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김광만,김경남 대한치과기재학회 1996 대한치과재료학회지 Vol.23 No.2
Two types of dental ceramics for metal-ceramic system(CeramcoⅡ, VMK 68) and one type of dental ceramic for all-ceramic system(Empress) were choosed and all were A2 shade. Specimens were made by manufacturer's instruction and divided by 3 experimental groups that mechanical polished using Sofu porcelain kit(Polish), furnace glazed using porcelain furnace(Glaze) and laser glazed using CO₂laser(Laser). Controls were roughened by #100 sandpaper. The color changes were measured L*, a*, b*, according to CIELab system by spectrophotometer (Minolta 3500D, Japan) and surface roughness were measured Ra and Rz by surface troughness tester(Surfrecord, Kosaka, Japan). The results were as follows: 1. Only all-ceramic systems (Empress)were glazed by laser but metal-ceramics systems (Ceramco Ⅱ and VMK 68) were cracked by laser. 2. All experimental groups had lower L* value and higher b* value but had no significant difference in a* value compared with control(p<0.05). 3. All-ceramic systems(Empress)had highest L* value and b* value but lowest a* value compared with other systems in all treatment groups(p<0.05). 4. The surface roughness of control were highest in all treatment groups and Empress were lowest in all products(P<0.05). Dental all-ceramic systems had a possibility to laser glazing and L* values were decreased and b* values were increased in polishing, glazing and laser glazing group.
Na+/K+, Na+/Rb+ 이온교환에 의한 치과용 도재의 강화
김광만,김경남 대한치과기재학회 1996 대한치과재료학회지 Vol.23 No.1
The purpose of this study was to determine the effects of strengthening by sodium/potassium, sodium/rubidium ion exchange because of rubidium ion was larger than potassium ion, and potassium ion was larger than sodium ion in same element group(alkali metal group). Ceramic block specimens(5×1×20mm) were made and glazed by manufacturer's instructions in three products(Ceradent, Korea, Ceramco Ⅱ, U.S.A., VMK 68,Germany). They were treated ion exchange with molten potassium nitrate salt(K), rubidium nitrate salt(Rb) and combined(K?? : Rb??=1:1) (K+Rb) at 450℃ for 4 hours and no treatment specimens were Control. Three point flexural strength measured by universal testing machine(Instron) with cross head speed of 0.25mm/min. 1. Ceradent was highest flexural strength in control group(p<0.01). 2. Flexural strength of Ceramco Ⅱ were increased in all ion exchanged groups compared with control(p<0.05). 3. RbNO₃groups were more effective in Ceradent and VMK 68(a<0.05). Ion exchange using rubidium nitrate was the more effective treatment for strengthening of Ceradent and VMK 68(a<0.05).
허만,김광수,이갑수,윤영득 서울대학교 국제지역원 1995 국제지역연구 Vol.4 No.1
최근의 세계경제흐름은 세계화와 지여화라는 두 가지 특징적인 양상을 보이고 있다. 오랜 기간 동안 끌어오던 우루과이협상의 타결과 세계무역기구 설립의 합의로 다자간 자유무역주의에 의한 무국경 경제시대가 도래한 반면, 다른 한편에서는 지역통합에 의한 세계시장의 분할이 활발하게 이루어지고 있다. EU는 세계경제의 지역화를 다른 어느 지역보다 더 가속화시키고 있다. EU는 지난 1987에 발효된 유럽단일의정서에 입각하여 1993년에 시장통합을 완성하였고 마스트리히트 조약의 체결로 공동시장의 단계를 넘어 경제동맹으로 진입하여 재정, 금융, 통화정책의 조화를 추구하는 단계로까지 발전하고 있다 따라서 본 연구에서는 EU통합의 심화과정을 살펴보고 그 과정에서 추진되고 있는 통상 및 산업정책으 방향이 어떠할지를 포괄적으로 살펴보는 데 그 목적을 두고 있다. 이러한 목적하에 본 논문에서는 우선 경제통합과는 동전의 양면과 같은 성격을 지니고 있으며 EU의 장기적인 추진목표가 되는 정치적 통합가능성을 그 역사적 발전배경을 통해 살펴보고 있다. 유럽연합의 통합운동은 신기능주의적 진보라고 할 수 있는 장기간의 과정을 거쳐 진행되어 왔고, 재정, 금융 및 통상정책의 통일과 조화에 주안점을 두고 왔으나 이것이 회원국 같은 정치적 협력에도 크게 기여한 것은 사실이다. 특히 마스트리히트 조약을 통한 통화통합 합의로 통합운동이 연방주의적 방향으로 선회하고 있으며 이 방향은 EU의 정치적 통합가능성을 한층 가속화시킬 것으로 전망된다. 통상정책에 있어서는 그 기조가 더욱 자유화의 경향으로 나갈 것인지 아니면 더욱더 보호주의적인 양상을 보일 것이가에 관심이 두어지고 있다. 마스트리히트 조약으로 통상정책결정이 중앙집권적 경향을 띠게 될 것으로 보이지만 EEA조약의 발효로 유럽연합의 무역정책이 더욱 유럽지향적이 되어 역외차별주의가 강화죌 우려가 있다. 