• Korean Journal of Remote Sensing
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• v.27 no.2
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• pp.121-130
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• 2011

This paper highlights the reconstruction of the rectilinear type of 3D rooftop model from satellite image data using centroid neural network. The main idea of the proposed 3D reconstruction method is based on the grouping of 3D line segments. 3D lines are extracted by 2D lines and DEM (Digital Elevation Map) data evaluated from a pair of stereo images. Our grouping process consists of two steps. We carry out the first grouping process to group fragmented or duplicated 3D lines into the principal 3D lines, which can be used to construct the rooftop model, and construct the groups of lines that are parallel each other in the second step. From the grouping result, 3D rooftop models are reconstructed by the final clustering process. High-resolution IKONOS images are utilized for the experiments. The experimental result's indicate that the reconstructed building models almost reflect the actual position and shape of buildings in a precise manner, and that the proposed approach can be efficiently applied to building reconstruction problem from high-resolution satellite images of an urban area.

• Korean Journal of Applied Biomechanics
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• v.12 no.2
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• pp.131-142
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• 2002

The purpose of this study was to analyze kinematic variables of a Mae-ukemi (forward breakfall :MU) in Judo through 3-D image analysis with five Judoka with over 2 years' career (2nd dan, 3rd dan). The kinematic variables include posture, and distance variables; the mean values and the standard deviations for each variable were obtained to analyze kinematic variables of a MU in Judo. From the data analysis and discussion, the following conclusions were drawn : 1) Posture variables : The angles of wrists during right before Mae-ukemi (RBU) were extended from the just MU position(MUP) and flexed from in the right after MU(RAU), and there was a difference in the displacement between the angles of the right and left wrists. The angles of elbows were flexed in the ready position from in the RAU. The angles of ankles were flexed from the ready position to that down position, extended from the down position to that transition, and flexed from the transition positiont to that RAU. 2) Distance variables : The distance height between the mat and shoulders in the RBU(32.2cm) to in the MUP(18.3cm) and in the RAU(20.5cm). during that height between the mat and hips in the RBU(48.0cm) to in the MUP(23.4cm), and in the RAU(30.6cm).

• The Korean Journal of Nuclear Medicine
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• v.39 no.3
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• pp.174-181
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• 2005

Purpose: Reduction of respiratory motion artifacts in PET images was studied using respiratory-gated PET (RGPET) with moving phantom. Especially a method of generating simulated helical CT images from 4D-CT datasets was developed and applied to a respiratory specific RGPET images for more accurate attenuation correction. Materials and Methods: Using a motion phantom with periodicity of 6 seconds and linear motion amplitude of 26 mm, PET/CT (Discovery ST: GEMS) scans with and without respiratory gating were obtained for one syringe and two vials with each volume of 3, 10, and 30 ml respectively. RPM (Real-Time Position Management, Varian) was used for tracking motion during PET/CT scanning. Ten datasets of RGPET and 4D-CT corresponding to every 10% phase intervals were acquired. from the positions, sizes, and uptake values of each subject on the resultant phase specific PET and CT datasets, the correlations between motion artifacts in PET and CT images and the size of motion relative to the size of subject were analyzed. Results: The center positions of three vials in RGPET and 4D-CT agree well with the actual position within the estimated error. However, volumes of subjects in non-gated PET images increase proportional to relative motion size and were overestimated as much as 250% when the motion amplitude was increased two times larger than the size of the subject. On the contrary, the corresponding maximal uptake value was reduced to about 50%. Conclusion: RGPET is demonstrated to remove respiratory motion artifacts in PET imaging, and moreover, more precise image fusion and more accurate attenuation correction is possible by combining with 4D-CT.

• International Journal of Naval Architecture and Ocean Engineering
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• v.6 no.2
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• pp.219-235
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• 2014

With the development of the technology of underwater moving bodies, the need for developing the knowledge of surface effect interaction of free surface and underwater moving bodies is increased. Hence, the two-phase flow is a subject which is interesting for many researchers all around the world. In this paper, the non-linear free surface deformations which occur during the water-exit of a circular cylinder due to its buoyancy are solved using finite volume discretization based code, and using Volume of Fluid (VOF) scheme for solving two phase flow. Dynamic mesh model is used to simulate dynamic motion of the cylinder. In addition, the effect of cylinder mass in presence of an external force is studied. Moreover, the oblique exit and entry of a circular cylinder with two exit angles is simulated. At last, water-exit of a circular cylinder in six degrees of freedom is simulated in 3D using parallel processing. The simulation errors of present work (using VOF method) for maximum velocity and height of a circular cylinder are less than the corresponding errors of level set method reported by previous researchers. Oblique exit shows interesting results; formation of waves caused by exit of the cylinder, wave motion in horizontal direction and the air trapped between the waves are observable. In 3D simulation the visualization of water motion on the top surface of the cylinder and the free surface breaking on the front and back faces of the 3D cylinder at the exit phase are observed which cannot be seen in 2D simulation. Comparing the results, 3D simulation shows better agreement with experimental data, specially in the maximum height position of the cylinder.

