• 전기의세계
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• v.26 no.3
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• pp.69-72
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• 1977

The effects of sharpness of needle electode on the spark voltage in needle-plane and needle-needle spark gaps at atmospheric pressure was investigated experimentaly in this paper. As the sharpness of needle electrode increases, the spark voltage increases, and the rate of increase is greater in needle-needle electrode than in needle-plane gap. the effects of sharpness is greater in small gap length. These characteristics can be explained by the electric field strength at the needle tip depending on the sharpness of needle, electro-static capacity between the electrodes, and the polarity effect in needle-plane gap. These experimental results will be able to play an important roles on the design of needle-needle gap as high voltage measurement devices and of needle-plane gap as high voltage rectifier equipments.

• Fibers and Polymers
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• v.1 no.1
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• pp.59-65
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• 2000

In order to investigate psychoacoustic characteristics of fibers, and to compare them with sound physical parameters, each sound of 25 different fabrics consisted of a single fiber such as wool, cotton, silk, polyester, and nylon was recorded. Sounds of specimens were transformed into critical band diagram and psychoacoustic characteristics including loudness and sharpness for each sound were calculated based on Zwicker＇s models. Physical parameters such as the level pressure of total sound (LPT), level ranges (ΔL), frequency differences (Δf), AR coefficients (ARC, ARF, ARE) were obtained in fast fourier transform (FFT) spectrum. Nylon taffeta showed higher values for loudness than 2.5 sone corresponding to human low conversation, while most silk fibers generated less louder showing lower values for loudness than 1.0 sone. Wool fibers had higher loudness mean value than that of cotton, while the two fibers didn't differ in LPT. Loudness showed high positive correlation coefficients with both LPT and ARC. Sharpness values were higher for wool fiber group than other fibers. Sharpness was not concerned with loudness, LPT, and ARC, but the fabrics with higher values for sharpness tended to show higher ΔL.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 1998.11a
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• pp.154-157
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• 1998

This study investigated the psychological and physiological responses to the sound of car horns produced by different. manufacturers. Ten female college students listened to the sound of the horns while their EEG responses on 6 sites were being measured, and rated each hem on psychological scales. Their EEG and psychological responses were investigated as to whether the responses were related to the loudness, sharpness, tonality, and roughness of the horns. The results indicated that the subjects felt more 'dominated' as the loudness and sharpness increased, that the subjects felt more 'pleasant' as the sharpness increased, that the subjects felt more 'dominant' as the tonality increased, and that the subjects felt more 'aroused' as the roughness increased. The physiological results showed that the fast alpha wave in the occipital lobe decreased in the relative power as the loudness, sharpness, and tonality increased, and that the delta wave in the occipital lobe increased and the slow alpha wave in the frontal lobe decreased in the relative power as the roughness increased.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.12 no.1
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• pp.115-121
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• 1982

In the study of the focal trough of panoramic radiograph, using the Moritta compony Panex-EC a series of 48 exposures were: taken with the 6-18 brass pins placed in the holes of the plastic model plate, then eveluated by 4 observers. The author analyzed the focal trough defined by the sharpness criteria and calcuated the vertical and horizontal magnification range in the corrected focal trough. The results were as follows; 1. Continuous focal trough was not defined in the anterior region using a very high degree of sharpness. 2. As degree of sharpness used in the analysis became less, focal trough was continuous in the anterior and posterior regions, symmetrized bilaterally, and the widths of the focal trough increased more in the posterior region. e. As sharpness criteria were reduced, the percentage range of image magnification increased on both vertical and horizontal magnification, and especially the percentage range of horizontal magnification was greater than that of vertical magnification.

• Smart Structures and Systems
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• v.24 no.5
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• pp.659-668
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• 2019

In digital image correlation, speckle image is closely related to the measurement accuracy. A practical global evaluation criterion for speckle image is presented. Firstly, based on the essential factors of the texture image, both the average particle size and image sharpness are used for the assessment of speckle image. The former is calculated by a simplified auto-covariance function and Gaussian fitting, and the latter by focusing function. Secondly, the computation of the average particle size and image sharpness is verified by numerical simulation. The influence of these two evaluation parameters on mean deviation and standard deviation is discussed. Then, a physical model from speckle projection to image acquisition is established. The two evaluation parameters can be mapped to the physical devices, which demonstrate that the proposed evaluation method is reasonable. Finally, the engineering application of the evaluation method is pointed out.

