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치은 섬유아세포에 대한 치주포대 추출물의 세포동성에 관한 연구
양승한,이만섭,박준봉,Yang, Seung-Han,Lee, Man-Sup,Park, Joo-Bong 대한치주과학회 1994 Journal of Periodontal & Implant Science Vol.24 No.3
It is well known that the application of dressings after periodontal surgery have benefits to provide the comforts to patient and to promote the healing process with action of bleeding control and temporary stabilization for the operated mobile teeth. But until recently the relationship between periodontal dressings and cells which are composed of periodontium has not been clear. The purpose of this study was to evaluate the cytotoxic effect of soluble extracts from the four different kinds of periodontal dressings, two of them were eugenol type (K.H.pack, Wondrpak) and the others were non-eugenol type (Coe-pak, Periocare), on the human gingival fibroblasts in vitro. Human gingival fibroblasts were primarily cultured from gingiva around third molar during the extraction for preventive purposes. Extracts solution were prepared with culture medium by means of imersing the consistent size of periodontal dressing made from plastic mold. Cell were inoculated into the 24 well plate with $3\;{\times}\;10^4\;cells/well$ of medium at $37\;^{\circ}C$, 100% of humidity, 5% of $CO_2$, incubator for 24 hours. After discard of the supernatant of medium, those cells were cultured with original, 1/2, 1/5, 1/10 diluted soluble extract for 24, 48 and 72 hours, and counted the number of cells using the hemocytometer at each designed time and concentration. Also, the cytotoxic effect of soluble extract was measured by Wataha's MTT assay method. In briefly, cells were inoculated and cultured into 96 well culture plate with $2\;{\times}\;10^4\;cells/well$ for 24 hours. Soluble extracts were applied to cultured cells and incubated for 48 hours at same condition. $50\;{\mu}l$ of MTT solution and DMSO were added into each well for the detection of absorbance with ELISA reader. The measured data were calculated by value of colorimetric assay for survival rate. The results were as follows ; In the case of eugenol type of dressing, original, 1/2 and 1/5 diluted extracts of K.H.pack showed very low survival rate. And original extract of Wondrpak showed strong cytotoxic effect and 1/2 diluted extract showed moderate cytotoxic effect. In the case of Non-eugenol type of dressings, only original extract of Coe-pak revealed strong cytotoxic effect and Periocare had little cytotoxic effect. It is concluded that eugenol type of dressings showed more cytotoxic effect than non-eugenol types. This study suggest that use of non-eugenol dressings after periodontal surgery is recommended.
양승한,김기훈,Yang, Seung-Han,Kim, Gi-Hun 대한기계학회 2001 大韓機械學會論文集A Vol.25 No.9
Improvement of machine tool accuracy is an essential part of quality control in manufacturing process. Among of all the errors of a particular machine tool, the thermal errors of the spindle have a notably significant effect on machining accuracy and have a direct influence upon both the surface finish and geometric shape of the finished workpiece. Therefore, this paper proposed new measurement method for thermal errors of the spindle in machine tools. The thermal errors are measured by a ball bar system instead of capacitance sensor system. The novel measurement method using ball bar system is more efficient, easier to use than conventional measurement system. And also the ball bar system is possible to measure both geometric errors and thermal errors at the same time.
양승한,김용식,윤병식,권기일,Yang, Seung Han,Kim, Yong Sik,Yoon, Byung Sik,Guon, Kee Il 한국압력기기공학회 2010 한국압력기기공학회 논문집 Vol.6 No.1
To enhance the reliability of ultrasonic testing system, MOST(Ministry of Science and Technology) bulletin 2004-13 was published in 2004.6 requiring performance demonstration in ultrasonic examination and MEST(Ministry of Education, Science and Technology) 2009-37 was published in 2009.9(formerly MOST bulletin 2004-13). In order to meet the MEST bulletin requirement and increase the reliability of ultrasonic testing, all the ultrasonic examination procedure and equipment should be performance demonstrated and qualified. In this paper, generic procedure for the ultrasonic examination of dissimilar metal welds are described and new technique are introduced.