• 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.

• Textile Coloration and Finishing
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• v.16 no.5
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• pp.8-18
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• 2004

In order to study on the color change of silk dyed with natural colorant due to light fading, and find out the effect of combination dyeing, colorant extracts of safflower red, safflower yellow and amur cork tree were used, either singly or in combination. In combination dyeing, safflower yellow or amur cork tree dyeing process was added on the top of the silk fabric was dyed with safflower red. Color change and light fastness were investigated by $L^*,\; a^*,\; b^*$ H, V/C, and Color difference. Brightness of silk fabric dyed with safflower red and safflower yellow increased gradually with increasing the radiation time of UV light, but amur cork tree was decreased and turned to dull. Color difference of dyed with Amur cork tree showed higher than the others. Combination dyeing of safflower red and amur cork tree provided better light fastness than the one of safflower red and safflower yellow.

• Journal of the Korean Society of Costume
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• v.28
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• pp.205-212
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• 1996

This paper is to study the characteristics of fabrics dyed with astringent unripe persimmon juice. The cotton silk rayon and nylon fabrics were dyed with astringet unripe persimmon juice. The structures of natural fabrics dyed fabrics and dyed fabrics followed by washing were examined by scanning electron mi-croscopy. Surface reflexibility of VIS trans-mittance of UV VIS and NIR were analyzed. The study conclues as follows: 1. Colour of cotton fabrics dyed with persim-mon juice became darkended as a function of exposing time to sunlight. That colour was chaged after washing. 2. Blocking effect of ultraciolet light and visible ray was increased in all dyed fabrics. Especially dyed cotton fabric blocked UV light perfectly and the blocking effect was still remained after 9 washings. 3. Persimmon juice dyeing produced coating effect to fabrics besides dyeing effect accord-ing to the scanning electron micrographs. In a word the cotton fabric dyed with per-simmon juice has blocking effect of UV light stiffness. Therefore I think persimmon juice dyeing is a very useful textile finishing and ex-pect a wide application of the technique in fu-ture.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.2
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• pp.63.3-64
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• 2017

KIC6118779 is an over-contact binary system having a short orbital period of about 0.36 days. The photometric data for this system are acquired by the observations of Kepler mission in the long cadence mode having a time resolution of about 30 minutes. It means that the Kepler light curves of the system may be strongly affected by phase smearing effect and the analysis of them without consideration of the phase smearing effect may result in wrong stellar properties. Additionally, this system also shows dynamical variation of light curve resulting from spot activity. For all those reasons, it is difficult to investigate KIC6118779, and the investigation should be carried out carefully. In this presentation, we introduce the phase smearing effect and carry out the light curve modeling with the 2015 version of the Wilson-Devinney binary code considering the phase smearing effect. Our results show that the system is a deep over contact binary system and has extremely low mass ratio of about 0.12. Moreover our spot modeling implies the cyclic migration of a big cool spot on the massive component.

• Proceedings of the KACD Conference
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• 2001.11a
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• pp.589.1-589
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• 2001

The aim of this study is to evaluate the effect of light intensity variation on the polymerization rate of composite resin using IB system(experimental equipment designed by Dr. IB Lee) by which real-time volumetric change of composite can be measured. Methods: Three commercial composites [Z100(Z1), AeliteFil(AF), SureFil(SF)] were photopolymerized with Variable Intensity Polymerizer unit (Bisco, U.S.A.) under the variable light intensity (75/150/225/300/375/450㎽$^2$) during 20sec.(omitted)

• Restorative Dentistry and Endodontics
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• v.24 no.2
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• pp.265-285
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• 1999

The purposes of this investigation were to observe the reaction kinetics of five commercial dual cured resin cements (Bistite, Dual, Scotchbond, Duolink and Duo) when cured under varying thicknesses of porcelain inlays by chemical or light activation and to evaluate the effect of the porcelain disc on the rate of polymerization of dual cured resin cement during light exposure by using thermal analysis. Thermogravimetric analysis(TGA) was used to evaluate the weight change as a function of temperature during a thermal program from $25{\sim}800^{\circ}C$ at rate of $10^{\circ}C$/min and to measure inorganic filler weight %. Differential scanning calorimetry(DSC) was used to evaluate the heat of cure(${\Delta}H$), maximum rate of heat output and peak heat flow time in dual cured resin cement systems when the polymerization reaction occured by chemical cure only or by light exposure through 0mm, 1mm, 2mm and 4mm thickness of porcelain discs. In 4mm thickness of porcelain disc, the exposure time was varied from 40s to 60s to investigate the effect of the exposure time on polymerization reaction. To investigate the effect on the setting of dual cured resin cements of absorption of polymerizing light by porcelain materials used as inlays and onlays, the change of the intensity of the light attenuated by 1mm, 2mm and 4mm thickness of porcelain discs was measured using curing radiometer. The results were as follows 1. The heat of cure of resin cements was 34~60J/gm and significant differences were observed between brands (P<0.001). Inverse relationship was present between the heat of reaction and filler weight % the heat of cure decreased with increasing filler content (R=-0.967). The heat of reaction by light cure was greater than by chemical cure in Bistite, Scotchbond and Duolink(P<0.05), but there was no statistically significant difference in Dual and Duo(P>0.05). 2. The polymerization rate of chemical cure and light cure of five commercially available dual cured resin cements was found to vary greatly with brand. Setting time based on peak heat flow time was shortest in Duo during chemical cure, and shortest in Dual during light cure. Cure speed by light exposure was 5~20 times faster than by chemical cure in dual cured resin cements. The dual cured resin cements differed markedly in the ratio of light and chemical activated catalysts. 3. The peak heat flow time increased by 1.51, 1.87, and 3.24 times as light cure was done through 1mm, 2mm and 4mm thick porcelain discs. Exposure times recommended by the manufacturers were insufficient to compensate for the attenuation of light by the 4mm thick porcelain disc. 4. A strong inverse relationship was observed between peak heat flow and peak time in chemical cure(R=0.951), and a strong positive correlations hip was observed between peak heat flow and the heat of cure in light cure(R=0.928). There was no correlationship present between filler weight % or heat of cure and peak time. 5. The thermal decomposition of resin cements occured primarily between $300^{\circ}C$ and $480^{\circ}C$ with maximum decomposition rates at $335^{\circ}C$ and $440^{\circ}C$.

