• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.37 no.4
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• pp.267-277
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• 2019

Photogrammetry and computer vision are identical in determining the three-dimensional coordinates of images taken with a camera, but the two fields are not directly compatible with each other due to differences in camera lens distortion modeling methods and camera coordinate systems. In general, data processing of drone images is performed by bundle block adjustments using computer vision-based software, and then the plotting of the image is performed by photogrammetry-based software for mapping. In this case, we are faced with the problem of converting the model of camera lens distortions into the formula used in photogrammetry. Therefore, this study described the differences between the coordinate systems and lens distortion models used in photogrammetry and computer vision, and proposed a methodology for converting them. In order to verify the conversion formula of the camera lens distortion models, first, lens distortions were added to the virtual coordinates without lens distortions by using the computer vision-based lens distortion models. Then, the distortion coefficients were determined using photogrammetry-based lens distortion models, and the lens distortions were removed from the photo coordinates and compared with the virtual coordinates without the original distortions. The results showed that the root mean square distance was good within 0.5 pixels. In addition, epipolar images were generated to determine the accuracy by applying lens distortion coefficients for photogrammetry. The calculated root mean square error of y-parallax was found to be within 0.3 pixels.

• The Journal of the Acoustical Society of Korea
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• v.34 no.1
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• pp.46-51
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• 2015

In fields of controlling acoustical noises, the overall adaptive control system is nonlinear due to the loudspeaker, amplifiers, converters, and microphones, etc. and the performance of noise control is decreased by the extent of nonlinearities, so an adaptive control system compensating nonlinear distortions is needed. In this paper, a new multi-channel adaptive noise controller was proposed, which was combined with the adaptive compensator to effectively linearize nonlinear distortions in the overall adaptive control system. Through computer simulations, the proposed adaptive compensator could linearize the nonlinear distortions and the proposed noise controller had better capability of controlling the noises than the conventional LMS controller.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.5
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• pp.1164-1170
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• 2011

In this paper, we propose accurate lattice extraction of elemental image array and pre-processing methods in computational integral imaging. Pre-processing methods remove distortions and noises of the image. Such distortions occurred in pickup systems are rotational errors. Distortions will degrade the resolution of reconstructed images. To overcome this problem, we propose our methods for extraction of elemental image array and pre-processing methods. Also, we describe that distortions affect the high quality reconstruction. Optical and computational experiments indicate that reconstructed images applied our methods is better than reconstructed images unapplied our methods.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.1
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• pp.201-207
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• 2015

The smartphone with camera can easily generate an image instead of a scanner. However the document image through a smartphone can have distortions related rotation or perspective. In this paper, we proposed a method to generate the document image in that distortions are reduced from the captured document image through a smartphone. For this, the original document image through a smartphone is preprocessed using the MSER-b technique to reduce the light effect. Then, the text area contour is extracted using the characteristics of the document image. Lastly, rotation or perspective distortions are reduced using the extracted text area contour. For experiments, the proposed method is compared two other products. Through experiments, we show that the distortions within the captured document image through smartphone can be effectively reduced.

• The Journal of Korean Academy of Prosthodontics
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• v.27 no.2
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• pp.53-78
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• 1989

This study was taken to observe the changes of the residual stress in the alloy and to measure 3 dimensional distortions of the long span ceramo-metal bridge. The materials used in this study were Pors-on 4 (Pd-Ag alloy), and Ceramco and Vita VMK 68 powders. The residual stress of the alloy was measured on the six specimens (dia. 8m/m) by the X-ray diffraction stress analyzer according to the kind of ceramic powder and different measuring stages. And, for the measurement of the distortions, fifteen specimens of the anterior 8-unit ceramo-metal brige were fabricated and subjected to the 3-D coordinate measuring machine. Variables included the 2 kinds of a ceramic powder and the presence or absence of a splint bar at the cast metal framework. The measuring stages in both were after casting, after degassing and after glazing. The following conclusions were obtained : 1. The residual stress of the alloy showed increasing tendency for the tension by the ceramic fusing, but there was not significance. 2. The tendency of the distortions in the cast metal frameworks were decrease of the width, the anterior displacement and sagging. 3. The amount of the distortions at the degassing stage were greater than that at the ceramic fusing stage. 4. The splint bar was effective to control the distortion only at ceramic fusing stage. 5. The sagging distortion in the Ceramco firing were even through all measuring stages, but in the Vita firing, pronounced at degassing stage.

