• Restorative Dentistry and Endodontics
• /
• v.36 no.2
• /
• pp.108-113
• /
• 2011

Objectives: To determine the effect of the spectral output of single and dual-peak light emitting diode (LED) curing lights on the microhardness and color stability of commercial resin composites formulated with camphorquinone and alternative photoinitiators in combination. Materials and Methods: Three light-polymerized resin composites (Z100 (3M ESPE), Tetric Ceram (Ivoclar Vivadent) and Aelite LS Posterior (Bisco)) with different photoinitiator systems were used. The resin composites were packed into a Teflon mold (8 mm diameter and 2 mm thickness) on a cover glass. After packing the composites, they were light cured with single-peak and dual-peak LEDs. The Knoop microhardness (KHN) and color difference (${\Delta}E$) for 30 days were measured. The data was analyzed statistically using a student's t-test (p < 0.05). Results: All resin composites showed improved microhardness when a third-generation dual-peak LED light was used. The color stability was also higher for all resin composites with dual-peak LEDs. However, there was a significant difference only for Aelite LS Posterior. Conclusions: The dual-peak LEDs have a beneficial effect on the microhardness and color stability of resin composites formulated with a combination of camphorquinone and alternative photoinitiators.

• Journal of the Optical Society of Korea
• /
• v.14 no.4
• /
• pp.415-419
• /
• 2010

A phosphor-conversion white light source is demonstrated using an InGaN-based blue laser diode (LD) and a yellow-emitting phosphor excited by the blue LD. The photometric and colorimetric properties of this blue-LD-based white light source are characterized. When injection current of the LD is 100 mA, luminous flux and luminous efficiency of the white light are found to be over 5 lm and 10 lm/W, respectively. When injection current is >90 mA, luminance is estimated to be larger than 10 Mcd/$cm^2$. In addition, color characteristics of the white light such as chromaticity coordinates, a correlated color temperature, and a color rendering index are found to be quite stable as current and temperature of the LD varies. The demonstrated LD-based white light source is expected to be used in high-brightness illumination applications with good color stability.

• Journal of the Korean Ceramic Society
• /
• v.52 no.6
• /
• pp.497-501
• /
• 2015

Inkjet printing is a widespread technology, offering advantages such as high-quality decoration, a continuous process, and the accurate direct reproduction of patterns or pictures. In inkjet printing technology, the dispersion stability of ceramic ink is one of the most important factors. In this study, the dispersion stability of blue $CoAl_2O_4$ ink for ceramic inkjet printing is systematically investigated. Blue $CoAl_2O_4$ pigment was synthesized by a solid-state reaction and then milled to less than 300nm in size. In order to investigate the influence of the viscosity on the dispersion stability, two types of $CoAl_2O_4$ ceramic inks (termed here Blue L and Blue H) were prepared using different volume ratios of ethylene glycol and ethanol. The Blue L and Blue H ink solutions contained cetyltrimethylammonium bromide(CTAB) as a dispersive agent. The viscosity, surface tension and jetting stability of the $CoAl_2O_4$ ceramic inks were analyzed using a rheometer, a surface tension meter and a dropwatcher. The dispersion stability of the $CoAl_2O_4$ ceramic ink was investigated by a multiple light-scattering method. Blue H, a ceramic ink with higher viscosity, showed much better dispersion stability than the Blue L ceramic ink.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2008.10a
• /
• pp.193-194
• /
• 2008

$Orgacon^{TM}$ products, based on the conducting polymer PEDOT/PSS, are very promising materials in cost-effective R2R production of large area electronics. This presentation will show both the progress in the surface resistance/VLT and progress in the stability (T/R.H. and light stability). A new generation of films, coating formulations and inks will be presented.

• Proceedings of the KIEE Conference
• /
• 2008.05a
• /
• pp.167-168
• /
• 2008

Organic light emitting diodes (OLEDs) show a lot of advantages for display purposes. Because OLEDs provide white light emission with a high efficiency and stability, it is desirable to apply OLEDs as an illumination light source and back light in LCD displays. We synthesized new emissive materials, namely $Zn(HPB)_2$ and Zn(HPB)q, which have a low molecular compound and thermal stability. We studied white OLEDs using $Zn(HPB)_2$ and $Zn(PQ)_2$. The fundamental structures of the white OLEDs were ITO / NPB (40 nm) / $Zn(HPB)_2$ (40 nm) / $Zn(PQ)_2$ (20 nm) / LiAl (120 nm). As a result, we obtained a maximum luminance of $4200cd/m^2$ at a current density of $440mA/cm^2$. The CIE (Commission International de l'Eclairage) coordinates are (0.319, 0.338) at an applied voltage of 10 V.

• Restorative Dentistry and Endodontics
• /
• v.17 no.1
• /
• pp.126-133
• /
• 1992

Tooth colored resin restorative materials are widely used in anterior teeth restorations. The color instability of resin was the main cause of failure in resin restorations. The purpose of this study was to investigate color stability and microhardness of serval visible light curing resins. Colorimetric measurements(Tokyo Denshoku Co., Japan) and microhardness tests(Matusuzawa, MXT 70, Japan) were made on six composite resins before and after controlled immersion treatments. The six composite resins were BIS - FILM(BISCO, USA), Durafill(Kulzer, Germany), Helioprogess(VIVADENT, Germany), Palfique(TOKUYAMA SODA, Japan), Silux(3M, USA), Photoclearfil(KURARAY, Japen). Six light curing resins showed significant color change after 2 weeks. Palfique exhibited the hightest $dE^*$ values and Helio progress presented the lowest $dE^*$ values. Photoclearfil showed the highest microhardness value. Durafill and Helio progress showed lower microhardness values. Microhardness values were decreased after 8 weeks in Bisfil, Palfique light, and Photoclearfil.

