• 대한치과기공학회지
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• 제35권1호
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• pp.1-17
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• 2013

Purpose: This study was to assess the extents of the release of metals from the non-precious alloys used for dental casting by measuring the differences in the extents of the release of metals by types of alloys, pH level and elapsed time. Methods: Uniform-sized specimens(10 each) were prepared according to the Medical Device Standard of the Korea Food and Drug Administration(2010) and International Standard Organization(ISO22674, 2006), using four types of alloys(one type of Ni-Cr and one type of Co-Cr used for fixed prosthesis, and one type of Ni-Cr and one type of Co-Cr used for removable prosthesis). A total of 12 metal-release tests were performed at one-day, three-day, and two-week intervals, for up to 20 weeks. The metal ions were quantified using an Inductively Coupled Plasma-Atomic Emission Spectrometer. Results: The results showed that the extent of corrosion was higher in the ascending order of Jdium-$100^{(R)}$, Bellabond-$Plus^{(R)}$, Starloy-$C^{(R)}$, and Biosil-$F^{(R)}$. The lower the pH and the longer the elapsed time were, the greater the increase in metal corrosion. At pH 2.4, the release of Ni from Jdium-$100^{(R)}$, a Ni-Cr alloy, was up to 15 times greater than the release of Co from the Co-Cr alloy from two weeks over time, indicating that the Ni-Cr alloy is more susceptible to corrosion than the Co-Cr alloy. Conclusion: It is recommended that Co-Cr alloy, which is highly resistant to corrosion, be used for making dental prosthesis with a non-precious alloy for dental casting, and that non-precious alloy prosthesis be designed in such a way as to minimize the area of its oral exposure. For patients with non-precious alloy prostheses, a test of the presence or absence of periodontal tissue inflammation or allergic reaction around the prosthesis should be performed via regular examination, and education on the good management of the prosthesis is needed.

• 대한치과보철학회지
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• 제29권3호
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• pp.181-196
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• 1991

The Purpose of this study was to evaluate the marginal fit of ceramo-metal crown according to the different ceramo-metal alloy types and the curvature of labio-cervical margin. Degudent $G^{(R)}$ as precious and $Verabond^{(R)}$ as non-precious ceramo-metal alloy were used. The abutment was preparaed with two different curvature types : a normal curvature type and a pronounced curvature type. 20 crowns were farbricated using four different combinations and their marginal fits were measured at 3 consecutive stages (before degassing, after degassing, after glazing) using microscope under 200 magnification. The results were as follows: 1 . Marginal fitness before degassing. The groups of precious ceramo-metal exhibited better marginal fit than the groups of non-precious ceramo-metal with significant difference(P<0.05) . In the same ceramo-metal groups, the normal curvature group exhibited better marginal fit than the pronounced curvature group but without significant difference(P>0.05). 2. Marginal fitness after degassing. By degassing, the group of pronounced curvature and non-precious ceramo-metal was deformed the most, and the degree of margin fitness of each group was the same as before degassing. 3. Marginal fitness after glazing The group of normal curvature and precious ceramo-metal exhibited better marginal fit than the group of pronounced curvature and non-precious ceramo-metal with significant difference(P>0.05), and the degree of margin fitness of each group was the same as before degassing.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 추계 학술발표회 제16권2호
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• pp.553-556
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• 2004

This paper is to investigate the spalling and fire endurance of high performance RC column member with PP fiber and lateral confinement of metal lath and non fire resistance removal type form. According to test results, combination of PP fiber and metal lath as well as use fire resistance non removal type form had favorable fire resistance by discharging internal vapour pressure and lateral confining. After fire endurance test, compressive strength decreased markedly caused by internal expansion pressure and crack. Residual strength of plain concrete was decreased to $22\%$. The use of PP fiber and lateral confinement of metal lath and non removal type form enhanced the residual strength above $40\%$. Especially, the combination of $0.1\%$ of PP fiber and lateral confinement with the level of 2.3T exhibited more than $51\%$ of residual strength. Therefore, to improve fire endurance and spalling resistance, the combination of $0.1\%$ of PP fiber and metal lath with 2.3T can be the proper measure.

• 동력기계공학회지
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• 제6권1호
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• pp.82-87
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• 2002

Not only ferrous but also non-ferrous materials such as aluminum, brass, plastic and woods need cutting operation in recent manufacturing industry. Over the past few years a considerable number of studies have been made on non-ferrous metal cutting. But more study is required to meet various engineering needs. The purpose of this paper is to preform an experiment on the influence of feed-rate adjustment and side rake angle in turning operations from non-ferrous metals. As a result, the surface roughness was reduced when a side-rake angle increases and feed-rate decreases in the case of the plastic, brass, aluminum, and paulownia. Therefore, this papers develop a new type bite that be used to adjust side-rake angle.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2003년도 추계학술대회논문집
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• pp.277-280
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• 2003

It was investigated that the "ㄱ" type angle product could be bended with a curvature during extrusion by extru-bending process. The bending process for the "ㄱ" type angle product can be developed by the hot metal extru-bending machine with the two punches moving in the different velocity. Because of non-symmetry of product, it is important to design the ruled surface contour of dies cavity for the welding and bending with two billets. So it is designed that the multi-hole container has two non-symmetric holes and non-symmetric contour of dies entrance. The results of the experiment show that "ㄱ" type angle product can be bended by the extrusion process and that the curvature of the product can be controlled by the velocity of punch and that the defects such as the distortion of section and the thickness change of the product and the folding and wrinkling of the product did not happen after the bending processing by the extrusion bending machine.

