• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 심포지엄 논문집 정보 및 제어부문
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• pp.105-106
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• 2007

We present a fast reconstruction technique for elliptic objects, which can be applied to real-time computer tomography (CT) for simple geometric objects. It will be also shown that only 3 projections are needed to reconstruct an ellipse. A piecewise quadratic model is also proposed for more efficient Kalman filter based support estimation, which is used for the fast reconstruction technique. The performance of the piecewise quadratic model is compared with that of the existing piecewise linear model. Simulation results for the fast reconstruction are also presented.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1998년도 추계종합학술대회 논문집
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• pp.927-930
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• 1998

This paper presents a new method for reconstructing 3 dimensional object model using a zoom camera. The proposed method uses zoom images to find the distance(D) between camera and object. Also the method uses images obtained around the object to find an $angle(\theta)$ between two connected planes of the object. With the D and $\theta,$ we can reconstruct the real sized 3-D model of object with less errors without stereo camera or rangefinder.

• 한국광학회지
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• 제24권3호
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• pp.120-124
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• 2013

본 논문에서는 임의의 모양, 크기, 및 초점 거리를 가지는 렌즈들의 불규칙한 배열을 통과하여 저장되는 영상으로부터 원본 2차원 객체의 모양을 복원하는 방법을 제시한다. 제안된 방법에서는 먼저 단일 물체점의 위치를 바꾸어가며 불규칙 렌즈 배열을 통한 촬영을 수행하여 각 물체점 위치에 대한 불규칙 렌즈 배열 영상들을 확보한다. 이와 같은 각 물체점별 불규칙 렌즈 배열 영상들을 임의의 모양을 가지는 2차원 물체에 대한 불규칙 렌즈 배열 영상과 비교하여 유사도를 산출함으로써 임의의 모양을 가지는 2차원 물체를 복원한다. 실험 결과를 통하여 원본 물체를 인식할 수 있는 수준으로 물체의 복원이 가능함을 확인하였다. 추후 보다 높은 해상도의 복원과 3차원 물체로의 확장을 위한 추가 연구가 필요함도 확인하였다.

• 한국광학회지
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• 제19권4호
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• pp.270-275
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• 2008

본 논문에서는 집적 영상의 획득과 복원을 통하여 장애물에 가려진 물체를 인식하는 기술은 제안하고 구현하였다. 집적 영상의 복원은 해당되는 화소 세기의1차 확률적 특성인 평균으로 구한다. 복원평면까지의 거리는 2차 확률적 특성인 표준 편차를 이용하여 구하고3차원 물체의 경계(edge)를 검출한다. 표준 편차의 합을 최소로 하는 거리에서 복원된 영상을 표적인식에 이용한다. 표적인식은 주성분 분석(principle component analysis, PCA) 분류기를 복원된 영상에 적용하였다. 표적 분류에 대한 판정은 분류기에 의해서 투영된 클래스의 평균 특징 벡터와 테스트 특징 벡터간의 유클리드 거리(Euclidean distance)를 이용한다. 실험 및 시뮬레이션을 통하여 가려진 표적을 본 논문에서 제안한 방법을 통하여 오차 없이 분류하였다.

• 한국정밀공학회지
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• 제17권5호
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• pp.76-83
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• 2000

Shape reconstruction is considered as a new technology to be useful and important in many areas such as RPD (Rapid Product Development) and reverse engineering, compared with the conventional design and manufacturing. In shape reconstruction, it becomes possible to reconstruct objects not by their measured shape data but those data extracted from the original shape. The goal of this research is to realize 3D shape construction by showing a possible way to analyze the input image data and reconstruct that original shape. The main 2 steps of the reconstructing process are getting cross-section data from image processing and linking loops between one slice and the next one. And the reconstructed object in this way is compared with the other object using a laser scanner and modelled by an commercial software.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년도 춘계학술대회논문집
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• pp.576-579
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• 2008

Electrical impedance(EIT) for the multi-phase flow visualization is an imaging modality in which the resistivity distribution of the unknown object is estimated based on the known sets of injected currents and measured voltages on the surface of the object. In this paper, an EIT reconstruction algorithm based on the extended Kalman filter(EKF) is proposed. The EIT reconstruction problem is formulated as a dynamic model which is composed of the state equation and the observation equation, and the unknown resistivity distribution is estimated recursively with the aid of the EKF. To verify the reconstruction performance of the proposed algorithm, experiments with simulated multi-phase flow are performed.

