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모웅남,이용준 조선대학교 구강생물학연구소 2003 口腔生物學硏究 Vol.27 No.1
Dental magnetic attachment have been applied to removable prosthetic appliances, maxillofacial prostheses, obturator and dental implant but they still have some problems such as low corrosion resistance in oral environments. To increase the corrosion resistance of dental magnetic materials, Nd-Fe-B materials were sealed with stainless steel, but pitting corrosion, intergranular corrosion and erosion corrosion occurred predominantly at welded zone and center of magnetic attachment in corrosive environment and mechenical wear condition. In order to develop corrosion resistance of magnetic materials, the surface modification of stainless steel for magnetic attachment sealing materials were investigated by utilizing potentiostat. Stainless steels containig 0.1~1.0 wt%Ti were fabricated with 12㎜ thickness by using vacuum furnace and roller. An then stainless steel were solutionized for 1hr at 1050℃. Samples were ion nitrided at 380℃ and 500℃ for 10, 20, and 30hrs. Electrochemical corrosion test were performed in 2 kinds of electrolyte solutions (0.9% NaCl, and 0.1MH_2S0. The surface and corrosion morphology of ion nitrided stainless steel were analyzed by utilizing optical microscopy SEM, XRD and WDX. It was found that Plasma nitriding at 380℃ compared with 500℃, Produced a good corrosion resistance as nitriding time increased. whereas stainless steel containing low Ti content showed that Pitting potential and corrosion potential decreased. Pitting corrosion resistance improved significantly in the case of plasma nitrided SS containing 100.0wt% Ti at 500℃ because that Ti act to retard the formation of carbides and to form a protective layer on surface which is responsible for the aggresive Clion. The nucleation rate and number of pit in the plasma nitriding at 500℃ decreased as Ti content increased owing to retard a nucleation and growth of chromium carbide or nitride in gram boundary.
배태웅,文炳周,辛元敎,宋模烈,李鉉旭,曺東進 東亞大學校生命資源科學大學附設 農業資原硏究所 1996 農業生命資援硏究 Vol.5 No.1
팽이 재배에 있어 가장 큰 문제 중의 하나는 雜菌에 대한 汚染, 특히 細菌에 의한 피해가 극심하므로 作業段階와 栽培過程 전반에 걸쳐 培地徵生物相의 經時的인 密度變化에 따른 雜菌의 培地內 流入時期를 조사하여 汚染菌의 發生消長을 알아보기 위해 現地農家에서 시험해 본 결과 接種후 培養室에서 菌絲培養을 시작한 5일후부터 細菌이 檢出되기 시작하여 菌긁기전까지 약 25일간 0.5∼3.1×10⁴cfu/g의 密度를 보였으나 經時的인 密度增加는 없었고, 菌絲培養이 끝난 뒤 菌긁기직후부터 細菌의 密度는 118.3×10⁴cfu/g으로 급격히 높아졌으며 子實體生育 기간동안에 시간이 경과함에 따라 密度가 현저하게 증가되는 경향을 나타냈다. 이는 培養室 안으로 흐르는 空氣를 통하여 甁內로 細菌이 流入되고 또한 菌긁기 직후 培地表面에 灌注하는 물과 加濕機에서 噴霧되는 물粒子가 細菌의 密度增加에 절대적으로 영향을 미치는 것으로 판단되므로 이때가 細菌性褐斑病菌에 感染되기 가장 용이한 시기로 생각된다. 眞菌은 菌긁기후 子實體生育 기간동안 1.17∼7.87×10⁴/g의 密度로서 菌絲培養 기간동안의 密度보다 다소 높게 檢出되었으나 대체로 經時的인 密度增加는 보이지 않았으며, 放線菌은 거의 검출되지 않거나 菌絲培養 후 5일째부터 다소 검출되기 시작했으나 밀도가 매우 낮았고 經時的으로도 증가되지 않았다. One of the most serious problem on the Enoki mushroom cultivation is the infection by pathogenicitic microorganisns, especially bacterial diseases causing serious economical losses in the mushroom production. It was carried out to find the tendency of the development of mushroom diseases by temporal changes and variation of the densities of media microflora through the cultivation periods and working stages in a mushroom farm. According to the results, several bacteria were detected from the fifth day after the inoculation and incubation of mycelium in the incubation room, and the density of bacterium was 0.5∼3.1×10⁴cfu/g media for 25 days before the inoculum-removing, although there was no increment of the density. Since the inoculum-removing after the spawn run, the density of bacterium was rapidly increased as 118.3×10⁴cfu/g media, and was significantly increased by time during the growth period of fruitbodies. It was hypothesized that it is the most suitable period for the pathogen infection because the bacterium might be introduced by the air in the incubation-room, and the increment of bacterium density might be affected by moisture supplied through watering or humidifier in the growing room after the inoculum-removing. Fungi were detected as the density as 1.17∼7.87×10⁴/g media and the density was slightly higher than that during the incubation period of hyphae, although there was no significant increment. Generally, the density of Actinomycetes was disregardfully low, or Actinomycetes were hardly ever found, although there was found some 5 days after incubation hyphae in few cases.