따라서 유럽연합의 통상정책 기조는 자유무역을 표방하지만 세계적 차원에서의 무차별 주의 원칙이 이루어지지 못하는 블록지향적 성격은 고수될 것으로 보인다. 유럽연합의 산업정책은 그 일차적 목적을 역내국 사업의 지역네트워크를 강화하여 내생적인 시장의 힘을 자극하기 위해 계속적인 구조조정을 물리적으로 촉발하는데 두고 있다. 그 정책적 접근은 종전의 산업간 구조적 불균형을 보상하기 위한 정부의 보조금지불제도를 폐기하고 상호인정의 원칙과 제도적 조화의 원칙과 보충성의 원칙에 기반을 둔 공동산업정책을 통해 지역, 산업, 기업 간의 경쟁환경을 조성하고 동시에 관련당사자간의 협력을 조장함으로써 세계적 차원에서의 경쟁력을 강화하는 방향으로 나아가고 있다. 유럽의 시장통합은 실질적으로 유럽의 산업과 기업에게 가장 큰 영향을 미치고 있으며 기업에게 기회도 제공하지만 동시에 위협이 되기도 하는 하나의 도전이 되고 있다. 그 영향에는 소속된 산업과 추구하는 전략 및 국제화 정도 등에 따라 차이가 나며, 유형별로는 비교적 규모가 큰 중견기업과 유럽지역에 이미 초국가적으로 활동하느 ㄴ기업들이 가장 큰 영향을 받는 것으로 나타났다. 전체적으로는 기업들이 시장단일화를 통한 경쟁심화에 긍정적인 반응을 보이고 있으며 주로 합리화와 주력사업의 전문화등을 통한 구조재조정과 생산성 향상에의 노력, 기존시장의 확보 및 신시장 개척 그리고 인수·합병 및 전략적 제휴 등을 통한 역내 및 역외간의 협력강화 등을 통해 변화된 시장환경에 보다 적극적이고 능동적인 대응책을 마련하고 있다. There have appeared two characteristics in the recent world economic trend: one is globalization and the other regionalization. With the Urguay Round resolved and the World Trade Organization established, multilateral free trade without national frontiers has come into existence, while a division of the world market by regional integration has also been in full process. The EU seems to more accelerate the regionalization trend of the world economy than any other region. The EU completed market integration in 1993 by the Single European Act. And going beyond the Common Market level, it is entering a new phase seeking harmonization in public finance, monetary and financial policies. Therefore, this paper is to study the process of deepening of the EU's integration and to review what its trade and industrial policies would be like. First, from the above point of view, this paper is to study a possibility of political integration, a long term objective of the EU that is closely connected with the economic integration. The integration movement of the EU, which can be termed as a neofunctionalism, has taken place over the long period of time, focussing on the unification and harmonization in public finance, monetary and financial policies, and trade and industrial policies. As a matter of fact, this process gad considerably increased political cooperation. In particular, due to the currency integration through the Maastricht Treaty, the integration movement gas been directed to the federal approach. This approach is expected to intensify the possibility of the EU's political integration. In regard of trade policy, its study focussed on whether the EU's policy will be directed more toward free trade or protectionism. Trade policy will be more centralized through the Maastricht Treaty, While due to the effectuation of the EEA treaty, it will be gradually more European, thus strengthening probably discriminatory practices toward non-European regions. Therefore the EU's basic trade policy will push forward with free trade on the one hand, but it will tilt to block-oriented tendency on the other hand. EU's industrial policy is based on the principles of reciprocal recognition and of institutional harmonization together with the application of the principle of subsidiarity. It aimes to strengthen competitive power of EU industries at the global level by fostering competition envirnment among regions, industries, and enterprises and by fostering the cooperation among relevant parties. The EU is fucussing its energy on strengthening of industrial regional network of member states and thus restructuring its industries to stimulate the indogeneous power of market. As a matter of fact, the integration of EU's market has made a great contribution to the European industries and its enterprises. The contribution varies according to industry, strategy, and degree of globalization. Looking closely into their typology, medium-sized and big-sized enterprises operating supranationally in Europe are most affected. In general, most of enterprises are positive in the deepening of competion through the integration of markets and are ready to more dynamically develop markets and to prepare acrive countermeasures by seeking new markets and at the same gime by merger and undertakings of enterprises.
