly and irregularly distributed synthetic grid data. Finally, the proposed model was applied to space-time real rainfall filed. It was found that location, size and direction of the rainfall field was successfully extracted.

• Atmosphere
• /
• v.24 no.1
• /
• pp.49-68
• /
• 2014

This study analyzed atmospheric conditions for the convergent cloud band (Cu-Cb line) in developing stage and its neighbouring convections formed over the East Sea on 1 February 2012, by using synoptic, satellites data, and WRF numerical simulation output of high resolution. In both satellite images and the WRF numerical simulation outputs, the Cu-Cb line that stretched out toward northwest-southeast was shown in the East Sea, and cloud lines of the L mode were aligned in accordance with the prevailing surface wind direction. However, those of the T mode were aligned in the direction of NE-SW, which was nearly perpendicular direction to the surface winds. The directions of the wind shear vectors connecting top winds and bottom winds of the moist layers of the L mode and the T mode were identical with those of the cloud lines of L mode and T mode, respectively. From the WRF simulation convection circulations with a convergence in the lower layer of atmosphere and a divergence above 1.5 km ASL (Above Sea Level) were identified in the Cu-Cb line. A series of small sized vortexes (maximum vortex: $320{\times}10^{-5}s^{-1}$) of meso-${\gamma}$-scale formed by convergences was found along the Cu-Cb lines, suggesting that Cu-Cb lines, consisting of numerous convective clouds, were closely associated with a series of the small vortexes. There was an absolute unstable layer (${\partial}{\theta}/{\partial}z$ < 0) between sfc and ~0.3 km ASL, and a stable layer (${\partial}{\theta}/{\partial}z$ > 0) above ~2 km ASL over the Cu-Cb line and cloud zones. Not only convectively unstable layers (${\partial}{\theta}_e/{\partial}z$ < 0) but also neutral layers (${\partial}{\theta}_e/{\partial}z{\approx}=0$) in the lower atmosphere (sfc~1.5 km ASL) were scattered around over the cloud zones. Particularly, for the Cu-Cb line there were convectively unstable layers in the surface layer, and neutral layers (${\partial}{\theta}_e/{\partial}z{\approx}=0$) between 0.2 and ~1.5 km ASL over near the center of the Cu-Cb line, and the neutralization of unstable layers came from the release of convective instability.

• The KIPS Transactions:PartB
• /
• v.11B no.3
• /
• pp.309-316
• /
• 2004

In this paper, we proposed the TDS(T-shape Diamond Search) based on the directions of above, below, left and right points to estimate the motion vector fast and more correctly in this method, we exploit the facts that most motion vectors are enclosed in a circular region with a radius of 2 fixels around search center(0,0). At first, the 4 points in the above, below, left and right around the search center is calculated to decide the point of the MBD(Minimum Block Distortion). And then w. above point of the MBD is checked to calculate the SAD. If the SAD of the above point is less than the previous MBD, this process is repeated. Otherwise, the right and left points of MBD are calculated to decide The points that have the MBD between right point and left point. Above processes are repeated to the predicted direction for motion estimation. Especially, if the motions of image are concentrated in the crossing directions, the points of other directions are omitted. As a result, we can estimate motion vectors fast. Experiments show that the speedup improvement of the proposed algorithm over Diamond Search algorithm(DS) and HEXgon Based Search(HEXBS) can be up to 38∼50％ while maintaining similar image Quality.