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평행부를 갖는 링 시험편의 인장특성 평가방법에 관한 연구
배봉국(Bong-Kook Bae),구재민(Jae-Mean Koo),석창성(Chang-Sung Seok) 대한기계학회 2003 대한기계학회 춘추학술대회 Vol.2003 No.8
In this study, we tried to establish the method of evaluating the tensile property of the ring specimen of Arsene which have gauge length. For this, we verified the effect of central piece by FEM before we made central piece, pins, clevises and ring specimens for ring test. Pre-test was carried out with thses specimens and the devices and proper tensile speed and stable contact condition was determined. The result of main test was calibrated by the curve of deformation of device and compared with the result of FEM. Finally, a proto-master curve which is able to convert ring test data to tentile property was shown and the distribution of the hoop stress on all ring tensile process was observed by FEM.
링 시험편을 이용한 ZIRLO 피복관의 크리프 특성 평가
배봉국(Bong-Kook Bae),구재민(Jae-Mean Koo),석창성(Chang-Sung Seok) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.11
In this study. we suggested the ring creep test using the ring specimen of Arsene for estimating the burst creep properties of the cladding in stead of burst creep test. For this objective. we used the load-displacement conversion relationship of ring specimen called LCRR which had been determined on our previous study at high temperature by performing the tensile test and the numerical analysis. Then we carried out both the ring creep test and the burst creep test between 350℃ and 600℃ which were higher then the in-service temperature of the cladding in a reactor. The creep properties from the ring creep test with applying LCRR were compared with those from the burst creep test of closed-end specimens. From the results, it could be seen an very strong relationship between them, especially in Larson-Miller parameter. So, it is expected that we can easily anticipate the creep properties of not only claddings but also various small pressure pipes using the ring creep test.
배봉국(Bong-Kook Bae),김형익(Hyung-Ick Kim),허용(Yong Huh),구재민(Jae-Mean Koo),석창성(Chang-Sung Seok) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.8
In this study, the ring tensile test at the high temperature was suggested to evaluate the hoop tensile properties of small pipe such as the cladding in the nuclear reactor. Using the Arsene's ring model, the ring tensile test was performed at the high temperature and the data was calibrated. From the numerical analysis, LCRR(load-displacement conversion relationship of ring specimen) was determined at the high temperatures. We can obtained the hoop tensile properties at high temperature by means of applying the LCRR to the calibrated data of the ring tensile test. From the result, it was observed that the strength decreased as the temperature increased, and the elongation dropped around 400℃. Additionally, there was a difference in view of the shape of fractured surface and the fracture mechanism between at the high temperature and at the room temperature.
배봉국(Bong-Kook Bae),송춘호(Chun-Ho Song),석창성(Chang-Sung Seok) 대한기계학회 2002 대한기계학회 춘추학술대회 Vol.2002 No.5
The creep burst tests of Zirlo claddings were performed in order to obtain high temperature deformation behavior and strength characteristics with testing temperature, which varying 350℃ to 600℃. Ultimate strength was in inverse proportion to temperature, strain rate was in proportion to stress. Rupture time and hoop strain was proportion to temperature. From this study, the criteria of fracture was suggested.
배봉국(Bong-Kook Bae),구재민(Jae-Mean Koo),석창성(Chang-Sung Seok) 대한기계학회 2003 대한기계학회 춘추학술대회 Vol.2003 No.4
In this study, the single notched specimen which was proposed the previous study was used to<br/> evaluate of the transverse tensile property of zircaloy cladding. The single notched specimen has<br/> notches which give stress intensity effect, so both FEM and experiment are needed for the same<br/> time. Take a coincidence of tensile behavior about both FEM and experiment, then obtain stress and<br/> strain from FEM only. The influence of notch was estimated by comparing the result of experimental,<br/> FEM. Then the relationship between stress-strain and displacement was evaluated.
