• 대한치과기공학회지
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• 제5권1호
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• pp.27-30
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• 1983

적은 경비로써 보다 양호한 치경부의 적합과 Shade를 얻고 치경부의 변색을 막기 위하여 도재소부용 귀금속과 비금속, 그리고 귀금속과 비금속위에 도금을 하는 4가지 유형으로 나누어 실험하였던 바 다음과 같은 결과를 얻게 되었다. 1. 도재소부용 귀금속으로 치관전체를 주조하는 경우는 수축율이 적고 연성이 뛰어나 경비가 많이 소요된다. 2. 비금속으로 치관전체를 주조하는 경우는 경비는 저렴하나 치경부의 적합성이 금속에 따라 차이가 있으며 그 중 Gemini II가 가장 우수하였다. 3. 비금속으로 치관 전체를 주조하고 10K의 Gold로 도금하는 경우는 적합성에서는 비금속과 동일하나 도금이 고리게 되지 않고 Shade에서도 별 효과가 없었다. 4. 치관의 윗부분은 비금속으로 먼저 주조하여 Degassing한 후 나머지 2mmwjd도의 치경부를 귀금속으로 주조하는 경우는 치경부의 적합성은 귀금속과 동일하게 우수하고 경비 또한 매우 저렴하였다.

• 한국의류산업학회지
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• 제23권4호
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• pp.439-447
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• 2021

The purpose of this study is to examine the evolution of precious metal and gem stores, and to derive the characteristics of this period from the government, industry, and consumers. Correspondingly, the contents of daily newspaper articles during this period were analyzed using Naver's news library search engine. The historical development process is as follows. Before the Korean War, precious metal jewelers operated in Jongno, Namdaemun, and Chungmuro, dealing with gold, silver, and platinum. Large stores not only sold jewelry and watches, but also functioned as craftsmen and watch repairers. After the war, a shopping district for precious metals and jewelry was formed around Midopa Department Store. By 1963, the number of jewelry stores in Seoul increased to about 130 and to about 280 by 1966. The characteristics of the government, industry, and consumers are as follows. The government continued to implement a policy to regulate the precious metal and jewelry industry. Despite challenges, the industry exhibited the potential for foreign currency acquisition and growth through domestic amethyst. Consumers could access information regarding precious metal jewelry in daily newspapers. In the late 1960s, various types of jewelry were distributed in line with an increase in income levels.

• 대한치과기공학회지
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• 제17권1호
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• pp.10-25
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• 1995

The purpose of this study is to get the difference of the castability in the production of partial denture between Precious Metal Alloys and Base Metal Alloys accompanied with the frequency of reuse. As materials for an experiment, we selected Baker-444 and Soo-444 and Soo-sung as Precious Metal Alloys, New Crown and Chrome Cobalt as Base Metal Alloys. And we tired to case all of them seven times. The experimental results were as follows : 1) In the probability of segments, Baker-444 showed 100$\pm$0.00%, Soo-sung 97.24$\pm$1.58%, New Crown 95.63$\pm$4.28%, and Chrome Cobalt 91.03$\pm$7.76%. Consequently, Precious Metal Alloys were decidely superior to Base Metal Alloys in the castability. 2) In the view of the acheived result, burn-out temperature and smocking time had greatly affected the castability. 3) After casting, Precious Metal Alloys were much less than Base Metal Alloys in the quantity of consumption. It made much difference from the the compiled stastics(p<0.01)

• 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.

• Journal of Advanced Marine Engineering and Technology
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• 제23권3호
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• pp.389-397
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• 1999

Recently the use of Pd catalyst have been continued to expand because of cost avaliabilityand performance advantages. Especially the Pd+Rh catalyst instead of the Pt+Rh catalyst had been used for most of three way catalysts because of the more stringent emission standards and its higher temperature effectiveness. The main purpose of this study is to investigate the design parameter impacts on the Pd+Rh cat-alyst for the automotive exhaust catalysts application. This study was investigated on the catalyst efficiency for the volume and the precious metal loading of the Pd+Rh ceramic monolithic cata-lyst. And experiments concerning the effects of volume and precious metal loading on Pd+Rh three way catalysts were conducted to examined the catalyst light-off temperature and conver-sion efficiency on higher volume demonstrated almost similar performance. But their effects on higher precious metal loading demonstrated considerably better performance.

