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.

TiN Ion-Plating이 교정용 브라켓의 접착강도에 미치는 영향

김석용,권오원,김교한 대한치과교정학회 1997 대한치과교정학회지 Vol.27 No.1

TiN ion-plating이 교정용 브라켓의 접착강도에 미치는 영향을 알아보기 위하여 세 종류의 서로 다른 기저면형태를 가지는 스테인레스 스틸제의 브라켓을 선택하고, TiN ion-plating 된 브라켓과 ion-plating 되지 않은 브라켓을 치아에 접착시켰을 때 초기 및 장기접착강도, 접착계면의 주사전자현미경 관찰, 파단면의 주사전자현미경 관찰을 비교 분석하여 다음과 같은 결론을 얻었다. · TiN ion-plating을 하지 않은 경우 24시간 후의 접착강도는 Micro-Loc형이 5.89±1.77MPa, Foil Mesh형이 4.27±1.12MPa, Undercut형이 2.64±0.58MPa로 Micro-Loc형이 가장 높았고, 그 다음이 Foil Mesh형 그리고 Undercut형의 순으로 나타났다(P<0.05). · TiN ion-plating시 24시간 후의 접착강도는 Micro-Loc형이 6.26±1.51 MPa, Foil Mesh형이 7.45±2.01MPa, Undercut형이 2.93±0.84MPa로 ion-plating 하지 않은 경우와 달리 Foil Mesh형이 Micro-Loc형보다 오히려 높게 나타났고, Undercut형이 역시 가장 낮은 접착강도를 나타내었다(P<0.05). Ion-plating 유무에 따른 24시간 후의 접착강도는 3가지형 모두에서 ion-plating시 증가하였으나 Foil Mesh형에서만 유의한 증가가 있었다(P<0.001). · 장기침적시 ion-plating의 유무에 관계없이 전반적으로 초기(1일)접착강도보다 증가하였으며 접착력의 안정성을 나타내었다. · 접착계면의 주사전자현미경 관찰 결과 브라켓 기저면의 형태나 ion-plating 유무에 관계 없이 레진이 브라켓 기저면으로 잘 퍼져 들어가 브라켓과 치아와의 사이에 견고한 접착면을 나타내었고, 장기침적의 경우도 같은 양상을 나타내었다. · 파단면의 주사전자현미경 관찰에서는 다양한 파괴양상이 나타났다. This study was conducted to see the effect of TiN ion-plating on the bond strength of orthodontic bracket. Three stainless-steel brackets with different base types were chosen; when TiN ion-plated brackets and non ion-plated brackets were bonded to the teeth, initial and long-term bond strength were measures. The observations of bonding surface and failure sites through the scanning electron microscope were analysed and compared. The summary of this study was as follows: · When TiN ion-plating was not applied, the Micro-Loc type was the highest in bond strength after 24 hours as 5.89±1.77MPa, followed by 4.27±1.12MPa for Foil Mesh type and 2.64±0.58MPa for Undercut type(P<0.05). ·Under TiN ion-plating, the bond strength after 24 hours showed: Micro-Loc type 6.26±1.51MPa, Foil Mesh type 7.46±2.01MPa, Undercut type 2.93±0.84MPa. Unlike in the case of non ion-plating, Foil Mesh type showed a higher strength than Micro-Loc type, with Undercut type still showing the lowest bond strength(P<0.05). The bond strength, after 24 hours, increased in case of ion-plated in all 3 types, but a significant increase was shown only in Foil Mesh type(P<0.001). · Under a long-term immersion, regardless of ion or non ion-plating, bond strength in general increased over the initial bond strength(one day), with more stability. · Through scanning electron microscopic observation of bonding surface, it was found that, regardless of the bracket base type or the application of ion-plating, the resin was thoroughly spreaded into bracket base to form a solid bonding surface between the bracket and the tooth. This was also true in case of a long-term immersion. · The scanning electron microscopic observation of failure sites revealed diverse failure patterns.

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

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.

수술의 함정 : 중심성 신경세포종 2례 2 Cases of Central Neurocytoma

김범태,주교성,장채칠,신원한,최순관,변박장 대한신경외과학회 1999 Journal of Korean neurosurgical society Vol.28 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.

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.

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.

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.

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.