김광만,김경남,이상배 대한치과기재학회 1997 대한치과재료학회지 Vol.24 No.1
Dental composite resins have many advantages but still have problems like low strength, hardness and poor color stabilities. Many studies related to color changes have been carried out but there is nothing about color changes by Korean foods and drugs. To evaluate the color changes caused by Kimchi and herb medicines, Aelitefil(Bisco Co., U.S.A.), Veridonfil(Hyosung T&C Co.,Korea), Z-100(3M Co., U.S.A.) and experimentally manufactured materials were chosen and all materials were A2 shade. The specimens(8mm dia., 2mm thickness) were made according to manufacturer's instructions and colors were measured by spectrophotometer(CD35000D, Minolta, Japan) according to CIEL*a*b* system. Then the specimens were immersed in Kimchi and herb medicines at 23℃, dark room and were measured color after 24, 48, 72hours and 7days. The color changes(ΔE) were calulated using ΔE={(ΔL*)²+(Δa*)²+(Δb*)}% equation and statistically tested by Duncans Multiple Range Test, Wilcoxon Test, Kruskal Wallis and Mann Whitney usage test. The results were as follows : 1. The color changes by Kimchi were greater than by herb medicines(P<0.05). 2. L* values decreased and a*, b* values increased by immersion in Kimchi(P<0.05). 3. There were no relationship of changes of L*, a*, b* values in case of treatment immersed in herb medicines. 4. The color changes of Z-11 were greatest among tested materials and those of Aelitefil were least. It was concluded that special considerations were needed to use in oral cavity and to manufacture the new composite resins because it was easily changed by Kimchi.
김광만,이종석,김경남,신상완 대한치과기재학회 1998 대한치과재료학회지 Vol.25 No.2
Dental impression materials are necessary for prosthodontic treatment and should have some desirable properties that easy to use, reprocuctibility to oral tissue, dimensional stability and compatibility to gypsum materials and additional silicone impression materials are used mostly. All materials have dimensional chage by thermal changes. So, impression materials shrink during cooling from oral temperature(37℃) to room temperature(23℃). 5 kinds of light body of addition silicone materials(imprint Ⅱ(IM), 3M Co., USA; Examix(EM), GC Co., Japan; Extrude(EX), Kerr Co., USA; Contrast(CT), Voco Co., Germany; Perfect(PF), Hankook JP, Korea) were chosen and the cylinderical specimens(6㎜ dia, 12㎜ height) were made and thermal expansion were measured by thermomechanical analyzer(TMA 2940. TA Instrument. U.S.A.) between 23℃ and 37℃. The data were analyzed by Mann Whitney U-Test. The results were as follows : 1. Thermal expansions of impression materials were increased in order to CT>PF≥EM>EX≥IM(p<0.05). 2. Anterior area had more dimensional change than posterior area in same impression materials. 3. Dimensional changes were more than 40㎛ at anterior area but less than 40㎛ at posterior area in all impression materials. In conclusion, thermal expansions of impression materials were significantly different from each other(p<0.05), and anterior area had more dimensional change than posterior area in same impression materials.
