• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.28 no.7
• /
• pp.1055-1063
• /
• 2004

In this study, we developed an automatic veneer sorting system controlled by nonlinear friction and nonlinear stiffness. With these nonlinear characteristics, it was difficult to analysis and to control the system in the fast. However it is necessary to consider nonlinear characteristics to satisfy accurate and rapid control demand in these days. We used not only nonlinear friction but also nonlinear stiffness and combined both to control the system. An experimental device was designed with 4 AC servo-motors and 2 Sensors. Through a series of experiment, we found nonlinear friction characteristics among roller versus veneer and veneer versus veneer and nonlinear stiffness characteristics with stacked veneers. Finally, we showed that the proposed control algorithm was very effective for veneer sorting system with nonlinear friction and stiffness.

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

• Journal of the Korean Wood Science and Technology
• /
• v.8 no.2
• /
• pp.9-16
• /
• 1980

The problem of tauns having the characteristics of severe variations in quality and unequally distributed moisture content in veneer sheets after drying for plywood could be cured to a proper even moisture distribution by the peeling of veneers in a prolonged period. The poor gluability of tauns was improved by applicaton of increased resin content of glue in spreading. Combinations of tauns with lauan and kapur for plywood showed good shear strength.

• Journal of the Korea Furniture Society
• /
• v.25 no.3
• /
• pp.233-237
• /
• 2014

The eco-friendly preservatives such as ACQ or CUAZ have been used in landscape architectural facilities these days. In this study, the decay efficacies of ACQ treatments were evaluated according to domestic veneer species, concentration of ACQ, weathering test, adhesive type, and fungus type. In case of veneer species, hinoki cypress and yellow poplar showed the highest and lowest decay resistance, respectively. And the decay resistance appeared to be greater in plywoods bonded by resorcinol resin-bonded plywood and non-weathering treated plywood than polyurethane resin-bonded plywood and weathering treated plywood.

• Journal of Dental Rehabilitation and Applied Science
• /
• v.22 no.3
• /
• pp.243-250
• /
• 2006

Due to high esthetic demands from patients, we are driven to fabricate natural-looking(form and color) restorations. In the past decade, the glass-ceramic in dentistry has been used as a material with variable crystals that affects the appearance, characteristics, and mechanical properties of metal-free fixed restoration. The conventional IPS Empress glass-ceramic is a heat-pressed, leucite reinforced material using the "lost wax" principle. This glass-ceramic has been successfully used for esthetic restorations such as all-ceramic crowns, inlays/onlays, and veneers for about 15 years. This article presents that the form and surface texture of clinical crown are duplicated by IPS-Empress system using "lost-wax technique".

• Journal of the Korean Wood Science and Technology
• /
• v.12 no.1
• /
• pp.38-43
• /
• 1984

Water soluble urea-melamine-phenol copolymer adhesive manufactured with 80 percent of urea resin contents was manufactured by different molar ratio for a high temperature curing type, and their properties and strengthes were examined through manufactures of plywood with Kapur (Dryobalanops spp.) veneers. The results are summarized as follows: 1. Specific gravities of air dried plywood manufactured from each adhesive ranged from 0.78 to 0.84 and their moisture contents met the KS requirement. 2. In dry and wet shear strength, $U_{80}M_{10}P_{10}$ copolymer resin showed the highest value and urea resin was the lowest, indicating that melamine and phenol were effective for increasing glue shear strength of urea resin. 3. In case of glue shear strength after boiling test, phenolic resin was the nest and melamine was not so effective as phenol on reinforcement of boiling water resistance of urea resin.

• Journal of Korean Society of Forest Science
• /
• v.30 no.1
• /
• pp.8-18
• /
• 1976

This study was carried out to exploit and utilize the exotic American Sycamore(Platanus occidentalis) grown in Korea as a veneer species for plywood manufacture. At present most parts of veneer Legs used in Korea were depended entirely upon the gonus Shorea woods(lauan logs) imported from Southeast Asia region. To decrease manufacturing cost and save imported lauan veneer logs, the effects on properties affecting to the six types of plywood made from proper veneer constructions composed by domestic American Sycamore and imported lauan veneers were compared and discussed. The study has important meanings for the promotion of plywood manufacture by domestic materials. Important items dealt with this study were dry and wet shear strength, moisture contents, specific gravties, and bending strength. By the results and discussions it may be summarized as follows: 1) In dry shear strength platanus(sycamore) core lauan plywood was shown most excellent strong results, and next orders were all lauan plywood, platanus faced lauan plywood, lauan core platanus plywood, lauan faced platanus plywood, and all platanus plywood. There was no difference between platanus core lauan plywood and all lauan plywood, but the differences between those plywoods and the other types of plywood were recognized. 2) In wet shear strength platanus core lauan plywood was shown excellent result the same as dry strength. The difference between platanus core lauan plywood and the other types of plywood was shown, but among the other types of plywood except platanus core lauan plywood were not recognized. 3) The differences among moisture contents according to the veneer construction were not recognized. 4) The plywood constructed by two or more sheets of lauan veneer was shown lower specific gravities than the plywood constructed by two or more sheets of platanus veneer. It is believed that this tendency due to the original specific gravities of veneer before construction. 5) The differences among specific gravities of lauan core platanus plywood, all platanus plywood and lauan faced platanus plywood were not recognized, and like this analyzed result among platanus core lauan plywood, all lauan plywood and platanus faced lauan plywood were not recognized. Accordingly it is believed that the differences are not shown among the plywood constructed by two or more veneers of same species. 6) In bending strength platanus core lauan plywood was shown most excellent values. Next orders were all lauan plywood, platanus faced lauan plywood and the other types of plywood. The differences among the plywood constructed by two or veneers of lauan were shown, but not shown among the plywood constructed by tow or more veneers of platanus.