• Journal of Astronomy and Space Sciences
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• v.12 no.2
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• pp.179-195
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• 1995

RT Per has been known as a close binary of which the orbital period has unpredictably varied so far. Although there are no agreements with the working mechanism for the changes of the period, two interpretations have been suggested and waiting for to be tested: 1) light-time effects due to the unseen 3rd and 4rd bodies (Panchatsaram 1981), 2) Abrupt period-changes, due to internal variations of the system (e.g. mass transfer or mass loss) superimposing to the light-time effect by a 3rd body (Frieboes-Conde & Herczeg 1973). In the point of view that the former interprepation models could predict the behavior of the changes of the orbital period theoretically, we checked whether the recent observed times of minimum lights follow the perdictions by the first model or not. We confirmed that the observed times of minimum lights have followed the variations calculated by the light-times effects due to the 3rd and 4rd bodies suggested by Panchatsatam. In this paper a total of 626 times of minimum lights were reanalyzed in terms of the light-time effects by the 3rd and 4rd bodies. We concluded that the eclipsing pair in SVCam system moves in an elliptic orbit about center of mass of the triple system with a period of about $42.^y2$, while the mass center of the triplet is in light-time orbit about the center of mass of the quadruple system with a period of $120^y$. The mean masses deduced for the 3rd and 4rd bodies were $0.89m_\odot$ and $0.82m_\odot$, respectively.

• Bulletin of the Korean Space Science Society
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• 2009.10a
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• pp.24.2-24.2
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• 2009

We present the results of new CCD photometry for the contact binary BX Peg, made during three successive months beginning on September 2008. As do historical light curves, our observations display an O'Connell effect and the November data by themselves indicate clear evidence for very short-time brightness disturbance. For these variations, model spots are applied separately to the two data set of Group I (Sep.--Oct.) and Group II (Nov.). The former is described by a single cool spot on the secondary photosphere and the latter by a two-spot model with a cool spot on the cool star and a hot one on either star. These are generalized manifestations of the magnetic activity of the binary system. Twenty light-curve timings calculated from Wilson-Devinney code were used for a period study, together with all other minimum epochs. The complex period changes of BX Peg can be sorted into a secular period decrease caused dominantly by angular momentum loss due to magnetic stellar wind braking, a light-travel-time (LTT) effect due to the gravitational effect of a low-mass third companion, and a previously unknown short-term oscillation. This last period modulation could be produced either by a second LTT orbit with a period of about 16 yr due to the existence of a fourth body or by the effect of magnetic activity with a cycle length of about 12 yr.

• Journal of Environmental Science International
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• v.23 no.9
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• pp.1573-1581
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• 2014

This study was conducted to examine the effect of LED light quality and supplemental LED light on growth and flowering for potted flowering plant of Kalanchoe. 1. Plant height of Kalanchoe was enhanced under Red, regardless of treatment time. 2. Root length and stem diameter of Kalanchoe were enhanced by Red+Blue. 3. The number of internodes was not influenced by LED light quality. Length of flower stalk of Kalanchoe increased under Red+Blue, but treatment time did not result in statistically significant differences. 4. Leaf area was not influenced by LED light quality in Kalanchoe. 5. The number of flower buds and open flowers was decreased by LED light treatment, but days to flowering was reduced by Red+Blue for 4 hr after sunset in Kalanchoe. 6. Chlorophyll and anthocyanin content was not significantly affected by LED light treatment, but anthocyanin content tended to increase by Blue 4 hr after sunset. 7. Fresh and dry weight did not increased by LED light treatment in Kalanchoe.

• KIEAE Journal
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• v.5 no.2
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• pp.35-41
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• 2005

This study was conducted to identify the effect of daylighting in hospitals on hospitalization time of patients and patients' outcomes in hospitals. Two major variations include orientation of hospital wards and the hospitalization times of various kinds of patients. Patients' data were obtained from two hospitals located in Seoul, Korea. The hospital buildings have north-facing and north-facing wards. The patients were classified according to the types of diseases and the orientation of the patient rooms. Then, statistical T-tests were applied in order to verify if natural light might shorter the hospitalization time of patients. The study also identified the types of diseases that were more responsive to the quantity of natural light in patient rooms. This information may be used as a basis for the development of guidelines for patient rooms in hospitals to achieve more effective healing environments. Likewise, the results may be applied to medical treatment buildings, recreational centers and hospital as well.