• Journal of Computational Design and Engineering
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• 제1권1호
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• pp.67-77
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• 2014

Most engineering software tools use typical menu-based user interfaces, and they may not be suitable for learning tools because the solution processes are hidden and students can only see the results. An educational tool for simple beam analyses is developed using a pen-based user interface with a computer so students can write and sketch by hand. The geometry of beam sections is sketched, and a shape matching technique is used to recognize the sketch. Various beam loads are added by sketching gestures or writing singularity functions. Students sketch the distributions of the loadings by sketching the graphs, and they are automatically checked and the system provides aids in grading the graphs. Students receive interactive graphical feedback for better learning experiences while they are working on solving the problems.

• 대한전자공학회논문지
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• 제11권6호
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• pp.38-43
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• 1974

임의의 전원임피이던스와 임의의 부하임피이던스 사이에 삽입할 때 입력반사계수가 가급적 넓은 주파수범위에서 최소가 되는 임피이던스 정합용 불균일선로 섹션을 설계하는 문제를 고찰하였다. 고려대상의 불균일선로는 수학적으로는 특수한 종류에 속하는 것이나 실제적으로는 완만하게 변하는 거의 모든 전송선로를 포괄할 수 있다. 입력반사 계수의 계산에서는 선로의 ABCD 파라미터의 테일러 급수전관식을 이용하였다. 그리고 설계문제를 비선형 구속조건을 가진 비선형 프로그래밍 문제로서 수식화하였으며 이것을 수차적비구속 최소법(Sequential Unconstrained Minimigation Technique)과 Fletcher-Powell 방법을 병용하여 풀었다. 결과적으로 이제까지 광대역 임피이던시 정합편 전송선제로서 발표된 가장 우수한 것보다 훨씬 특성이 개선된 것을 얻을 수 있었다.

• 전자공학회논문지
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• 제50권12호
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• pp.159-167
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• 2013

스트레오뷰(Stereoview) 시스템에서 카메라 위치 또는 광원의 변화는 양안에 해당하는 두 영상 사이에서 휘도에 대한 색상 분포에 차가 발생 한다. 이러한 색상변화 차는 입체영상(3D) 코딩의 품질을 저하 시키거나 적합하지 않는 프레임이 발생한다. 이러한 휘도에 대한 색상분포 차를 보정하기 위하여 본 논문에서는 스트레오뷰 코딩을 위한 효율적인 히스토그램 구간 보정방법을 제안하였다. 제안한 방법은 타겟뷰의 히스토그램을 분석하여 두 개의 영역으로 구분한 후 기준이 되는 영상의 히스토그램과 영역별 최대 매칭 영역을 분석하여 컬러편차를 보정하도록 하였다. 그리고 제안한 히스토그램 매칭 방법을 다른 컬러 보정방법과 비교하여 휘도 성분 교정을 검증 하였다. 실험 결과 제안하는 알고리즘이 연산 속도와 휘도 교정 PSNR(Peak Signal to Noise Ratio) 결과에서 더 좋은 결과를 보였다.

• 한국전자파학회논문지
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• 제15권2호
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• pp.206-211
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• 2004

진행파 슬롯 배열 안테나에서 반사파에 의한 부엽을 억제하기 위한 새로운 방법을 제안한다. 이 방법에서는 통상적으로 사용되는 정합부하 대신에 여러 단의 높이가 감소한 도파관과 마지막 단에 연결된 단락회로가 사용되었다. 제안된 방법의 타당성을 보이기 위해 Ku-대역에서 동작하는 도파관 슬롯 안테나를 제작 시험하였다. 측정결과로부터 제안된 방법을 사용하여 반사파에 의한 부엽을 억제할 수 있음을 확인하였다.

