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Calcium sulfate-Hydroxyapatite 혼합재의 물성 및 치근천공 치유효과에 관한 연구
이승종,김경남,Lee, Seung-Jong,Kim, Kyoung-Nam 대한치과보존학회 1997 Restorative Dentistry & Endodontics Vol.22 No.2
Treatment of root perforation elicits special considerations due to its blood-contaminated circumstances. It is known that conventional dental restorative materials are all leaking. Calcium sulfate is the material which react with water to become chemically set. This study, therefore, was performed to develop a new compound containing calcium sulfate and to evaluate its physical and biological characteristics. Three materials were used, IRM, calcium sulfate, calcium sulfate-hydroxyapatite compound. The composition of the calcium sulfate-hydroxyapatite compound was basically 50 % of calcium sulfate and 50 % of hydroxyapatite mixed with guajacol. The materials were mixed in conventional way and underwent four physical test procedures, setting time, solubility test, compressive strength, and marginal leakage test. All materials were evaluated under the scanning electron microscope to examine the marginal sealing ability. Animal experiment was also performed to test the materials' tissue response. Twenty-four dog's premolars were tested with either furcation perforations or apical retro-fillings. From the results, we found that calcium sulfate possess the good marginal sealing ability. However, calcium sulfate creates many voids which is caused by crystal thrusting action when it reacts with water. It seemed that the voids caused disintegration of the material which eventually lead to tissue reaction. By compounding calcium sulfate and hydroxyapatite, we were able to obtain the better physical properties but it showed larger marginal gap between the material and the root surface. Within the six weeks observation period, both IRM and calcium sulfate-hydroxyapatite compound showed good tissue responses in animal experiment. It is concluded that calcium sulfate would be the material of choice in root perforation repair, but the physical property needs to be further improved.
폐유 및 폐유정제유의 가스화에서 주요 변수인 산소와 증기의 최적 공급비 예측
이승종(Seung Jong Lee),윤용승(Yong Seung Yun) 한국공업화학회 2002 공업화학 Vol.13 No.4
가연성 폐기물의 환경적합적인 처리와 폐기물내 에너지의 재활용을 위한 방법의 하나로 가스화 반응이 효과적이다. 가스화 반응에 영향을 주는 주요 인자인 산소 및 증기를 동시에 변화시켰을 때 가연성 폐기물의 가스화에 미치는 영향을 살펴보았다. 폐유와 폐유정제유를 대상 연료로 하였으며 산소와 증기를 동시 변화시키면서 전산해석을 수행하였다. 산소량이 증가할수록 H_2 및 CO의 생성량과 냉가스 효율은 증가한 후 감소하는 경향을 나타내었고 CO_2의 생성량은 감소한 후 증가하였다. 증기량이 증가할수록 H_2와 CO_2는 서서히 증가하였고 CO는 감소하는 경향을 나타내었다. 산소 및 증기의 공급 범위에 따라 약간씩 차이는 있지만, 폐유의 경우 산소/연료비 1.0∼1.3의 영역에서 H_2와 CO의 생성량은 최대치를 나타낸 후 감소하는 경향을 나타내었고, 정제유의 경우 산소/연료비 1.1∼1.3의 영역에서 폐유와 유사한 경향을 나타내었다. 생성가스를 연료가스로 활용하고 회재는 용융 처리를 목적으로 가스화할 경우에 대한 폐유 및 정제유의 적절한 가스화기 주입 조건을 도출하였다. The gasification reaction is very effective not only in the treatment of combustible wastes but to reuse the potential energy generated from the wastes as well as meeting the environmental regulation. The performance of gasification of the combustible wastes was determined numerically by varying the key gasification reaction variables: the oxygen and steam intake relative to the feed-stock. The feed-stocks chosen in this study were waste oil and refined oil. The simulation was performed by changing the combination of key variables. As the oxygen intake was increased, the production of CO and H_2 as well as the cold gas efficiency all increased initially, and then they all decreased after reaching a maximum point. On the other hand, the CO_2 decreased initially and then increased. As the steam intake was increased, the production of H_2 and CO_2 increased slowly, however, the production of CO decreased. The optimal O_2/fuel ratios for the maximum production of H_2 and CO was determined to by 1.0-1.3 and 1.1-1.3 for the waste oil and the refined oil, respectively. The oxygen and steam feed ratios of the waste oil and the refined oil were derived from the assumption that in the gasification the product gas was utilized as fuel and the slag was converted to the environmentally benign slag.