• Journal of Dental Rehabilitation and Applied Science
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• v.34 no.3
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• pp.175-185
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• 2018

Purpose: The aim of this clinical study was to evaluate the efficacy and safety of a self - applied paint - on whitening gel combined with wrap to increase the effect of a whitening gel and minimize gingival irritation. Materials and Methods: Ninety adult volunteers were randomly treated to a control group and two experimental groups using whitening gel containing 2.8% and 3.0% hydrogen peroxide for 30 persons each. They had used the wrap and whitening gel on maxillary 4 anterior teeth for 30 minutes per day during 2 weeks. Whitening tooth color response was measured by VITA shade guide and ShadeEye $NCC^{(R)}$. And side effects were assessed from interview and intraoral examination. The efficacy and safety evaluations were statistically analyzed. Results: In the evaluation with VITA shade guide, there was significantly the whitening effect in experimental groups compared with the control group. In the evaluation with ShadeEye $NCC^{(R)}$, the 3.0% experimental group showed significantly the whitening effect compared to the control group and the 2.8% experimental group (P < 0.05). There were some complaints of minor side effects, but there did not find abnormal symptoms of the gingival stimulation in all groups. Conclusion: A self - applied paint - on whitening gel combined with wrap can be used as a useful self-whitening material because the whitening effect increases as the concentration of hydrogen peroxide from 2.8% to 3.0% and also no significant side effects are observed.

• The Journal of the Convergence on Culture Technology
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• v.6 no.3
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• pp.185-191
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• 2020

This study aims to understand the differences in cultural and emotional perceptions about the color image of public healthcare facilities in Romania, an Eastern European country that is relatively lacking in recognition but is gradually expanding trade. For this, color images were selected through a review of previous studies, and a questionnaire survey was constructed based on the colorimetric data by visiting 8 public healthcare facilities such as medical facilities, 4 social sports facilities, and 8 nursing facilities. An online survey was conducted on the color image of public facilities with 89 Koreans and 86 Romanians, and frequency and cross-analysis was conducted using the SPSS statistical analysis program to examine the color images of public healthcare facilities of Koreans and Romanians. The difference in perception was identified. As a result, it was found that there was a statistically significant difference in the perception of color images of public healthcare facilities between countries in vocabulary evaluation and image evaluation, and this was interpreted as different meanings for groups residing in different cultures. Therefore, it implies that cultural differences in perception should be considered when establishing an environment related to this in the future.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.45 no.2
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• pp.65-73
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• 2008

The characterization process for the accurate color reproduction in mobile phone with camera and LCD is popular. The camera and LCD characterization, gamut mapping process is necessary to map the camera's input color stimulus, CIEXYZ value, into the LCD's output color stimulus. Each characterization is the process estimating the relation between input and output signals. In case of LCD, because of output device, the output color stimulus for the arbitrary input signal can be measured by spectro-radiometer However, in the camera, as the input device, the characterization is an inaccurate and needs the manual works in the process obtaining the output signal because the input signal can not be generated. Moreover, after gamut mapping process, the noise is increased because the optimized gamma tone curve of camera for the noise is distorted by the characterization. Thus, this paper proposed the system of obtaining the output signal of camera and the method of gamma correction for the noise. The camera's output signal is obtained by RGB values of patches from captured the color chart image. However, besides the illumination, the error for the location of the chart in the viewfinder is generated when many camera modules are captured the chart. The method of correcting the position to correct the error from manual works. The position of camera is estimated by captured image. This process and moving of camera is accomplished repeatedly, and the optimized position can be obtained. Moreover, the lightness curve of camera output is corrected partly to reduce the noise from the characterization process.