김창섭(Chang Sub Kim),배봉국(Bong Kook Bae),성도영(Do Young Sung) 대한기계학회 2010 大韓機械學會論文集A Vol.34 No.11
대형 드럼세탁기의 낙하 충격에 대한 포장재의 동적 거동 분석을 수행하였다. 해석에는 충격 해석에 널리 쓰이고 있는 LS-DYNA 를 사용하였으며, 자유 낙하 시의 충격 가속도와 유효 응력, 그리고 고속 카메라를 통한 포장재 압축 변형 비교를 통해 해석 결과의 신뢰성을 검증하였다. 완충 특성 및 포장재 구조 에 대한 파라미터 분석을 통해 기존 포장 구조에 대한 설계 개선안을 도출하였으며, 유통 시험을 통해 유효성을 검증하였다. 본 연구에서 사용한 해석 기법 및 분석 방법 등을 통해, 향후 드럼 세탁기의 완충 성능 및 재료비 개선에 효과적으로 기여할 수 있을 것으로 기대된다. The analysis of the dynamic behavior of the packaging of a drum washing machine has been carried out under the drop impact conditions. LS-DYNA software is used for performing the finite element analysis, and the validations are performed by comparing with the impact acceleration, effective stress and deformation of cushioned package with high-speed camera during free drop test. By analyzing the cushion characteristics and the design parameters of the original packaging, a packaging with an improved design is developed, and this design is validated on the basis of the results of the distribution test which consists of drop test, vibration test, stacking test, squeez test and so on. The drop impact simulation and analysis methods developed in this study can be adopted to successfully improve the cushioning provided by the packaging and to reduce the cost involved in developing new packaging for drum washing machines.
조성근(Sung - Keun Cho),배봉국(Bong - Kook Bae),석창성(Chang - Sung Seok) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.11
Tracing the study of the burst test of steam generator tube, few studies have been reported to effect<br/> of external pressure acting on secondary-side in service condition. In this study the burst tests of<br/> Inconel 690TT were conducted in order to evaluate burst strength characteristics under the effect of<br/> external pressure. We obtained the result that the burst strength of Inconel 690TT increased when<br/> external pressure increased while both total circumferential elongation and uniform burst elongation<br/> were not affected. Also, according to the increased of external pressure, the size of the burst opening<br/> became smaller and the tear was getting severe.
조성근(Sung-Keun Cho),배봉국(Bong-Kook Bae),석창성(Chang-Sung Seok) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.5
The failure of a steam generator tube brings economic loss from decreasing efficiency and makes it difficult to ensure the safety of a nuclear plant, so the investigation of fracture characteristics is essentially needed. It is known that the hoop stress is the main fracture reason of a SGT. However, in the fracture analysis of a SGT, the longitudinal tensile properties of a SGT or even original material has been used instead of hoop tensile properties, because a SGT is thin and has too small diameter to be manufactured into the standard tensile specimen in hoop direction. In this study, both ring tensile test which can measure the hoop tensile properties from a small tube and longitudinal tensile test were conducted. As a result, we obtained the tensile properties of a SGT.
김창섭(Chang Sub Kim),배봉국(Bong Kook Bae),성도영(Do Young Sung) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.4
대형 드럼세탁기의 낙하 충격에 대한 포장재의 동적 거동 분석을 수행하였다. 해석에는 충격 해석에 널리 쓰이고 있는 LS-DYNA를 사용하였으며, 자유 낙하 시의 충격 가속도와 유효 응력, 그리고 고속 카메라를 통한 포장재 압축 변위 비교를 통해 해석 결과의 신뢰성을 검증하였다. 완충 특성 및 포장재 구조에 대한 파라미터 분석을 통해 기존 포장 구조에 대한 설계 개선안을 도출하였으며, 드럼세탁기 포장재 설계 Guide를 제시하였다. 본 연구에서 사용한 해석 기법 및 분석 방법 등을 통해, 향후 드럼 세탁기의 완충 성능 및 재료비 개선에 효과적으로 기여할 수 있을 것으로 기대된다. Dynamic behavior of a package of a drum washing machine under the drop impact conditions has been carried out. LS-DYNA software is used for the finite element analysis and the validations are performed by comparing with the impact acceleration, stress and deformation of cushioned package with high-speed camera during free drop test. An improved design is proposed for original design and package design guide of wash ing machine is provided by analysis of cushion characteristics and package structure's design parameter. The drop impact simulation and analysis methods presented in this research can be successfully applied to improve cushion performance and reduce costs to develop new packages of the drum washing machines.