• Journal of the Optical Society of Korea
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• v.15 no.3
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• pp.310-317
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• 2011

Perceptibility and acceptability are the most often used threshold units in the field of color science. The former refers to a just perceptible difference and the latter evokes a tolerable color difference. Such thresholds can be very significant to color quality control processes in the printing industry and should be defined in quality measure units. Optical density (OD) and color difference models are usually utilized as color quality measures and have been provided in a considerable number of commercial measuring devices such as spectrophotometers. However, their merits and traits are far less understood in the literature. The present study intends to evaluate performance of those color quality measures including the OD and widely known color difference models, e.g. ${\Delta}E{^*}_{ab}$, ${\Delta}E_{CMC(l:c)}$ and ${\Delta}E{^*}_{00}$. A set of psychophysical assessments were carried out in order to accumulate the perceptibility and acceptability thresholds data, and their central trend was compared with the color quality measure estimates.

• Proceedings of the Optical Society of Korea Conference
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• 2003.07a
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• pp.80-81
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• 2003

The psychophysical experiments were carried out by a panel of eleven observers on the image difference pairs displayed on the LCD (liquid crystal display)to quantify the quality changes of complex images imparted by the typical image processing operations. There were six different kinds of pairs according to their original image. The three types of visual tests performed were： pair-to-pair comparison of image differences for ordering the differences between images introduced by single or combination of image lightness change, contrast change, blurring, and sharpening, perceptibility and acceptability tests using ascending or descending series of image difference pairs ordered according to the size of their visual differences. (omitted)

• The Journal of Advanced Prosthodontics
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• v.15 no.2
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• pp.93-100
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• 2023

PURPOSE. The aim of this study is to evaluate the effect of resin cement color, cement thickness, and thermocycling on the final color of monolithic lithium disilicate crowns. MATERIALS AND METHODS. A total of ninety prepared central incisors of typodont teeth were restored with lithium disilicate crowns which have different cement thicknesses (40 ㎛, 80 ㎛, and 120 ㎛) and cement shades (clear, yellow, and white). Color parameters of restorations were measured with a spectrophotometer in three different steps 1) before cementing 2) after cementing and 3) after thermocycling with 10000 cycles. Color differences (ΔE₀₀) were calculated with the CIEDE2000 formula and evaluated according to perceptibility (0.8) and acceptability (1.8) thresholds. The ΔE₀₀ data were analyzed by using two-way ANOVA before and after thermocycling (α = .05). RESULTS. There was no interaction between the cement shade and the cement thickness factors. After cementation, the mean ΔE₀₀ was under the perceptibility threshold in the group of 40 ㎛ cement thickness and clear cement while it was between the perceptibility and acceptability thresholds (0.8 < ΔE₀₀ < 1.8) for all other groups. After thermocycling, the ΔE₀₀ values were between the perceptibility and acceptability thresholds for all experimental groups. Although there were no significant differences among the groups, thermocycling increased the color difference values. CONCLUSION. The cementation of restorations with clear, yellow, and white resin cements resulted in color differences with uncemented restorations except for the group cemented with clear cement in 40 ㎛ cement thickness. All study groups revealed perceptible color change after thermocycling.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.29 no.1
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• pp.191-201
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• 1999

Purpose: To know whether there would be a difference among spiral tomograms of different slice thicknesses in the measurement of distances which are used for dental implant planning. Materials and Methods: 10 dry mandibules and 40 metal balls were used to take total 120 Scanorailll tomograms with the slice thickness of 2 mm, 4 mm and 8 mm. 3 oral radiologists interpreted each tomogram to measure the distances from the mandibular canal to the alveoalr crest and buccal. lingual and inferior borders of mandible. 3 observers recorded grades of 0, 1 or 2 to evaluate the perceptibility of alveolar crest and the superior border of mandibular canal. ANOVA with repeated measure. Chi-square tests and intrac!ass correlation coefficient(R₂, α) were used For statistical analysis. Results: There was not a statistically significant difference among spiral tomograms with different slice thicknesses in the measurement of the distances and in the perceptibility of alveolar crest and mandibular canal(p>0.05). All of them showed a good relationship in the reliability analysis. The perceptibility of alveolar crest and mandibular canal was almost similar and an excellent relationship was seen on all of them. Conclusions: There would be no significant difference. no matter which spiral tomogram of any slice thickness may be used in dental implant planning. considering the thickness of dental implant fixture.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.7
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• pp.1718-1724
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• 2009

This paper is aimed at studying the sexuality elements and their perceptibility in the sports photographs and images of internet portal media. The sexuality elements are composed of athletes' uniform, body and external feature. In an analysis of sports' users through portal media, there were some differences in an experimental group of men. There was the difference between an experimental group of men and a of men and women sports game. The perceptibility of sexuality imaged by sports images of men and women games in portal media was higher in an of men and women sports game than the experimental group of men. Accordingly, the sexuality imaged through sports images of portal media had a higher effect on sports' men-users.

