• Korean Journal of Geomatics
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• 제4권1호
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• pp.31-37
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• 2004

The aim of this research is comparing the existing approximation models (e.g. Affine Transformation and Direct Linear Transformation) with Rational Function Model as a substitute of rigorous sensor model of linear array scanner, especially push-broom sensor. To do so, this research investigates the mathematical model of each approximation method. This is followed by the assessments of accuracy of transformation from object space to image space by using simulated data generated by collinearity equations which incorporate or depict the physical aspects of linear array sensor.

• International Journal of Aeronautical and Space Sciences
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• 제17권4호
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• pp.593-603
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• 2016

This paper presents the development of linear quadratic regulation and output tracking algorithms using output feedback when both the measurement and performance output equations contain direct feedthrough terms. Although all physical systems can be modeled without direct feedthrough, there are still many situations where system models with direct feedthrough are important. For this situation, we modify previous work on the same topic for systems without direct feedthrough. It is shown that for the regulation problem, the optimal output feedback gain for a direct feedthrough case can be directly obtained, via a transformation, from the approach used for systems without direct feedthrough. However, for the tracking problem, a new set of coupled matrix equations for determining the optimal output feedback gain is derived from the necessary conditions for minimizing the cost function. The effectiveness of the developed algorithms is demonstrated using numerical examples.

• 한국측량학회지
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• 제5권2호
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• pp.47-55
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• 1987

본 연구에서는 내부표정요소와 외부표정 요소를 모두 미지수로 취급하는 직접선형변환의 기본식을 유도하여 비반복적으로 직접 후방교회를 실시할 수 있는 알고리즘을 개발 전산화 하였으며, 기존의 입체도화기와 Digitizer를 이용하여 상좌표를 측정하였다. 입체도화기와 Digitizer를 이용한 상좌표 측정 및 직접선형변환의 타당성을 입증하기 위하여 양해석법으로 자료추출을 실시하였으며, 절대좌표에 대한 표준오차를 분석하였다.

• 대한공간정보학회지
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• 제13권2호
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• pp.39-43
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• 2005

본 연구에서는 비측량용 시진기의 해석 모델로서 주로 사용되는 직접선형변환(Direct Linear Transformation) 모델의 매개변수로부터 물리적 사진기 매개변수를 산정하는 데 있어서의 정확도를 분석하였으며, 사진측량 작업에서 직접선형변화 모델의 사용을 최적화 하였다. 모의 관측 자료를 사용하여, 다양한 경우에 대하여 물리적 사진기 매개변수를 직접선형변환에 의한 방법과 번들 조정에 의한 방법으로 각각 계산하였으며, 두 결과에 대해 검사점들의 평균제곱근오차를 비교함으로써 직접선형변환을 적용함에 있어서 지상기준점의 배치를 최적화 하였다.

• 한국CDE학회논문집
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• 제12권5호
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• pp.354-365
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• 2007

We present novel methods to generate a sequence of shapes that represents the pattern of morphological development or transformation of Bezier curves. The presented methods utilize the intrinsic geometric structures of a Bezier curve that are derived from rib and fan decomposition (RFD). Morphological development based on RFD shows a characteristic pattern of structural growth of a Bezier curve, which is the direct consequence of development path defined by fans. Morphological transformation based RFD utilizes development patterns of source and target curves to mimic the theory of evolutionary developmental biology: although the source and target curves are quite different in shapes, we can easily find similarities in their younger shapes, which makes it easier to set up feature correspondences for blending them. We also show that further controls on base transformation for intensity of feature blending, and extrapolation can compensate the immaturity of blended curves. We demonstrate the experimental results where transformation patterns are smoother and have unique geometric style that cannot be generated using conventional methods based on multi-linear blending.

