• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.3
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• pp.1035-1039
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• 2010

Activation products generated by photoneutrons in concrete shielding wall around electron linac were estimated for a high energy X-ray container cargo inspection system. Monte carlo code, MCNPX2.5.0 was used for reference system of 9MeV fixed type dual-direction container cargo inspection system installed at major harbors in Korea. Activation products inventory generated by photoneutron (n,$\gamma$) reaction are estimated, and then radiation dose rate is calculated from the results.

• Journal of Biomedical Engineering Research
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• v.21 no.5
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• pp.527-535
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• 2000

For a reliable patient set-up verification, better portal films are needed to track relevant features. Simulator films are compared with portal films as a reference image in radiotherapy planning. This shows some possibilities of the use of image information of simulator images for enhancement and restorations of portal images which are very poor in quality compared with the simulator images. This paper present an approach that combine an associative memory, a kind of artificial neural networks with fuzzy image enhancement technique using genetic algorithm which determines the fuzzy region of membership function by the use of maximum entropy principles. A higher portal image quality than conventional technique is achieved.

• KIPS Transactions on Computer and Communication Systems
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• v.5 no.9
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• pp.237-246
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• 2016

DIBR (Depth Image Based Rendering) is a multimedia technology that generates the virtual multi-view images using a color image and a depth image, and it is used for creating glasses-less 3-dimensional display contents. This research describes the effect of depth accuracy about the objective quality of DIBR-based multi-view images. It first evaluated the minimum depth quantization bit that enables the minimum distortion so that people cannot recognize the quality degradation. It then presented the comparative analysis of non-uniform domain-division quantization versus regular linear quantization to find out how effectively express the accuracy of the depth information in same quantization levels according to scene properties.

• The KIPS Transactions:PartB
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• v.15B no.5
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• pp.477-486
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• 2008

Facial expression, which changes face geometry, usually has an adverse effect on the performance of a face recognition system. To improve the face recognition rate, we propose a normalization method of facial expression to diminish the difference of facial expression between probe and gallery faces. Two approaches are used to facial expression modeling and normalization from single still images using a generic facial muscle model without the need of large image databases. The first approach estimates the geometry parameters of linear muscle models to obtain a biologically inspired model of the facial expression which may be changed intuitively afterwards. The second approach uses RBF(Radial Basis Function) based interpolation and warping to normalize the facial muscle model as unexpressed face according to the given expression. As a preprocessing stage for face recognition, these approach could achieve significantly higher recognition rates than in the un-normalized case based on the eigenface approach, local binary patterns and a grey-scale correlation measure.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.3
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• pp.289-297
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• 2011

The explicit finite element method is an essential tool for solving large problems with severe nonlinear characteristics, but its results can be difficult to interpret. In particular, it can be impossible to evaluate its acceleration responses because of severe discontinuity, extreme noise or aliasing. We suggest a new post-processing method for transient responses and their response spectra. We propose smoothing methods using a Gaussian kernel without in depth knowledge of the complex frequency characteristics; such methods are successfully used in the filtering of digital signals. This smoothing can be done by measuring the velocity results and monitoring the response spectra. Gaussian kernel smoothing gives a better smoothness and representation of the peak values than other approaches do. The floor response spectra can be derived using smoothed accelerations for the design.

• Journal of Korean Society of Steel Construction
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• v.12 no.1 s.44
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• pp.65-73
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• 2000

The behavior of double angle connections is analyzed by 3D finite element method using ABAQUS(ver 5.8). Moment-rotation curves for the connections are generated, as well as stress distribution for angle and bolt. Double angle connections have various angle thickness, gage distance and number of bolt. Parameters, such as initial stiffness, plastic tiffness, reference load and curve shape parameter were obtained by regression method using Richard's formula. These parameter lead to predict nonlinear behavior of double angle connection. Design curves giving the parameters of the moment-rotation curves are generated. These parameters are primarily a function of the angle thickness, gage distance and the number of bolts in the connection. Using these parameters, connection moment and its ratio to the full plastic moment capacity Mp of the beam are calculated.

• Journal of Broadcast Engineering
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• v.14 no.1
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• pp.3-14
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• 2009

Currently, H.264/AVC is used in many multimedia applications. Also, The MPEG-2 main profile which supports B pictures for bi-directional motion prediction is widely used in applications such as HDTV and DVD’s. Therefore, transcoding the MPEG-2 main profile to the H.264/AVC baseline is necessary for universal multimedia access. In this transcoding architecture including the GOP structure conversion, the proposed algorithms adopt the adaptive search range selection through the linearity test of a predictive motion vector and adaptive mode selection using the reference region complexity information. The proposed algorithms extremely reduce the computational complexity while maintaining the video quality.

• Journal of Korea Multimedia Society
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• v.1 no.1
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• pp.26-36
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• 1998

It is very important study field in computer vision 'How we obtain 3D information from 2D image'. For this purpose, we must know position of camera, direction of light source, and surface reflectance property before we take the image, which are intrinsic information of the object in the scene. Among them, surface reflectance property presents very important clues. Most previous researches assume that objects have only Lambertian reflectance, but many real world objects have Non-Lambertian reflectance property. In this paper the new method for analyzing the properties of surface reflectance and reconstructing the shape of object through estimation of reflectance parameters is proposed. We have interest in Non-Lambertian reflectance surface that has specular reflection and diffuse reflection which can be explained by Torrance-Sparrow model. Photometric matching method proposed in this paper is robust method because it match reference image and object image considering the neighbor brightness distribution. Also in this thesis, the neural network based shaped reconstruction method is proposed, which can be performed in the absence of reflectance information. When brightness obtained by each light is inputted, neural network is trained by surface normal and can determine the surface shape of object.

• The Transactions of the Korean Institute of Power Electronics
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• v.5 no.4
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• pp.309-317
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• 2000

This paper presents the switching angle and voltage to maximize torque/efficiency and minimize torque ripple in the 4-phase 6-poles Switched Reluctance Motor(SRM). SRM drive has high saturation and nonlinear characteristics of inductance. So we cannot hard to find optimal condition by using analytic method. Therefore it is hard to find the operating the switching angle and voltage through the approximated analysis and computer simulation by using SIMULINK according to the speed and torque required by load. From the results, we can say that the optimum average voltage is determined by the load only and the speed is determined by the optimum turn-on/off angle only. And the maximum efficiency and minimum torque ripple depend on switching angle, not on voltage. And then one-chip microcontroller controls the switching angle and voltage of an asymmetrical inverter in the SRM driver. This drive method, which is expect that the driving methods, which are maximizing torque/efficiency and minimizing torque ripple, will be suitable for the electric vehicle, the industrial application and household appliances.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.26 no.4
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• pp.443-452
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• 2008

To deduce 3D linear information which express shapes of buildings out of airphoto by fusion of airphoto and LiDAR data, this research went through 2 process. First, research made LiDAR data into projected data of 2D based on airphoto. For this, the virtual points were added to solve the visual problem of building boundary area which has poor information because the attribute in LiDAR data. Research construct irregular triangular nets from modified LiDAR data and judge visual triangular nets out of image. Through this, research can make reference to information of triangular nets in each image pixel. Second, 3D information was extracted from stereo images segments by combining extracted information of visible region and 2D irregular triangular nets. Matching way based on TIN for segments from stereo images was used. Matching condition based on TIN can improve about 20% of edge matching accuracy compared to existing quadrilateral condition of epipolar geometry.