• 한국전자파학회논문지
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• 제8권5호
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• pp.534-544
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• 1997

Levenberg-Marquardt (LMA)와 유전 알고리즘(GA)을 결합한 새로운 잡종알고리틈을 반복적으로 사용하여, 비용함수의 실 극소값(global minimum)을 주는 2차원 강산란체의 유전율 분포를 재구성한다. 비용함수에 사용되는 산란파는 원통형 각모드로 전개되며, 이 중 유효 전파모드만이 이용된다. 유효 전파모드만을 사용하여 비용함수를 정의함으로써 주어진 산란체를 재구성하는데 필요한 입사파 개수의 최소값이 공식화된다. 수치해석 결과로부터,LMA는 수렴 속도가 빠르나 강산란체를 재구성할 수 없고, GA는 강산란체의 재구성은 가능하나 수렴 속도가 느린 반면, 결합 알고리즘을 이용하는 역산란 방법은 LMA와 GA의 장점만을 취합한 방법임이 입증된다.

• International journal of advanced smart convergence
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• 제11권2호
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• pp.22-29
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• 2022

In this paper, for the purpose of designing an real-time unmanned monitoring system, the YOLOv5s (small) object detection model was applied on the NVIDIA TX2^TM AI (Artificial Intelligence) edge computing platform in order to design the fundamental function of an unmanned monitoring system that can detect objects in real time. YOLOv5s was applied to the our real-time unmanned monitoring system based on the performance evaluation of object detection algorithms (for example, R-CNN, SSD, RetinaNet, and YOLOv5). In addition, the performance of the four YOLOv5 models (small, medium, large, and xlarge) was compared and evaluated. Furthermore, based on these results, the YOLOv5s model suitable for the design purpose of this paper was ported to the NVIDIA TX2^TM AI edge computing system and it was confirmed that it operates normally. The real-time unmanned monitoring system designed as a result of the research can be applied to various application fields such as an security or monitoring system. Future research is to apply NMS (Non-Maximum Suppression) modification, model reconstruction, and parallel processing programming techniques using CUDA (Compute Unified Device Architecture) for the improvement of object detection speed and performance.

• Nuclear Engineering and Technology
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• 제56권10호
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• pp.4247-4253
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• 2024

We propose a new method of X-ray backscatter imaging which is a significant development of the well known flying spot approach. Instead of sweeping the imaged object by pencil X-ray beam, and recording the amplitude of backscattered radiation in order to form the raster image, the object is irradiated with a fan beam of X-rays, forming a line on the imaging plane. By properly chosen motion of the collimating slit, a set of lines, which makes up a 2D sinogram of the original object, can be collected. The backscatter image can then be obtained using one of the tomographic reconstruction algorithms, such as the filtered backprojection, which is well known in computed tomography or nuclear medicine. The feasibility of the method has been demonstrated experimentally using a prototype scanner with an industrial X-ray source. The main advantage of our method is the essentially more efficient use of the available X-ray source beam, by illuminating the object with a substantially larger photon flux at each time point. As a result, the image can be obtained at much shorter acquisition time and/or at much lower source power.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.36-39
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• 2004

Electrical impedance tomography (EIT) has been suffered from the severe ill-posedness which is caused by the inherent low sensitivity of boundary measurements to any changes of internal resistivity values. So, small noise occur unexpected reconstruction image. Generally in EIT system, if measured voltage includes noise, we can't find object location and resistivity values. In this paper, we propose digital filter for measured voltage in EIT. Newton-Raphson is the most..popular algorithm in EIT, but noise cause to blur image. We use Fourier transform (FT) in order to minimize the noise and design the filter. After filtering, result of reconstruction image is improved better than before filtering.

• 대한전자공학회논문지
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• 제15권6호
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• pp.8-22
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• 1978

근래에 발전하고 있는 Artificial Intelligence 또는 Synthetic Image 등 넓은 의미에서의 영상처리에 관하여 해석학적인 설명을 시도하였다. 일반적으로 얻어지는 "영상" 또는 "사진"에 반하여 간접적으로 얻어진 Synthetic Image의 대표적인 예로서 3차원 영상 재 구성 (3-Dimensional Image Reconstruction)을 들 수 있으며, 이의 최근 의학 및 생명 과학 분야는 물론 공학 및 물리학 분야의 비파괴 검사(NDT)등 많은 분야에의 응용에 급격한 발전을 보고 있다. 본 논문은 3차원 CT (Computerized Topography)의 기본을 이루는 3차원 영상 재구성 처리에 관한 기본적인 문제를 two-dimensional signal processing의 관점에서 다루었다.

