Sandblast 처리한 상아질면의 접착에 관한 연구

김교한,나환옥,황성욱 경북대학교 의학연구소 2000 경북대학교병원의학연구소논문집 Vol.4 No.1

Dentin adhesion was studied on sandblasted dentin with 4-MET/MMA-TBB resin. The effect of change of air pressure, with or without pretreatment and primer on tensile bond strength, was mainly investigated. In the effect of air pressure at sandblast treatment, the higher pressure showed the increase of tensile bond strength. The pretreatment with 10-3 solution after sandblast treatment increased tensile bond strength in the almost conditions. Application of primer also increased the tensile bond strength, confirmed the effect of primer application after sandblast treatment. Alumina particle was not found on the dentin surface in the SEM and EDAX examination.

α+β型 Ti-6Al-4V 合金의 機械的 性質 및 破壞靭性에 미치는 二重溶體化 處理의 影響

金敎漢 慶北大學校 齒科大學 1989 慶北齒大論文集 Vol.6 No.1

Double solution treatment method was used to investigate the effect of microstructure on mechanical properites and fracture toughness of α+β type Ti-6Al-4V alloy. In solution treatment, equiaxed α phase is resulted by 1st solution treatment and acicular α phase by 2nd solution treatment. So two conditions were considered to know the effect of equiaxed and acicular α pahse. First condition is that the amount of acicular α and equiaxed α is changed relatively while total α phase amount is keeped constant. Second one is that the amount of aciclar α phase is changed while equilaxed α ratio is keeped constant. By examined the mechanical properties and fracture toughness of double solution treatmented sepcimens, following results are obtained. 1. Yield strength, elongation and reduction of area have almost same values at double solution treatmented conditions. 2. Fracture toughness shows its the highest value at the condition that the difference between 1st and 2nd double soulution treatment is 100 degree. 3. Fracture toughness of Ti-6Al-4V alloy is affected by the morphology of acicular α phase, such that, when acicular α phase is arranged with block unit, fracture toughness is increased.

InP/InGaAs HPT's 제작을 위한 ITO/n^+-InP 옴 접촉 특성연구

황용한,한교용 영남대학교 공업기술연구소 2001 工業技術硏究所論文集 Vol.29 No.1

The use of a thin film of indium between the ITO and the n+-InP contact layers for InP/InGaAs HPTs was studied without degrading ifs excellent optical transmittance properties. ITO/n+-InP ohmic contact was successfully achieved and the specific contact resistance of about 6.6×10-4Ω㎠ was measured by use of the transmission line method (TLM), The DC characteristics of InP/InGaAs HPTs with ITO emitter contacts was compared with that of InP/InGaAs HBTs with the opaque emitter contacts.

치과재료와 환경호르몬

김교한 대한치과기재학회 1998 대한치과재료학회지 Vol.25 No.3

치과 임플란트용 순 Ti의 접촉부식 거동

김교한,허만수,김형일,황운석,高田 雄京,奧野 攻 대한치과기재학회 1999 대한치과재료학회지 Vol.26 No.4

One of the fields in which titanium(Ti) is becoming increasingly valuable is the field of biomaterials. Ti had shown its good corrosion resistance, high strength to weight ratio, and compatibility with human tissues. Such applications of Ti in this area involve replacing stainless steel and cobalt-chromium alloy implant which are used in skull, shoulder joint, spine, and dental implant. In dental field, titanium has been used as dental implant, so it becomes necessary to examine and estimate the anti-corrosion ability of Ti and its alloys at the severe conditions such as crevice corrosion and galvanic corrosion. The purposes of this study was to examine the corrosion mechanisms of the pure Ti showing good corrosion resistance under an oral corrosion environment when it is coupled with dental casting Type Ⅱ and Type Ⅳ gold alloys. These coupling corrosion mechanisms were studied in three conditions. First was by measuring the resting potential of pure Ti, when it was uncoupled and coupled with Type Ⅱ and Type Ⅳ alloys. Second was by measuring anode polarization behavior of pure Ti, Type Ⅱ and Type Ⅳ alloys, and third was by detecting dissolved ions from the pure Ti, uncoupled and coupled with Type Ⅱ and Type Ⅳ gold alloys which were immersed in 0.9% NaCl solution for 7 days. The resting potential showed a low potential value at the initial stage but increasing into a high value (to 0.18 V) with time elapse and reached a stable value. On the contrary, the potentials of Type Ⅱ and Type Ⅳ gold alloys were in their values at the initial stage of immersion, then decreased with the time and reached stable values, being higher than the value of pure Ti. When pure Ti coupled with Type Ⅱ and Type Ⅳ gold alloys, the resting potential of coupled one was between the values of each one. When Type Ⅱ and Type Ⅳ gold alloys were coupled with pure Ti, there was an increase in Ag, Cu, and Zn. Also, Zn ions released the high potential precious metal alloys, compared to the uncoupled case. Ti ion was not detected at any cases of pure Ti or coupled with gold alloys. It was thought that one of the causes of the increase in Ag, Zn, and Cu ions when Ti was coupled with dental gold alloys was that Ag, Zn, and Cu ions were selectively dissoluted from the Ag rich regions around grain boundary and the casting defects. In conclusions, the results of this study suggest that the pure Ti was very stable when coupled with the gold alloys in oral cavity.

