• The Journal of Korean Academy of Prosthodontics
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• v.16 no.1
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• pp.38-44
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• 1978

Color is an important factor in dental esthetics. Application of natural tooth color will not fail to produce pleasing results. But a standardized method of shade matching has not been adopted. If we are to overcome the color matching problem in dentistry, an understanding of the nature of color and light is essential. The purpose of this study was to compare the effects of different light sources and different background colors on the ability of observers to correctly match shades of artifical teeth. And observation was made to determine if the time spent in making a shade match was a factor in the correctness of the response. A test method was devised and 50 individuals made observations which were recorded and analyzed. $X^2$-test gave results indicating that the time factor had no effect on the response made. An analysis of variance showed the following effects significant at the five percent level; (1) light source (2) background color (3) subject. The following conclusions can be drawn from this study; (1) The time spent in making shade selection is not a factor in the correctness of the selections. (2) The light source used is an important factor in matching tooth shade; and there is no significant difference between the light sources in shade matching. (3) Under the conditions of this study, the greatest accuracy in shade matching was obtained on the brown background.

• Journal of Ginseng Research
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• v.8 no.1
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• pp.65-74
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• 1984

This experiment was carried out to study the effects of light intensity and soil water regimes on the growth of ginseng seedling. The results were as follows: 1. The maximum light intensity and optimum temperature in 1,le photosynthesis of ginseng seedling were 10,000 lux and 23 $^{\circ}C$. Respiration rate was increased at high temperature. 2. Air and soil temperature under the shading were increased as the increase of light intensity but soil water contents were decreased as the increase of light intensity, whereas air and soil temperature were decreased as the increase of precipitation under the shade b5: soil water contents were increased as the increase of precipitation under the shade. 3. The higher the transmittance of the shade, the greater the specific leaf weight (S.L.W.) and stomatal density. In contrast, however, the contents of total chlorophyll, chlorophyll a and b, and stomatal length was decreased. There was no any significant difference light intensity of the a/b ratio of chlorophyll. 4. The highest photosynthesis was occurred in ginseng leaves grown under the shade 5% L.T.R. and net photosynthesis rates increased with increasing soil water contents. 5. Optimum condition for usable seedling yield were 5% L.T.R. and 3.3% precipitation under the shade. Useless seedling increased with increasing precipitation under the shade.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.8
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• pp.5619-5626
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• 2015

The zenithal light is the one that is entered down into the interior space or the spaces such as the inner court, through windows high located in the wall or openings of the roof. The aim of this study is to analyze the types of mechanism for the zenithal light by studying some examples related to the zenithal opening, and to investigate those characteristics. One of the most important features is a structural unit of the skylight entering the room. In this study, according to the structural unit, the direct light type, the duct-type and the shade type was distinguished, and each type can be divided into several modified types. Precisely, the direct light type is divided into an unexposed type and an exposed type of the source of light. The duct type is also divided into an intensive duct type and a distributed duct type. The shade type is classified into a ceiling surface shade, a reflections objet shade, a double ceiling shade and a wall shade.

• Korean Institute of Interior Design Journal
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• v.19 no.5
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• pp.3-10
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• 2010

In the history of art and architecture, there are different characteristics in relationship between light and space. Among them, two characteristics seem to be fundamental : The first is that contrast between light and darkness is more articulated. Direct sunlight penetrates into the dark interior space made by heavy masonry structure. This is generally found in the traditional western religious buildings. The second is that light is mixed with darkness and becomes shade. Shade is different from shadow that is usually perceived as the opposite of light. Sunlight is filtered under through the big horizontal roof and rice paper walls in the traditional far-east Asian architecture and becomes weak ambient light. In this shade, there is no strong contrast between light and darkness. This difference is not only originated from the architectural differences, but also originated from the conceptual differences about light, space, and the world in two cultures. This paper tries to study the philosophical, aesthetical backgrounds as well as case examples in art and architecture of two characteristics. Based on the case studies, this paper aims to analyze the main perceptual structure. Finding the relationship between light, space, and human body by making three dimensional models is the crucial analysis method of this research. Although in real life and experiencing the world, these two characteristics are not clearly separated, comparative study based on different cultures gives opportunity to think of diverse perspectives on light and space.

