• Korean Journal of Computational Design and Engineering
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• v.11 no.3
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• pp.164-171
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• 2006

As collaborative design and configuration design are of increasing importance in product development, it becomes essential to exchange the feature and parametric CAD models among participants. A history-based parametric method has been proposed and implemented. But each translator which exchanges the feature and parametric information tends to be heavy because to implement duplicated functions such as the identification of the selected geometries, mapping between features which have different attributes. Furthermore. because the history-based parametric translator uses the procedural model as the neutral format, which is the XML macro file, the history-based parametric translators need a geometric modeling kernel to generate an internal explicit geometric model. To ease the problem, we implemented a shared integration platform, the TransCAD. The TransCAD separates translators from the XML macro files. The translators for various CAD systems need to communicate with only the TransCAD. To support the communication with the TransCAD, we exposed the functions of the TransCAD by using the Automation APIs, which is developed by Microsoft. The Automation APIs of the TransCAD consist of the part modeling functions, the data extraction functions, and the utility functions. Each translator uses these functions to translate a parametric CAD model from the sending CAD system into the XML format, or from the in format into the model of the receiving CAD system This paper introduces what the TransCAD is and how it works for the exchange of the feature and parametric models.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.05a
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• pp.315-319
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• 2009

Investigation of the lateral force fluctuations in an axisymmetric overexpanded compressed truncated perfect (CTP) nozzle for the shutdown transient is presented. These nozzles experience side-loads during start-up and shut-down operations, because of the flow separation at nozzle walls. Two types of flow separations such as free shock separation (FSS) and restricted shock separation (RSS) shock structure occur. A two-dimensional unsteady numerical simulation has been carried out over an axisymmetric CTP nozzle to simulate the lateral force fluctuations in nozzle during shutdown process. Reynolds Averaged Navier-Stokes equations are numerically solved using a fully implicit finite volume scheme. Governing equations are solved by coupled implicit scheme. Two equation k-$\omega$ SST turbulence model is selected. Unsteady pressure is measured at four locations along the nozzle wall. Present pressure variation compared well with the experimental data. During shutdown transient, separation pattern varies from FSS to RSS and finally returns to FSS. Several pressure peaks are observed during the RSS separation pattern. These pressure peaks generate lateral force or side loads in rocket nozzle.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.37 no.1
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• pp.11-20
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• 2000

This paper presents the method of extracting the contour and shape parameters for moving object tracking in traffic scenes. The contour is extracted by applying difference image method in reduction image and the features are extracted from original image to grow the accuracy of tracking. We used features such as circle distribution, center moment, and maximum and minimum ratio. Data association problem is solved by these features. Kalman filters are used for moving object tracking on real time. The simulation results indicate that the proposed algorithm appears to generate feature vectors good enough for multiple vehicle tracking.

• International Journal of Advanced Culture Technology
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• v.8 no.3
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• pp.284-290
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• 2020

In this paper, we propose a method to generate and optimize the height map that is suitable to render a soap bubble. The height map represents the flow speed of soap bubbles. To this end, we have analyzed the flow of the soap bubble surface through experiment, derived the moving speed value for each section. Some image filters have been used for optimization that reflects the parameters of the derived height map. In addition, in order to verify the results of the study, actual data measuring the surface flow speed of soap bubbles, the speed of the initial height map, and the optimized height map speed have been compared and tested. Through this study, we reach the issue that it is possible to express the variable flow speed of soap bubbles with the optimized height map, and it will help to express various fluids.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.3
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• pp.1595-1613
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• 2017

The IR camera and laser-based IR projector provide an effective solution for real-time collection of moving targets in RGB-D videos. Different from the traditional RGB videos, the captured depth videos are not affected by the illumination variation. In this paper, we propose a novel feature extraction framework to describe human activities based on the above optical video capturing method, namely spatial-temporal texture features for 3D human activity recognition. Spatial-temporal texture feature with depth information is insensitive to illumination and occlusions, and efficient for fine-motion description. The framework of our proposed algorithm begins with video acquisition based on laser projection, video preprocessing with visual background extraction and obtains spatial-temporal key images. Then, the texture features encoded from key images are used to generate discriminative features for human activity information. The experimental results based on the different databases and practical scenarios demonstrate the effectiveness of our proposed algorithm for the large-scale data sets.