• Proceedings of the KIEE Conference
• /
• 2007.07a
• /
• pp.2018-2019
• /
• 2007

Organic light emitting diodes (OLEDs) show a lot of advantages for display purposes. Because OLEDs provide white light emission with a high efficiency and stability, it is desirable to apply OLEDs as an illumination light source and back light in LCD displays. We synthesized new emissive materials, namely $Zn(HPB)_2$ and Zn(HPB)q, which have a low molecular compound and thermal stability. We studied white OLEDs using $Zn(HPB)_2$ and Zn(HPB)q. The fundamental structures of the white OLEDs were ITO / NPB (40 nm) / $Zn(HPB)_2$ (40 nm) / Zn(HPB)q (20 nm) / LiAl (120nm). As a result, we obtained a maximum luminance of $15325cd/m^2$ at a current density of $997\;mA/cm^2$. The CIE (Commission International de l'Eclairage) coordinates are (0.28, 0.35) at an applied voltage of 9.75 V.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2006.06a
• /
• pp.416-417
• /
• 2006

Organic light emitting diodes (OLEDs) show a lot of advantages for display purposes. Because OLEDs provide white light emission with a high efficiency and stability, it is desirable to apply OLEDs as an illumination light source and back light in LCD displays. We synthesized new emissive materials, namely [2-(2-hydroxyphenyl)benzoxazole] ($Zn(HPB)_2$) and [(2-(2-hydroxyphenyl)benzoxazole)(8-hydoxyquinoline)] (Zn(HPB)q), which have a low molecular compound and thermal stability. We studied white OLEDs using $Zn(HPB)_2$ and Zn(HPB)q. The fundamental structures of the white OLEDs were ITO/PEDOT:PSS (23 nm)/NPB (40 nm)/$Zn(HPB)_2$ (40 nm)/Zn(HPB)q (20 nm)/$Alq_3$ (10 nm)/LiAl (120 nm). As a result, we obtained a maximum luminance of $15325\;cd/m^2$ at a current density of $997\;mA/cm^2$. The CIE(Commission International de l'Eclairage) coordinates are (0.28, 0.35) at an applied voltage of 9.75 V.

• Journal of the Society of Cosmetic Scientists of Korea
• /
• v.23 no.3
• /
• pp.48-74
• /
• 1997

Retinlyl Palmitate, the skin normalizerm is useful to promote greater skin elasticity, to diminish lipid peroxidation and skin roughness following UV exposure, and promote a youthfulgeneral skin appearance. In manufacturing creams, Retinyl Palmitate, which is a derivative of retinol, is used since reionol is easily oxidized by heat and light. However, only a small mount of retinol, is used since using a large amount of it may be harmful to its stability. In this study, thermal stability and UV stability of W/O-, W/S-, O/W-, and MLV-type creams containing 5% of retinyl palmitate and 10% of tocopheryl acetate are measured by Chroma Meters, and the content of RP is quantitatively analyzed by HPLC at 25 $^{\circ}C$ and 45 $^{\circ}C$. Also, how RP has been changed by heat, light, etc. is measured by HPLC, and toxicity of the changed substance is studied. Particle size of each type of the cream if measured, cellular renewal is measured by using DHP and Chroma Meters in order to study their efficacy and effect, moisture content is measured by using Corneometer and Tewameter, and how much wrinkles are improved is studied by using Image Analyzer. Development of MLV-type cream containing 5% of RP and 10% of TA, and satisfying conditions for better creams has been successful.

• Korean Journal of Human Ecology
• /
• v.17 no.2
• /
• pp.355-366
• /
• 2008

The purpose of this study is to investigate the effects of eye shadow color(brown, purple), lipstick color(red, red purple, and yellow red), and lipstick tone(vivid, light, dull, and dark) and clothing tone(vivid, light, dull, and dark) on image formation. Sets of stimulus and response scales(7 point semantic) were used as experimental materials. The stimuli consisted of 64 color photos manipulated with the combination of eye shadow color, lipstick color, lipstick tone, and clothing tone using computer simulation. The subjects were 384 female undergraduates living in Gyeongnam Province. Image factor of the stimulus was composed of 4 different components: attractiveness, visibility, cuteness, and stability. Eye shadow color, lipstick tone and clothing tone independently influenced on visibility, cuteness, and stability. Lipstick color independently influenced on the stability. In color coordination of clothing and makeup of the same hue, 1) visibility image can be created by the coordination of eye shadow color with lipstick color or clothing tone, or lipstick color with lipstick tone. 2) Cuteness image can be produced by the coordination of eye shadow color with lipstick or clothing tone, lipstick color with lipstick or clothing tone. 3) Stability image can be showed by the coordination of eye shadow color with lipstick tone.