• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.37 no.3
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• pp.189-198
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• 2019

In photogrammetry, single photo resection is a method of determining exterior orientation parameters corresponding to a position and an attitude of a camera at the time of taking a photograph using known interior orientation parameters, ground coordinates, and image coordinates. In this study, we proposed a single photo resection algorithm that determines the exterior orientation parameters of the camera using cosine law and linear equation-based three-dimensional coordinate transformation. The proposed algorithm first calculated the scale between the ground coordinates and the corresponding normalized coordinates using the cosine law. Then, the exterior orientation parameters were determined by applying linear equation-based three-dimensional coordinate transformation using normalized coordinates and ground coordinates considering the calculated scale. The proposed algorithm was not sensitive to the initial values by using the method of dividing the longest distance among the combinations of the ground coordinates and dividing each ground coordinates, although the partial derivative was required for the nonlinear equation. In addition, since the exterior orientation parameters can be determined by using three points, there was a stable advantage in the geometrical arrangement of the control points.

• 전자공학회논문지 IE
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• v.46 no.1
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• pp.37-43
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• 2009

In this paper, we propose a new algorithm for 3D model retrieval based on spherical coordinate system. We obtains sample points in a polygons on 3D model. We convert a point in cartesian coordinates(x, y, z) to it in spherical coordinate. 3D shape features are achieved by adopting distribution of zenith of sample point in spherical coordinate. We used Osada's method for obtaining sample points on 3D model and the PCA method for the pose standardization 3D model. Princeton university's benchmark data was used for this research. Experimental results numerically show the precision improvement of proposed algorithm 12.6% in comparison with Vranic's depth buffer-based feature vector algorithm.

• Proceedings of the KIEE Conference
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• 2003.04a
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• pp.281-284
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• 2003

본 논문에서는 비선형 단상부하에 의해 발생하는 전류 고조파를 보상하기 위한 단상능동전력필터의 제어방법을 제안한다. 정규의 단상에 시간지연을 주어 가상의 두 번째 상을 만들어 단상시스템을 두 축을 갖는 직교 좌표로 변환시킬 수 있다. 두 개의 상은 3상 2상 변환에서 사용하는 것과 같이 직교 좌표 시스템을 만들 수 있다. 이 것은 순시 무효전력을 계산하는 방법인 복소계산을 가능하게 한다. 고정 좌표계에서 순시무효전력이론을 적용한 기존의 방법 대신, 본 논문에서는 수정된 동기 좌표계를 이용하여 정상분과 역상분을 계산하여 보상전류 지령치를 결정하였다. 제안된 방법은 고조파저감과 PF개선에 있어 우수한 성능을 보여준다. 시뮬레이션 패키지(PSIM)를 사용하여 모의실험을 하였으며, 제안된 방법의 유효성을 입증하였다.

• Transactions of the Korean Society of Mechanical Engineers
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• v.12 no.5
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• pp.1158-1174
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• 1988

A numerical technique is developed for the solution of fully developed turbulent recirculating flow in the passage of variable area using the non-orthogonal coordinate transformation. In the numerical analysis, primitive pressure-velocity finite difference equations were solved by SIMPLER algorithm with 2-equation turbulence model and algebraic stress model (ASM). QUICK scheme on the differencing of convective terms which is free from the inaccuracies of numerical diffusion has been applied to the variable grids and the results compared with those from HYBRID scheme. In order to test the effect of streamline curvatures on turbulent diffusion Lee and Choi streamline curvature correction model which has been obtained by modifying the Leschziner and Rodi's model is testes. The ASM was also employed and the results are compared to those from another turbulence model. The results show that difference of convective differencing schemes and turbulence models give significant differences in the prediction of velocity fields in the expansion region and outlet region of the combustor, however show little differences in the parallel flow region.

