• Transactions on Control, Automation and Systems Engineering
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• 제4권1호
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• pp.92-99
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• 2002

To obtain visual information of a target object, a camera should be placed within the visibility region. As the visibility region is dependent on the relative position of the target object and the surrounding object, the position change of the surrounding object during a task requires recalculation of the visibility region. For a fast computation of the visibility region so as to modify the camera position to be located within the visibility region, we propose a spherical projection method. After being projected onto the sphere the visibility region is represented in $\theta$-$\psi$ spaces of the spherical coordinates. The reduction of calculation space enables a fast modification of the camera location according to the motion of the surrounding objects so that the continuous observation of the target object during the task is possible.

• 한국방사선학회논문지
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• 제3권3호
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• pp.23-25
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• 2009

Gd-157 material has very large neutron capture cross section in the thermal region. So it is very useful to shield material for thermal neutrons. Futhermore, in the neutron capture experiment and calculation, the neutron absorption and scattering are very important. Especially these effects are conspicuous in the resonance energy region and below the thermal energy region. In the case of very narrow resonance, the effect of scattering is to be more considerable factor. In the present study, we obtained energy dependent neutron absorption ratios of natural indium in energy region from 0.003 to 100 keV by MCNP-4B Code. The coefficients for neutron absorption was calculated for circular type and 1 mm thickness. In the lower energy region, neutron absorption is larger than higher region, because of large capture cross section (1/v). Furthermore it seems very different neutron absorption in the large resonance energy region. These results are very useful to decide the thickness of sample and shielding materials.

• 한국멀티미디어학회논문지
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• 제23권5호
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• pp.633-640
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• 2020

Defect region segmentation of TFT-LCD images is performed by combining defect pixels detected by a defect detection method into defect region, or by using morphological operations to segment defect region. Therefore, the result of segmentation of the defect region is highly dependent on the defect detection result. In this paper, we propose a method which segments defect regions sequentially according to the possibility of being included in defect regions in TFT-LCD images. The proposed method repeats the process of detecting a seed using the median value and the median absolute deviation of the image, and segments the defect region using the seeded region growing method. We confirmed the superiority of the proposed method to segment defect regions using pseudo-images and real TFT-LCD images.

• 한국컴퓨터산업학회논문지
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• 제3권12호
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• pp.1669-1678
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• 2002

대칭 영역 탐색은 대칭 정보를 이용하여 사전 정보없이 얼굴영역을 추출 할 수 있다. 그러나 눈, 코, 입등과 같은 얼굴의 특징 부위보다 탐색할 마스크의 크기가 커져야 함으로 이 방법은 계산 시간이 많이 걸린다. 본 논문에서는 얼굴 영상에 대하여 사전 정보 없이, 적은 계산량으로 얼굴 영역 추출이 간으하도록 대칭 영역 탐색을 이용한 축소 영상에서의 얼굴 영역의 추출과 그 특징에서의 대칭값에 따른 영상을 이용하여 원영상에서는 영역 분할을 통한 얼굴 영역 추출 방법을 제안하고 실험을 통하여 이를 확인하였다.

• 대한의용생체공학회:의공학회지
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• 제10권3호
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• pp.331-342
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• 1989

This paper presents a new algorithm that extracts lung region in X-Rays and enhance.j the region. Comparing to prior algorithms that enhance whole X-Ray image, this algorithm leads more effective results. For this algorithm extracts lung region first, and enhances the lung region excluding parameters of other region. For choosing optimal threshold, we compare OTSU's mothod with the proposed method. We obtain lung boundary using contour following algorithm and Rray level searching method in gray level rescaled image. We Process histogram equalization in lung region and obtain enhanced lung image. By using the proposed algorithm, we obtain lung region effectively in chest X-Ray that need in medical image diagnostic system.

• Structural Engineering and Mechanics
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• 제57권4호
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• pp.587-602
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• 2016

In structural reliability analysis, the response surface method is widely adopted because of its numerical efficiency. It should be understood that the response function must approximate the actual limit state function accurately in the main region influencing failure probability where it is evaluated. However, the size of main region influencing failure probability was not defined clearly in current response surface methods. In this study, the concept of sub-region of interest is constructed, and an improved response surface method is proposed based on the sub-region of interest. The sub-region of interest can clearly define the size of main region influencing failure probability, so that the accuracy of the evaluation of failure probability is increased. Some examples are introduced to demonstrate the efficiency and the accuracy of the proposed method for both numerical and implicit limit state functions.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년도 춘계학술대회논문집
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• pp.130-133
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• 2008

In this paper the trust region method is studied and applied in aerodynamic shape optimization. The trust region method is a gradient-based optimization method, but it is not as popular as other methods in engineering computations. Its theory will be explained for unconstrained optimization problems and a trust region subproblem will be solved with the dogleg method. After verifying the trust region method with analytical test problems, it is applied to aerodynamic shape design optimization and the performance of airfoil is improved successfully.

• 한국멀티미디어학회논문지
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• 제18권2호
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• pp.138-148
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• 2015

Object detection methods based on background learning are widely used in video surveillance. However, when a car runs with headlights on, these methods are likely to detect the car region and the area illuminated by the headlights as one connected change region. This paper describes a method of separating the car region from the area illuminated by the headlights. First, we detect change regions with a background learning method, and extract blobs, connected components in the detected change region. If a blob is larger than the maximum object size, we extract candidate object regions from the blob by clustering the intensity histogram of the frame difference between the mean of background images and an input image. Finally, we compute the similarity between the mean of background images and the input image within each candidate region and select a candidate region with weak similarity as an object region.

• Journal of Welding and Joining
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• 제8권3호
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• pp.79-88
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• 1990

Welded joint often contains soft or softened regions such as the HAZ of TMCP steel welded with high heat input. In this study, the equivalent yield strength of plate structure containing softened region was predicted by FEM analysis, and its incremental behavior was explained with the results of the analysis. The calculated results of yield strength indicated the following for the plate structures. 1) As the softened region starts to yield, shear stress begins to build up along the boundary between base metal and softened region. This results in multi-axial stress condition which gives restraint on the softened region. 2) Restraint effect has a significant influence on the distribution of the shear stress, the nominal stress, and the strain. 3) The yielding behavior of softened region becomes the same as that of base metal when both ratios of length to width and thickness to width of softened region are larger than 30 and 13 respectively.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2003년도 학술대회지
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• pp.329-334
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• 2003

Design of pre-compression region(trapping region) of the valve plate is an important element to minimize the pressure fluctuation in a cylinder and in discharge process, and pump noise. In this study, we tried to prove what the characteristics of the oil hydraulic pump would be according to the angle of the trapping region. Three kinds of asymmetrical valve plates were used. As a result, we found that by designing the trapping region, the slope of the pressure rise in the cylinder port from low-pressure suction region to high-pressure discharge region is relaxed and the pressure fluctuation width and the discharge pressure pulsation are reduced. Therefore, because the pump gets smooth pressure fluctuation and low fluid Impact, the pump noise is reduce.