• Current Optics and Photonics
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• v.5 no.5
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• pp.514-523
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• 2021

Methods for absolute depth estimation have received lots of interest, and most algorithms are concerned about how to minimize the difference between an input defocused image and an estimated defocused image. These approaches may increase the complexity of the algorithms to calculate the defocused image from the estimation of the focused image. In this paper, we present a new method to recover depth of scene based on a sharpness-assessment algorithm. The proposed algorithm estimates the depth of scene by calculating the sharpness of deconvolved images with a specific point-spread function (PSF). While most depth estimation studies evaluate depth of the scene only behind a focal plane, the proposed method evaluates a broad depth range both nearer and farther than the focal plane. This is accomplished using an asymmetric aperture, so the PSF at a position nearer than the focal plane is different from that at a position farther than the focal plane. From the image taken with a focal plane of 160 cm, the depth of object over the broad range from 60 to 350 cm is estimated at 10 cm resolution. With an asymmetric aperture, we demonstrate the feasibility of the sharpness-assessment algorithm to recover absolute depth of scene from a single defocused image.

• Korean Journal of Veterinary Research
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• v.62 no.1
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• pp.8.1-8.6
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• 2022

The aim of this prospective study was to investigate the effects of focal spot size of X-ray tube on sharpness of clinical radiographic images of dogs and cats. Radiographic images of 24 stifle joints, 15 carpi, 18 lumbar spines, 61 thoraxes, and 47 abdomens of 102 dogs and 4 cats were obtained in the present study, using 2 X-ray tubes with nominal focal spots of 2.0 mm and 0.6 mm, respectively. The sharpness of specific anatomical structures in all the images of 5 projections was assessed. The radiographic sharpness of various anatomical structures of lumbar spine and cortex of stifle with fine focal spot was increased significantly compared with broad focal spot images. In addition, the blurred motion was significantly higher in the fine focal spot images of thorax. In conclusion, our study suggests that a selective use of fine foci for imaging of lumbar spine or cortex of stifle enhanced radiographic sharpness.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.2
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• pp.133-140
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• 2014

3D stereoscopic display is becoming increasingly common. Most stereoscopic displays still require the viewers to wear 3D glasses to watch 3D contents. As it is widely known, especially in shutter glass method, 3D glasses normally cause to reduce the perceived colorfulness and sharpness considerably as well as brightness. In this paper, we have estimated and analyzed the degradation of perceptual brightness in 3D images viewed through the shutter glasses by using CIECAM02 model. This study focuses on loss of colorfulness and sharpness when PDP-TV is watched at 3D mode in shutter-glass type 3D-TV. We analyze perceptual colorfulness and sharpness of 3D display with glasses and propose a method to compensate 3D colorfulness and sharpness for the best 3D experience.

• Proceedings of the IEEK Conference
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• 2001.10a
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• pp.76-79
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• 2001

In Japan in of today, there is no aspect in which the quantity of waste glass bottle discharged from ordinary homes decreases. Moreover, the kind of shape and color of the waste glass bottles are increasing little by little. In the recycling of the glass bottle, it becomes a problem that many kind of the color is abounding. It is possible to use the transparent glass bottle as raw material of the glassware. Since the reproduction of the color is difficult, the colored glass bottle is not possible to use as a raw material. Therefore, the processing of these glass bottles entirely depends on the reclamation. In Japan, the security of the new reclaimed land is very difficult for the reason of the environmental damage. Moreover, the life expectancy in many reclaimed lands is anticipated with within two years. Therefore, the development of the processing method of glass bottle other than reclamation becomes a rapid problem. At present it is examined that it is used of an aggregate of the colored pavement, as one of the application methods of colored glass bottle. The particle size of produced glass aggregate is also 5mm or less, because the thickness is 5mm or less on almost glass bottles. And almost glass particles have the sharp tip. The application as the aggregate is limited for this sharpness of the particle. This study was carried out for the purpose of the establishment of sharpness measuring method of the glass aggregate particle. It is possible that the injury degree to human in the handling is known, if showing the sharpness of the aggregate particle at the objective numerical value is possible. And the application of the glass aggregate is spread. In this research, the balloon fracture method was used for the sharpness measurement of the glass particle. This method is based on the completely new idea, and it is possible to express completely the possibility of injury to the human. It is reported with the detailed result in full paper, because this study is continuous in order to get the JIS which is industrial standard of Japan.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.21 no.1
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• pp.137-143
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• 1991

In the study of the focal trough of panoramic radiograph using Panoura Eight-S (the Yoshida company), a series of 63 X-ray films were taken with the 8-19 metal pins placed in the holes of the plastic model plate and evaluated by 4 observers. The author analized the focal trough defined by the sharpness criteria and calculated dimension of focal trough in the horizontal plane. The results were as follows; 1. Focal trough was not continued in the anterior region within a very high degree of sharpness. 2. With optional sharpness, the width of anterior and posterior focal trough was approximately l3㎜ and 60㎜ respectively. 3. The focal trough was narrow in the anterior region and was flared laterally with symmetry in posterior region. 4. Sharp image began to show at the position of 18㎜ posteriorly from the most anterior position of chin rest.