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수종 이원중합 레진 씨멘트의 중합률 및 세포 독성에 관한 실험적 연구
이정석,노병덕,박성호 大韓齒科保存學會 1995 Restorative Dentistry & Endodontics Vol.20 No.1
AbstractThe degree of conversion of composite resin was known to have influence on the mechani- cal properties of composite materials such as hardness, strength, wear resisitance, dimensio- nal and color stability. Also unreacted monomer was reported to be harmful to the pulp. So the degree of conversion was a very important factor in the success of composite resin restorations.In recent, the dual cure resin cement was developed with the advocations that it could increase the curing rates in the sites where the curing ligt could not reach. Moreover many manufactors added some adhesive components in the resin cement.This study was undertaken to observe the effects of curing depth and light curing times on the degree of conversion of dual cure resin cements. CR INLAY CEMENT, DUAL CEMENT and OPTEC BOND, by the Fourier transform Infrared analysis, changing the curing depth 1mm, 2mm and 3mm, and varying the light curing time 20 seconds, 40 seconds and 80 seconds at each depth. The cytotoxicity of dual cure resin cements was tested by the in vitro MTT method using L929 cell. The results was evaluated and compared statistically.The results were obtained as follows: 1. The dual cure resin cements reavealed various degree of conversion, CR INLAY CE- MENT and DUAL CEMENT had a tendency to be more reactive to the light cure and OPTEC BOND was a more chemical one. 2. CR INLAY CEMENT and DUAL CEMENT showed the lowest degree of conversion in 2 mm depth, and in 3mm depth the degree of conversion increased, which were due to the chemical cure of dual cures, but OPTEC BOND showed decreasing degree of conversion with increasing curing depth and all experimental groups showed lower degree of conversion than CHEMICAL group which cured in dark room with no light, so the weak light?uring of dual cure resin cement prevented the chemical cure. (P<0. 05) 3. CR INLAY CEMENT and DUAL CEMENT showed increasing degree of conversion in 1 mm and 3 mm, according to the increasing cure times, but in 2 mm depth the degree of conversion decreased with increasing light?uring times and OPTEC BOND showed contrary tendency, but there was no ststistical importance in the differences among the experimental group.(P>0.05) 4. The optical density by MTT assay of extractions of CR INLAY CEMENT, DUAL CE- MENT and OPTEC BOND revealed no statitically important differences comparing with optical density of negative control.(P>0.05) 5. CR INLAY CEMENT showed a tendency of increaing cytotoxicity with days and DUAL CEMENT and OPTEC BOND showed higher cytotoxicity in 2 days than in 4 days, but there was no statistical importance in the differences. (P>0.05)
신병철,송의호,양재석 國立 昌原大學校 産業技術硏究所 1999 産技硏論文集 Vol.13 No.-
This paper deals with the design of controller which is used to rectifier for communication. Mathematical small-signal modeling and characteristic analysis are performed about DC/DC converter and three-phase AC/DC converter. Bode plots are obtained by the mathematical small-signal modeling. By the PSpice simulation, performance of the controller is proved respectively in line regulation and load.
이상윤,라병욱,박동수,황인헌,이덕동,신영남,박성배,이동욱,박용석,박형근,손상호,권태근,채경락,정경득 慶北大學校 自然科學大學 1986 自然科學論文集 Vol.4 No.-
An Ac-type Plasma Display Panel (PDP) operating with Ne-Ar(0.1%) Penning mixture gas is fabicated. The characterics of the panel with electrodes covered with thin and thick dielectric layers are studied. The brightness of the Neon-orange light emitted by the panel measured as function of applied voltage and frequency. As an application, a graphic display system equipped with PDP showing still and moving pictures is made.