• 대한치과보철학회지
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• 제34권2호
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• pp.363-372
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• 1996

A common site of fracture in maxillary complete denture is on the anteroposterior midline that coincides with the notch for relief of the labial frenum. Various approaches to reduce the incidence of this type of fracture have been suggested. The most widely used technique is the reinforcement of acrylic resin denture base with several solid metal forms. But few comparative studies on the efficacy of metal reinforcements have been reported. This study was conducted to compare reinforcing effects of commonly available metal reinforcements, which include wire, metal mesh embedded in the denture base and metal plate affixed to the impression surface of denture base by silicoating technique. This was load on the posterior. The strain gauges were oriented perpendicular to the anteroposterior midline of maxillary polished denture surface at one labial and the four palatal sites Non-renforced denture was used as control. The results were as follows : 1. In the non-reinforced denture group, only tensile strains on the palatal polished surface were observed. The tensile strains decreased in the order of incisive papilla, posterior denture border area, mid palatal area and rugae area. Compressive strain was observed on the labial polished surface. 2. As compared with the non-reinforced denture group, the metal plate or the metal mesh reinforced denture groups showed reduced palatal tensile strains,and the metal mesh reinforcement had a better reinforcing effect than the metal plate. But both reinforced denture groups showed no difference in the amount of compressive strain on the labial polished surface when compared to the non-reinforced denture group. 3. The metal wire positioned just above the labial notch decreased the compressive strain on the labial polished surface. But the presence of metal wires in the palatal polished surface caused increase in tensile strains in the area.

• 전기의세계
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• 제25권1호
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• pp.104-107
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• 1976

The switching characteristics of Non-crystalline As-Te-Si-Ge thin film device using Ag, In and Al metal for electrode, has been investigated. Threshold voltage and holding current of each sandwich type device varied due the to formation of the potential barrier in between non crystalline solid and electrode interface.

• 대한치과기공학회지
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• 제34권4호
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• pp.337-344
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• 2012

Purpose: This study examined the corrosion level by alloy type and pH, and used the corrosion levels as the dental health data. The study utilized one Ni-Cr alloy for the full and removable partial denture metal frameworks and two Ni-Cr alloys for porcelain-fused-to-metal crown, among the non-beryllium dental casting non-precious Ni-Cr alloys. Methods: The alloy specimens were manufactured in $10cm^2$ and stored in the corrosive solution(pH 2.2-4.4) in the electrical water bath($37^{\circ}C$) for seven days. Afterwards, the metal ions were quantitatively analyzed using the ICP. Results: Of the three metal alloys, Bellabond-Plus$^{(R)}$alloy and SOLIBOND N$^{(R)}$alloy, with 22% or higher chrome chemical contents, had higher corrosion resistance than Jdium-100$^{(R)}$alloy with 20% chrome chemical content. In all three alloys, the corrosion of Ni was highest, and metal ion corrosion was higher in the pH 2.2 corrosive solution. Conclusion: Although Ni-Cr alloy was not very corrosive, a Ni-allergic patient should not have Ni-Cr alloy prosthesis. The Ni-Cr alloy for porcelain-fused-to-metal crown should be designed for the dental porcelain to cover the whole crown.

• JSTS:Journal of Semiconductor Technology and Science
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• 제8권1호
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• pp.51-65
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• 2008

The article presents the recent research development in polymer ferroelectric non-volatile memory. A brief overview is given of the history of ferroelectric memory and device architectures based on inorganic ferroelectric materials. Particular emphasis is made on device elements such as metal/ferroelectric/metal type capacitor, metal-ferroelectric-insulator-semiconductor (MFIS) and ferroelectric field effect transistor (FeFET) with ferroelectric poly(vinylidene fluoride) (PVDF) and its copolymers with trifluoroethylene (TrFE). In addition, various material and process issues for realization of polymer ferroelectric non-volatile memory are discussed, including the control of crystal polymorphs, film thickness, crystallization and crystal orientation and the unconventional patterning techniques.

• 대한금속재료학회지
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• 제48권6호
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• pp.551-556
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• 2010

In this report, we describe mold materials that were used to produce movable metal type by the investment casting method during the Joseon dynasty period in Korea. Samples were obtained from the Wibuinja collection, which is held by the National Museum of Korea. Most of the mold material remnants were found in the depressed areas of the movable type specimens, and we therefore performed non-destructive analyses including XRF, EDS, and XRD. Through these analyses, we were able to identify the mold remnants as hydrocerussite [trilead dihydroxide dicarbonate, $Pb_3(CO_3)_2(OH)_2$] formed in platy hexagonal crystallites. Hydrocerussite was first used to make white pigments and cosmetics in ancient Greece, but this is the first report of hydrocerussite used as mold material applied around a disposable pattern for investment casting. The results of this study will further the understanding of the production process for early movable metal type and ancient casting technologies.