• Journal of Advanced Marine Engineering and Technology
• /
• v.24 no.2
• /
• pp.8-16
• /
• 2000

The thread load distribution as applied to large stud bolts for steam turbines is investigated using the finite element method. The stress concentration in tapered threads is studied with varying prestress and taper angle. Based upon the thread load distribution, the optimal taper angles to reduce the stress concentration are determined for various prestresses. The presented finite element model is validated by comparing results of the calculated thread load with analytic ones. The optimal taper angles obtained from this research can be used in designing tapered threads of large stud bolts for steam turbines.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2011.06a
• /
• pp.413-414
• /
• 2011

• 월간 기계설비
• /
• s.64
• /
• pp.69-75
• /
• 1995

일본의 근대수도는 100년을 넘는 역사를 갖고 있으며 보급률은 95$\%$에 달하고 대부분의 국민이 수도에 의존하여 건강하고 위생적인 생활을 이루는 기반시설로서 정착하고 있다. 그러나, 건축후 25년을 경과한 맨션 100만동 이상의 거주자가 급수$\cdot$급탕의 적수$\cdot$청수$\cdot$부식누수의 피해에 고민하고 있다. 전번 NHK의 프라임 10에서 $\ulcorner$고치려고 해도 고쳐지지 않는 고령화 맨션의 우울 $\lrcorner$이라고 하는 제목으로서 맨션배관정비개수비 4억엔으로 고민하는 거주자의 곤혹의 실태가 영상으로 호소되었다. 매년 150만호가 건축되는 주택의 급수급탕배관의 대부분이 라이닝강관과 테이퍼 나사 조인트 분기공법으로 시공되고 있다.

• The Journal of Korean Academy of Prosthodontics
• /
• v.48 no.3
• /
• pp.215-223
• /
• 2010

Purpose: The present study was aimed to evaluate the level of cortical bone strain during the placement of an implant. The primary concern was to investigate if the extent of overloading area near the marginal bone could be affected by microthread fabricated at the cervical 1/3 of an implant. Materials and methods: Three dimensional finite element analysis was used to simulate the insertion of 3 implants. Control model was $4.1{\times}10$ mm implant (Submerged model, Dentis Co,, Daegu, Korea) equipped with a main thread only. Type I was with main thread and microthread, and Type II had similar thread pattern but was of tapered body. A PC-based finite element software (DEFORM 3D ver 5, SFTC, Columbus, OH, USA) was used to calculate a total of 3,600 steps of analysis, which simulated the whole insertion. Results: Results showed that the strain field in the marginal bone within 1 mm of the implant wall was higher than 4,000 micro-strain in the control model. The size of bone overloading was 1-1.5 mm in Type I, and greater than 2 mm in Type II implants. Conclusion: These results indicate that the marginal bone may be at the risk of resorption on receiving the implant for all 3 implant models studied. Yet, the risk was greater for Type I and Type II implants, which had microthread at the cervical 1/3.

• Proceedings of the KSME Conference
• /
• 2007.05a
• /
• pp.636-641
• /
• 2007

This research focuses on the development of an analytical model loosening mechanism of dental implant system. The model is utilized for predictions of preload values for internal and external types of implants. It identifies the effects of various parameters such as friction, geometric factors and mechanical properties on the loosening mechanism of the implant system. The results of analytical model are compared to those of the numerical method for validation.