• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제48권2호
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• pp.141-146
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• 1999

The eigenvalue equations of multiple waveguides with step-index profile are derived by using the WKB theory. Phase changes unique to step-index discontinuity areintroduced when applying the WKB connection formula to turning points. The transfer matrix method is employed for the analysis of multiple structure and the derived eigenvalue equation are represented in the recursive form. The results by the WKB are compared with those by the FEM for a three-waveguide coupler.

• 전자공학회논문지B
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• 제32B권1호
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• pp.39-49
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• 1995

Stereo vision is useful to obtain three dimensional depth information from two images taken from different view points. In this paper, we reduce searching area for correspondence by using the intra-scanline constraint, and utilize the inter-scanline constraint and the property of disparity continuity among the neighboring pixels for relaxation. Nodes with 3-D stucture are located on the axes of two views, and have matching possibility of correspondent pixels of two images. A matching is accepted if a node at the intersection of the disparity axes has the greatest matching possibility. Otherwise, the matching possibility of the node is updated by relaxation with the cooperation of neighboring nodes. Further relaxation with competition of two views is applied to a matching possibility of randomly selected node. The consensus of two views increases the confidence of matching, and removes a blurring phenomenon on the discontinuity of object. This approach has been tested with various types of image such as random dot stereogram and aerial image, and the experimental results show good matching performance.

• 전자공학회논문지B
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• 제33B권2호
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• pp.77-87
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• 1996

Existing area-based stereo matching algorithms utilize a single rectangular correlation area for computing cross-correlation between corresponding points in stereo images, and compute disparity by finding the peak in the vicinity of depth discontinuity, since, because of inconstnat disparities around discontinuities, the cross-correlation becomes low in such area. Inthis paper, a new area-based matching strategy is proposed exploiting multiple directional correlation masks instead of a single one. The proposed technique computes multiple cross-covariance functions using each oriented mask. Peaks are detected from each covariance function and the disparity is computed by choosing the location with the highest covariance value. Proposed approach can also be applied to compute disparity gradients without obtaining dense depth data. A number of examples are presented using synthetic and natural stereo images.

• 한국통신학회논문지
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• 제13권2호
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• pp.182-191
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• 1988

직결합(direct coupling) 급전 방식을 사용한 대수 주기형으로 배열된 마이크로 스트립 안테나(Log Periodic Microstrip Array Antenna)를 7.2-12.4GHz주파수 대역에서 설계하였다. 전송 선로 해석 방법에 유전체 및 도체 손실과 불연속에 의한 영향을 고려하여 각 안테나 소자를 설계하였으며 주 전송 선로와 각 안테나 소자 간의 임피던스 정합을 위하여 급전 위치를 최적화하여 정하였다. 측정한 결과 전 주파수 대역에서 정재파비가 2.4이하여??며 53%의 대역폭을 얻었다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 신호처리소사이어티 추계학술대회 논문집
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• pp.179-182
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• 2003

This paper proposes a new stereo matching algorithm using both the divide-and-conquer method and the DSI(Disparity Space Image) technique. Firstly, we find salient feature points on the each scanline of the left image and find the corresponding feature point at the right image. Then the problem of a scanline is divided into several subproblems. By this way, matching of the subintervals is implemented by using the DSI technique. The DSI technique for stereo matching process is a very efficient solution to find matches and occlusions simultaneously and it is very speedy. In addition, we apply three occluding patterns to process occluded regions, as a result, we reduce mismatches at the disparity discontinuity.

• 전자공학회논문지A
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• 제32A권1호
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• pp.79-88
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• 1995

A subreflector of an offset dual reflecor antenna system mounted on satelite is analyzed by Uniform Geometrical Theory of Diffraction(UTD). In order to get the total electric field at an observation point, the reflected field and the diffracted fields obtained by UTD are summed. The reflected point and the diffracted points which have to satisfy nonlinear equations are obtained by numerical methods. The numerical results show taht diffracted fields eliminate the discontinuity of reflected fields at the shadow boundary. To show the validity of our results, the field pattern of the symmetric hyperboloidal reflector is computed and compared with S. W. Lee et al.'s results. At various obsevation angles, radiation patterns of offset ellipsoidal subreflectors offseted by a circular corn and by an elliptic corn are obrained, repectivelly.

• 제어로봇시스템학회논문지
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• 제1권2호
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• pp.105-111
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• 1995

This paper proposes a segmentation algorithm using gray-level discontinuity and surface reflectance ratio of input images obtained under different illumination conditions. Each image is divided by a certain number of subregions based on the thresholds. The thresholds are determined using the histogram of fusion image which is obtained by ANDing the multiple input images. The subregions of images are projected on the eigenspace where their bases are the major eigenvectors of image matrix. Points in the eigenspace are classified into two clusters. Images associated with the bigger cluster are fused by revised ANDing to form a combined edge image. Missing edges are detected using surface reflectance ration and chain code. The proposed algorithm obtains more accurate edge information and allows to more efficiently recognize the environment under various illumination conditions.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.1870-1875
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• 2003

Optimization has been used in many engineering problems and must be one of the essential components during design process now. It is the process of maximizing the performance called an objective function of a system while satisfying some constraints, so finite element method is generally required in order to obtain these values during optimization. However, there are some difficulties to obtain them by means of FEM, where the changes of design variables cause the distortion and the regeneration of mesh that may result in inaccuracy and inefficiency. In order to overcome this problem, this paper proposed an alternative that the eXtended FEM introduced and developed by Ted Belytschko was applied to the optimization process because the key points of the X-FEM lie in that the discontinuity can be represented independently on the mesh by a function called in an enrichment function.

• Communications for Statistical Applications and Methods
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• 제13권2호
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• pp.205-217
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• 2006

In this paper, we consider the problem of testing for a change of the parameter function ${\theta}(t)$ that may have a discontinuity at some unknown point ${\tau}$. We introduce a varying-h moving estimate to test the null hypothesis that ${\theta}(t)$ is continuous against the alternative that ${\theta}({\tau}-){\neq}{\theta}({\tau}+)$. Simulation results are provided for illustration.

• 대한전자공학회논문지SP
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• 제38권2호
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• pp.199-207
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• 2001

본 논문에서는 곡률을 이용한 3차원 영상의 에지 기반 표면 분할 알고리즘을 제안한다. 제안한 방법은 표면 분할의 중요한 특징 요소인 에지 검출의 과정에서 3차원 영상의 깊이 정보를 스캔라인별로 2차 곡선으로 근사화하고, 각 곡선의 구분점에 대하여 곡률 계산을 적용하여 에지를 결정한 후, 영역을 그룹화 한다. 기존의 알고리즘은 jump 에지와 crease 에지로 구분하는 다른 처리 과정으로 에지를 검출하고, 특히 crease 에지에 대해서 면 방향의 불연속정도를 결정하는데 어려움이 많았다. 제안한 알고리즘은 기하학적인 접근방법으로 근사화된 곡률 계산을 이용한 단일 처리 과정의 적용과 곡률의 불연속정도를 결정하는데 보다 용이한 방법을 제시한다. 이러한 효율적인 에지 검출을 기반으로 여러 가지 3차원 영상에 대한 실험을 통하여 제안한 방법의 성능이 기존의 방법보다 우수함을 확인하였다.