• Journal of the Korean earth science society
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• v.18 no.6
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• pp.522-528
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• 1997

Gravity surveys with accompanying spirit levelings were carried out in Mt. Hangye area. From these survey results, orthometric height correctioins were calculated. The correction reaches 5 cm when the height difference is 900 m in this area. The corrections were also calculated using an available Bouguer anomaly map, and they are little different from the previous results. In conclusion, orthometric height corrections are necessary in precise spirit leveling, specially in higher lands, and they can be easily calculated from an available Bouguer anomaly map without laborious gravity surveys.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.7
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• pp.1278-1290
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• 2008

This paper proposes a preprocessing method and a neural network based character recognizer to enhance the overall performance of the license plate recognition system. First, plate outlines are extracted by virtual line matching, and then the 4 vertexes are obtained by calculating intersecting points of extracted lines. By these vertexes, plate image is reconstructed as rectangle-shaped image by bilinear transform. Finally, the license plate is recognized by the neural network based classifier which had been trained using delta-bar-delta algorithm. Various license plate images were used in the experiments, and the proposed plate normalization enhanced the recognition performance up to 16 percent.

• Journal of the Korea Convergence Society
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• v.11 no.10
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• pp.45-51
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• 2020

Recently, many games provide data related to the users' game play, and there have been a few studies that predict opponent move by combining machine learning methods. This study predicts opponent move using match data of a real-time strategy game named ClashRoyale and a multi-label classification based on machine learning. In the initial experiment, binary card properties, binary card coordinates, and normalized time information are input, and card type and card coordinates are predicted using random forest and multi-layer perceptron. Subsequently, experiments were conducted sequentially using the next three data preprocessing methods. First, some property information of the input data were transformed. Next, input data were converted to nested form considering the consecutive card input system. Finally, input data were predicted by dividing into the early and the latter according to the normalized time information. As a result, the best preprocessing step was shown about 2.6% improvement in card type and about 1.8% improvement in card coordinates when nested data divided into the early.

• Proceedings of the Korean Society of Computer Information Conference
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• 2014.07a
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• pp.431-432
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• 2014

본 논문 에서는 3차원 튜브 형태의 구조를 3차원 좌표를 갖는 점집합으로 추출했을 때, 이 점 집합에서 튜브를 관통하는 단위 벡터 및 방향성(orientation)을 구하는 알고리즘을 제안하였다. 이 알고리즘은 3차원 좌표를 정사영시킴으로써 2차원으로 차수를 낮추고, 그 처리를 간단하게 하였다. 또 내부를 구성하는 최대 넓이 폐곡선을 구성하는 점을 선택하는 방법을 제안하였다. 실험에서 제안한 방법은 정규화 된 튜브를 처리했을 때 중심(centroid) 및 방향성(orientation)을 의도한 값과 거의 동일하게 얻을 수 있었다.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1129-1131
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• 2005

본 논문은 저가형 고정도 아날로그 디지털 혼합형 엔코더에서 센서 취부 오차에 의해 발생하는 정지 2축 좌표상의 두 아날로그신호의 크기, 위상오차 문제 보상에 관한 연구이다. 기존의 혼합형 엔코더에서 문제시되고 있는 두 아날로그 위치정보 신호의 크기문제는 상대 크기에 대하여 정규화 함으로써 해결하였으며, 센서 취부시 발생하는 위치오차문제는 정지 2축 좌표축을 센서의 위치 오차분을 보상할 수 있도록 회전함으로써 보상할 수 있었다. 또한 제안된 새로운 방식의 위치 검출기법을 DSP의 QEP기능과 A/D변환기를 사용한 실험을 통하여 그 타당성을 검증하였다.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.3
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• pp.1015-1027
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• 1996

In this paper, a numerical procedure for the calculation of the incompressible Navier-Stokes equations in a generalized nonorthogonal body fitted coordinate system is proposed and is validated through three test problems. Present numerical procedure derives the pressure equation by using the pressure substitution method on the regular grid system, and discretized momentum equations are based on the covariant velocity components. Cavity flow, backward facing step flow, and two dimensional channel flow with a sinusoidal wavy wall are chosen as three test problems. Numerical solutions obtained by present procedure shows a good agreement with previous numerical and/or experimental results. Convergence rate is also satisfactory.