• Membrane and Water Treatment
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• v.4 no.3
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• pp.157-174
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• 2013

The present study is devoted to the validation of a new method for in line electrokinetic characterisation of deposits on membrane surfaces. This method is based upon simultaneous measurements of transversal streaming potential and permeates flux at constant pressure before and during the deposit formation. Dead-end filtration experiments were conducted with negative flat membranes forming a narrow slit channel, negative hollow fiber membranes and mono-dispersed suspensions of (negatively charged) polystyrene latex and (positively charged) melamine particles at various concentrations. It was observed that the overall streaming potential coefficient increased in absolute value with the deposited latex quantity, whereas it decreased and changed of sign during the filtration of melamine suspensions. By considering a resistance-in-series model, the streaming potential coefficient of the single deposit ($SP_d$) was deduced from the electrokinetic and hydraulic measurements. The independence of $SP_d$ with respect to growth kinetics validates the measurement method and the reliability of the proposed procedure for calculating $SP_d$. It was found that $SP_d$ levelled off much more quickly when filtration was performed through the slit channel. This different behaviour could result from a non-uniform distribution of the deposit thickness along the membrane given that the position of measuring electrodes is different between the two cells.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2003.11a
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• pp.17-20
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• 2003

The EMC's rheological effects on molding process are evaluated in this study. When considering mold processing for IC packages, the major concerning items in current studies are incomplete fill, severe wire sweeping and paddle shifts etc. To simulate EMC's fast curing rheokinetics with 3D mold flow behavior, one should select appropriate rheometry which characterize each EMC's rheological motion and finding empirical parameters for numerical analysis current studies present the new rheometry with parallel plate rheometry for reactive rheokinetic experiments, the experiment and numerical analysis is done with the commercial higher filler loaded EMC for the case of Thin Quad Plant Packages (TQFP) with package thickness below 1.0 mm. The experimental results and simulation results based on new rheometry matches well in point of the prediction of wire sweep, filling behavior of melt front advancement and void trapping position.

• Journal of the Korean Society of Propulsion Engineers
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• v.18 no.3
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• pp.78-83
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• 2014

A special part such as a flow passage opening device is required to prevent the disconnection of fuel transfer in a pressurized fuel tank. To meet this requirement, the device utilizing an acceleration follow-up technique was invented. RecurDyn, a dynamic analysis tool, is introduced in this article to predict the device's performance and to determine parameters affecting it. In the analysis, it is shown that balancing weights can open the passage in accordance with fuel position.

• Journal of Digital Convergence
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• v.13 no.7
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• pp.177-182
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• 2015

In a MPC(Multi-Pulse Coding) using excitation source of voiced and unvoiced, it would be a distortion of voice waveform. This is caused by normalization of synthesis speech waveform of voiced in the process of restoration. To solve this problem, this paper present APC-MPC of amplitude-position compensation in a multi-pulses each pitch interval in order to reduce distortion of synthesis waveform. Also, I was implemented that the APC-MPC in coding system. And I evaluate the SNRseg of APC-MPC in 8kbps coding condition of convergence system. As a result, SNRseg of APC-MPC was 13.9dB for female voice and 14.3dB for male voice respectively. And so, I expect to be able to this method for cellular phone and smart phone using excitation source of low bit rate.

• International Journal of Naval Architecture and Ocean Engineering
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• v.10 no.6
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• pp.730-740
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• 2018

Hydrofoil is the direct component to generate thrust for underwater glider. It is significant to improve propulsion efficiency of hydrofoil. This study optimizes the shape of a hydrofoil using Free-Form Deformation (FFD) parametric approach and Surrogate-based Optimization (SBO) algorithm. FFD approach performs a volume outside the hydrofoil and the position changes of control points in the volume parameterize hydrofoil's geometric shape. SBO with adaptive parallel sampling method is regarded as a promising approach for CFD-based optimization. Combination of existing sampling methods is being widely used recently. This paper chooses several well-known methods for combination. Investigations are implemented to figure out how many and which methods should be included and the best combination strategy is provided. As the hydrofoil can be stretched from airfoil, the optimizations are carried out on a 2D airfoil and a 3D hydrofoil, respectively. The lift-drag ratios are compared among optimized and original hydrofoils. Results show that both lift-drag-ratios of optimized hydrofoils improve more than 90%. Besides, this paper preliminarily explores the optimization of hydrofoil with root-tip-ratio. Results show that optimizing 3D hydrofoil directly achieves slightly better results than 2D airfoil.

• 대한방사선치료학회:학술대회논문집
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• 2005.06a
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• pp.13-17
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• 2005

Introduction : For stereotactic radiosurgery (SRS) of a tumor in the region whose movement due to respiration is significant, like Lung lower lobe, the gated therapy, which delivers radiation dose to the selected respiratory phases when tumor motion is small, was peformed using the Respiratory gating system and its clinical effectiveness was evaluated. Methode and Materials : For two SRS patients with a tumor in Lung lower lobe, a marker block (infrared reflector) was attached on the abdomen. While patient' respiratory cycle was monitored with Real-time Position Management (RPM, Varian, USA), 4D CT was performed (10 phases per a cycle). Phases in which tumor motion did not change rapidly were decided as treatment phases. The treatment volume was contoured on the CT images for selected treatment phases using maximum intensity projection (MIP) method. In order to verify setup reproducibility and positional variation, 4D CT was repeated. Result : Gross tumor volume (GTV) showed maximum movement in superior-inferior direction. For patient $\#$1, motion of GTV was reduced to 2.6 mm in treatment phases ($30\%\~60\%$), while that was 9.4 mm in full phases ($0\%\~90\%$) and for patient $\#$2, it was reduced to 2.3 mm in treatment phases ($30\%\~70\%$), while it was 11.7 mm in full phases ($0\%\~90\%$). When comparing two sets of CT images, setup errors in all the directions were within 3 mm. Conclusion : Since tumor motion was reduced less than 5 mm, the Respiratory gating system for SRS of Lung lower lobe is useful.