• 한국HCI학회:학술대회논문집
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• 2008.02a
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• pp.623-628
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• 2008

We present a new method of extracting foreground object from background image for vision-based game interface. Background Subtraction is an important preprocessing step for extracting the features of tracking objects. The image is divided into the cells where the Local Histogram with Gaussian kernel is computed and compared with the corresponding one using Bhattacharyya distance measure. The histogram-based method is partially robust against illumination change, noise and small moving objects in background. We propose a Multi-Scaled Integral Histogram approach for noise suppression and fast computation.

• Journal of Satellite, Information and Communications
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• v.8 no.4
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• pp.159-163
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• 2013

In this paper, we propose a new method to deinterleave multi-stage stagger PRI signals of pulse radars using the electronic intelligence systems. While former algorithms were based on hardware PRI tracker only using the first deviation of the TOA of radar signals, this paper uses the first and the second deviation of TOA of radar signals and uses the PRI histogram method to deinterleave multiple PRIs of pulse radars. This algorithm can be used for deinterleaving various PRI signals at electronic intelligence systems.

• Proceedings of the KIEE Conference
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• 2005.10b
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• pp.619-621
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• 2005

This paper proposes apractical design method for ship-to-ship missiles' autopilot. When the pre-designed analogue autopilot is implemented in digital way, theygenerally suffer from severe performance degradation and instability problem even for a sufficiently small sampling time. Also, aerodynamic uncertainties can affect the overall stability and this happens more severely when the nonlinear autopilot is digitally implemented. In order to realize a practical autopilot, two main issues, digital implementation problem and compensation for the aerodynamic uncertainties, are considered in this paper. MIMO (multi-input multi-output) nonlinear autopilot is presented first and the input and output of the missile are discretized for implementation. In this step, the discretization effect is compensated by designing an additional control input. Finally, we design a parameter adaptation law to compensate the control performance. Stability analysis and 6-DOF (degree-of-freedom) simulations are presented to verify the proposed adaptive autopilot.

• 유체기계공업학회:학술대회논문집
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• 2001.11a
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• pp.177-184
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• 2001

For two kinds of the multi-stage centrifugal pump with diffuser vanes and return channel vanes the meanline performance prediction is applied to get information of hydraulic performance at each internal flow station, because only flange-to-flange test curves are available. As a first step of redesign fur higher efficiency, the impeller geometry is numerically investigated in the present study. Quasi-3D inviscid loading distributions are obtained, for the two impellers, using the state-of-the-art method of impeller 3D design, which provides a guide to optimal redesign. Full 3D turbulent flow fields are thereafter analyzed, using the specialized CFD code, to confirm the redesign results. The inherent limitation of the traditional graphic method of impeller design, which most of domestic pump manufacturers are now employing, is found.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.3
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• pp.301-306
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• 2006

The electron drift velocity W and the product of the longitudinal diffusion coefficient and the gas number density $ND_{L}$ in the $0.525\;\%$ and $5.05\;\%$ $C_{3}F_8-Ar$ mixtures were measured by using the double shutter drift tube with variable drift distance over the E/N range from 0.03 to 100 Td and gas pressure range from 1 to 915 torr. And we determined the electron collision cross sections set for the $C_{3}F_8$ molecule by STEP 1 of electron swarm method using a multi-term Boltzmann equation analysis. Our special attention in the present study was focused upon the vibrational excitation and new excitations cross sections of the $C_{3}F_8$ molecule.

• Journal of International Society for Simulation Surgery
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• v.3 no.1
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• pp.9-11
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• 2016

Purpose In this paper we proposed bi-directional hierarchical regression for accurate human finger landmark detection with only using depth information.Materials and Methods Our algorithm consisted of two different step, initialization and landmark estimation. To detect initial landmark, we used difference of random pixel pair as the feature descriptor. After initialization, 16 landmarks were estimated using cascaded regression methods. To improve accuracy and stability, we proposed bi-directional hierarchical structure.Results In our experiments, the ICVL database were used for evaluation. According to our experimental results, accuracy and stability increased when applying bi-directional hierarchical regression more than typical method on the test set. Especially, errors of each finger tips of hierarchical case significantly decreased more than other methods.Conclusion Our results proved that our proposed method improved accuracy and stability and also could be applied to a large range of applications such as augmented reality and simulation surgery.

