Alumina Core와 Lithium Disilicate Core의 분광반사율 변화에 관한 연구

이기대 (Kee-Dae Lee),김주원 (Joo-Won Kim) 대구보건대학 2008 대구보건대학 論文集 Vol.28 No.-

The purpose of this study is to provide efficient results on reflective spectrum of Alumina core and Lithium Disilicate core in oral conditions. A data for the study comes from experiments; reflective spectrum by Spectrophotometer(TC1800, Japan). The results are summarized as follows; Reflective spectrums set up during the cooling of the sintered porcelain veneer will also play a part in improving the bond strength. Ceramo-metallic systems are deliberately designed with a very small degree of thermal mismatch in order to leave the porcelain in a stage of compression. It is important to note that the high expansion porcelains used in metal-ceramics have an increased tendency to devitrify because of their Alkali content.

도재소부용금합금의 강도 및 도재소부층의 미세조직에 관한 연구

곽동주 ( Dong Ju Kwak ),이기대 ( Kee Dae Lee ) 한국위생과학회 2009 한국위생과학회지 Vol.15 No.2

신경망을 이용한 상류수위에 대한 하류의 홍수유출예측

최창진(Choi, Chang Jin),이정훈(Lee, Jung Hun ),권기대(Kwon, Ki Dae),지홍기(Jee, Hong Kee) 대한토목학회 2012 대한토목학회 학술대회 Vol.2012 No.10

齒科用 Ag-Pd-Cu 3元合金 및 Au添加合金의 時效硬化特性

이기대,곽동주 대구보건대학 1999 대구보건대학 論文集 Vol.19 No.-

The Ag-Pd-Cu alloys containing a small amount of Au is commonly used for dental purposes, because this alloy is cheaper than Au-base alloys for clinical use. However, the most important characteristic of this alloy is age-hardenability, which is not exhibited by other Ag-base dental alloys. The specimens used were Ag-Pd-Cu ternary alloys and Au addition alloy. These alloys were melted and casted by induction electric furnace and centrifugal casting machine in Ar atmosphere. These specimens were solution treated for 2hr at 800% and were then quenched into iced water, and aged at 350~550℃. Age-hardening characteristics of the small Au-containing Ag-Pd-Cu dental alloys were investigated by means of metallurgical microstructures, X-ray diffraction and electron microscope observations, energy dispersed spectra and electron probe microanalysis. Principal results are as follows : The case of hardening in stage Ⅰ was due to the formation of the L1o type face-centered tetragonal PdCu-ordered phase in the grain interior and hardening in stage I was affected by the Cu concentration. In stage Ⅱ, decomposition of the αsolid solution to a PdCu ordered phase(L1o type) and an Ag-rich α₂ phase occurred and a discontinuous precipitation occurred at the grain boundary. From the electron microscope study, it was concluded that the cause of age-hardening in this alloy is the precipitation of the PdCu ordered phase, which has AuCu Ⅰ type face-centered tetragonal structure. Precipitation procedure was α→α+α₂+PdCu→α₁+α₂+PdCu at Pd/Cu =1. Ag-Pd-Cu alloy is more effective dental alloy as ageing treatment and is suitable to isothermal ageing at 450℃.

치과용 고농도Pd계 금-은-팔라듐합금의 시효경화특성

이기대,이화식 대구보건대학 2001 대구보건대학 論文集 Vol.21 No.-

An Ag-Pd-Cu alloys containing a small amount of Au is commonly used for dental purposes, because this alloy is cheaper than Au-base alloys for clinical use. However, the most important characteristic of this alloy is age-hardenability, which is not exhibited by other Ag-base dental alloys. Dental Ag-Pd-Cu alloys exhibit the characteristics of age-hardenability. Palladium represses the sulphurization of silver, and the age-hardenability is caused by the addition of copper. In order to improve the corrosion resistance, a small amount of gold is added to the commercial alloys. The specimens used were Ag-Pd-Cu ternary alloy and Ag-Pd-Cu-Au alloy. These alloys were melted and casted by induction electric furnace and centrifugal casting machine in Ar atmosphere. They were rolled and drawn into plate and wire shape. These specimens were solution treated for 2hr at 800℃ and were then quenched into iced water, and aged at 350~550℃ Principal results are as follows : Hardening occured in two stages, stage Ⅰ in low temperature and stage Ⅱ in high temperature regions, during continuous aging. From the electron microscope study, it was concluded that the cause of age-hardening in this alloy is the precipitation of the PdCu ordered phase. It was very effective that addition of small amount of Au increased hardenability in Ag base dental alloy and increasing the Pd content of Ag base alloys also increased base dental alloy and increasing the Pd content of Ag base alloys also increased hardenability. The formation of the lamellar structure develpoed from grain boundaries by discontinuous precipitation. Ag-Pd-Cu alloy is more effective dental alloy as ageing treatment and is suitable to isothermal ageing at 450℃.