• Restorative Dentistry and Endodontics
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• v.41 no.3
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• pp.159-166
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• 2016

The purpose of this review was to suggest practical criteria for the clinical translucency evaluation of direct esthetic restorative materials, and to review the translucency with these criteria. For the evaluation of reported translucency values, measuring instrument and method, specimen thickness, background color, and illumination should be scrutinized. Translucency parameter (TP) of 15 to 19 could be regarded as the translucency of 1 mm thick human enamel. Visual perceptibility threshold for translucency difference in contrast ratio (${\Delta}CR$) of 0.07 could be transformed into ${\Delta}TP$ value of 2. Translucency differences between direct and indirect resin composites were perceivable (${\Delta}TP>2$). Universal and corresponding flowable resin composites did not show perceivable translucency differences in most products. Translucency differed significantly by the product within each shade group, and by the shade group within each product. Translucency of human enamel and perceptibility threshold for translucency difference may be used as criteria for the clinical evaluation of translucency of esthetic restorative materials.

• Korean Institute of Interior Design Journal
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• v.23 no.4
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• pp.211-219
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• 2014

The internal streets of mixed-use commercial complexes, which are the extension of urban streets, are being changed from a mediating space aiming at movement to a staying-type space according to the change of mixed-use commercial complexes. And they function as a resting place of user with court and plaza, and act as an urban public space, and accommodate an activity arising from the gathering of many people. As a result, a role of new relaxation and community space is played in the center of the city. And the aspect of publicness is brought into relief. Hence, this study is intended to examine the characteristics that the internal streets of mixed-use commercial complexes have, and furthermore, it is intended to show the planning characteristics in the contemporary mixed-use commercial complexes. With regard to the method of research, first, space configuration and role of internal streets was examined according to the change of mixed-use commercial complexes on the basic of precedent research and literature review. And the internal streets of mixed-use commercial complexes were classified into doorway part, traffic line, and open space. And the characteristics of internal streets in the mixed-use commercial complexes through the concept of architectural 'publicness' were derived as accessibility, amenity, perceptibility, openness, connectivity and symbolism. The internal streets of mixed-use commercial complexes should be changed by the space planning to secure continuity with the city on the basis of accessibility and connectivity and to reinforce visual openness in the internal streets in order to improve amenity and perceptibility, accordingly the mixed-use commercial complexes will be also born again as symbolic public space in the city. Variously changing elements to improve publicness very importantly act on the planning of internal streets in the mixed-use commercial complexes, and therefore researches should be continuously carried out.

• Journal of Korean Society for Atmospheric Environment
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• v.15 no.5
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• pp.599-611
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• 1999

Now that the plume of point source was suspected to have strong impact on visibility impairment in Pusan, we evaluated visibility impairment impact of the pulme from Pusan Thermo Electric Power Plant in Pusan. Level-1 and-2 analyses were carried out using VISCREEN(Visual Impact Screen model). The emission rates for this Pusan Thermo Electric Power Plant was projected to be 116g/s of nitrogen oxides(as $NO_2$). The source fails the level-1 test with a Plume perceptibility(ΔE) of 30, nearly 15 times the screeing threshold. To characterize worstcase meteorological conditions for level-2 screening, we obtained meteorological data from Mar., 1996 to Feb., 1997 of Pusan Thermo Electric Power Plant. The source fails the level-2 test with a ΔE of 17, nearly 8.5 times the screening threshold. These analyses indicated that adverse visibility impairment could not be ruled out. Therefore a Level-3 analysis was performed using PLUVUE II(Plume Visibility model). As a result, maximum reduction of visual range for 0900LST in winter was 0.9%. Visual impact of the plume from vast point source was judged to be considerable in terms of background visibility of urban area.

• Journal of Advanced Navigation Technology
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• v.18 no.1
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• pp.44-49
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• 2014

In recent, watermarking technology have been paying attention to methods avoiding illegal use and reproduce of digital contents. Then, in order to protect the right of digital contents, a watermark image is inserted into original images. In different watermarking methods, several technologies using Ant Colony Algorithm have been studied. In this paper, we propose a watermarking method using a discrete optimization method in the ants colony algorithm. This proposed method resembls the process that ants follow the pheromone traps to find out food. And when a watermark image is inserted into original images, the proposed method considers the deployment of obstacles or the balance between cells in the entire digital image. Simulation results show that the proposed method is increased in robustness of watermarked image and is decreased in the perceptibility of watermarking compared to the previous methods.

• Proceedings of the KSPS conference
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• 2007.05a
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• pp.84-87
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• 2007

The final purpose of this paper is to prove that, under noisy environment, there is significant difference of perceptibility of the place of articulation between fortis plosives and aspirated plosives in Korean. For this research, a perceptual experiment had been made. Two groups of subjects heard stimuli with noise and were required to answer which sound they had heard. The result is that, with noise, aspirated plosives cannot be heard clearly whereas fortis plosives can be heard well.