• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.8A
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• pp.679-688
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• 2012

In this paper, performance improved hole-filling algorithm including boundary noise removing pre-process which can be used for an arbitrary view synthesis with given two views is proposed. Boundary noise usually occurs because of the boundary mismatch between the reference image and depth map and common-hole is defined as the occluded region. These boundary noise and common-hole created while synthesizing a virtual view result in some defects and they are usually very difficult to be completely recovered by using only given two images as references. The spiral weighted average algorithm gives a clear boundary of each object by using depth information and the gradient searching algorithm is able to preserve details. In this paper, we combine these two algorithms by using a weighting factor ${\alpha}$ to reflect the strong point of each algorithm effectively in the virtual view synthesis process. The experimental results show that the proposed algorithm performs much better than conventional algorithms.

• Journal of the Korean Society for Nondestructive Testing
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• v.17 no.4
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• pp.237-247
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• 1997

A geometrical inverse heat conduction problem is solved for the infrared scanning cavity detection by the boundary element method using minimal energy technique. By minimizing the kinetic energy of temperature field, boundary element equations are converted to the quadratic programming problem. A hypothetical inner boundary is defined such that the actual cavity is located interior to the domain. Temperatures at hypothetical inner boundary are determined to meet the constraints of mea- surement error of surface temperature obtained by infrared scanning, and then boundary element analysis is peformed for the position of an unknown boundary (cavity). Cavity detection algorithm is provided, and the effects of minimal energy technique on the inverse solution method are investigated by means of numerical analysis.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38C no.5
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• pp.409-419
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• 2013

Kinect released by Microsoft in November 2010 is a motion sensing camera in xbox360 and gives depth and color images. However, Kinect camera also generates holes and noise around object boundaries in the obtained images because it uses infrared pattern. Also, boundary flickering phenomenon occurs. Therefore, we propose a real-time virtual-view video synthesis algorithm which results in a high-quality virtual view by solving these problems. In the proposed algorithm, holes around the boundary are filled by using the joint bilateral filter. Color image is converted into intensity image and then flickering pixels are searched by analyzing the variation of intensity and depth images. Finally, boundary flickering phenomenon can be reduced by converting values of flickering pixels into the maximum pixel value of a previous depth image and virtual views are generated by applying 3D warping technique. Holes existing on regions that are not part of occlusion region are also filled with a center pixel value of the highest reliability block after the final block reliability is calculated by using a block based gradient searching algorithm with block reliability. The experimental results show that the proposed algorithm generated the virtual view image in real-time.

• Information and Communications Magazine
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• v.31 no.3
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• pp.96-102
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• 2014

지난 반세기 동안 전세계 통신 기술은 기지국-셀간 1:1 대응을 기반으로 설계 되고 만들어 졌다. 이에 따라 셀 간 경계에서의 통신 품질 저하는 당연한 현상으로 받아 들여졌다. 이와 같은 전제 하에 무선 경계에서 통신 품질 향상을 목표로 다양한 스케줄링 기법, ICIC, eICIC[1] 등의 간섭 회피 기법등이 연구 되었다. 하지만 이러한 방식은 기지국간 정보 공유의 제한과 delay에 의해서 실용성이 현저히 떨어진다. 이를 극복하기 위해 모든 정보를 공유하는 가상화(cloud) 기술이 대안으로 떠오르고 있다. 현재 국내 통신 사업자인 KT는 LTE통신망에 가상화 기술을 적용하여 세계 최초로 가상화 기반 LTE 통신서비스를 제공하고 있다. 이에 본고에서는 현재 구현되어 있는 가상화 기술과 현황, 앞으로 구현될 기술에 대해서 알아본다.

• Journal of computational fluids engineering
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• v.18 no.3
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• pp.34-41
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• 2013

We develop a novel immersed boundary (IB) method based on implicit direct forcing scheme for incompressible flows. The proposed IB method is based on an iterative procedure for calculating the direct forcing coupled with the momentum equations in order to satisfy no-slip boundary conditions on IB surfaces. We perform simulations of two-dimensional flows over a circular cylinder for low and moderate Reynolds numbers. The present method shows that the errors for estimated velocities on IB surfaces are significantly reduced even for low Reynolds number with a fairly large time step while the previous methods based on direct forcing failed to provide no-slip boundary conditions on IB surfaces.

