배달 미니 게임 개발:"최고의 웨이터를 꿈꾸며"

김정훈,정한교,김영옥,김중곤,박정윤,윤진성,김경식 호서대학교 반도체제조장비국산화연구센터 2001 반도체장비학술심포지움 Vol.2001 No.-

본 미니 게임은 웨이터라는 직업을 모티브로 하여서 남녀노소 누구나 재미를 느낌과 동시에 기억력 향상시켜 주는 게임제작이라는 목적아래 제작되었다.본 논문에서는 이 게임의 제작과정을 기술하고자 한다.이 게임은 제3회 AGC(한국 아마추어 게임제작 공모전)에서 우수 작으로 선정되었다.

치과 주조용 저금합금의 개발에 관한 연구

김교한,김형일 대한치과기재학회 1996 대한치과재료학회지 Vol.23 No.2

The purpose of this study was to develop the dental casting low carat gold alloys based upon Au-Ag-Cu ternary alloy. Three types of low carat gold alloy containing 46, 55 and 66wt. % of gold, content respectively, which were balanced with total amount of Au plus Ag of 74wt. %, were melted and casted to evaluate the mechanical properties, corrosion resistance, melting range and cytotoxicity. The obtained results were summarized follows : ·In mechanical properties, the type K-Ⅱalloys, which was increased in the amount of Pt component, showed 115MPa of yield strength, 400MPa of ultimate tensile strength and 150 of vicker's hardness value and these values are higher than those of K-Ⅰ, K-Ⅲ alloy of 30% in yield strength, 50% in ultimate tensile strength and 10% in hardness value. ·Age hardening effect was confirmed in all three alloys. ·Melting ranges of these alloys were in the range of 910-1050℃ ·Higher corrosion resistance was confirmed in the potential range of oral cavith. ·The cytotoxicity of alloys was evaluated by the cell growth and morphologic changes, Each alloy showed normal growth rate and cellular morphology.

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.

전기화학법에 의해 형성된 Ti 양극산화피막의 특성

김태영,손원우,권태엽,강인규,김교한 大韓齒科器材學會 2002 대한치과재료학회지 Vol.29 No.3

The effects of electrolyte concentration and current density on the behaviour of volt-time curve of the anodizing, morphology, roughness, crystallinity and composition of the oxide layer were studied. Microstructural morphology, crystallinity, composition and surface roughness of oxide layer were analyzed by observed by scanning electron microscopy(SEM) and X-ray diffractometry(XRD), Energy-dispersive spectrometer(EDS), Electron Probe Micro Analyzer(EPMA)and roughness tester, respectively. The results of this study showed that the voltage incresed as the anodizing time increase. The growth of the oxide film developed a barrier layer to a pore-like layer with an increasing of current density, arising a spark discharge. On the morphology of anodic oxide layer the number and size of porosity was increased by increasing anodizing time at a constant concentration of electrolyte. The size of porosity and the roughness of the anodic oxide layer were increased by the increasing of concentration of electrolyte. The anodic oxide layer obtained in the conditions of this experiment was identified as anatase. The crystallinity of oxide layer was decreased by increasing the concentration of electrolyte at constant current density, and increased by the increasing current density at constant electrolyte concentration. In the EPMA analysis of anodic oxide layer, the concentration of phosphorous was increasing the electrolyte concentration and increasing the final voltage at constant electrolyte concentration, The ratio of O/Ti of the oxide layer obtained in this experiment was near 2 confirming this oxide layer was TiO₂

치과용 Au-Ag-Cu-Pd 합금의 시효경화특성

김형일,김영근,장명익,김교한 대한치과기재학회 1997 대한치과재료학회지 Vol.24 No.1

The relationship between the isothermal age-hardening behavior and the phase transformation process in a dental casting Au-Ag-Cu-Pd alloy was investigated by means of hardness test, X-ray diffraction study. 1. The isothermal age-hardening behavior in the 350∼450℃ temperature range showed a similar tendency in the changes. However, the initial hardening was faster and the maximum hardness was higher and the overaging with softening was slower on aging at the lower temperature. 2. By the isothermal aging at 350∼450℃, the metastable Ag-rica α₁’and AuCu Ⅰ’orderd phases were formed from the supersaturated α phase prior to the final formation of the equilibrium Ag-rich α₁’and AuCu Ⅰordered phases. 3. By aging at 450℃, the age-hardening was attributed to the lattice strains of the parent phases resulting from the transformation of the αphase resulting from the transformation to the metastable phases. The X-ray diffraction peaks of the αphase showed a distinct shift toward both the high and low diffraction angles during transformation.

