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자일리톨, 후노란, 제2인산칼슘 및 카제인포스포펩타이드배합껌이 법랑질의 광질재침착에 미치는 영향에 관한 실용실험연구
이병진,배광학,박우철,양준영,황수정,노정,백대일,김종배 대한구강보건학회 2003 大韓口腔保健學會誌 Vol.27 No.4
The object of this study was to investigate caries preventive effect of chewing gum containing xylitol, funoran, calcium hydrogen phosphate and casein phosphopeptide by examining Vickers' hardness and surface roughness with confocal laser microscope. Early caries-like lesions were created using 0.1 M lactic acid-sodium hydroxide buffer(pH 4.0). 8 pieces of 3am diameter bovine enamel specimen with early caries-like lesions were mounted into the recesses of lingual surface of the acrylic mandibular removable appliance. 13 subjects were the appliance for daytime and chewed control and experimental gums 7 times in a day, for 3 days. In order to evaluate the remineralization effect of chewing gum on specimens, we measured vickers' hardness number after chewing gum, 1 day, 2 days, 3 days after and calculated surface roughness immediately after chewing gum. Vickers' hardness number of experimental chewing gum was significantly higher than control in 2 and 3 days after. Surface roughness of experimental chewing gum was significantly lower than control immediately after chewing gum. These results showed that experimental gum has more effective in remineralization of bovine tooth enamel, and it is more effective at immediately after chewing.
최진영,민철기,명훈,황순정,서병무,이종호,정필순,김명진 大韓顎顔面成形再建外科學會 2003 Maxillofacial Plastic Reconstructive Surgery Vol.25 No.4
융비술시 실리콘 고무는 다루기 쉽고 조직 반응이 적어 현대 많이 돌출의 합병증이 생길 수 있다. 저자등은 이러한 실리콘의 단점을 보완할 수 있는 goretex를 사용하여 융비술을 시행하고 비첨에 대해서 자가연골을 이식하여 만족할 만한 결과를 얻었기에 goretex가 안면부 연조직의 증강을 위한 이식재료로 적합하다고 생각되어 문헌고찰과 함께 보고하는 바이다. Many different materials have been used to provide augmentation of the nasal dorsum. this include both autogenous and homogenous materials,as well as allografts. Silicone among the artificial materials has been most widely used. The silicone has some advantages and disadvantages. Goretex(expanded polytetra-fluoroethylene) which has widely used in vascular surgery and abdominal surgery can be used for facial soft tissue augmentation. The author presemts 2 cases of nasal augmentaion using goretex with literature review.
이세기,문덕환,이채관,황용식,선병관,손병철,김대환,이창희,김휘동,이채언 인제대학교 백병원 2002 仁濟醫學 Vol.23 No.5
Objectives: For the purpose of preparing the fundamental data and assessing the status of exposure level of chemical substances in painting process. Methods and Materials: The author determined the concentration of organic solvents, lead(Pb), Chromium(Cr), and Toluene-2, 4-diisocyanate(TDI) in air of painting process to 90 industries classified by 15 types of manufacturing industry during a period from Jan. 1st 2001 to Dec. 31st 2001. Results: The results were as follows: 1. The geometric mean level of each chemical substance was 0.1706 ppm for exposure index in organic solvents, 0.0019㎎/㎥ for Pb, 0.0024 ㎎/㎥ for Cr, and 0.0004ppm for TDI, respectively. 2. The exposure level of each chemical substances by type of painting was the highest in dipping and brush painting for organic solvent, in spray-painting for TDI, and in spray gun-painting for Pb and Cr, respectively. 3. The exposure level of each chemical substances by type of local ventilation equipment was higher in enclosed and booth type for organic solvents. Cr, and TDI, and in exterior type for Pb, respectively than those of other types. 4. The exposure level of each chemical substances by type of hazardous material arresting media was higher in using water for organic substances, in using bag filter for Pb, TDI, respectively than those of other types. Conclusion: According to above results, this study suggests that the exposure level by type of industry exceeded the exposure level in wooden furniture and metal furniture manufacturing industry for organic solvents and Pb, respectively.
Hwang, Byoung Chul,Lee, Tae Ho,Park, Seong Jun,Oh, Chang Seok,Kim, Sung Joon Trans Tech Publications, Ltd. 2010 Materials science forum Vol.654 No.-
<P>Ductile-to-brittle transition behavior of high-nitrogen 18Cr-10Mn-0.35N austenitic steels containing Ni and Cu was investigated by means of Charpy impact test and fractographic analysis. The commonly observed fracture mode of the specimens tested at -196 oC was transgranular cleavage-like brittle with flat facets occurring along {111} crystallographic planes, thereby leading to the occurrence of ductile-to-brittle transition. For all the steels investigated in the present study, the ductile-to-brittle transition temperature (DBTT) measured from Charpy impact tests was much higher by 90 to 135 oC than that predicted by empirical equation strongly depending on N content. The combined addition of Ni and Cu enabled the 18Cr-10Mn-0.35N steels to have the lowest DBTT, which could be explained by relatively high austenite stability and favorable effect of Cu as well as the absence of delta-ferrite.</P>
냉간가공에 따른 오스테나이트계 18Mn-18Cr 고질소강의 기계적 특성
황병철 ( Byoung Chul Hwang ),이태호 ( Tae Ho Lee ),신종호 ( Jong Ho Shin ),이종욱 ( Jong Wook Lee ) 대한금속재료학회(구 대한금속학회) 2014 대한금속·재료학회지 Vol.52 No.1
The effects of nitrogen content, cold working, and stress relief treatment on the mechanical properties of high-nitrogen 18Mn-18Cr austenitic steels with different nitrogen content are investigated with respect to the specimen direction and location. The yield and tensile strengths usually increased with increasing nitrogen content and cold working, and they additionally increased after stress relief treatment. Based on these results, we propose a semi-empirical equation to predict the yield and tensile strengths of high-nitrogen 18Mn-18Cr austenitic steels. On the other hand, we discuss the ductile-brittle transition behavior depending on cold working and stress relief treatment in terms of the temperature sensitivty of yield stress.
대기 플라즈마 용사법으로 제조된 철계 혼합 코팅층의 마모특성
黃昞哲,安志勳,李聖鶴,吳重錫 대한금속재료학회 2002 대한금속·재료학회지 Vol.40 No.3
The objective of this study is to investigate the correlation between microstructure and the wear resistance of various ferrous blend coatings applicable to cylinder bores. Seven types of ferrous spray powders, two of which were stainless steel powders and the others were blend powders of ferrous powders mixed with Al_2O_3-ZrO_2 powders, were sprayed on a low-carbon steel substrate by atmospheric plasma spraying. Microstructural analysis of the coatings showed that iron oxides were formed in the austenitic (or martensitic) matrix by oxidation during spraying, while Al_2O_3-ZrO_2 oxides were mainly formed in the matrix for the blend coatings. The wear test results revealed that the blend coatings showed the better wear resistance than the ferrous coatings because they contained a number of hard Al_2O_3-ZrO_2 oxides. However, they had rough worn surfaces because of the preferential removal of the matrix and the cracking of oxides during wear. The STS 316 coating showed the slightly worse wear resistance than the blend coatings, but they showed the excellent wear resistance to a counterpart material resulting from homogeneous wear in oxides and matrix due to the smaller hardness difference between them. In order to improve the overall wear properties with consideration of the wear resistance of a counterpart material, the hardness difference between oxides and matrix should be minimized, while the hardness should be maintained up to a certain level by forming an appropriate amount of oxides.