• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.429-429
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• 2007

In this study, it was investigated about the variation of luminance properties in LED backlight with geometrical shape such as prism or lens shape on the light-entering face. Generally, LED light source has the loss in backlight system because it has horizontal direction light. PMMA(Poly-Methyl-Meta-Acrylate) is used LGP(Light-Guide-Plate) in conventional backlight system. PMMA has low refraction angle. so that. horizontal direction light was not used in backlight system. The addition of geometrical shape in light-entering face in LGP improves the luminance characteristics because it prevents horizontal direction light generation in light-entering-face. Prism or lens shape in same pitch disposition was almost same without these treatment such as the value of 1% rising. Besides. It is particular that the gap of these shape such as the value of 0.407~0.22mm prevents horizontal direction light, so then it contributes luminance rising at 5.6%.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.32 no.1
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• pp.86-92
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• 2019

Although perylene bisimide derivatives have advantages such as excellent thermal stability and high luminance efficiency, they have poor solubility characteristics in organic solvents. In this research, in order to improve the solubility characteristics, we prepared perylene bisimide derivatives (1C) and (2C) with swallow-tail substituted imide, which is known to lead to excellent solubility. The structures and properties of swallow-tail perylene bisimide (1C) and (2C) were analyzed by $^1H-NMR$, FT-IR, UV/Vis spectroscopy, and thermogravimetric analysis (TGA). The maximum absorption wavelengths of (1C) and (2C) in the UV/Vis spectrum were 558 nm and 556 nm, respectively, and the maximum emission wavelengths were 602 nm and 600 nm, respectively. In the TGA, (1C) demonstrated good thermal stability with less than 5 wt% weight loss up to $242^{\circ}C$. In the solubility test, (1C) and (2C) exhibited solubilities of more than 5 wt% in chloroform, ethyl acetate, and dimethylformamide, but not in methanol. When the compounds (1C) and (2C) were mixed with PMMA (polymethyl methacrylate), thin films showed peaks at 679 nm and 677 nm, respectively, in the photoluminescence spectra. (1C) was found to be a possible candidate as red organic phosphor for hybrid LEDs.

• Journal of Radiation Industry
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• v.17 no.2
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• pp.173-181
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• 2023

3D printing is a technology that can transform and process computerized data obtained through modeling or 3D scanning via CAD. In the medical field, studies on customized 3D printing technology for clinical use or patients and diseases continue. The importance of research on filaments and molding methods is increasing, but research on manufacturing methods and available raw materials is not being actively conducted. In this study, we compare the characteristics of each material according to the manufacturing method of the phantom manufactured with 3D printing technology and evaluate its usefulness. We manufactured phantoms of the same size using poly methyl meta acrylate (PMMA), acrylonitrile butadiene styrene (ABS), and Poly Lactic Acid (PLA) based on the international standard phantom of aluminum step wedge. We used SITEC's radiation generator (DigiRAD-FPC R-1000-150) and compared the shielding rate and line attenuation coefficient through the average after shooting 10 times. As a result, in the case of the measured dose transmitted through each phantom, it was confirmed that the appearance of the dose measured for phantoms decreased linearly as the thickness increased under each condition. The sensitivity also decreased as the steps increased for each phantom and confirmed that it was different depending on the thickness and material. Through this study, we confirmed that 3D printing technology can be usefully used for phantom production in the medical field. If further development of printing technology and studies on various materials are conducted, it is believed that they will contribute to the development of the medical research environment.

• The Journal of Korean Academy of Prosthodontics
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• v.44 no.6
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• pp.690-698
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• 2006

Statement of problems. The heat produced during polymerization of polymer-based provisional materials may cause thermal damage to the vital pulp. Purpose. This study was performed to evaluate the exotherm reaction of the polymerbased provisional materials during polymerization by differential scanning calorimetry and to compare the temperature changes of different types of resins. Material and methods. Three dimethacrylate-based materials (Protemp 3 Garant, Luxatemp Plus, Luxatemp Fluorescence) and five monomethacrylate- based material (Snap, Alike, Unifast TRAD, Duralay, Jet) were selected. Temperature changes of polymer-based provisional materials during polymerization in this study were evaluated by D.S.C Q-1000 (TA Instrument, Wilmington, DE, USA). The following three measurements were determined from the temperature versus time plot: (1) peak temperature, (2) time to reach peak temperature, (3) heat capacity. The data were statistically analyzed using one-way ANOVA and multiple comparison Bonferroni test at the significance level of 0.05. Results. The mean peak temperature was $39.5^{\circ}C({\pm}\;1.0)$. The peak temperature of the polymer-based provisional materials decreased in the following order: Duralay > Unifast TRAD, Alike > Jet > Luxatemp Plus, Protemp 3 Garant, Snap, Luxatemp Fluorescence. The mean time to reach peak temperature was 95.95 sec $({\pm}\;64.0)$. The mean time to reach peak temperature of the polymer-based provisional materials decreased in the following order: Snap, Jet > Duralay > Alike > Unifast TRAD > Luxatemp Plus, Protemp 3 Garant, Luxatemp Fluorescence. The mean heat capacity was 287.2 J/g $({\pm}\;107.68)$. The heat capacity of the polymer-based provisional materials decreased in the following order: Duralay > TRAD, Jet, Alike > Snap, Luxatemp Fluorescence, Protemp 3 Garant, Luxatemp Plus. Conclusion. The heat capacity of materials, determined by D.S.C., is a factor in determining the thermal insulating properties of restorative materials. The peak temperature of PMMA was significantly higher than others (PEMA, dimethacrylate). No significant differences were found among PEMA (Snap) and dimethacrylate (P >0.05). The time to reach peak temperature was greatest with PEMA, followed by PMMA and dimethacrylate. The heat capacity of PMMA was significantly higher than others (PEMA, dimethacrylate). No significant differences were found among PEMA and dimethacrylate (P >0.05).