인산염계 실리카 매몰재의 성분변화에 따른 티타늄의 주조특성
김광만,은진원,이상배,김경남 대한치과기재학회 1999 대한치과재료학회지 Vol.26 No.2
A large increase in the use of titanium in density is driven by the desire to take advantage of titanium's excellent biocompatibility and its high resistance to corrosion. The development of investments suitable for titanium castings is critical because their mechanical properties are greatly affected by the surface-reacted layer. The purposes of this study were to evaluate the characteristics of Titanium Vest Ⅱ(CO) and experimentally produced four phosphate- bonded SiO₂ investments(EA, EB, EC, ED). A great deal of attention was focused on the influence of investments, such as setting time, compressive strength, casting compatibility, casting defects, surface microhardness and interfacial zone of the cast titanium. The following results were obtained; 1. The setting time of all experimental groups were significantly shorter than control group(p<0.05). 2. Experimental groups were significantly greater than control group in compressive strength of 1hr and 2wks(p<0.05) and there was no significant difference among the experimental groups(->0.05). Compressive strength after 2wks was significantly greater than 1hr in all tested groups(p<0.05). 3. EA was showed the highest casting compatibility and CO the lowest. 4. There was no fin in the casting of all groups. There were small porosities in a dental x-ray inspection of EA. 5. CO was showed the highest microhardness at the distance of 50 ㎛ from the surface. 6. The interfacial zone was composed of four layers in all groups. There was irregular and thick layer in CO. According to these results, titanium is castable with experimentally produced phosphate-bonded SiO₂investments. In addition, there is room for further investigation of investment materials to improve the precise casting of titanium.
김광만,김경남 대한치과기재학회 1999 대한치과재료학회지 Vol.26 No.3
The molding technique of dental ceramics are very important. Because dental ceramics are purchased with powder state, they must be mixed with adhesive liquids or water for plasticized materials. The procedures to mix with liquids, condense and build up were very careful and mechanical properties of dental ceramics were closely related with them. If it will be possible to use of light curing liquids, molding procedures will be easier than using water. To evaluate the physical properties of dental ceramics using light curing molding liquids, light curing liquids were made with triethylene glycol dimethacrylate(balance), camphoroquinone(1%) and ethyldimethylaminobenzoate(1%) and one type of dental ceramics(Ceradent, Ssangyong Co., Taegu, Korea) was chosen(A3 dentin). The specimens were formed in mold(25×5×3㎜) using light curing liquid for experimental group(LC) and using distilled water for control group(CO). LC were light cured and air-fired for elimination of organic materials and CO were vacuum fired. Sintering shrinkage was measured by measuring microscope(Measuroscope Ⅱ, Nikon Co., Tokyo, Japan), 3-point flexural strength was measured by universal testing machine(Instron 6022, Instron Co., High Wycomb, U.K.), and color was measured according to CIEL*a*b* system by spectrophotometer(Minolta 3500D, Minolta Co., Osaka, Japan). The results were analyzed by Wilcoxon Rank Sum Test. Sintering shrinkage and flexural strength of LC lower than CO(p<0.5). But they were acceptable to standards of ISO specification : 6872. L*, a* values of LC had higher than those of CO(p<0.5), but b* value of LC had no significance compared with CO(p>0.5) and ΔE was 26.7. The application of light curing liquids for molding liquids of dental ceramics was considerable, especially core materials, because of color changes.
