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CAD/CAM을 이용한 구치부 전부도재 고정성 국소의치 지르코니아 코어의 연결부 설계에 따른 파절강도
서준용,박인임,이근우,Seo Jun-Yong,Park In-Nim,Lee Keun-Woo 대한치과보철학회 2006 대한치과보철학회지 Vol.44 No.1
Statements of problem: Zirconia core is used for posterior fixed partial dentures because it's good mechanical properties. Stress is concentrated on connectors in fixed partial dentures, so the proper design of connector areas is needed for adequate mechanical long-term properties of any prosthesis. The area of connector is critical, but tooth size and surrounding soft tissue limit the connector design. Purpose: The purpose of this study is to compare fracture strengths between different connector designs of zirconia core for posterior fixed partial dentures manufactured with CAD/CAM system and determining the optimal connector design satisfying strength and hygiene. Material and method: The following four groups of 40 posterior fixed partial denture specimens(each group 10) were fabricated as followed; group 1 vertical height of connector is 3mm (control group, all groups have the same condition); group 2, lingual vertical 1mm reinforcement on connector; group 3, lingual vertical 2mm reinforcing on connector and group 4, lingual vertical 3mm reinforcing on connector. Specimens were subjected to compressive loading on the central fossa of pontic by instron. SEM was used to identify the initial crack and characterize the fracture mode. Results: The results were as follows: 1. The mean fracture load of the non-lingual reinforcing group was 1212N and the lingual vertical 1mm reinforcing group was 1510N, the lingual vertical 2mm reinforcing group was 1882N, the lingual vertical 3mm reinforcing group was 1980N. 2. The reinforcing groups were statistically significant compared to non-reinforcing groups(P<0.001). 3. There were 2, 3mm reinforcing groups that were statistically significant compared to 1mm reinforcing groups(P<0.001), and the 3mm reinforcing group was not statistically significant compared to 2mm reinforcing groups(P>0.05) 4. Fractures were initiated in gingival embrasures of connectors and processed to the loading site. Conclusion: In this study, lingual reinforcement of connector for improved strength of zirconia based fixed partial denture is nessasary. And long-term study for clinical application is required
서준용,고재문,고형일 한국정보시스템학회 2001 情報시스템硏究 Vol.10 No.1
E-commerce has not only brought about a great change in the way we exchange goods and services but also revolutionized the way we handle business transactions. In addition, it has a significant influence upon the present business structure, and most of firms in service industry as well as manufacturing are considering adopting E-commerce in a serious manner. Most vessels purchase merchandises through a number of shipping agents. As the amount of harbor materials increase, the number of vessels and their navigation frequency also increase. As a result, the amount of procurement for ships has increased. Traditional means such as telephone and fax to handle ever-increasing harbor transaction, however, has proved to be very time-consuming and cost ineffective. Therefore, people are starting to look for more effective ways. In this paper, an internet-based scheme of 13213 transaction is proposed to handle procurement problem between shipping agency and shipping company, and between vessel and suppliers as a more effective approach to streamline such problems. We extract problems of shipping agency through task-analysis and present a scheme that performs decision making and procurement as a system agent with brokering structure. Purchaser and supplier are offered material information rapidly and task loads are minimized by the scheme. Also, the system can support decision making of purchasing goods, and information is shared among purchaser, supplier and system through the system interface.