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.

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.

치과주조용 저카라트 금합금의 시효경화

김형일,김종렬,안호경,장명익,설효정,김교한 대한치과기재학회 1997 대한치과재료학회지 Vol.24 No.2

The age-hardening behavior of a commercial dental casting low-carat gold alloy was investigated by means of differential thermal analysis, hardness test, optical microscopic observation and X-ray diffraction study. The following results were obtained. 1. By the isothermal aging of this alloy at 300∼400℃, the hardness increased markedly at the initial stage and continued to increased gradually for the time, and then decreased dractically after longer aging time. 2. The hardening was attributed to the formation of the metastable AuCu I' ordered phase from the α matrix. 3. The overaging with softening was attributed to the precipitation of the fine lamellar structure which was composed of the Ag-rich α1 and AuCu I ordered phases.

Ti표면의 전처리방법이 4-META/MMA-TBB 레진과의 접착강도에 미치는 영향

김교한,서세광 대한치과기재학회 1999 대한치과재료학회지 Vol.26 No.2

The present study investigated the effectiveness of several surface pretreatment methods on the bonding of Ti to adhesive resin. Commercially pure Ti and Ti-6Al-4V alloy were bonded by 4-META/MMA-TBB resin to stainless rods. Each specimen was polished with No. 1.000 sandpaper and then treated with various surface treatment methods, such as 50 ㎛ size of Al₂O₃particles sandblasting, tinplating, silicoating, combination of sandblasting and tinplating and combination of sandblasting and silicoating. The surface of pure Ti treated with sandblasting was roughened to irregular and retentive pattern and aluminum content on the treated surface was increased. The surface morphology treated with tinplating was similar to nontreated one and the surface composition showed almost no change. The surface morphology of silicoating groups was similar to the one of silicoated after sandblasting condition and in both group, carbon content was significantly increased. The surfaces morphology of tinplating was not changed at all. The surface observation results of commercially pure Ti and Ti-6Al-4V alloy specimens were similar, but Ti-6Ai-4V alloy specimens were similar, but Ti-6Al-4V alloy showed more amount of tin precipitations at tinplating groups. Average tensile bond strength of each group was ranged from 21.20 to 31.64 MPa. The tensile bond strength of each group did not show a difference at the 0.05 significance in one-way ANOVA test. Fracture mode of each specimens was almost resin cohesive fracture, and some adhesive fracture-like area was proved to be cohesive fracture in higher magnification. Thus, bonding strength of resin-Ti interface was stronger than that of 4-META/MMA-TBB resin itself.

Vital Bleaching이 법랑질 접착에 미치는 영향

김종해,권태엽,권용훈,김교한 大韓齒科器材學會 2003 대한치과재료학회지 Vol.30 No.4

The objective of this in vitro study was to evaluate the effect of bleaching on the composite to enamel bond and surface hardness change. Extracted human premolars were treated with 35% hydrogen peroxide (Sigma Chemical Co, USA) for 1hr/day at 0, 3, 6 and 9 day respectively. For the obsrvation of surface mophology alteration due to the treatment with hydogen peroxide, a SEM (S-4300, Hitachi, Japan) was used. The specimens were ground flat using serial SiC papers and ground ultra-finely using a 0.1㎛ diamond compound paste. To measure the microhardness, five non-carious premolars were ground using SiC papers and ten indentations were made on the surfacd with Vickers hardness tester (FM-7 FUTURE-TEC Inc., Japan). To evaluate shear bond strength, composite was bonded with One Up Bond-F, Prompt L-Pop, AQ Bond to the non-bleached and bleached enamel surface of sixty non-carious premolars. The bonding procedure is postponed for 1 week after bleaching and shear bond strength was measured. All specimens with a SEM. Bleaching created some enamel porosity but the teeth showed nonsignificant morphological chonge as bleaching time increased from SEM analysis. Most microhardness change occured on the first day of bleaching. Bleaching with 35% hydrogen peroxide did not result in significant change in the shear bond strength of composite resin to enamel. In the shear bond strength test, the fractured surfaces of specimens showed mixed adhesive and cohesive failure behavior.