• 구강회복응용과학지
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• 제22권3호
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• pp.203-210
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• 2006

Although porcelain fused to metal crowns made from non-precious metal have good mechanical properties, they also have disadvantages such as the poor biological acceptability and the low corrosional resistance. Titanium is used as the alternative metal for porcelain fused to metal crowns, in spite of difficulties in casting. For that reason non-precious alloy including titanium which is easy to cast is currently used. This study evaluated the bond strength between non-precious alloy including titanium and Ni-Cr alloy. $Tilite^{(R)}V$ as non-precious alloy including titanium, $Rexilium^{(R)}V$ as Ni-Cr alloy and $Omega900^{(R)}$ and $Vintage(Regular)^{(R)}$ as porcelain powders were used. The results were as follows. 1. In comparison with the kind of alloy, the bond strength of $Tilite^{(R)}V$ was lower than that of $Rexilium^{(R)}V$. There was no significant difference between two groups. 2. In comparison with the kind of porcelain powder, the bond strength of $Omega900^{(R)}$ was higher than that of $Vintage(Regular)^{(R)}$ in $Tilite^{(R)}V$. There was significant difference between two groups(p < 0.05).

• 대한치과보철학회지
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• 제30권1호
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• pp.73-83
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• 1992

Now composite resin restoration is clinically accepted in the repair of fractured PFM case, many mechanical surface treatment methods are performed to increase retentive force. The main purpose of this study was to compare the retentive force among the possible surface treatments and to insure the best method for the clinical application to the fractures porecelain and the exposed metal surface. To compare and to analyze the retentive force of repair resin, porcelain specimen were divided into 2 groups, etching group and non-etching group, and etching group were treated with 37% $H_3PO_4$, 1.23% APF, 10% HF and non-etching groups were treated with diamond bur, micro-sandblasasting. Also, metal specimens were divided by 2 groups : one was non-precious metal group which was treated with diamond bur, micro-sandblasting and tin plating and electrolytic etching, the other was precious metal group which was composed of micro-sandblasting treatment only and tin plating treatment with micro-sandblasting. Each specimen had been restored for 48 hours and the bond strength of each specimen was calculated with Universal testing machine. The results were as follows : 1. Porcelain specimen had higher bonding strength than metal specimen for the repair resin(P<0.01). 2. In porcelain specimen, 10% HF etching group had the highest bonding strength among etching and non-etching group. 3. Metal specimen treated with micro-sandblasting had highest bonding strength among the non-sandblasting had hightest bonding strength among the non-precious group, tin plating group had higher bonding strength than micro-sandblasting group between the precious metal groups. 4. Bonding strength of tin plating was increased in precious metal group only.

• 대한치과기공학회지
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• 제33권1호
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• pp.37-45
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• 2011

Purpose: Heat pressed ceramics, used for all ceramic restorations, have the additional advantage of being technically less change through using of the lost-wax technique. Conceptually, combining the ceramic with the clinically proven reinforcing ability of a metal framework would be advantageous; however, cause of mismatching of fusion between ceramics and metal frameworks which from differences of casting temperature and coefficient of thermal expansion, pressed ceramics could not be used with a metal framework. The purpose of this study was to compare shear bond strength of press-to metal ceramic to porcelain fused non precious metal and feldspatic porcelain fused non precious metal. Methods: The 30 metal specimens were casted in a porcelain fused non precious metal nickel-chromium alloy. They were divided into 3 groups by surface treatment and applied ceramic: $125{\mu}m$ aluminium oxide sandblasting and veneered feldspatic porcelain (group FP), $125{\mu}m$ aluminium oxide sandblasting and had press-to-metal ceramic applied (group PC), porcelain bonder (gold bonder) fused on surface of metal specimens and had press-to-metal ceramic applied (group PCG). In each group 10 metal specimens were used. The press-to-metal ceramic applied 20 specimens had ash-free wax pattern applied, the metal-wax complexes invested, and were pressed with heat press ceramic. All specimens were subjected to shear bond strength test at a crosshead speed of 1.0 mm/min. Results: The results of measured in Mean SD and data were analyzed by one-way AVOVA (p= .05) and Tukey HSD test (p= .05).: group FP $16.090{\pm}1.841$ MPa, group PC $12.620{\pm}1.8256$ MPa, group PCG $10.920{\pm}0.9283$, significant differences between all groups (p < .05). Significant differences were found in each between group FP and group PC, group FP and group PCG (p < .05). Conclusion: The shear bond strength of press-to-metal ceramic to porcelain fused non precious metal was described higher in unused gold bonder group than used gold bonder groups.