• Journal of Ocean Engineering and Technology
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• v.12 no.3 s.29
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• pp.86-95
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• 1998

CAD/CAM program developers have made substantial progress in enabling engineers to design, analyze, visualize, visualize, and simulate the performance of structures and systems. Many researchers, however, agree that there is still a way to go before the existing commercial computer software can be used in ship structural analysis to their full potential as solvers which can identify opportunities to reduce man-hours and cut costs. CAD systems used for these works in ship yards are general-purposed and not custom-tailored for ship structures, which force end-users to do tiresome and routine works. The new preprocessor "MeshGen" announced in this study can load several ship types and user-friendly generate their FE meshes employing the object-oriented approach based on the parametric and top-down design. Also "MeshGen" reduces dramatically the time required to prepare CAD models under window-based environments on desktop personal computers and makes it much easier and faster for end-users to change topology and material properties.

• Journal of Korean Association for Spatial Structures
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• v.6 no.2 s.20
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• pp.93-105
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• 2006

In order to investigate the effect of the height of application point of lateral loads and reinforcing steel bars in walls and columns in improving the seismic behavior of confined concrete block masonry walls, an experimental research program is conducted. A total of twelve one-half scale specimens are tested under repeated lateral loads. Specimens are tested to failure with increasing maximum lateral drifts while a vertical axial load was applied and maintained constant. The specimens adopted are two-dimensional (2D) hollow concrete block masonry walls with different parameters such as shear span ratio, inflection point and percent of reinforcement in confining columns and walls. Test results obtained for each specimen include cracking patterns, load-deflection curve, and strains in reinforcement and walls in critical locations. Analysis of test data showed that above parameters generate a considerable effect on the seismic performance of confined concrete block masonry walls.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.1 no.1
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• pp.87-94
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• 2001

Silicon nitride films grown by plasma-enhanced chemical vapor deposition (PECVD) are useful for a variety of applications, including anti-reflecting coatings in solar cells, passivation layers, dielectric layers in metal/insulator structures, and diffusion masks. PECVD systems are controlled by many operating variables, including RF power, pressure, gas flow rate, reactant composition, and substrate temperature. The wide variety of processing conditions, as well as the complex nature of particle dynamics within a plasma, makes tailoring SiN film properties very challenging, since it is difficult to determine the exact relationship between desired film properties and controllable deposition conditions. In this study, SiN PECVD modeling using optimized neural networks has been investigated. The deposition of SiN was characterized via a central composite experimental design, and data from this experiment was used to train and optimize feed-forward neural networks using the back-propagation algorithm. From these neural process models, the effect of deposition conditions on film properties has been studied. A recipe synthesis (optimization) procedure was then performed using the optimized neural network models to generate the necessary deposition conditions to obtain several novel film qualities including high charge density and long lifetime. This optimization procedure utilized genetic algorithms, hybrid combinations of genetic algorithm and Powells algorithm, and hybrid combinations of genetic algorithm and simplex algorithm. Recipes predicted by these techniques were verified by experiment, and the performance of each optimization method are compared. It was found that the hybrid combinations of genetic algorithm and simplex algorithm generated recipes produced films of superior quality.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.5
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• pp.872-878
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• 2003

In this paper, we developed a simulator which can generate the polarization waves for the indoor wireless communications based on three dimensional ray tracing technique and verified the simulation results comparing with the measured data in indoor wireless propagation environments. Using the developed simulator, we analyzed the channel characteristic and polarization diversity reception characteristic for the vertical, horizontal and circularly polarized waves. From the analysis results, in the case of using circularly polarized wave it can be clearly seen that the multipath fading is markedly reduced compared to the vertical and horizontal polarized waves due to the reception characteristic of removing the odd time reflected waves.

• Journal of information and communication convergence engineering
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• v.1 no.4
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• pp.183-188
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• 2003

The $4^{th}$ generation mobile communications, through several radio access networks such as WLAN, Bluetooth, UMTS, GPRS, CDMA 1X, and IMT-2000 in the same area offering different type of coverage, will support interactive multimedia services in additions to wider bandwidths, higher bit rates, and service portability. Regardless of various radio access networks, they will also support robust security mechanisms, as well as seamless mobility and common authentication. In this paper, we give an overview of WLAN security and examine its security problems. We also explain the enhanced security schemes, such as port-based authentication, EAP, and IEEE 802.1X. For secure wireless communications, several possible security solutions are offered and evaluated in various respects to improve WLAN security. This paper will make a contribution to provide more secure wireless communications to cellular operators embracing WLAN technology as a means to generate new revenues based on data services.