• 한국생산제조학회지
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• 제26권1호
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• pp.108-113
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• 2017

In this paper, we proposed a three-dimensional(3D) scanning system based on laser vision technique for 3D model reconstruction. The proposed scanning system consists of line laser, camera, and turntable. We implemented the 3D scanning system using low quality elements. Although these are low quality elements, we reduced the 3D data reconstruction errors greatly using two methods. First, we developed a maximum brightness detection algorithm. This algorithm extracts the maximum brightness of the line laser to obtain the shape of the object. Second, we designed a new laser control device. This device helps to adjust the relative position of the turntable and line laser. These two methods greatly reduce the measuring noise. As a result, point cloud data can be obtained without complicated calculations.

• 한국음향학회지
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• 제8권4호
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• pp.23-28
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• 1989

본 논문에서는 컴퓨터에 의한 초음파 홀로그램의 구성과 영상 재생방법을 연구하였으며 이를 광학적 재생방법과 비교 분석하였다. 초음파 홀로그램은 초음파 변환자를 기계적으로 c-scan $(128\times128 step)$하여 구성하였고 물체에 대한 영상은 Rayleigh-Sommerfeld 식과 DFT 알고리즘을 이용하여 컴퓨터 재생하였다. 본 실험에서 는 중심주파수가 5MHz이고 촛점 거리가 5cm 인 초음파 변환자와 기계적인 c-scanning 시스템을 사용하여 음향 홀로그래피 시스템을 구성하였고 알루미늄 판에 S자 형태를 새긴 샘플을 제작하여 실험하였다. 실험결과 컴퓨터에 의해 재생된 영상은 실체와 동일한 고질의 영상임을 확인하였다.

• 대한전기학회논문지:시스템및제어부문D
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• 제51권5호
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• pp.212-219
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• 2002

In this paper, the epipolar geometry, genera17y used as a pin-hole camera model, is newly adapted to our proposed method that enables the affine reconstruction of the 3D object from two projected views. The proposed method models the projective projection of inherent X-ray imaging system, obviates the need to attach artifirially constructed material on the body, and requires none of the prior-knowledge regarding to intrinsic and extrinsic parameters of two X-ray imaging systems. The optimum numerical solution is obtained by applying the least mean square estimator to corresponding points on two projected X-ray planes. The performance of this proposed method is Quantitatively analyzed using computer synthesized model of Cochlear implantation electrodes. In simulated experiments, the propnsed method is insensitive to the added random noise, the scaling factor change, the center point change, and rotational angular change between two projection planes, as well as enables the stable 3D reconstruction in least square sense even in worst testing cases.

• 제어로봇시스템학회논문지
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• 제9권1호
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• pp.50-56
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• 2003

In electrical impedance tomography(EIT), various image reconstruction algorithms have been used in order to compute the internal resistivity distribution of the unknown object with its electric potential data at the boundary. Mathematically the EIT image reconstruction algorithm is a nonlinear ill-posed inverse problem. This paper presents a new combined method based on genetic algorithm(GA) and modified Newton-Raphson(mNR) algorithm via two-step approach for the solution of the static EIT inverse problem. In the first step, each mesh is classified into three mesh groups: target, background, and temporary groups. The mNR algorithm can be used to determine the region of group. In the second step, the values of these resistivities are determined using genetic algorithm. Computer simulations with the 32 channels synthetic data show that the spatial resolution of reconstructed images by the proposed scheme is improved compared to that of the mNR algorithm at the expense of increased computational burden.

• 전기전자학회논문지
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• 제20권3호
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• pp.226-234
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• 2016

전기 저항 단층촬영법(ERT)은 대상체 내부 단면의 저항률 분포를 추정하고 이를 영상화하는 기술이다. ERT의 영상복원은 매우 비정치성이 강한 역문제의 일종으로 의미있는 영상을 얻기 위해서는 조정기법이 사용된다. 대표적으로 l2-norm 조정기법, l1-norm 조정기법, Total Variation 조정기법이 사용되며, 조정기법에 따라 ERT의 영상복원 성능이 달라진다. 즉, 상황에 맞는 적절한 조정기법의 사용은 ERT 영상 복원을 개선할 수 있다. 따라서, 본 논문에서는 모의실험을 통하여 상황에 따른 세 가지 조정기법의 영상복원 성능을 비교하였다.