• Title/Summary/Keyword: Glass edge

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A STUDY ON THE ATTRITION OF MAXILLARY CENTRAL INCISORS IN KOREAN (한국인 상악중절치의 교모에 관한 연구)

  • Park, Chong-Wha
    • The Journal of Korean Academy of Prosthodontics
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    • v.16 no.1
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    • pp.32-37
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    • 1978
  • The purpose of this study was to apply the position, the form and the angle of the attrition in the natural maxillary central incisors shown on the labial surface to the artificial teeth in the field of prosthetic dentistry. So we should exactly alter the molds of artificial teeth in individual cases in order to make artificial teeth more natural. 226 extracted teeth of the maxillary central incisors were chosen as materials. I have exactly examined the teeth with a magnifying glass and a circular graduator under concentrated light. The observation brought me the following results: 1) The attrition was most prevailing at the range from the mesial angle to the middle part of cutting edge in the left maxillary central incisor, and distal angle of cutting edge in the right maxillary central incisor. 2) On the attrite form of both angles, the angulated form was more than 4 times as frequent as rounded form in the mesial angle, and almost equal in the distal angle. 3) On the attrite form of cutting edge, mesial attrite form including mesial angle was most frequent in the left maxillary central incisor, and distal attrite form including distal angle in the right maxillary central incisor. 4) The angle made by the labial surface and the attrite surface was about $39^{\circ}$, and more than 70% of the total examined teeth were included at the range from $31^{\circ}\;to\;50^{\circ}$. 5) None attrite form at the cutting edge was about 12% and completely attrite form at the cutting edge was about 27% of examined teeth.

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Fabrication of La2O3-TiO2-SiO2 System Glass Derived from a Sol-Gel Process

  • Iwasaki, Mitsunobu;Masaki, Hitoshi;Ito, Seishiro;Park, Won-Kyu
    • Journal of the Korean Ceramic Society
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    • v.44 no.3 s.298
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    • pp.137-141
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    • 2007
  • $La_{2}O_{3}-TiO_{2}-SiO_{2}$ glass, a type that could not obtained so far by the conventional melting method, was prepared successfully using a sol gel process. Glass derived with the sol-gel process has compositions of $5La_{2}O_{3}-5TiO_{2}-90SiO_{2},\;5La_{2}O_{3}-10TiO_{2}-85SiO_{2}$, and $5La_{2}O_{3}-20TiO_{2}75SiO_{2}$. The UV-visible absorption edge of all glass compositions was below 400 nm. The measured density is in the range of 2.55-2.89, and was nearly identical to the calculated density and the refractive index of the glasses derived from the sol-gel ranges from 1.545 to 1.645. The molar additive coefficient of $TiO_{2}$ measured in this ternary system is lower than the calculated value, while the value of $La_{2}O_{3}$ is higher.

Encapsulation Method of OLED with Organic-inorganic Protective Thin Films Sealed with Flat Glass (평판 유리로 봉인된 유-무기 보호 박막을 갖는 OLED 봉지 방법)

  • Park, Min-Kyung;Ju, Sung-Hoo
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.25 no.5
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    • pp.381-386
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    • 2012
  • To study encapsulation method for large-area organic light emitting diodes (OLEDs), red emitting OLEDs were fabricated, on which $Alq_3$ as organic buffer layer and LiF and Al as inorganic protective layers were deposited to protect the damage of OLED by epoxy. And then the OLEDs were attached to flat glass by printing method using epoxy. The basic structure of OLED doped with rubrene of 1 vol.% as emitting layer is ITO(150 nm) / 2-TNATA(50 nm) / ${\alpha}$-NPD(30 nm) / $Alq_3$:Rubrene(30 nm) / $Alq_3$(30 nm) / LiF(0.7 nm) / Al(100 nm). In case of depositing $Alq_3$, LiF and Al and then attaching of flat glass onto OLED, current density, luminance, efficiency and driving voltage were not changed and lifetime was increased according to thickness of Al as inorganic protective layers. The lifetime of OLED/$Alq_3$/LiF/Al_4/glass structure was 139 hours increased by 15.8 times more than bare OLED of 8.8 hours and 1.6 times more than edge sealed OLED of 54.5 hours.