키토산을 첨가한 콤포짓트 레진의 기계적 성질과 항균성에 관한 연구
최낙찬,모웅남,이용준 조선대학교 구강생물학연구소 2003 口腔生物學硏究 Vol.27 No.1
The purpose of this study was to evaluate the mechanical and anti-microbial properties of newly prepared chitosan G for human gingival fibroblast. Compressive strength, diametral tensile strength and tensile strength of specimens of resin composite, with or without chitosan G incorporated, were measured. Using a SEM (S-4700, Hitach, Japan), pictures of microbes were taken and adherent capability of microbes to the surface of resin composite was investigated. The results were as follows; 1. The values of compressive strength, diametral tensile strength and tensile strength, composite resin containing 7㎎/㎖ chitosan G were higher than the control group(p>0.05) but composite resin containing 40 ㎎/㎖ chitosan G were either the same or lower than the control group(P<0.05) 2. The MIC of newly prepared chitosan G for S mutans KCTC 3065 and C albicans KCTC 7965 were more than 2 ㎎/㎖. 3. The adherent capability of microbes significantly decreased as the amount of chitosan G increased in the test specimens compared to the control group for C aibicans KCTC 7965 (P<0.05) but there was no statistical significance for S mutans KCTC 3065(p>0.05) . 4. The cytotoxicity of newly prepared chitosan G for human gingival fibroblast was not showed. In conclusion, resin composite with chitosan G incorporated did not show any statistically significant difference for mechanical properties (p>0.05) but it showed a significant antimicrobial effect against C albicans (P<0.05).
최과 교정용 스테인리스 강 선재의 신선 가공법이 내식성에 미치는 영향
고영무,모웅남,최한철 大韓齒科器材學會 2003 대한치과재료학회지 Vol.30 No.1
The dental orthodontic wire requires good mechanical properties, such as elastic strength, combined with a high resistance to corrosion. For increasing elastic strength and delaying onset of stress corrosion cracking, drawing methods(one-step and two-step drawing) have been used in this study to extend service life of metal components, However, there is no information on the electrochemical corrosion behavior of drawn wires for orthodontics. To increase elastic strength, good corrosion resistance, and biocompatibility, the electrochemical characteristics of drawn wire have been researched by field emission scanning microscope and potentiodynamic method in 0.9% NaCl solution. The one-step drawn wire showed the formation of rough surface. The hardness and tensile strength of two-step drawn wire increased. Electrochemical measurements showed that, in the case of two-step drawn wire, the corrosion resistance and pitting potential increased compared with two-step drawn wire due to the drawing induced small surface roughness, such as scratch, whereas passivation and active current density decreased as the reduction in area for drawing increased.
최한철,고영무,모웅남 大韓齒科器材學會 2003 대한치과재료학회지 Vol.30 No.3
The first factor to decide the success of dental implantation is sufficient, osseointegration between implant fixture and its surrounding bone tissue. Thus many studies about this have been under actively. In recent, one of them is to increase the roughness of the surface of an implant fixture by treating the surface of an implant fixture in various ways, increase the contact area between an implant fixture and its surrounding bone tissue and so induce a sufficient osseointegration between them. The roughness of the surface on an implant fixture can be increased by coating the smooth surface of an implant fixture with hydroxyapatite or titanium particles or by treating the surface with acid. But these ways can cause the failure of implantation in the long run due to the separatation of coated particles from an implant fixture and sometime; can't attain the sufficient osseointegration because of emitting ion into the surrounding bone tissue. To develop dental implant materials, fabrication and physical properties of sintered stainless steel have studied using hardness tester, tensile tester, SEM, TEM, EPMA, EDX. Stainless steel compacts containing Cu (2-10 wt%) were prepared either by electroless Cu-plating method which result in the increased homogenization in alloying powder or by Cu-elemental powder addition method on the stainless steel powder Experimental investigation foucusing on mechanical property was performed for Cu-added samples to study the effects of Cu content, electroless Cu-plating method, and Cu-elemental powder addition method on the surface characteristics of sintered stainless steel in Mo and Cu in sintered stainless steel on the mechanical behaviors. Microstructural characterization revealed that Cu-addition by electroless Cu-plating method resulted in less porous material compared that prepared by Cu-elemental powder addition method. Since Cu is blown to be effective in reducing the precipitation of chromium carbide at sensitization temperature, Cr concentration in electroless Cu-plating method was uniformly distributed in the grain boundary and in the matrix. The sintered density in electroless Cu-plating method increased with reducing porosity as a result of the Cu-uniform distribution due to electroless Cu plating during the sintering process. The amount of Cu added in the sintered stainless steel affected significantly tensile strength which increased with 4 wt% Cu and decreased with more than 7 wt% Cu.