• Restorative Dentistry and Endodontics
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• v.47 no.1
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• pp.9.1-9.11
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• 2022

Objectives: This study investigated the microhardness, flexural strength, and color stability of bleach-shade resin composites cured with 3 different light-curing units. Materials and Methods: In this in vitro experimental study, 270 samples were fabricated of bleach and A2 shades of 3 commercial resin composites (Point 4, G-aenial Anterior, and Estelite Sigma Quick). Samples (n = 5 for each trial) were cured with Bluephase N, Woodpecker LED.D, and Optilux 501 units and underwent Vickers microhardness and flexural strength tests. The samples were tested after 24 hours of storage in distilled water. Color was assessed using a spectrophotometer immediately after preparation and 24 hours after curing. Data were analyzed using 3-way analysis of variance and the Tukey test (p ≤ 0.001). Results: Samples cured with Optilux exhibited the highest and those cured with LED.D exhibited the lowest microhardness (p = 0.023). The bleach shade of Point 4 composite cured with Optilux displayed the highest flexural strength, while the same composite and shade cured with Sigma Quick exhibited the lowest (p ≤ 0.001). The color change after 24 hours was greatest for the bleach shade of G-aenial cured with Bluephase N and least for the A2 shade of Sigma Quick cured with Optilux (p ≤ 0.001). Conclusions: Light curing with polywave light-emitting diode (LED) yielded results between or statistically similar to those of quartz-tungsten-halogen and monowave LED in the microhardness and flexural strength of both A2 and bleach shades of resin composites. However, the brands of light-curing devices showed significant differences in color stability.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.7 no.1
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• pp.110-115
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• 2004

This experiment was conducted to investigate the effect of light intensities on the growth responses, carbohydrate contents and the characteristics of leaf gas exchange in Miscanthus sinensis and Pennisetum purpurascens. The plant height and leaf length were increased to about 30% in the sun. However, those were reduced severely in the shade, and leaf necrosis was also observed. The representative growth index and the dry weight of 2 species were 50% higher than shade and the rate was reduced according to the decrease of light intensities. Total carbohydrate contents showed very similar changes to that of dry weight. However, any notable influences were observed at above the light intensities of 250~500${\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ in the half shade. The size of spikes and the earliest spiking appeared in the sun and the spike color was decolorized as decreased in light intensities, irrespective of species. Photosynthetic rate of 2 species was 2 times higher in the sun than those in the shade, and it showed the typical photoresponses of sun plant. Stomatal conductances and intercelluar $CO_2$ concetration showed similar changes to that of photosynthetic rate. On the contrary, vapor pressure deficit was increased more in the shade than in the sun.

• Restorative Dentistry and Endodontics
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• v.24 no.2
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• pp.299-309
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• 1999

The composite resin, due to its esthetic qualities, is considered the material of choice for restoration of anterior teeth. With respect to shade control, the direct-placement resin composites offer some distinct advantages over indirect restorative procedures. Visible-light-cured (VLC) composites allow dentists to match existing tooth shades or to create new shades and to evaluate them immediately at the time of restoration placement. Optimal intraoral color control can be achieved if optical changes occurring during application are minimized. An ideal VLC composite, then, would be one which is optically stable throughout the polymerization process. The shade guides of the resin composites are generally made of plastic, rather than the actual composite material, and do not accurately depict the true shade, translucency, or opacity of the resin composite after polymerization. So the numerous problems associated with these shade guides lead to varied and sometimes unpredictable results. The aim of this study was to assess the color changes of current resin composite restorative materials which occur as a result of the polymerization process and to compare the color differences between the shade guides provided with the products and the actual resin composites before- and after-polymerization. The results obtained from this investigation should provide the clinician with information which may aid in improved color match of esthetic restoration. Five light activated, resin-based materials (${\AE}$litefil, Amelogen Universal, Spectrum TPH VeridonFil-Photo, and Z100) and shade guides were used in this study. Three specimens of each material and shade combination were made. Each material was condensed inside a 1.5mm thick metal mold with 10mm diameter and pressed between glass plates. Each material was measured immediately before polymerization, and polymerized with Curing Light XL 3000 (3M Dental products, USA) visible light-activation unit for 60 seconds at each side. The specimens were then polished sequentially on wet sandpaper. Shade guides were ground with polishing stones and rubber points (Shofu) to a thickness of approximately 1.5mm. Color characteristics were performed with a spectrophotometer (CM-3500d, Minolta Co., LTD). A computer-controlled spectrophotometer was used to determine CIELAB coordinates ($L^*$, $a^*$ and $b^*$) of each specimen and shade guide. The CIELAB measurements made it possible to evaluate the amount of the color difference values (${\Delta}E{^*}ab$) of resin composites before the polymerization process and shade guides using the post-polishing color of the composite as a control, CIE standard D65 was used as the light source. The results were as follows. 1. Each of the resin composites evaluated showed significant color changes during light-curing process. All the resin composites evaluated except all the tested shades of 2100 showed unacceptable level of color changes (${\Delta}E{^*}ab$ greater than 3.3) between pre-polymerization and post-polishing state. 2. Color differences between most of the resin composites tested and their corresponding shade guides were acceptable but those between C2 shade of ${\AE}$litefil and IE shade of Amelogen Universal and their respective shade guides exceeded what is acceptable. 3. Comparison of the mean ${\Delta}E{^*}ab$ values of materials revealed that Z100 showed the least overall color change between pre-polymerization and post-polishing state followed by ${\AE}$litefil, VeridonFil-Photo, Spectrum TPH, and Amelogen Universal in the order of increasing change and Amelogen Universal. Spectrum TPH, 2100, VeridonFil-Photo and ${\AE}$litefil for the color differences between actual resin and shade guide. 4. In the clinical environment, the shade guide is the better choice than the shade of the actual resin before polymerization when matching colors. But, it is recommended that custom shade guides be made from resin material itself for better color matching.