• Korean Journal of Optics and Photonics
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• v.31 no.2
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• pp.88-95
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• 2020

In this study, we present methods to quantitatively analyze and correct the distortions and biocular parallaxes in a head-up display (HUD). To analyze asymmetrical distortions, five kinds of distortions are proposed and evaluated at five eye positions of an eyebox. The differences between distortions evaluated at the four corners of the eyebox and that at the center are defined as the relative distortions, which occur due to head motion of the driver. We also define the convergence and divergence parallaxes at six biocular positions in the eyebox to quantitatively analyze them. Using these analytical methods, we constrain the degree of biocular parallaxes and distortion changes with eye position to be small, so that an optical system nearly free from them can be obtained by optimization design for HUD optics.

• Korean Journal of Forensic Psychology
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• v.11 no.3
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• pp.267-285
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• 2020

The Statement evidence is an important method of proof in the criminal investigation and trial. Under certain conditions set by Korean Criminal Procedure Law, paper records of interrogations are admissible in criminal courts. However, it is shown that distortions are ever-present in paper records. Therefore, this study attempted to examine the effect of the investigator's belief about the veracity of a suspect on distortions of paper records. Ninety police investigators were randomly allocated into one of the three conditions('guilty belief', 'innocent belief', 'neutral belief'), and all the investigators were then asked to document a paper record while watching a prefilmed interrogation interview of the crime. The results showed that (1) the investigator's belief had significant effects on distortions. (2) All groups did more commissions than omissions. (3) matters subject to interrogation also had significant effects on distortions. In the conclusion, implications and limitations of the study were disscussed.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1999.06a
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• pp.332-338
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• 1999

A coupled thermal-mechanical analysis has been presented for the thermal distortions of the ventilated disk brakes during IS braking operations. The FEM results show that the bendings and distortions of the disk toward the left side are decreased, but the sinusoidal distortion of the disk rubbing surface along the arc length of the vent hole is highly increased by increasing the convective air cooling effects, which is heavily related to the squeal, wear and micro-thermal crackings at the rubbing surfaces due to uneven dissipation rates of friction heatings.

• Korean Journal of Psychosomatic Medicine
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• v.3 no.1
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• pp.64-71
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• 1995

Cognitive-behavioral approach can be clinically applied to coping with stress, because cognitions are playing a central mediating role in the occurances of stress and stress reactions. In other words, cognitive distortions can be associated with causing and/or maintaining psychopathology. The goal of cognitive-behavioral approach is to help the patients identify and alter cognitive distortions and maladaptive assumptions. This approach is aimed not at curing but rather at helping the patients to develop better coping strategies to deal with their life and work. The cognitive-behavioral techniques often used in this approach include problem solving, hypothesis-testing, self-monitoring, cognitive challenges, generating alternatives to automatic cognitive distortions, self-instruction, attribution and reattribution, and techniques to control or suppress thoughts. This approach is considered to be helpful for treatment and prevention of psychiatric disorders including psychosomatic disorders, in which stress can greatly affect their onset and course.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.10
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• pp.22-29
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• 2006

This paper considers the lens distortions such as a fisheye distortion and a perspective distortion. While a fisheye lens has a wide field-of-view, it causes a large distortion to the images. Regardless of a fisheye lens or a rectilinear lens, a lens generates perspective distortion in a vertical direction when the lens views in an upward direction or downward direction. These distortions deform images differently from human visual functions. Therefore, this paper presents a method to correct the distortions, and whereby, the research in this paper enlarges choices of images to image processing algorithm that may select the distorted images and the corrected images depending on applications. An infinite polynomial model is employed in the fisheye radial distortion correction, and the vertical perspective distortion correction is done by using a vanishing point. The methods introduced in this paper are implemented on the images captured by a rear-view camera installed on a vehicle and showed their robustness of the correction.