• 새물리
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• 제68권12호
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• pp.1324-1330
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• 2018

The elastic scatterings for the ${\alpha}+^{40}Ca$ and the ${\alpha}+^{58}Ni$ systems at $E_{lab}=240MeV$ have been analyzed within the framework of the Coulomb-modified Glauber model using two kinds of Gaussian density parameters for the target nuclei. The first one is to use Gaussian density parameters obtained from the root-mean-square radius. The second one is to use parameters calculated by matching the Gaussian density to the two-parameter Fermi density. The results with surface-matched Gaussian densities provide reasonable agreement with the experimental data, but the results without matching do not. The oscillatory structures observed in the angular distributions of both system can be interpreted as being due to the strong interference between the near-side and the far-side scattering amplitudes. The differences between the phase shifts obtained from the two methods are examined. We also investigate the effect of these differences on the differential and reaction cross sections, the transmission functions and the strong absorption radii.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2008년도 춘계학술대회 논문집
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• pp.307-310
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• 2008

Nonlinear Vortex Strength Correction Method is developed for improvement of vortex lattice method which can't calculate the separated flow conditions and the viscous effect. In this method, the vortex strength on the blade surface is determined by matching the lift force from vortex lattice method with the lift force from aerodynamic coefficients table as the same circulation is added to or subtracted from all chord wise vortices. For considering the nonlinearities due to the neighboring blade sections, sophisticated Newton-Rapson algorithm is applied. The validation of this method was done by comparing the simulations with the measurements on the NREL Phase-VI horizontal axis wind turbine(HAWT) in the NASA Ames wind tunnel under uniform conditions. This method gives good agreements with experiments in most cases.

• Journal of Electrical Engineering and Technology
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• 제10권2호
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• pp.676-687
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• 2015

Path planning algorithms are used to allow mobile robots to avoid obstacles and find ways from a start point to a target point. The general path planning algorithm focused on constructing of collision free path. However, a high continuous path can make smooth and efficiently movements. To improve the continuity of the path, the searched waypoints are connected by the proposed polynomial interpolation. The existing polynomial interpolation methods connect two points. In this paper, point groups are created with three points. The point groups have each polynomial. Polynomials are made by matching the differential values and simple matrix calculation. Membership functions are used to distribute the weight of each polynomial at overlapped sections. As a result, the path has $G^2$ continuity. In addition, the proposed method can analyze path numerically to obtain curvature and heading angle. Moreover, it does not require complex calculation and databases to save the created path.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• 제17권3호
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• pp.181-195
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• 2013

This study considers an air and liquid-filled geomembrane tube section resting on a horizontal foundation. All quantities are normalized to obtain geometrically similar solutions in the static equilibrium condition. Analytic solutions are expressed in closed form. The solution for the air or liquid-filled tube section is derived systematically as an extreme case of the air and liquid-filled tube section. The validity of these solutions is confirmed by comparing to previous study, and some results are shown for the characteristic parameters and shapes of air and/or liquid-filled cases. Using the result of present study, one can estimate the shape and characteristic parameters of a tube section without numerical integrations or iterations.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1988년도 전기.전자공학 학술대회 논문집
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• pp.335-338
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• 1988

A numerical method is presented for the scattering by the perfectly conducting cylinder with arbitrary cross sections. The relevant integral equation considered by the E-field formulation is solved by method of moments, and thereby the surface current induced as well as the radar cross section of the scatterer are numerically computed to specify the scattering nature of the scatterer. Two separate methods, one with point matching and the other Galerkin's method, are considered to make cross checks to the results obtained. Taking two half pulses suggested to expand the surface current shows savings in computation time and accurate solutions for the corners on the scatterer.

• 한국컴퓨터정보학회논문지
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• 제21권9호
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• pp.19-25
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• 2016

This paper is to recognize and play tab chords from guitar musical sheets. The musical chord area of an input image is segmented by changing the image in saturation and applying the Grabcut algorithm. Based on a template matching, our approach detects tab starting sections on a segmented musical area. The virtual block method is introduced to search blanks over chord lines and extract tab fret segments, which doesn't cause the computation loss to remove tab lines. In the experimental tests, the prototype based classification outperforms Bayesian method and the nearest neighbor rule with the whole set of training data and its performance is similar to that of the support vector machine. The experimental result shows that the prediction rate is about 99.0% and the number of selected prototypes is below 3.0%.