• FLOWER RESEARCH JOURNAL
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• v.17 no.2
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• pp.75-80
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• 2009

The objective of this research was to select the native shade tolerance plant which grows well from landscape objective of the urban. Seven species native ground cover plants were evaluated on the growth and chloropyll under 0, 40, 60, 90% shading treatments. Hosta longipes was showed the quite good growth from 60% level of natural light. The plant growth of Liriope platyphylla was good within $144.2{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$ intensity which is 90% shade level of natural light. But, Dryiopteris crassirhizoma was judged with shade tolerance plant which grow quite well from shading condition level of 60% degree. Carex siderosticea was showed the highest plant length and plant width in 40% shading of natural light more than at conditon too much shading. Hosta longipes, Liriope platyphylla, Dryiopteris crassirhizoma, and Carex siderosticea were as shade tolerance plant with increases chlorophyll content well to overcome a light restrictive condition and is adapted to seem with the result.

• Journal of Dental Rehabilitation and Applied Science
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• v.25 no.1
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• pp.13-22
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• 2009

The composite resin, due to its esthetic quality, is considered the material of choice for restoration of anterior teeth. To get a satisfactory result in the composite resin restorations, it is necessary to choose right shade. At present, most of the commercial composite resins are based on the Vita Lumin shade guides or shade guides that are provided by their company, but color differences among them might be expected even using the same shade in various materials. This study is to measure color differences between various light-cured composite resins and shade guides and to provide the clinicians with information which may aid in improved color match of esthetic restoration. Four kinds of light-cured composite resins (Gradia Direct (GD), Z250 (Z250), Clearfil AP-X (AP-X), Esthet X (E X)) and shade guides with A2 and A3 shade were used. Three specimens of each material and one specimen of each shade guide were made. Each composite resin was filled into the Teflon mold (1.35 mm depth, 8 mm diameter), followed by compression, polymerization and polishing with wet sandpaper. Shade guides were grinded with polishing stones and rubber points to a thickness of approximately 1.35 mm. Color characteristics were performed with a spectrophotometer(color i5, GretagMacbeth, USA). A computer-controlled spectrophotometer was used to determine CIELAB coordinates ($L^*$, $a^*$, $b^*$) of each specimen and shade guide. The CIELAB measurements made it possible to evaluate the amount of the color difference values (${\Delta}E^*ab$) between composite resins and shade guides. CIE standard D65 was used as the light source. The results were as follows : 1. Among the $L^*$, $a^*$, $b^*$ values of most of 4 kinds of composite resin specimens which are produced by same shade, there were significant differences(p<0.05). 2. Among all 4 kinds of composite resin specimens which are produced by same shade, there were color differences that is perceptible to human eye(${\Delta}E^*>3.3$). 3. Between most of composite resin specimens investigated and their corresponding shade guides, there were color differences that is perceptible to human eye(${\Delta}E^*>3.3$). 4. In the clinical environment, it is recommended that custom shade guides be made from resin material itself for better color matching. Shade guides supplied by manufacturers or Vita Lumin shade guide may not provide clinicians a accurate standard in matching color of composite resins, and there are perceptible color differences in most of products. Therefore, it is recommended that custom shade guides be made from resin material itself and used for better color matching.

• Journal of Bio-Environment Control
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• v.15 no.4
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• pp.406-411
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• 2006

New Guinea impatiens (Impatiens hawkeri) shows very sensitive responses to different light conditions. Due to these phenomena, testers of DUS (distinctness, uniformity and stability) for granting plant variety protection right often have problems distinguishing genetic or physiological differences. New Guinea impatiens 'Fishlimp 149' was grown under several light intensities in a rain-sheltered vinyl house to observe differences of plant growth and flowering. As compared with the control (avg. $1,010{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$), treatments of shade-1 (avg. $599{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$) and shade-2 (avg. $88{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$) showed increased plant height, plant width, leaf size and pedicel length. On the contrary, these growth parameters decreased in shade-3 (avg. $30{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$) with the lowest light intensity. Shade-1 treatment enhanced flower characteristics such as flower diameter, upper petal width, side petal width and lower petal length. However, these characteristics were suppressed by lower light intensities than that in shade-1. Anthocyanin contents of shoot, leaf and pedicel decreased with increasing shading, but that of flower petal was the greatest of the shade-1 treatment. Shade-1 treatment showed the greatest Hunter a value analyzed by a colorimeter, and L and b values increased with increasing shading. Shade-1 treatment seemed to be provided the most proper light condition for DUS test of New Guinea impatiens. Additionally, anthocyanin accumulation on New Guinea impatiens during DUS test was due to not genetic differences but physiological phenomenon.