• 대한치과보철학회지
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• 제18권1호
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• pp.87-97
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• 1980

To compare the castability of various alloys popularly used in Korea for porcelain-fused-to-metal restorations, author selected Degudent G as precious alloy, J.P. 92 as semiprecious alloy and Vera Bond, Rexillium III, Unit Bond, Fine Bond as non precious alloys. With nylon lines and gauge waxes, author made the wax patterns for the castability comparison test. In the same conditions, wax patterns were invested, burned out and cast. Author obtained the following results from this study. 1. The castability of Degudent G as precious alloy for porcelain-fused-to-metal crown and bridge was the best of all. 2. The castability of nonprecious alloys was less than Degudent G as precious alloy, but their differences were not large. 3. The castability of Rexillium III is the best of all nonprecious alloys and that of Vera Bond, Unit Bond had nearly the same results. 4. Semiprecious alloy (J.P. 92) was less castable than nonprecious alloys.

• 대한치과보철학회지
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• 제34권4호
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• pp.869-902
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• 1996

Flexion of a metal/ceramic fixed partial denture(EPD) frameworks under function can cause fracture of porcelain or deterioration of the cement seal. This study evaluated the flexion characteristics of three-unit mandibular FPD frameworks, repacing the second pre-molar under compressive load(200g, 400g). Testing was accompished with real-time holographic interferometry, using 6 porcelain fused-to metal frameworks. Tested alloys were non-precious alloy(Heracles, Holland), semi-precious alloy(Degudent U, Germany) and precious alloy(Degudent H, Germany). Changes of the fringe patterns according to the heat treatment(porcelain firing cycle), various loads(200g, 400g), occlusal forms(occlusal porcelain veneering, facial porcelain veneering), various alloys and post-soldering units were compared. Dental study model(Nissan dental products, Inc. D51DP-500A, Japan) and six 3-unit metal/ceramic fixed partial denture frameworks were used as experimental materials. 36 holograms were taken on fixed dental study model by using the 10mW He-Ne laser and real-time holographic interferometry. On the basis of this study, the following conclusions can be drawn : 1. In the frameworks for facial porcelain veneering, the semi-precious alloy framework was least deformed and precious alloy framework, non-precious alloy framework orderly before heat treatment, and the deformation was not shown great difference among three alloys after heat treatment and post-soldering. 2. In the frameworks for occlusal porcelain veneering, the precious alloy framework was greatest deformed and the deformation was not difference between semi-precious alloy framework and non-precious alloy framework before, after heat treatment, and the deformation was not shown great difference among three alloys after post soldering. 3. In the non-precious alloy frameworks for facial porcelain veneering and occlusal porcelain veneering, the deformation was greatly decreased after heat treatment and conversely increased after post-soldering. 4. In the semi-precious alloy framework for facial porcelain veneering, the deformation was not detectable after heat treatment and increased after post-solder. And in the frame-work for occlusal porcelain veneering, the deformation was slightly decreased after heat treatment and increased after post-soldering. 5. In the precious alloy framework for facial porcelain veneering, the deformation was greatly decreased after heat treatment and increased after post-soldering, And in the framework for occlusal porcelain veneering, the deformation was greatly decreased after heat treatment and decreased after post-soldering.