• 대한치과보철학회지
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• 제16권1호
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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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• 제8권1호
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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.

• 한국산학기술학회논문지
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• 제16권8호
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• pp.5619-5626
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• 2015

천광(Zenithal Light)은 벽의 높은 곳에 위치한 창이나 지붕의 열린 부분으로부터 내부 혹은 중정과 같은 내부와 비슷한 공간에서 하강하면서 들어오는 빛으로, 본 연구에서는 이러한 천광을 이루는 천창의 다양한 사례들과 함께 빛이 들어오는 방식에 대한 유형을 구분하고 그 특성을 살펴보았다. 즉, 천창의 가장 큰 특징을 형성하는 것 중 하나로서 빛을 실내에 유입하는 구조적인 장치에 주목하고 이러한 장치인 매개체에 따라 크게 직사광형 덕트형, 쉐이드형으로 구분하고, 각각 세부적으로 변형된 유형으로 나누었다. 즉, 직사광형은 광원 비노출형과 광원 노출형으로 덕트형천창은 집중형과 분산형으로, 쉐이드형은 천정면형, 반사판형, 이중천창형, 수직벽면형 등으로 구분될 수 있다.

• 한국실내디자인학회논문집
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• 제19권5호
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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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• 제47권1호
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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.

• 한국환경복원기술학회지
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• 제7권1호
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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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• 제24권2호
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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.

• 화훼연구
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• 제17권2호
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• pp.75-80
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• 2009

본 연구는 음지에서 잘 자라는 자생 지피식물 선발을 위해 7종의 자생식물을 대상으로 광 조건을 달리하여 생장반응을 조사하였다. 비비추는 자연광의 60% 차광에서 가장 좋은 생장을 보였으며, 맥문동은 90% 차광에서 생육이 매우 좋았다. 관중은 60% 차광에서 생육이 가장 우수 하였으며, 대사초는 40% 차광에서 초장과 초폭이 신장이 좋았고 엽수도 많았다. 비비추, 맥문동, 관중 및 수호초는 차광율이 높을수록 엽록소 함량이 점차 증가되었으며, 맥문동은 완전음지나 자연광에서는 개화되지 않았다.

• 구강회복응용과학지
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• 제25권1호
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• pp.13-22
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• 2009

심미적인 특성을 가진 복합레진은 전치부 수복용 재료로 많이 이용되고 있다. 복합레진 수복 시 만족스러운 결과를 얻기 위해서는 색조의 선택이 중요한 역할을 한다. 현재 대부분의 수복용 복합레진은 Vita Lumin 색조견본(shade guide)이나 각각의 회사에서 제공하는 색조견본을 사용하고 있으나, 색조 견본 사이의 색차와 수복물과 견본 사이에 색차가 예상되어 그 차이를 규명하여 임상적인 선택 시에 도움이 되고자 하였다. 4종의 광중합 복합레진(Gradia Direct (GD), Z250 (Z250), Clearfil AP-X (AP-X), $Esthet{\cdot}X$ ($E{\cdot}X$))과 A2와 A3의 색조 견본을 사용하였다. 각 재료마다 3개의 시편과 1개의 색조 견본을 제작하였다. Teflon 주형(깊이 1.35 mm, 직경 8 mm)에 각각의 복합레진을 채우고 응축한 후에 중합하여 젖은 사포로 연마하였다. 색조 견본을 연마용 stone과 고무를 이용하여 1.35 mm 두께로 연마하였다. 컴퓨터에 의해 조절되는 spectrophotometer(color i5, GretagMacbeth, USA)를 이용하여 시편과 색조견본의 색의 특성을 CIELAB coordinates ($L^*$, $a^*$, $b^*$)로 평가하였다. CIELAB 계측을 통하여 복합레진과 색조 견본의 색차(${\Delta}E^*ab$)를 비교 평가 하였다. 광원으로는 CIE standard D65를 사용하였다. 다음과 같은 결과를 얻었다. 1. 동일한 shade로 설계된 여러 제조회사의 복합레진 시편의 $L^*$, $a^*$, $b^*$ 값 간에 유의할 만한 수준의 차이를 나타냈다(p<0.05). 2. 동일한 shade로 설계된 여러 제조회사의 복합레진 시편 간에 대부분 육안으로 인지할 만한 색차(${\Delta}E^*ab>3.3$)값을 나타냈다. 3. 동일한 shade로 설계된 여러 제조회사의 복합레진과 제조회사에서 제공되는 shade guide 및 Vita Lumin shade guide 간에 대부분 육안으로 인지할 만한 색차(${\Delta}E^*ab>3.3$)값을 나타냈다. 4. 임상에서 보다 나은 색 조화를 얻어 심미성을 향상시키기 위해서는 실제 수복물로 제작한 custom shade guide의 제작이 필요할 것으로 생각된다. 제조사에 의해 제공되는 색조 견본이나 Vita Lumin 색조 견본은 임상의에게 복합레진의 색조 선택 시에 정확한 기준을 제공하지는 않았고, 대부분의 제품에서 인지할 수 있는 색차가 있었다. 그러므로 보다 나은 색조 선택을 위해 수복용 레진으로 제작한 맞춤형 색조 견본을 사용하는 것을 추천한다.

• 생물환경조절학회지
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• 제15권4호
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• pp.406-411
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• 2006

뉴기니아 봉선화(Impatiens hawkeri)는 광조건에 따라 생리적 반응이 매우 민감한 것으로 알려져 있다. 이러한 현상 때문에 신품종 보호 재배심사(DUS test)시 나타나는 여러 증상들이 유전적인 요인에 의한 것인지 혹은 생리적 증상인지를 판단하는데 어려움이 따른다. 이러한 어려움을 극복하기 위하여 뉴기니아 봉선화 'Fishlimp 149'를 비가림 하우스에 정식하고 광도조건에 따른 생육 및 화색발현을 구명하기 위하여 몇 가지 광도조건의 처리를 하였다. 실험결과 대조구 ($1,010{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$)에 비해 차광 1($599{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$) 및 차광 2($88{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$) 처리구에서 초장, 초폭, 잎 크기 및 소화경 등이 현저히 증가되었다. 그러나 가장 광도가 낮은 차광 3($30{\mu}mol{\cdot}m^{-2}{\cdot}s^{-1}$)에서는 오히려 이들이 대조구에 비해 감소되었다. 개화특성 조사에서는 차광 1처리가 화경, 상부 꽃잎폭, 측면 꽃잎폭, 하부 꽃잎길이 등에서 가장 좋은 결과를 보였다. 안토시아닌 함량의 경우 줄기, 잎 및 소화경에서는 차광에 의해 감소되었으나 소화경의 경우 차광 1처리에서 가장 높은 결과를 보였다. 이상의 결과를 종합해 볼 때, 차광 1처리가 뉴기니아 봉선화의 생장특성을 조사하는데 가장 적절한 것으로 판단되며, 생육과정 중 나타나는 안토시아닌 축적은 유전적인 요인이 아닌 환경적인 요인에 의한 생리적인 현상인 것으로 생각된다.