• Journal of the Korean Society of Radiology
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• v.15 no.5
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• pp.705-713
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• 2021

The modulation transfer function (MTF) is calculated to analyze the resolution of the spatial frequency of the image acquired from the x-ray imaging system. In general, the response function of the detector acquires a line spread function (LSF) using a slit-camera, and derives a modulation transfer function through a Fourier transform. Because of the fact that the x-ray must always be incident on the center of the slit-camera, the tilt of the detector and slit-camera caused by the experimenter will affect the detector performance. In addition, if the tilt increases, the performance evaluation of the x-ray image system will be problematic. In this study, we analyzed the experimental and analytical models in the modulation transfer function, ie, the Fourier domain, based on the experimental error and analyzed the effect on the spatial frequency. Furthermore, performance evaluation is being carried out for various x-ray imaging systems, and experimental errors are indispensable, and the extent to which they can be tolerated should be reviewed.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.5
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• pp.1182-1191
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• 1994

This paper presents an enhanced method of slit beam projection intended for the rapid measurement of 3-dimensional surface profiles of dies and molds. Special emphasis is given to optimizing the design of optical system so that the measuring accuracy can be maximized by adopting two-plane camera calibration together with sub-pixel image processing techniques. Finally, several measurement examples are discussed to demonstrate that an actual measuring accuracy of $\pm$ 0.2 mm can be achieved over the measuring range of 500 mm{\times}300mm{\times}200mm$.

• Journal of the Korean Society of Propulsion Engineers
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• v.20 no.4
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• pp.1-8
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• 2016

An experimental study was performed for the combustion-field visualization of the burner which burns the liquid hydrocarbon fuel atomized by an ultrasonic oscillator. Configurations of the flame and combustion-field were caught by both high-speed camera and thermo-graphic camera, and those images were analyzed in detail through a post-processing. As a result, the combustion-field grew and reaction-temperature rose due to the strengthening of combustion reaction with the increasing flow-rate of carrier-gas. In addition, a phenomenon of flame flickering was discussed through the comparative analysis of the variational behaviors between the visible flame and IR (Infrared) flame-field.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 1999.05a
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• pp.168-173
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• 1999

Many sensors such as a laser, CCD camera to obtain 3D information have been used, but most of calibration algorithms are inefficient since a huge memory and an experiment data for laser calibration are required. In this paper, the calibration algorithm of a slit beam laser based on triangulation method is introduced to calculate 3D information in the real world. The laser beam orthogonally mounted on the XY table is projected on the floor. A Cm camera observes the intersection plane of a light and an object plane. The 3D information is calculated using observed and calibration data. This method saves a memory and an experimental data since the 3D information are obtained simply triangulation method.

• Progress in Medical Physics
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• v.27 no.1
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• pp.37-45
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• 2016

In proton therapy, in vivo proton beam range verification is very important to deliver conformal dose to the target volume and minimize unnecessary dose to normal tissue. For this purpose, a multi-slit prompt-gamma camera module made of 24 scintillation detectors and 24-channel signal processing system is under development. In the present study, we have developed and tested a dual-mode signal processing system, which can operate in the energy calibration mode and the fast data acquisition mode, to process the signals from the 24 scintillation detectors. As a result of performance test, using the energy calibration mode, we were able to perform energy calibration for the 24 scintillation detectors at the same time and determine the discrimination levels for the detector channels. Further, using the fast data acquisition mode, we were able to measure a prompt-gamma distribution induced by a 45 MeV proton beam. The measured prompt gamma distribution was found similar to the proton dose distribution at the distal fall-off region, and the estimated beam range was $17.13{\pm}0.76mm$, which is close to the proton beam range of 16.15 mm measured by an EBT film.

• Journal of the Institute of Convergence Signal Processing
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• v.10 no.1
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• pp.13-22
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• 2009

In this paper, we propose the 3D shape reconstruction method that combine the mosaic method and the active stereo matching using the laser beam. The active stereo matching method detects the position information of the irradiated laser beam on object by analyzing the color and brightness variation of left and right image, and acquires the depth information in epipolar line. The mosaic method extracts feature point of image by using harris comer detection and matches the same keypoint between the sequence of images using the keypoint descriptor index method and infers correlation between the sequence of images. The depth information of the sequence image was calculated by the active stereo matching and the mosaic method. The merged depth information was reconstructed to the 3D shape information by wrapping and blending with image color and texture. The proposed reconstruction method could acquire strong the 3D distance information, and overcome constraint of place and distance etc, by using laser slit beam and stereo camera.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.3 no.4
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• pp.859-865
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• 1999

Many sensors such as a laser, and CCD camera to obtain 3D information have been used, but most of algorithms for laser calibration are inefficient since a huge memory and experiment data are required. This method saves a memory and an experimental data since the 3D information are obtained simply triangulation method. In this paper, the calibration algorithm of a slit km laser based on triangulation method is introduced to calculate 3D information in the real world. The laser beam orthogonally mounted on the XY table is projected on the floor. A CCD camera observes the intersection plane of a light and an object plane. The 3D information is calculated using observed and calibration data.

• Journal of the Korean Society for Precision Engineering
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• v.32 no.6
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• pp.537-542
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• 2015

The measurement of 3D shape is important in inspecting the quality of product. In this paper, we present a 3D shape measurement system of fastener using a camera and a slit laser. Calibration structure with slits is used in the extrinsic calibration of the camera and laser. The pose of the camera and laser is computed under the same world coordinate system in the calibration structure. Reflection of laser light on the metal surface causes many difficulties in the robust detection of them on image. We overcome this difficulty by using color and dynamic programming. Motor stage is used to rotate the fastener to recover the whole 3D shape of the surface of it.

• Proceedings of the Korean Information Science Society Conference
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• 2001.10b
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• pp.481-483
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• 2001

최근 전자제품의 초소형화에 따라, PCB 기판위의 부품의 집적도를 높이기 위해, 기존의 리드대신 부품 밑면에 볼(ball)이 격자형태로 배열되어 있는 BGA(Ball Grid Array) 형태의 팩키지가 많이 사용되고 있다. 하지만, BGA의 구조상 한번 장착되면 외관검사가 불가능하므로, 장착전 BGA의 검사가 필수적이다. BGA의 검사항목중 가장 중요한 항목인 볼 높이검사를 실시간으로 하기 위해서는 고속 비접촉 3차원 측정기술이 요구된다. 본 논문에서는 일반카메라보다 100배이상 높이 프로파일 취득속도가 빠른 3D smart camera와 레이저 슬릿광(slit ray)을 이용하여 고속으로 BGA 볼의 3D 프로파일을 얻은 후, clipping과 morphological filter를 사용하여 인접한 볼표면에서의 난반사로 인한 에러 데이터를 보정하여 정확한 3D 영상을 취득할 수 있는 시스템을 소개한다.

• Journal of the Korean Society of Propulsion Engineers
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• v.20 no.3
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• pp.9-16
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• 2016

An experimental study was performed to investigate the combustion characteristics of the liquid hydrocarbon fuel atomized by an ultrasonic oscillator. Configuration of the flame was caught by the high-speed camera, and images were analyzed in detail through a post-processing. In addition, the fuel consumption was measured using the balance during the combustion reaction. As a result, the consumption of atomized fuel increased with the increasing flow-rate of carrier-gas, but any correlation between the air/fuel ratio and carrier-gas flow-rate was not found. The variation of flame area was dependent on the fuel consumption and input power of the ultrasonic oscillator. FFT (Fast Fourier Transform) analyses using the flame area were conducted in order to discuss flame flickering.