• The Journal of Korean Academy of Prosthodontics
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• v.43 no.4
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• pp.466-477
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• 2005

Statement of problem : Problem of matching the appearance of porcelain restorations with the patient's natural dentition has always been a concern to dental clinicians. Recently, demands for esthetics, even in restorations requiring strength, has brought a revolution to dentistry and increased use of zirconia. Among the various factors, shade and translucency or the core can significantly affect the overall esthetics of the restoration and should be considered when selecting an all-ceramic system. Purpose : The purpose of this study was to spectrophotometrically evaluate the influence of different zirconia systems and core thickness on the final shade of all-ceramic restorations using the CIEL$^*a^*b^*$ system. Material and Methods: Core specimens (n : 20 per group) of In-Ceram Alumina, In-Ceram Zirconia, Digident CAD/CAM Zirconia, Cercon Zirconia were fabricated 20mm in diameter. 10 specimens of each group were fabricated at core thickness of 0.5mm and 0.7mm. These core specimens were veneered with shade Al & A3 porcelain of the recommended manufacturer. CIEL$^*a^*b^*$ coordinates were recorded for each specimen with a spectrophotometer (Model CM-2600d, Minolta, Japan). Color differences were calculated using the equation ${\Delta}E^*=[({\Delta}L^*)^2+({\Delta}a^*)^2+({\Delta}b^*)^2]^{\frac{1}{2}}$. Results : 1. Specimens of core thickness 0.5mm and 0.7mm did not exhibit clinically perceived color difference. 2. Regarding shade reproducibility, In-Ceram Alumina and In-Ceram Zirconia showed significant difference within each group. 3. Cercon Zirconia group showed the highest $L^*$ value and Digident Zirconia group showed lowest $a^*$ & $b^*$ value. 4. Generally the shade difference between materials was higher in the A3 shade group than in the Al shade group. Conclusion: Within the limitations of this study, there was no color difference after increase in core thickness and every all-ceramic system has color characteristics that clinicians have to consider when selecting materials. Also, manufacturers of different porcelain systems must make every effort to achieve color reproducibility.

• Journal of Korea Multimedia Society
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• v.13 no.5
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• pp.674-683
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• 2010

For the purpose of color reproduction under standard viewing conditions, recently, color display devices have developed for the colorimetric color reproduction. However the real viewing condition of color display devices is quite different from that. Therefore, it is very important for reproduced colors viewed under real conditions to match the color appearance under standard situations. There are various models that can be used to reproduce corresponding colors considering the chromatic adaptation of the human visual system. However neutral point or chromatic adaptation for the luminance level is not enough. In this paper, we propose a model that find adapting white points for the variations of the luminance levels under the same illuminant. This model is modeled by the proportion of Euclidian distance for luminance level. It is the adapting white function of the sigmoid type for surround luminance level. In the model, the optimal coefficients are obtained from the Hunt's experimental result. It is applied in the chromatic adaptation model using the neutral point of the various viewing conditions. And the neutral point can be used as the theoretical standard which determines the reference white of the color display devices.

• Journal of Korea Multimedia Society
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• v.13 no.5
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• pp.641-650
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• 2010

Color image sensors (CIS) output color images through image sensors and image signal processing. Image sensors that convert light to electrical signal are divided into CMOS image sensor and CCD image sensor according to transferring method of signal charge. In general, a CIS has RGB output signals from tri-stimulus XYZ of the scene through image signal processing. This paper presents an adaptive colorimetric analysis method to obtain chromaticity and luminance using CIS under various environments. An image sensor for the use of colorimeter is characterized based on the CIE standard colorimetric observer. We use the method of least squares to derive a colorimetric characterization matrix between camera RGB output signals and CIE XYZ tristimulus values. We first survey the camera characterization in the standard environment then derive a SGL(shutter-gain-level) function which is relationship between luminance and auto exposure (AE) characteristic of CIS, and read the status of an AWB(auto white balance) function. Then we can apply CIS to measure luminance and chromaticity from camera outputs and AE resister values without any preprocessing. Camera RGB outputs, register values, and camera photoelectric characteristic are used to analyze the colorimetric results for real scenes such as chromaticity and luminance. Experimental results show that the proposed method is valid in the measuring performance. The proposed method can apply to various fields like surveillant systems of the display or security systems.