• International Journal of Aeronautical and Space Sciences
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• 제13권4호
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• pp.458-467
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• 2012

In this study, the linear viscoelastic response of a rectangular laminated plate is investigated. The viscoelastic properties, expressed by two basic spring-dashpot models, that is Kelvin and Maxwell models, is assumed in the range to investigate the influence of viscoelastic coefficients to mechanical behavior. In the present study, viscoelastic responses are performed for two popular equivalent single-layered theories, such as the first-order shear deformation theory (FSDT) and third-order shear deformation theory (TSDT). Compliance and relaxation modulus of time-dependent viscoelastic behavior are approximately determined by Prony series. The constitutive equation for linear viscoelastic material as the Boltzmann superposition integral equation is simplified by the convolution theorem of Laplace transformation to avoid direct time integration as well as to improve both accuracy and computational efficiency. The viscoelastic responses of composite laminates in the real time domain are obtained by applying the inverse Laplace transformation. The numerical results of viscoelastic phenomena such as creep, cyclic creep and recovery creep are presented.

• 대한토목학회논문집
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• 제7권4호
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• pp.125-132
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• 1987

사진측량(寫眞測量)에서 이용되는 번들조정(調整)은 공선조건(共線條件)을 기초로 하며, 많은 비지형(非地形)분야에서 이용되고 있다. 그러나 비측량용(非測量用)사진기의 경우 지표(指標)가 없고 내부(內部) 및 외부표정요소(外部標定要素)의 초기근사값을 모르기 때문에, 이를 필요로 하는 번들조정(調整)에는 적용할 수 없다. 상좌표(像座標)로 부터 절대좌표(絶對座標)가 근사값을 요구하지 않고 직접변환되는 DLT(direct linear transformation) 프로그램이 Marzan과 Karara에 의해 개발되었다. 본(本) 논문(論文)에서는, 비측량용(非測量用)사진기에 의한 근거리사진측량(近距離寫眞測量)의 정확도(正確度)를 향상시키기 위해 DLT프로그램을 수정하였다. 수정된 프로그램에는 과대오차(過大誤差)의 검출(檢出) 및 외부표정요소(外部標定要素)의 계산과정을 포함시켰으며, 반복계산수를 증가시켰다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1988년도 추계학술대회 논문집 학회본부
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• pp.388-393
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• 1988

New circuit D-Q transformation concept is introduced to analyze AC converters such as inverters, rectifiers and cyclo-converters with ease. The equivalent linear time invariant circuit is obtained by substituting switches with equivalent turn-ratio variable transformers and changing balanced AC reactors into equivalent DC reactors combined by gyrators. This circuit enables us to utilize the powerful linear system analysis techniques such as Laplace transform otherwise which could not be applied to the time varying switching systems. Direct substitution of switches of DC converters with transformers is shown as a preliminary. Then the modeling procedure is shown for a controlled rectifier-inverter circuit. Finally an analysis example is proposed for a buck-boost inverter and the result is compared with the conventional approach. This approach is applicable to all AC converter families to determine the AC transfer functions and the DC operating points. It is identified that the switching systems are equivalent to the RLC filter circuits with transformers and gyrators.

• 한국레이저가공학회:학술대회논문집
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• 한국레이저가공학회 2005년도 춘계학술발표대회 논문집
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• pp.3-8
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• 2005

The robot systems are widely used in the welding manufacturing. The essential tasks to operate the welding robot are the acquisition of the position and/or shape of the parent metal. For the seam tracking or the robot automation, many kinds of contact and non-contact of the system which monitors the shape of the welding part is described. This system uses the line-type structured laser diode and the visual sensor. It includes the correction of radial distortion which is often found in the image from the camera with short focal length. Direct Linear Transformation (DLT) is used for the camera calibration. The three dimensional shape of the parent metal is obtained after simple linear transformation. Therefore, the system operates in real time. Some experiments are carried out to evaluate the performance of the developed system.

• 대한전기학회논문지
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• 제35권4호
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• pp.148-155
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• 1986

This paper presents a new decoupled power system state estimation method. The decoupling is achieved via simple linear transformation on power measurements in contrast with the modified fast decoupled state estimation method which assumes decoupling by direct negligence of the off-diagonal blocks of the observation functions. The new estimation method is compared with the modified decoupled state estimation method against IEEE-14 bus model power system and 25 bus model power system in several system conditions. It is observed that the proposed method shows better convergence performance and filtering performance than a modified fast decoupled state estimation.