• Korean Journal of Optics and Photonics
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• v.2 no.4
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• pp.179-185
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• 1991

Twyman-Green interferometer is developed for assessment of IR optical system performance. Light source is $CO_2$ gas laser which has 10.6$\mu \textrm m$ wavelength. The light beam is expanded to 2.5 cm dia by Ge lens and splitted by ZnSe parallel plane plate. One of the beams is reflected by refernce mirror which is operated PZT. The fringe will be detected by a pyro-electric vidicon camera and displayed by a CRT monitor. Here, the IR firinge is recorded on the thermal paper. In visible region, the light source is He-Ne laser. The fringe is detected by a CCD camera and displayed by the CRT monitor. The intensity of the fringe is digitized by a image card and processed by a PC. The wavefront aberration function, PSF and OTF are calculated. The results are displayed in 3-D graphs on the monitor or printed out by a line printer.

• Journal of IKEEE
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• v.23 no.1
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• pp.44-52
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• 2019

We implement an educational indoor autonomous mobile robot system that integrates LiDAR sensing information with RGB-D camera image information and exploits the integrated information. This system uses the existing sensing method employing a LiDAR with a small number of scan channels to acquire LiDAR sensing information. To remedy the weakness of the existing LiDAR sensing method, we propose the 3D structure recognition technique using depth images from a RGB-D camera and the deep learning based object recognition algorithm and apply the proposed technique to the system.

• Nuclear Engineering and Technology
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• v.51 no.1
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• pp.155-162
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• 2019

To reduce the secondary damage caused by leakage accidents in plant piping systems, a constant surveillance system is necessary. To ensure leaks are promptly addressed, the surveillance system should be able to detect not only the leak itself, but also the location of the leak. Recently, research to develop new methods has been conducted using cameras to detect leakage and to estimate the location of leakage. However, existing methods solely estimate whether a leak exists or not, or only provide two-dimensional coordinates of the leakage location. In this paper, a method using multiple cameras to detect leakage and estimate the three-dimensional coordinates of the leakage location is presented. Leakage is detected by each camera using MADI(Moving Average Differential Image) and histogram analysis. The two-dimensional leakage location is estimated using the detected leakage area. The three-dimensional leakage location is subsequently estimated based on the two-dimensional leakage location. To achieve this, the coordinates (x, z) for the leakage are calculated for a horizontal section (XZ plane) in the monitoring area. Then, the y-coordinate of leakage is calculated using a vertical section from each camera. The method proposed in this paper could accurately estimate the three-dimensional location of a leak using multiple cameras.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.34 no.5
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• pp.371-381
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• 2021

A machine vision inspection system consists of a camera, optics, illumination, and image acquisition system. Especially a scanning system has to be made to measure a large inspection area. Therefore, a machine vision line scan camera needs a line scan light source. A line scan light source should have a high light intensity and a uniform intensity distribution. In this paper, an offset calibration and slope calibration methods are introduced to obtain a uniform light intensity profile. Offset calibration method is to remove the deviation of light intensity among channels through adding intensity difference. Slope calibration is to remove variation of light intensity slope according to the control step among channels through multiplying slope difference. We can obtain an improved light intensity profile through applying offset and slope calibration simultaneously. The proposed method can help to obtain clearer image with a high precision in a machine vision inspection system.

• Nuclear Engineering and Technology
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• v.54 no.12
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• pp.4652-4659
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• 2022

Among the detector materials available at room temperature, thallium bromide (TlBr), which has a relatively high atomic number and density, is widely used for gamma camera imaging. This study aimed to verify the usefulness of TlBr through quantitative evaluation by modeling detectors of various compound types using Monte Carlo simulations. The Geant4 application for tomographic emission was used for simulation, and detectors based on cadmium zinc telluride and cadmium telluride materials were selected as a comparison group. A pixel-matched parallel-hole collimator with proven excellent performance was modeled, and phantoms used for quality control in nuclear medicine were used. The signal-to-noise ratio (SNR), contrast to noise ratio (CNR), sensitivity, and full width at half maximum (FWHM) were used for quantitative analysis to evaluate the image quality. The SNR, CNR, sensitivity, and FWHM for the TlBr detector material were approximately 1.05, 1.04, 1.41, and 1.02 times, respectively, higher than those of the other detector materials. The SNR, CNR and sensitivity increased with increasing detector thickness, but the spatial resolution in terms of FWHM decreased. Thus, we demonstrated the feasibility and possibility of using the TlBr detector material in comparison with commercial detector materials.