치과용비귀금속합금의 파단조직에 미치는 주형온도의 영향

이기대,정현곤 慶北大學校 齒科大學 1987 慶北齒大論文集 Vol.4 No.1

The purpose of this study was to investigate the effect of mold temperature on the change in fractured microstructure of Ticonium Premium 100 (Ni-Cr alloy) and Regalloy (Co-Cr alloy). Tensile specimens were casted from the types of alloys by centrifugal casting machine in mold temperatures of 500, 600, 700, 800, 900 and 1,000℃. After testing the tensile strength of castings, the microstructure and the pattern of fracture were investigated. The grain size of Ticonium Premium 100 and Regalloy increased with the increase of mold temperature.

齒科嬌正用線材의 物理的 性質에 미치는 熱處理의 影響

李基大,權五源,成材鉉 慶北大學校 齒科大學 1985 慶北齒大論文集 Vol.2 No.1

The physical properties of .016" orthodontic wires by heat treatment were studied in tension, bending, hardness and microstructures. The wires were tested in the as-manufactured and heat-treated conditions. The results were as follows: Ultimate tensile strength and yield strength were slightly increased by heat treatment, but Elgiloy was the most effective by geat treatment. The strength of Elgiloy showed the highest value after heat treatment above 6 minutes at 500, 600℃. Also, bending fluxure modulus of elasticity were progressively increased by heat treatment. the hardness number of Australian of as-manufactured wires showed the highest value, and Elgiloy showed the highest value by heat treatment. Microstructure of as-manufactured wires showed fibrous interlocking grains, and a coarse grains after heat treatment and an austenite structure after solution heat treatment.

低濃度 Al-Ag合金의 時效擧動에 미치는 電氣抵抗의 變化

李基大 慶北大學校 産業開發硏究所 1980 硏究報告 Vol.8 No.-

It is confirmed by measuring electric resistance of the dilute Al-0.3wt%Ag alloy to form G.P. zones at relatively high temperatures in the nucleation and growth mechanism. Increase of as-quenched resistivity due to the concentration fluctuation at the quenching temperature is found when quenched at lower temperatures. Ageing behaviours in the alloys having remarkable fluctuation variously change with the vacancy concentration. These behaviours are interpreted in terms of the difference in the growth rate of G.P. zones nucleated in the region of higher and lower solute concentration induced by the fluctuation and in terms of the changes of this difference with vacancy concentration.

도재소부용 고금함유금합금의 조성적 특성에 관한 연구

이기대 대구보건전문대학교 2006 대구보건대학 論文集 Vol.26 No.-

The success of the porcelain fused to metal (PFM) restoration depends not only on the choice of materials but to a larger degree on the technical skills and understanding of both the clinicians and technicians. The design of the compositions of PFM is very important to esthetic restorative materials applying to porcelain. The purpose of this study is characteristics of high gold alloys for dental porcelain- fused to metal. The high Au alloy containing high gold contents is respectively Au(86%), Pt(5%), Pd (4%), Ag(2%), In(1%), Sn(1%), Ti(1%). These alloys are composed mainly of gold, platinium, silver and palladium with a few percent of the additional elements. By the addition of small amounts of elements such as In, Sn Ti, the fine grain castings are produced in gold alloy. These alloys have mechanical properties characteristics of Type I and Typ ∏ gold alloys. These alloys are useful to porcelain-metal restorations and dental laboratory. Also dental laboratory tests are successful to porcelain-metal restorations using these alloys. The porcelain fused to metal (PFM) alloys containing gold are commonly use for dental purposes in dental laboratory. The chief effectiveness to the development of porcelain fused to metal(PFM) as a restorative material, either in prosthetic or crown & bridge procedures, is a success in which the economical and commercial factors is the principal force. Clinical application of these alloys can be directed toward the economical and commercial manufacture and production.

도재소부용 저금함유금합금의 합금조성 및 물리적 특성에 관한 연구

이기대 대구보건전문대학 2007 대구보건대학 論文集 Vol.27 No.-

The success of the porcelain fused to metal (PFM) restoration depends not only on the choice of materials but to a larger degree on the technical skills and understanding of both the clinicians and tenicians. The design of the compositions of PFM is very important to esthetic restorative materials applying to porcelain. The purpose of this study is characteristics of low gold alloys for dental porcelain-fused to metal. The high Au alloy containing high gold contents is respectively Au(67%), Pt(3%), Pd(13%), Ag(12%), In(2%), Sn(2%), Ti(1%). These alloys are composed mainly of gold, platinium, silver and palladium with a few percent of the additional elements. By the addition of small amounts of elements such as In, Sn Ti, the fine grain castings are produced in gold alloy. These alloys have mechanical properties characteristics of Type III and Type IV gold alloys. These alloys are useful to porcelain-metal restorations and dental laboratory. Also dental laboratory tests are successful to porcelain-metal restorations using these alloys. The porcelain fused to metal(PFM) alloys containing gold are commonly use for dental purposes in dental laboratory. The chief effectiveness to the development of porcelain fused to metal(PFM) as a restorative material, either in prosthetic or crown & bridge procedures, is a success in which the economical and commercial factors is the principal force. Clinical application of these alloys can be directed toward the economical and commercial manufacture and production.