• Journal of Dental Rehabilitation and Applied Science
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• v.28 no.2
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• pp.213-221
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• 2012

The purpose of this study was to evaluate the stability of external stain that long term attrition caused by tooth brushing affected the color variation of external stain of IPS e.max Press Porcelain. The specimen was made by IPS e.max Press LT ingots, and treated the shade of external staning as Orange, A, B, C, D After conducting horizontal toothbrush strokes about 11,000 / 22,000 / 44,000 / 66,000 / 88,000, Color changers of the external stained layer was measured with SpectroShade$^{tm}$ MICRO(MHT, Italy). The result of this study was obtained as follows: 1. After 11,000 strokes, the color changes of shade were greater in Orange shade than the other 4 shade groups. And even though toothbrush strokes were increased until 88,000, there were no statistical significant color changes about the external stain shade variation. 2. The amount of color variation about increasing of toothbrushing strokes was irregular(no consistent increasing, or decreasing), and it was no statistical significant changes According to these results, the long term tooth-brushing doesn't affect the changes of external stain about IPS e.max press porcelain. And it doesn't reduce the stability of external stain clinically. Later, it will be needed to study other factors affecting the external stain.

• The Journal of the Korea Contents Association
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• v.10 no.12
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• pp.236-242
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• 2010

The porcelain fused metal was made through the progressive fused process of porcelain on substructure of metal material. The substructure was made using novel SLM method. The objective of this study was to observe the color change of porcelain using spectrophotometer equipment according to porcelain fused step and production methods after conducting the process of casting and SLM method of the substructure. The color change by step was indicated that fused opaque porcelain groups(CN1, CC1, CT1, SC1, ST1) had color difference(${\Delta}E$=30) by comparison with fused body porcelain groups(CN2, CC2, CT2, SC2, ST2) and fused glazing porcelain groups(CN3, CC3, CT3, SC3, ST3) (p<0.05). and there was no color difference between the substrates(CN, CC, CT) made by the casting method and the substrates(SC, ST) made by the SLM method. so, the color change was expressed by fused change of porcelain, and this study showed that the color of porcelain fused metal made by the SLM method can be applied clinical trials.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.42 no.5 s.305
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• pp.19-28
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• 2005

Real surround viewing conditions in watching the color display devices such as TV and PC monitor are quite different from the standard viewing conditions. Human visual system is adapted chromatically under the different viewing conditions in luminance levels and chromaticity of illuminants. Accordingly, the reproduced colors of the same chromaticity will appear as quite different color. Therefore, it is necessary that the displayed colors are reproduced to be appeared as the original colors in the standard viewing conditions. In this paper, we propose a chromatic adaptation model for the variations of the surround illuminants' chromaticity under the same luminance conditions. In proposed chromatic adaptation model, we calculate each gain of L, M, and S as nonlinear functions according to the chromaticity of the surround illuminants. And the optimal coefficients are obtained from the corresponding colors data of the Breneman's experiments. The proposed chromatic adaptation model is compared with the conventional chromatic adaptation models. In the experimental results, the proposed model has very good performance in the whole range of luminance levels. We also experimentally confirmed that the reproduced corresponding colors using the proposed chromatic adaptation are appeared as the original colors when the real surround viewing conditions are different from the standard viewing conditions.

• The Journal of the Convergence on Culture Technology
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• v.6 no.1
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• pp.163-169
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• 2020

The purpose of this study is to find out whether the environment is based on the Color Universal Design (CUD, CUD Recommended Color Set Guidebook), which is located in the area with the highest proportion of elderly people in the city of Busan in Korea. Five nearby parks in the walking district of Busan were selected to measure the environmental color with a spectrophotometer(Minolta CM-2600d) and web color search. The range of the color survey was limited to the pavement; public facilities(sign, benches, restroom), and exercise&sports facilities. The results of the study are as follows. Overall, the Y color group was dominant, with similar color usage and intensity, and similar levels of saturation. This was analyzed based on the Color Universal Design theory, suggesting that the visual characteristics of the elderly were not taken into account, and the Neighborhood Park located in Busan was found to lack the environmental color of consideration for the visual characteristics. In addition, this study could act as a basic study that can be applied to social and environmental colors that reflect the color perception and cognitive characteristics of the elderly.