• Journal of Drive and Control
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• v.20 no.4
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• pp.92-99
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• 2023

Autonomous vehicles should recognize and respond to the specified speed to drive in compliance with regulations. To recognize the specified speed, the most representative method is to read the numbers of the signs by recognizing the speed signs in the front camera image. This study proposes a method that utilizes YOLO-Labeling-Labeling-EfficientNet. The sign box is first recognized with YOLO, and the numeric digit is extracted according to the pixel value from the recognized box through two labeling stages. After that, the number of each digit is recognized using EfficientNet (CNN) learned with the virtual environment dataset produced directly. In addition, we estimated the depth of information from the height value of the recognized sign through regression analysis. We verified the proposed algorithm using the virtual racing environment and GTSRB, and proved its real-time performance and efficient recognition performance.

• Proceedings of the KIEE Conference
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• 2004.11c
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• pp.30-32
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• 2004

With 3-D vision measuring, camera calibration is necessary to calculate parameters accurately. Camera calibration was developed widely in two categories. The first establishes reference points in space, and the second uses a grid type frame and statistical method. But, the former has difficulty to setup reference points and the latter has low accuracy. In this paper we present an algorithm for camera calibration using perspective ratio of the grid type frame with different line widths. It can easily estimate camera calibration parameters such as lens distortion, focal length, scale factor, pose, orientations, and distance. The advantage of this algorithm is that it can estimate the distance of the object. Also, the proposed camera calibration method is possible estimate distance in dynamic environment such as autonomous navigation. To validate proposed method, we set up the experiments with a frame on rotator at a distance of 1, 2, 3, 4[m] from camera and rotate the frame from -60 to 60 degrees. Both computer simulation and real data have been used to test the proposed method and very good results have been obtained. We have investigated the distance error affected by scale factor or different line widths and experimentally found an average scale factor that includes the least distance error with each image. The average scale factor tends to fluctuate with small variation and makes distance error decrease. Compared with classical methods that use stereo camera or two or three orthogonal planes, the proposed method is easy to use and flexible. It advances camera calibration one more step from static environments to real world such as autonomous land vehicle use.

• Proceedings of the Korea Contents Association Conference
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• 2009.05a
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• pp.79-82
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• 2009

In this paper, we propose new image processing method to detect fire image. At captured image from camera, we using OpenCV library to implement various image processing techniques such like differential image, binarization image, contour extraction, remove noise(morphology open, close), pixel calculation, flickering extraction, etc.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.10
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• pp.5039-5055
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• 2018

The quality of natural outdoor images captured by visible camera sensors is usually degraded by the haze present in the atmosphere. In this paper, a fast image dehazing method based on visible image and near-infrared fusion is proposed. In the proposed method, a visible and a near-infrared (NIR) image of the same scene is fused based on the dual-tree complex wavelet transform (DT-CWT) to generate a dehazed color image. The color of the fusion image is regulated through haze concentration estimated by dark channel prior (DCP). The experiment results demonstrate that the proposed method outperforms the conventional dehazing methods and effectively solves the color distortion problem in the dehazing process.

• The Journal of the Korea Contents Association
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• v.5 no.4
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• pp.111-121
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• 2005

The appearance of digital culture swiftly has changed the culture in domestic and international arenas before and after the year 2004 and the image and animation have become two of the most important expression media in contemporary age. Among the Japanese animations that have demonstrated the rapid development of cartoon and animation in the world, the director Dakahata Isao's 'Graves of the Fireflies' that has influenced many works has been evaluated as one of the noticeable works that has a unique method and scenario dramatization in terms of producing the original novel into an animation. This study investigates the metaphor and symbolism shown in this work according to each sequence, divides the production ability in the work into three elements and applies them to the important elements such as camera, colors and mise-en-scene when the original work is depicted into image. It can be summarized in more detail as in the following: firstly, I study the rhythm of camera corresponding to the symbolism of the angle that the camera has and production; secondly, I analyze the artistic elements appeared in the process of expressing the original work into the image, especially the production for the colors and symbolism contained in them and the composition of screen. Thirdly, I analyze how effectively the atmosphere for the situations for the original work is expressed in animation with the aid of one of the image elements, mis-en-scene. It is expected that the analyzed findings will be effective as a way of overcoming the limitation of expressions that the original work in text and the study on these processes will become good examples to the relevant workers and will be the good references to the producers who are interested in the creation of animation in Korea.