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자가 중합 임시수복용 레진의 경화 시 외부환경 변화에 따른 치아의 온도변화
오우식,백진,김형섭,우이형,Oh, Wu-Sik,Baik, Jin,Kim, Hyung-Seob,Woo, Yi-Hyung 대한치과보철학회 2006 대한치과보철학회지 Vol.44 No.5
Statement of the problem: The cold-cured resins used in fabrication of the provisional crown and fixed partial dentures could cause pulpal damage by heat generated during exothermic polymerization reactions. Purpose: In this in vitro study investigates the how external conditions such as material of the matrix, thickness of the matrix and thickness of dentin affect the temperature of the tooth during polymerization reaction of the cold-cured resins. Material and methods : To measure the temperature of the resin, metal die was maintained to the temperature of $37^{\circ}C$ with water bath to simulate the temperature of thetooth and thermocouple was placed in the center of the metal die. Acrylic pipe was cut in height of 1, 2, 3, 6, 10 mm and placed on the metal die and mixed resin was pored in the acrylic pipe As the resin polymerized temperature was recorded with the thermometer. Temperature of the resin using matrix was recorded by using the individual tray relieved in different thickness 2, 5, 7, 10 mm. The material of the matrix was irreversible hydrocolloid impression material, vinyl polysilloxane impression material and vacuum-formed template Temperature rise of the resin using different thickness of tooth section was record ed by placing tooth section on the metal die and placing resin over the tooth section. Results : Conclusion : 1. Temperature rise increased as the thickness of the resin increased but there was no significant differences over 3 mm thickness of the resin. 2. The lowest temperature rise was showed in irreversible hydrocolloid impression material and vinyl polysilloxane impression material vacuum-formed template as in orders. 3, Temperature rise of the resin decreased regardless of the thickness of the matrix when vinyl polysilloxane impression material was used as the matrix. 4 When irreversible hydrocolloid impression material was used as matrix, the temperature rise of the resin decreased as the thickness of the matrix increased and there was no temperature rise when thickness of the matrix reached 10 mm, 5. The temperature rise of the resin did not decreased when Polypropylene vacuum-formed template was used as the matrix. 6, The temperature of the resin increased as the thickness of the dentin decreased.
남명수,오우식 한국생산성학회 2001 生産性論集 Vol.15 No.3
This study examined the information effect of open market stock repurchase program on stock price in Korean Stock Exchange. The sample period is from 1996 to 2000. The result confirms that the information effect exists and is positive in KSE like NYSE. The anomalous phenomenon is found that even after stock repurchase announcement, the abnormal returns still exist for the long time. This means that the repurcase announcement informs the market of the underpricing of current stock and the stock repurchase program is used as a tool to increase the stock price. Such being the case, the cause of information effect of stock repurchase was explored. Our study shows that the firms with the high level of cash flows, the high portion of large shreholders and the high target repurchase ratios have the higher repurchase effect but the ex-ante profit forecastes have no effect on the stock repurchase program. Finally this study finds that the repurchase program is used to control the underpriced stock price, and also the wealth of shareholders is enlarged by the productivity of shareholders through the repurchase program.
남명수,오우식 한국생산성학회 2003 生産性論集 Vol.17 No.2
Recently, many executives and managers pay a great deal attention to the importance of intellectual capital because it is expected to provide decision-makers with the sources for competitive advantage. The purpose of this study is to establish the framework for the management of intellectual capital and then to test relationships among intellectual capitals, firm market values and financial productivity. The empirical results are as follows. First, the regression model by intellectual capital factors represents statistical significance between market value and intellectual capital. Second, the positive relationship between the intellectual capital and market value shows a statistically significant result. Third, intellectual capital and financial productivity are positively related and statistically significant. The results also show that there is a positive and statistically significant relationship between financial productivity and market value.