An Experimental Study of Ultra-Precision Turning of Optical Glass(BK7) (광학유리(BK7) 초정밀절삭의 실험적 연구)

  • Kim, Min-Jae;Lee, June-Key;Yun, Yeong-Gon;Lee, Hyeon-Sung;Hwang, Yeon;Kim, Hye-Jeong;Kim, Jeong-Ho
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.20 no.4
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    • pp.382-385
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    • 2011
  • There is an immense need to obtain nanometric surface finish on optical glass owing to the advantage of improved performance of the components. But owing to brittleness and hardness, optical glass is one of the materials that is difficult to ultra-precision turning. According to the hypothesis of ductile mode machining, regardless of their hardness and brittleness, will undergo a transition from brittle to ductile machining region below a critical undeformed chip thickness. Below this threshold, it is suggested that the energy required for plastic formation. Thus, plastic deformation is the predominant mechanism of material removal in machining these materials in this mode. An experimental study is conducted diamond cutting for machining BK7 glass. The investigation presents the feasibility of achieving nanometric surface and the understanding the mechanism of cutting glass, proving the cutting edge radius effect.

Deposition of $\alpha$-Si:H thin films by PECVD method (플라즈마 화학증착법을 이용한 $\alpha$-Si:H박막의 제조)

  • 정병후;문대규;임호빈
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 1991.10a
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    • pp.63-67
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    • 1991
  • Amorphous silicon films were deposited on glass, [100] single crystal silicon wafer with thermally grown silicon dioxide, and [100] silicon wafer substrates by Plasma Enhanced Chemical Vapor Deposition(with argon diluted silane source gas). Growth rate, UV optical band edge, and the hydrogen quantity in the amorphous silicon films have been investigated as a function of the preparation conditions by measuring film thickness, UV-absorbency, and FT-IR transmittance. The growth rate of the ${\alpha}$-Si:H films increases with increasing substrate temperture, flow rate and R.F. power density. The UV optical band edge shifts to blue with the increases in the deposition pressure. Increasing substrate temperature shifts the UV optical band edge of the films to red. Hydrogen quantity in the ${\alpha}$-Si:H films increases with an increases in the R.F. powr and decreases with an increase in the substrate temperature.

J-Integral under Transient Temperature State (천이온도 상태에서의 J적분)

  • 이강용;박정수
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.15 no.6
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    • pp.1781-1791
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    • 1991
  • For the cracked plate under transient temperature distribution, J-integral is expressed in the form of line integral by using convolution integral. The J$_{1}$ integral is calculated for a through line center cracked steel plate under thermal and mechanical loading conditions and the calculated values are in good agreement with previous results. The effect of inertia term on the J$_{1}$ integral is not negligible for a glass but for a steel. For the glass plate, the rates of J$_{1}$ integral value to time increase if the values of material properties such as specific heat, thermal conductivity, thermal diffusivity and Young`s modulus as well as crack length and temperature difference in cracked edge increase.

Tensile Properties of Plain Weave Glass Fabric Reinforced Epoxy Resin Laminates at Low Temperatures (평직유리섬유 강화 에폭시 적층판의 저온 인장 특성)

  • Kim, Yon-Jig
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.32 no.9
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    • pp.788-795
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    • 2008
  • To understand the tensile behaviors of GFRP at low temperature, three types of specimen have been used in this study. Tensile properties and fracture mechanisms for three orthogonal orientations of plain weave glass fabric reinforced epoxy resin laminate were investigated at temperature range of about -30 to $15^{\circ}C$. The tensile properties of axial and edge type specimen decrease slightly with decreasing temperature to $-20^{\circ}C$. However, at $-30^{\circ}C$ the decreases in the tensile properties increased considerably. Below $-20^{\circ}C$, thickness type specimen showed a marked decreases in the tensile properties. It was obvious that the fracture manner of thickness type specimen was adhesive failure at above $-10^{\circ}C$ and a mixed adhesive and cohesive failure at below $-20^{\circ}C$.