• The Journal of Korean Academy of Prosthodontics
• /
• v.53 no.2
• /
• pp.138-143
• /
• 2015

Purpose: The aim of this study was to compare the translucency of two different laminate ceramic veneers with and without glazing. Materials and methods: Ten millimeter side square-shaped specimens in 0.3 mm and 0.6 mm thick were fabricated for the following materials with and without glazing (n=80): A1 shade IPS e.maxPress (IEM) and Styleveneers (STV). The color coordinates (CIE $L^*a^*b^*$) of the specimens were measured with a colorimeter. The Translucency parameter (TP) was calculated from the color difference of the material on a black versus a white background. For comparisons between materials and between the 'not glazed' and 'glazed' groups, unpaired t-test was used to analyze the data (P=.05). Results: The TP ($Mean{\pm}SD$) of 'not-glazed' and 'glazed' group of IEM specimens at 0.3 mm thickness were $45.99{\pm}3.00$ and $49.53{\pm}2.28$ and the TP at 0.6 mm thickness were $32.82{\pm}2.59$ and $43.02{\pm}0.98$, respectively. Likewise, the TP of 'not-glazed' and 'glazed' group of STV specimens at 0.3 mm thickness were $47.03{\pm}3.65$ and $50.95{\pm}3.05$ and the TP at 0.6 mm thickness group were $34.48{\pm}1.28$ and $43.39{\pm}1.20$, respectively. As the glazing of ceramic veneer differed, the TP of each ceramic veneer showed statistically significant difference. But, the result between the products was not statistically different. Conclusion: Within the limitations of this study, we are concluded that the glazing process changed translucency of laminate ceramic veneers and the TP would not be affected by products.

• The Journal of Korean Academy of Prosthodontics
• /
• v.49 no.4
• /
• pp.308-315
• /
• 2011

Purpose: The purpose of this study was to colorimetrically evaluate the masking effect of different opacity of ingots on the final shade of IPS Empress Esthetic$^{(R)}$ laminate veneer restorations using the CIE $L^*a^*b^*$ system. Materials and methods: Six porcelain disks of IPS Empress Esthetic$^{(R)}$ system (translucency: E 01, E 03, E 0C-1, E TC-1, E TC-2, E TC-3) were fabricated with 7 mm in diameter and 0.6 mm in thickness. Six extracted human incisors (shade: A1, A3, A4, B2, B3, C3) were used as the abutment specimens. The incisors were prepared using a diamond wheel and made with a flat labial surface on the middle 1/3. For each combination of different shades of abutments and copings, the change in color was measured with a colorimeter. CIE $L^*a^*b^*$ coordinates were recorded for each specimen. Color differences (${\Delta}E$) were calculated. Descriptive statistical analysis was done. Results: ${\Delta}E$ values were significantly affected by coping translucency and abutment shade (P<.05). The color differences (${\Delta}E$) of laminate veneers among abutments with A3, B3, C3, and A4 shade were mostly below 2.7 which was within the clinically acceptable range, while color differences between A4 and B2, A3 and B2, and A1 and A4 showed more than 2.7. Conclusion: The final color of IPS Empress Esthetic$^{(R)}$ laminate veneers were significantly influenced by translucency of the coping and shade of abutment teeth. The large value difference of abutment teeth limited the masking ability by laminate veneers.

• The Journal of Korean Academy of Prosthodontics
• /
• v.31 no.1
• /
• pp.1-10
• /
• 1993

The purpose of this study was to evlauate the microleakage of 3 dentin bonding agents using different dentin pretreatment method under simulated physilogic pressure in cementing the porcelain laminate veneer. Noncarious 60 human maxillary molars were selected and randomly assigned to 4 groups of 15 each. The group with the margin placed on the enamel was classified as the control and the groups with the margin placed on root surface were subdivided into 3 groups according to the dentin bonding agents used. The group using All Bond 2 was classified as experimental group 1, the group using Scotchbond MP was classified as experimental group 2, and the group using Gluma was classified as experimental group 3. Roots were removed at 3mm below the cementoenamel junction, and reductions of the teeth for the porcelain laminate veneer were done on the mesial 1/2 of the buccal surface of each teeth. The pulp was extirpated and the pulp chamber was cleaned with 37% phosphoric acid for the patency of dentinal tubule. Under simulated physiologic pressure, porcelain laminate veneers were cemented to the teeth using each dentin bonding agent and luting cement. After cementation, all samples were stored at 36t in water for 24 hours and thermocycled for 1500 cycles, then immersed in 0.5% basic fuchsin solution and the teeth were sectioned longitudinally by using diamond saw and the extent of microleakage was measured. The following results were obtained, 1. Microleakage was observed in a few samples of control group but all the samples of experimental groups. 2. The control group showed the less extent of microleakage than the experimental groups. In experimental groups the experimental group 1 & the experimental group 2 showed similiar extent of microleakage and the experimental group 3 showed the greater extent of microleakage than other groups. Conclusively, practicing the porcelain laminate veneers in the clinic, although the margin of the porcelain laminate veneer should be placed on enamel, in the case that it is inevitable to place the margin of the porcelain laminate veneer on the root surface, it is recommened to use dentin bonding agents which use no dentin pretreatment or a dentin pretreatment which can leave the smear plugs.