• Journal of the Optical Society of Korea
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• 제12권3호
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• pp.131-135
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• 2008

Computational integral imaging(CII) has the advantage of generating the volumetric information of the 3D scene without optical devices. However, the reconstruction process of CII requires increasingly larger sizes of reconstructed images and then the computational cost increases as the distance between the lenslet array and the reconstructed output plane increases. In this paper, to overcome this problem, we propose a novel CII method using a depth conversion technique. The proposed method can move a far 3D object near the lenslet array and reduce the computational cost dramatically. To show the usefulness of the proposed method, we carry out the preliminary experiment and its results are presented.

• The Journal of the Acoustical Society of Korea
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• 제18권2E호
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• pp.18-23
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• 1999

This paper proposes a method of separately determining three intrinsic mechanical parameters of an unknown object in the framework of ultrasound inverse scattering tomography. Those parameters are the speed of sound, density, and absorption whose values are given as the solution of an inhomogeneous Helmholtz wave equation. The separate reconstruction method is mathematically formulated, the integral equations are discretized using the sinc basis functions, and the Newton-Raphson method is adopted as a numerical solver in a measurement configuration where the object is insonified by an incident plane wave over 360˚ and the scattered field is measured by detectors arranged in a rectangular fashion around it. Two distinct frequencies are used to separate each parameter of three Gaussian objects that are either located at the same position or separately from each other. Computer simulation results show that the separate reconstruction method is able to separately reconstruct the three mechanical parameters. The absorption parameter turns out to be a little difficult to reconstruct as compared with the other two parameters.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2012년도 춘계학술대회
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• pp.155-157
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• 2012

본 논문에서는 집적 영상 기술에 기반한 컴퓨터 3D 영상 복원을 이용하여 비선형 3D 영상 상관기를 제안한다. 제안하는 방법에서는 먼저 기준 3D 물체와 목표 3D 물체의 요소 영상들을 렌즈 어레이를 통해 픽업한다. 이 픽업된 영상에 컴퓨터 집적 영상 복원 방법을 사용하여 목표 평면 영상과 기준 평면 영상들이 복원된다. 복원된 기준 평면 영상과 목표 평면 영상들 간의 비선형 상호상관을 통해 인식을 수행한다. 제안된 방법의 유용함을 보이기 위해 기존의 방법과 비교하여 기초적인 상관관계 실험을 수행하고 그 결과를 발표한다.

• International Journal of Air-Conditioning and Refrigeration
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• 제8권2호
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• pp.11-22
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• 2000

Holographic interferometric tomography can provide reconstruction of instantaneous three-dimensional gross flow fields. The technique however confronts ill-posed reconstruction problems in practical applications. Experimental data are usually limited in projection and angular scanning when a field is captured instantaneously or under the obstruction of test models and test section enclosures. An algorithm, based on a series expansion method, has been developed to improve the reconstruction under the ill-posed conditions. A three-dimensional natural convection flow around two interacting isothermal cubes is experimentally investigated. The flow can provide a challenging reconstruction problem and lend itself to accurate numerical solution for comparison. The refractive index fields at two horizontal sections of the thermal plume with and without an opaque object are reconstructed at a limited view angle of 80$\circ$. The experimental reconstructions are then compared with those from numerical calculation and thermocouple thermometry. It confirms that the technique is applicable to reconstruction of reasonably complex, three-dimensional flow fields.