요추간판탈출증에서 현미경 수술과 경피적 자동수핵제거술에 대한 비교연구

신원한,장재칠,주교성,김범태,최순관,변박장 순천향의학연구소 1997 Journal of Soonchunhyang Medical Science Vol.3 No.1

A retrospective study of operative results were carried out in a series of 164 patients who were performed microdiscectomy and 57 patients performed automated percutaneous lumbar discectomy (APLD) for herniated lumbar discs between January 1, 1990 and June 30, 1996 at the Department of Neurosurgery, Soonchunhyang University Hospital. The operative results were analysed, and the correlation between preoperative clinicoradiological factors and postoperative clinical results were statistically assessed. The major results were as follows : 1. Of 164 microdiscectomy cases, 102 were males and 62 were females, mean age was 42.4 years and incidence was the highest in the 5th decade, and of 57 APLD cases, 43 were male and 14 female, mean age was 32.2 years and incidence was the highest in the 3rd decade. 2. The preoperative symptoms and signs were lumbago(98.2%), radiating pain(96.3%), positive straight leg raising test(77.4%), motor weakness(27.4%), claudication(13.4%) & voiding difficulty(2.4%) in microdiscectomy cases, and lumbago(98.2%), radiating pain(98.2%), positive straight leg raising test(70.2%) & motor weakness(17.5%) in APLD cases. 3. Number of operated levels were performed 226 in microdiscectomy and 74 in APLD. The most commonly operated levels of two groups were L4-5 level. 4. Operative results 1) The overall success rates by Prolo's scale were 87.1% in microdiscectomy and 80.7% in APLD, respectively. 2) In younger age group (below 30 years) and in non-compensatory group, success rates were significantly higher in microdiscectomy. 3) As to protrusion and degeneration on MRI, clinical results of moderate protrusion and degeneration of discs in microdiscectomy were statistically significant, and those of mild protrusion and degeneration of discs in APLD were also statistically significant. 4) The most common cause of failure was inappropriate removal of disc material in microdiscectomy and sequestered discs in APLD. According to the above results, there were no differance in overall success rates between microdiscectomy and APLD. But clinical results seem to be influenced by the age, existence of compensation, and by the degree of protrusion and degeneration of discs as prognostic factors. If the selection of operative procedure between microdiscectomy and APLD for herniated lumbar disc is carefully done with clinical and radiologic findings of patients, good outcome might be achieved.

Sandblast 처리한 상아질면의 접착에 관한 연구

김교한,나환욱,황성욱 대한치과기재학회 1997 대한치과재료학회지 Vol.24 No.1

Dentin adhesion was studied on sandblasted dentin with 4-META/MMA-TBB resin. The effect of change of air pressure, with or without pretreatment and primer on tensile bond strength, was mainly investigated. In the effect of air pressure at sandblast treatment, the higher pressure showed the increase of tensile bond strength. The pretreatment with 10-3 sloution after sandblast treatment increased tensile bond strength in the almost conditions. Application of primer also increased the tensile bond strength, confirmed the effect of primer application after sandblast treatment. Alumina particle was not found on the dentin surface in the SEM and EDAX examination.

국산화 개발한 치과용 저금합금의 시효경화 거동

김교한,권오원,김형일 대한치과기재학회 1997 대한치과재료학회지 Vol.24 No.1

To define the optimum heat treatment temperature and time of the developed three types of low karat gold alloys, hardness test, DTA and x-ray diffraction methods were used. The results were as follows. *The optimum temperature of heat treatment was at 400℃ in K-Ⅰ, K-Ⅱ and K-Ⅲ alloys. *The proper time of age-hardening was 10 minute in K-Ⅰ alloy, and 10-30-minutes in K-Ⅱ alloys. *The stable phases of three types of low karat gold alloys were Ag-rich α₁ phase, Cu-rich α₂ phase and AuCuⅠ phase in case of K-Ⅰ alloy, and α1 phase and AuCuⅠ phase were coexisted in K-Ⅱ and K-Ⅲ alloy. *The cause of the decrease of hardness by overageing was the α₁ phase and AuCu Ⅰ phase, which were precipitated in the grain boundary.

急性間歇性 Porphyria의 5例報告

白漢基,金成七,金光一,宣汪周,申舜鉉,金敎命 한림대학교의료원 1977 人間科學 Vol.1 No.3

쵸퍼시스템의 傳達特性에 관한 硏究

任漢錫,金洛敎 건국대학교 부설 산업기술연구소 1982 논문집 Vol.7 No.-

Chopper system has been recently employed in variable-speed DC motor drives by the manner in which the average load voltage is reduced below that of the source. The output current can be continuous or discontinuous during the operation period. When the load current becomes discontinuous, the output gain is greatly reduced and this would result in sluggish response and poor accuracy at light loads. Hence, in this paper, the transfer characteristics of a chopper system is to be investigated and the method is studied to compensate the reduction of gain.