李基萬,李黃田,鄭吉生 건국대학교 1977 學術誌 Vol.21 No.2
A total of 1627 Korean cattle were studied to measure live weight, withers height, body length, chest girth, belly girth, carcass weight and to calculate correlation coefficients among traits studied as well as to make linear regression equation. Among traits studied, the highest correlation coefficient was the correlation of chest girth with carcass weight. At interval of 10cm of chest girth, every regression equation was calculated, and according to this equation estimated carcass weights were tabled. 1.All average values of traits studied over 3 year cattle, the male values were higher than the female one. The larger variation of belly girth in female will be due to the cause of pregnant cows. 2.The correlation of chest girth with carcass weight was the highest of all traits studied, except for the trait of live weight. The correlation coefficients of chest girth with carcass weights were r = 0.693, r = 0.806 in both sexes, respectively. 3.The linear regression equations of live weight, withers height, body length, chest girth, belly girth on carcass weight were calculated. 4.Instead of complicated formulae, the simple regression equations of chest girth on carcass weight were calculated at intervals of 10cm chest girth and estimated carcass weight was tabled.
분무 열분해에 의한 Ba1-xSrxFe12O19계 자성 미립자의 제조 및 특성 변화
김동현,김광만,김경남,최세영,심인보,이용근 大韓齒科器材學會 2004 대한치과재료학회지 Vol.31 No.1
Magnetic particles with alternating magnetic field are expected to be useful as thermoseeds in hyperthermic cancer treatment, since they can be targeted and confined to the cancer site. Hard magnetic ferrites such as barium ferrite and strontium ferrite are good candidates for thermoseeds of hyperthermia because of their great hysteresis loss. In order to verify the effect of Sr-substitution to Ba-site, synthesized Ba1-xSrxFe12O19 microspheres with various compositions through spray pyrolysis followed by sol synthesis using barium nitrate, strontium acetate and iron nitrate. Coercive force was increased with increasing substitution amount of Sr whereas magnetic saturation was almost constant. Spherical microspheres with average diameter of 11.7~17.0 ㎛ were produced by spray pyrolysis at 400~1000℃. The mean size was dependent on the pyrolysis temperature and flow rate of carrier gas. In order to obtain a single phase of SrFe12O19 crystal, the spray pyrolyzed spheres were undertaken subsequent heat-treatment above 1000℃. During the subsequent heat-treatment, however, spherical microspheres were agglomerated because of necking between particles. Further study has to be continued working on synthesis of pure SrFe12O19 crystal by means of improvement of pyrolysis temperature scheme and extend the heating period.
컴포머(Compomer)와 복합레진의 색조안정성에 대한 비교연구
김희재,김광만,김경남 대한치과기재학회 2000 대한치과재료학회지 Vol.27 No.4
Compomer materials have the advantages of glass-ionomer cements and similar physical properties of composite resins. But there were a few studies about the color stability of compomers. In this study, two commercial compomers, Dyract and F2000, and two composite resins, Estelite and Z100, were used. They were stored in 37℃ water bath for 1 week and in 60℃ water bath for another 1 week and then they were aged with 150k1x xenon lamp for 1 week and another 1 week. The original colors just after light cured as the control color were measured by a spectrophotometer according to the C.I.E. L*a*b* Systems, and the colors stored in 60℃ water bath for 1 week, the colors aged with xenon lamp for 1 week in dry and wet condition, the color aged with xenon lamp for 2 weeks in dry and wet condition, were measured by the same method and compared with the control color. The results were as follows. The □E values of dyract after water bath storage and xenon lamp aging were over 10, and the □E values of F2000 after xenon lamp aging were 3.3-6.35. and the □E values of Z100 after xenon lamp aging were 3.3-5.23, and there were not ? E values of Estelite over 3.3 When the thickness of specimen increased the L*, a*, b* values of all material except Dyract were significantly increased(P<0.05), and Compared with dry condition, the L* values were significantly reduced, and the b* values were significantly increased in wet condition(P<0.05). It was concluded that Dyract compomer was not acceptable for and esthetic restorative material in permanent teeth for the color changes were over 10, and F2000 compomer had the color stability similar to the Z100 composite resin.