• Polymer(Korea)
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• v.32 no.3
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• pp.276-283
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• 2008

Kind of monomer(MMA, EA, BA, St)and the monomer ratio(80/20 to 20/80) where changed in the preparation of the core shell binder, and property was improved the plasma processing. Each material changed by plasma treatment time($1{\sim}10\;s$) to change to measure the tensile strength, contact angle and adhesion peel strength for the core shell binder optimal conditions for handling the output of the surface treatment. The type of polymerization and composition of the binder is a regardless initiator of APS, the reaction temperature of $85^{\circ}C$ to 0.3 wt% of the surfactant used to indicate when the conversion rate was the highest, core shell composite particle binder got two glass temperature curves. Core shell binder after the plasma processing contact angle change is the PEA/PSt 38 percent of cases within five seconds to indicate slight decrease was a decline rapidly if not handled $0^{\circ}$ to reach. Tensile strength PSt/PMMA varies $46.71{\sim}46.27\;kg_f$/2.5 cm and adhesion strength PEA/PMMA varies $7.89{\sim}14.44\;kg_f$/2.5 cm increases. Overall, adhesion strength of core shell composite particle is in the order of order PEA>PBA>PSt for shell monomer MMA.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1921-1924
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• 2005

In this paper, three-dimensional finite element analysis have been performed to investigate the biomechanics of vertebroplasty in patient. In order to apply various properties of the spine, the functional relation between the well-known apparent density and HU(Hounsfield unit) from CT image were employed and thus real material property can be assigned to each element of FE model. The FE analysis showed similar results with the experiments. With this approach accurate analysis of the spine and the clinical application can be expected.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.11a
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• pp.170-171
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• 2006

The chemical shift of SiOC film was observed according to the flow rate ratio. SiOC film has the broad main band of $880{\sim}1190cm^{-1}$ and the sharp Si-$CH_3$ bond at $1252cm^{-1}$, and the infrared spectra in the Si-O-C bond moved to low frequency according to the increasing of an oxygen flow rate. The chemical shift affected the carbon content in the SiOC film, and the decreasing of carbon atoms elongated the C-H bonding length, relatively. The main bond without the sharp Si-$CH_3$ bond at $1252cm^{-1}$ consisted of Si-C, C-O and Si-O bonds, and became the bonding structure of the Si-O-C bond.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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• pp.699-702
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• 2004

Next generation lithography technologies, such as EBL(Electron Beam Lithography), X-ray lithography, SPL(Scanning Probe Lithography), have been studied widely for getting over line width limitation of photolithography. Among the next generation lithography technologies, SPL has been highlighted because of its high resolution advantage. But is also has problem which are slow processing time and sample size limitation. The purpose of this study is complement of present SPL system. Brand new SPL system was made. SPL test was performed with the system in ultra thin PMMA(polymethlymethacrylate) film.

• The Journal of the Korean dental association
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• v.25 no.11 s.222
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• pp.1019-1028
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• 1987

결손된 치질과 변색된 법랑질을 수복하기 위해 많은 재료와 술식이 개발되어왔다. 즉 silicate cement, PMMA resin, BISGMA composite resin, glass ionomer cement, porcelain등이 이용되어 왔으나 이것들은 biocompatible하지 않아 이상적인 재료는 아니다. 따라서 인간의 결손된 enamel을 수복할 수 있는 새로운 생역학적인 재료가 필요하게 되었다. 필자는 최근 관심의 대상이 되고 있는 porcelain laminate veneer system(층상 도재 전장관)에 관하여 문헌을 중심으로 고찰해 보고자 한다(국내에서는 장완식 교수께서 1987년 6월10일 보철학교실 세미나에서 video tape를 통해 소개한바 있음). 여기서는 Hobo, Iwata(1985)등이 소개한 castable apatite ceramic material을 이용한 laminate veneer술식에 관해 기술하고 내화성 모형(refractory cast)을 이용한 laminate술식과 비교 기술하고자 한다.

• Proceedings of the KAIS Fall Conference
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• 2004.06a
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• pp.264-266
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• 2004

본 연구에서는 4차 암모늄염의 대전방지 현상을 알아보기 위하여 아크릴기가 있는 2-(dimethyl amino)ethyl methacrylate(DMA)를 알킬화 시켜 대전방지제를 합성하고, 자외선 경화 반응을 통해 대전방지 기능이 지속적으로 유지되게 하였다. 여기에서 얻어진 대전방지제를 PMMA 판에 코팅하여 코팅 도막의 전기저항의 변화를 관찰한 결과, 대전방지제의 함량이 20part 이상으로 높아질 때 표면저항 값이 낮아지는 현상을 볼 수 있었다. 또한 대전방지제의 함량이 10part인 경우, 상대습도가 $20\%$ 증가할 때 저항 값은 $10^2{\Omega}/cm^2$까지 감소하는 결과를 볼 수 있었다.