Home-built Solid-state NMR Probe for Membrane Protein Studies

  • Kim, Yong-Ae;Hwang, Jung-Hyun;Park, Jae-Joon
    • Bulletin of the Korean Chemical Society
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    • v.24 no.9
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    • pp.1281-1283
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    • 2003
  • Proteins in highly oriented lipid bilayer samples are useful to study membrane protein structure determination. Planar lipid bilayers aligned and supported on glass slide were prepared. These stack of glass slide with planar lipid bilayers are not well fit for commercial solid-state NMR probe with round coil. Therefore, homebuilt solid-state NMR probe was built and used for a stack of thin glass plates and RF coil is wrapping directly around the flat square sample. The overall filling factor of the coil is much better and the large surface area enhances the extent to orientation by providing uniform environments for the phospholipids and the high ratio of circumference to area reduces edge effects. $^1H\;and\;^{15}N$ double resonance probe for 400 MHz NMR (9.4T) with a flat coil (coil size: 11 mm ${\times}$ 20 mm ${\times}$ 4 mm) is constructed and tested.

Energy and strength in brittle materials

  • Speranzini, Emanuela
    • Smart Structures and Systems
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    • v.23 no.4
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    • pp.373-385
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    • 2019
  • A study concerning the strength of brittle materials is presented in this paper. The failure behavior was investigated examining the plane of the crack after the failure and comparing the results obtained with those deriving from the fracture mechanics theory. Although the proposed methods are valid in general for brittle materials, the experiment was performed on glass because the results are more significant for this. Glass elements of various sizes and different edge finishes were subjected to bending tests until collapsing. The bending results were studied in terms of failure load and energy dissipation, and the fracture surfaces were examined by means of microscopic analysis, in which the depth of the flaw and the mirror radius of the fracture were measured and the strength was calculated. These results agreed with those obtained from the fracture mechanics analysis.

The Strain Evaluation of the Notch tip Area for the CFRP/GFRP Hybrid Laminate Plate using the SENT Specimen (SENT시험편을 이용한 CFRP/GFRP 하이브리드 적층재의 노치선단부 변형률 평가)

  • Kang, Ji Woong
    • Journal of the Korean Society of Safety
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    • v.29 no.5
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    • pp.15-21
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    • 2014
  • The aim of this work is conduct the study on light weight and structural performance improvement of the composite wind power blade. GFRP (Glass Fiber Reinforced Plastic) pre-empted by CFRP(Carbon Fiber Reinforced Plastic), the major material of wind power blade, was identified the superiority of mechanical performance through the tensile and fatigue test. SENT(Single Edge Notched Tension) specimen fracture test was conducted on the specimen that laminated together 2 ply CFRP with 4 ply GFRP through DIC(Digital Image Correlation) analysis. The SENT specimen thickness and $a_0/W$ ratio is 1.45 mm and 0.2, respectively. The fracture test accomplished with displacement control with 0.1 mm/min at the room temperature. The experimental apparatus used for the fracture test consisted of a 50kN universal dynamic tester and CCD camera connected to a personal computer (PC), which was used to record images of the specimen surface. Following data acquisition, the images and load-displacements were transferred to the PC, on which the DIC software was implement. The experiment and DIC analysis results show that CFRP/GFRP laminated composite exhibits improvement of the strength, compared with that of the existing blade material. This study shows the result that the strength of CFRP rotor blade of wind turbine satisfies through the experimental and DIC method.