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압력용기용 SA516/70 강의 고온피로균열 진전거동에 대한 연구
박경동(K. D. PARK),김정호(J. H. KIM),윤한기(H. K. YOON),박원조(W. J. PARK) 한국해양공학회 2001 韓國海洋工學會誌 Vol.15 No.2
The fatigue crack propagation behavior of the SA516/70 steel which is used for pressure vessels was examined experimentally at room temperature, 150℃, 250℃ and 370℃ with stress ratio of R=0.1 and 0.3. The fatigue crack propagation rate da/dN related with the stress intensity factor range △K was influenced by the stress ratio within the stable growth of fatigue crack(Region Ⅱ) with an increase in △K. The resistance to the fatigue crack growth at high temperature is higher in comparison with that at room temperature, and the resistance attributed to the extent of plasticity-induced by compressive residual stress according to the cyclic loads. Fractographic examinations reveal that the differences of the fatigue crack growth characteristics between room and high temperatures are mainly explained by the crack closure and oxide-induced by high temperature.
박경동(K. D. PARK),김정호(J. H. KIM),윤한기(H. K. Yoon),박원조(W. J. PARK) 한국해양공학회 2001 韓國海洋工學會誌 Vol.15 No.2
Elastic-plastic fracture toughness J<SUB>IC</SUB> can be used as an effective design criterion in elastic plastic fracture mechanics. Most of these systems are operated at high temperature and J<SUB>IC</SUB> values are affected by temperatuere. therefore, the J<SUB>IC</SUB> value at high temperature must be determined for use of integrity evaluation and designing of such systems. Elastic-plastic fracture toughness J<SUB>IC</SUB> tests were performed on SA516/70 carbon steel plate and test results were analyzed according to ASTM E 813-87, ASTM E 813-89 and ASTM E 1152-87. Safety and integrity are required for reactor pressure vessels because, they are operated in high temperature. there are single specimen method, which used as evaluation of safety and integrity for reactor pressure vessels. In this study, elastic-plastic fracture toughness(J<SUB>IC</SUB>) and J-△a of SA 516/70 steel used as reactor pressure vessel steel are measured and evaluated at room temperature, 150℃, 250℃ and 370℃ according to unloading compliance method.
cake-less 고농축 연속여과시스템의 연구개발 (3)
최희규(H. K Choi),정한식(H. S Chung),정효민(H. M Jeong),박원조(W. J. Park),최병근(B. K. Choi),JunIchiro Tsubaki 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.11
Filtration is fundamental unit operation aimed at the separation of solids from the suspension by means of porous medium that retains the solids and allows the liquid to pass. Cake filtration is widely used in industry to separate solid particles from suspension in liquid. When the cakes are used as products in actual field, the solid-liquid separation has some problem such as high concentration cake, contamination of flocculants and batch type process of filtration. In this study, it has been developed the high performance cake-less filtration system whose condensed slurry layer maintains fluidity. The development of this novel filtration system allowed us to be unnecessary the scrapping operation of cake as well as to collect the high condensed slurry with more easily. These results clearly show that the new device will be realized for the making high condensed and fluidity slurry. It could be confirmed that the concentration of condensed slurry achieved 35 vol% with slurry fluidity. It is demonstrated that if particles are well dispersed, condensed slurry by filtration can be drained without scraper. In our new filtration system (DECAFF system), the specification of the system and operation conditions can be determined from a pre-filtration test.
금속기 복합재료 제조를 위한 예비성형체의 압축강도 평가
송태훈(T. H. Song),이현준(H. J. Lee),박원조(W. J. Park) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.5
Preforms of Metal Matrix Composite were made from aluminum borate whisker. And two inorganic binder which SiO₂ sol and Al₂O₃ sol were used to make preform and then it were sintered in 1000℃, 1050℃ and 1100℃. The binding ability of the binder has influence on the compressive strength of the preform. The compressive strengths and status of adhesions of those preform were examined were investigated. The result of the compressive strength depending on the kinds of inorganic binders, amount of inorganic binders and the sintering temperatures.