• Journal of Broadcast Engineering
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• v.21 no.6
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• pp.878-888
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• 2016

This paper proposes an efficient method to remove the boundary artifacts of rendered views caused by damaged depth maps in the 3D video system. First, characteristics of boundary artifacts with the compression noise in depth maps are carefully studied. Then, the artifacts suppression method is proposed by the iterative projection onto convex sets (POCS) algorithm with setting the convex set in pixel and frequency domain. The proposed method is applied to both texture and depth maps separately during view rendering. The simulation results show the boundary artifacts are greatly reduced with improving the quality of synthesized views.

• Journal of Korean Society of Steel Construction
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• v.12 no.2 s.45
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• pp.221-230
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• 2000

Checking the stability of anisotropic plates with free edges, it is impossible that buckling loads and modes are found via existing classical methods about various loads and boundary conditions. For solving this problems. finite difference method(FDM) is used to analyze the buckling behaviors for arbitrary boundary conditions. Using FDM, it is difficult to treat the fictitious points on free edges. So, this paper analyzes buckling behaviors of analytic models with one edge free and the other edges clamped and with opposite two edges free and other two edges clamped. The various buckling loads and mode characteristics through numerical results are given for buckling behaviors of anisotropic plates on free edges.

• Progress in Medical Physics
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• v.15 no.3
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• pp.167-172
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• 2004

A Siemens HD-270 MLC$^{TM}$, a virtual-micro MLC, allows to the application of a smooth field edge method due to the finite leaf-width of MLC. This technique was implemented into a Pinnacle planning system in order to evaluate the dose distributions during the planning stage. The necessary dosimetric aspects, such as undulation and effective penumbra, were investigated with variations in the resolutions of a virtual-micro MLC and field edge angle. The positional accuracy of the couch movement was also assessed for clinical implementation. The overhead time for planning and treatment was confirmed as negligible.e.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.10C
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• pp.981-990
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• 2006

In this paper, we introduce the concept of a subcarrier-based virtual multiple antennas (SV-MIMO) for OFDM cellular systems, where the multiple antenna techniques are performed on a set of subcarriers, not on the actual multiple antennas. The virtual multiple antenna system can support multiple users simultaneously as well as reduce inter-cell interference (ICI) form adjacent cells with a single antenna. Also, this technique is easily extended to multiple antenna environments. The virtual multiple antenna techniques can be divided into a virtual smart antenna technique and a virtual MIMO technique. Especially, this method effectively reduces ICI at cell boundary with frequency reuse factor equal to 1, and can support flexible resource allocation depending on the amount of interference. It is shown by simulation that the proposed method is superior to conventional method under the same condition of data transmission.

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.494-494
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• 2023

수치모형을 활용하여 하천 흐름을 해석하기 위해서는 하도의 형태를 나타내는 지형자료가 요구되며, 주흐름 방향에 직각 방향으로의 횡단면도는 다량의 자료가 필요하다. 측량을 통한 횡단면도의 확보는 시간과 비용이 많이 소요될 뿐 아니라 날씨와 같은 외부적 요인에 따라 측량 결과물의 정확도가 달라질 수 있다. 또한 하천의 유속이 매우 빠를 때에는 정확도 높은 횡단 측량자료를 얻기는 불가능하며 접근이 어려운 지역이나 중소규모의 하천 측량자료는 구축되어 있지 않은 실정이다. 이에 따라 위성영상과 수치표고모델(Digital Elevation Model, DEM)에 기반하여 하천구역과 하도의 특성을 정의하는 방법이 대안으로 제시되고 있다. 본 연구에서는 하천지형 측량자료가 존재하는 섬진강댐부터 오수천 합류전까지를 대상으로 가상하도 생성기법을 적용하고, 1차원 하천흐름해석을 수행하여 가상하도 구축방안의 유효성을 검토하고자 하였다. 위성영상 자료를 활용하여 하천구역을 정의하였으며 DEM에서 추출된 표고에 기반하여 제방고와 횡단면도를 구축하였다. 구축된 횡단면도와 실단면 비교시, DEM 표고 및 하천구역 정의 지점의 정확도에 따라 제방고가 달라지는 것으로 나타났으며, 홍수터에 대한 고려가 포함되지 않아 실단면과 다소 차이가 있는 것으로 확인된다. 구축한 지형자료를 1차원 하천흐름해석 모형인 K-River에 적용하였으며, 상류단 경계조건으로는 섬진강댐 방류량을 하류단 경계조건으로는 등류조건을 적용하였다. 구축영역 내 존재하는 지류의 유입량은 측방유입으로 고려하였다. 수치모의 결과로부터 구축된 횡단면의 최심고와 실단면의 최심고가 유사한 지점에서는 수위재현성이 양호한 것으로 확인되었다.