• Smart Media Journal
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• v.7 no.1
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• pp.31-36
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• 2018

In this paper, we propose automatic screen on / off method of OST-HMD screen using gaze depth estimation technique. The proposed method uses MLP (Multi-layer Perceptron) to learn the user's gaze information and the corresponding distance of the object, and inputs the gaze information to estimate the distance. In the learning phase, eye-related features obtained using a wearable eye-tracker. These features are then entered into the Multi-layer Perceptron (MLP) for learning and model generation. In the inference step, eye - related features obtained from the eye tracker in real time input to the MLP to obtain the estimated depth value. Finally, we use the results of this calculation to determine whether to turn the display of the HMD on or off. A prototype was implemented and experiments were conducted to evaluate the feasibility of the proposed method.

• Transactions of the Korean Society of Automotive Engineers
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• v.16 no.6
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• pp.74-80
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• 2008

A combustion of CAI engine is purely dominated by fuel chemical reactions. In order to simulate the combustion of CAI engine, it should be considered the effect of fuel components and chemical kinetics. So it needs enormous computational power. To overcome this problem reduced problem of needing massive computational power, chemical kinetic mechanism and multi-zone method is proposed here in this paper. A reduced chemical kinetic mechanism for a gasoline surrogate was used in this study for a CAI combustion. This gasoline surrogate was modeled as a blend of iso-octane, n-heptane, and toluene. For the analysis of CAI combustion, a multi-zone method as combustion model for a CAI engine was developed and incorporated into the computational fluid dynamics code, STAR-CD, for computing efficiency. This coupled multi-zone model can calculate 3 dimensional computational fluid dynamics and multi-zoned chemical reaction simultaneously in one time step. In other words, every computational cell interacts with the adjacent cells during the chemical reaction process. It can enhance the reality of multi-zone model. A greatly time-saving and yet still relatively accurate CAI combustion simulation model based on the above mentioned two efficient methodologies, is thus proposed.

• Nuclear Engineering and Technology
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• v.55 no.6
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• pp.2172-2194
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• 2023

A variational nodal method (VNM) with unstructured-mesh is presented for solving steady-state and dynamic neutron diffusion equations. Orthogonal polynomials are employed for spatial discretization, and the stiffness confinement method (SCM) is implemented for temporal discretization. Coordinate transformation relations are derived to map unstructured triangular nodes to a standard node. Methods for constructing triangular prism space trial functions and identifying unique nodes are elaborated. Additionally, the partitioned matrix (PM) and generalized partitioned matrix (GPM) methods are proposed to accelerate the within-group and power iterations. Neutron diffusion problems with different fuel assembly geometries validate the method. With less than 5 pcm eigenvalue (k_eff) error and 1% relative power error, the accuracy is comparable to reference methods. In addition, a test case based on the kilowatt heat pipe reactor, KRUSTY, is created, simulated, and evaluated to illustrate the method's precision and geometrical flexibility. The Dodds problem with a step transient perturbation proves that the SCM allows for sufficiently accurate power predictions even with a large time-step of approximately 0.1 s. In addition, combining the PM and GPM results in a speedup ratio of 2-3.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.5
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• pp.9-16
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• 2018

Images with lower illumination from the light source or with dark regions due to shadows, etc., can improve subjective image quality by using retinex-based image enhancement schemes. The retinex theory is a method that recognizes the relative lightness of a scene, rather than recognizing the brightness of the scene. The way the human visual system recognizes a scene in a specific position can be in one of several methods: single-scale retinex, multi-scale retinex, and multi-scale retinex with color restoration (MSRCR). The proposed method is based on the MSRCR method, which includes a color restoration step, which consists of three phases. In the first phase, the existing MSRCR method is applied. In the second phase, the dynamic range of the MSRCR output is adjusted according to its histogram. In the last phase, the proposed method transforms the retinex output value into the display dynamic range using a logarithm transformation function considering human visual system characteristics. Experimental results show that the proposed algorithm effectively increases the subjective image quality, not only in dark images but also in images including both bright and dark areas. Especially in a low lightness image, the proposed algorithm showed higher performance improvement than the conventional approaches.