X-선 프랙토그라피를 이용한 피로파면 해석에 관한 연구
임만배(M. B. Lim),박원조(W. J. Park),손종동(J. D. Song),최갑송(G. S. Choi) 한국동력기계공학회 2007 한국동력기계공학회 학술대회 논문집 Vol.- No.-
The effect of different shot peening treatment on the fatigue crack growth behavior of an aluminum alloys has been investigated. The fatigue crack propagation rate of two aluminum alloys were observed to be slightly improved by the compressive residual stresses induced during the shot peening treatment. The fractography observation was performed using a scanning electron microscope on fatigue fracture surface and the striation spacing and size depended on repeated stress level and shot peening velocity. The diffraction pattern of small areas were measured by using the X- ray beam of ф0.2㎜ in the fracture surface. The characteristic X- ray of Cu-Kα and the lattice plane (311) of aluminum alloy were selected to obtain a middle diffraction angle. The changes in X-ray material parameters were described directly related to the process of fatigue until the initiation of fatigue crack and X-ray diffraction pattern ring and pole figure could be explained the failure prediction with stress distribution.
송태훈(T. H. Song),이현준(H. J. Lee),Jiang Jun,허선철(S. C. Huh),박원조(W. J. Park) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.10
It is known that the high-frequency induction hardening treatment is effective as surface hardening. the strength of this method is that make control the surface layer depth. In this study, carbon steel (SMS3C) was induction-hardened and adjusted to have three different surface hardness levels through the tempering process. The effect of induction hardening and tempering process were investigated as wear test and facture toughness test. At wear test, zirconia (ZrO2) ball was used as a relative wear material and ball-on-disk test was applied for searching wear properties. The results showed that friction coefficient and wear rate decreased with increasing surface hardness in the 50N. But the other condition of load were shown differently. and at accompanied the fracture toughness test, the results showed that as the hardening layer is as deeper K<SUB>IC</SUB> increased.
SM53C강의 고주파열처리 후 인장특성 및 평면변형률 파괴인성평가에 관한 연구
임만배(M. B. Lim),전현배(H. B. Jeon),송태훈(T. H. Song),박원조(W. J. Park) 한국동력기계공학회 2007 한국동력기계공학회 학술대회 논문집 Vol.- No.-
The purpose of this study is to investigate the effect of induction surface hardened on the tensile strength and fracture toughness of SM 53C steel. The tensile strength behaviour of it was estimated by the induction hardening and tempering treatment. The strength and fracture toughness values decreased with increasing of the induction hardening depth. It was observed from the SEM observation on the deformed specimen that the stretch zone width was showed in the fracture surface by the all specimen. Therefore, elastic plastic fracture toughness values could not be valid that induction hardening has martensite structure and this caused compressive residual stress on the test specimen surface.
핵융합로용 저 방사화 페라이트강(JLF-1)의 피로균열진전 거동
윤한기(H.K. Yoon),이상필(S.P. Lee),공유식(Y.S. Kong),김사웅(S.W. Kim),박원조(W.J. Park),A.Kohyama(A. Kohyama) 대한기계학회 2002 대한기계학회 춘추학술대회 Vol.2002 No.5
The objective of this study is to investigate fatigue life and fatigue crack propagation behavior in the Reduced Activation Ferritic Steel (RAFs) JLF-I. The experiment of fatigue life for JLF-I steel have been carried out for the stress ratio R=0 at room temperature. The fatigue crack propagation behavior of the JLF-I steel was investigated by the constant-amplitude loading test for the stress ratios R=0.1, 0.3 and 0.5 respectively. The effects of stress ratios and specimen size on the fatigue crack growth behaviors for JLF-I steel were discussed within the Paris law. At room temperature, the fatigue limits of longitudinal and transverse direction to the rolling direction were 470 MPa and 490 MPa at 1X 10_7<br/> cycles. respectively. The base material of JLF-I steel showed the isotropic behavior in fatigue properties of the rolling direction and the test temperature. The fatigue crack propagation rate of a half size specimen was similar to that of a full size specimen at the stress ratios of 0.1, 0.3 and 0.5 respectively. The fatigue crack propagation behavior of this material was evaluated by using a half size specimen.