http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Al-Alloy 7075-T651 의 부식피로균열 성장거동에 관한 연구(1)
한지원,우흥식,김봉철 한국산업안전학회 1998 한국안전학회지 Vol.13 No.4
Fatigue crack growth rates(i.e. crack initiation and crack growth of short, and long crack) are investigated using commercial plates of high strength Al alloy 7075-T651 for the transverse-longitudinal(T-L) direction in air, water and sea water. Also, the evaluation direct current potential drop(D.C.P.D) method and the fractographical analysis by SEM are carried out. Near threshold region, short crack growth rates were much faster than those of comparable long cracks, and these short crack growth rates actually decrease with increasing crack growth and eventually merge with long crack data. Fatigue crack propagation rates in aggressive media(i.e. sea water) increase noticeably over three times those in air. One of the most significant characters in this phenomenon as a corrosion-fatigue causes an acceleration in crack growth rates. Sea water environment, particularly Cl^- solution brings the most detrimental effects to aluminum alloy. The result of fractographical morphology in air, water and sea water by SEM shows obvious dimpled rupture and typical striation in air, but transgranular fracture surface in water and sea water.
최용식,한지원,김규성 한국산업안전학회 1991 한국안전학회지 Vol.6 No.3
In this study, a crack closure behavior of Al-alloy 5052-H38 was investigated. The fatigue test was performed by the four-point bending test under the contast amplitude load. Stress ratio R was changed from-1.0 to 0.5. To measure the fatigue crack opening point, the graph of load vs. subtracted displacement by computer program was obtained from the K-Y polotter. In order to gain the displacement data, a strain gage was attached at the back surface against the notched side. Using the conception of crack closure and influence of on crack growth rate a model for crack growth rate is developed for Al-alloy 5052-H38.
최용식,한지원,우흥식 한국산업안전학회 1993 한국안전학회지 Vol.8 No.4
The growth of short cracks can be well described in terms of the effective stress intensity factor range, which is calculated on the base of crack closure. The relation between the crack opening SIF and crack length is determined from the experimental results. The crack opening SIF of short cracks, K_(op) can be predicted from the crack opening SIF at threshold of long crack, K_(op.L). The growth rate of short cracks at notch root can be predicted from the crack opening SIF of short cracks, K_(op), and the growth equation of long cracks in region Ⅱ.
홍성수,강기준,한지원 한국산업안전학회 1998 한국안전학회지 Vol.13 No.3
The low grade domestic kaoline, such as pink-C and white-D, was converted to metakaoline, which has pozzolanic reactivity by heat treatment in the temperature range of 600℃ to 1000℃ for preparing the spacer. The spacer was used for supporting the reinforced steel rod during construction to improve the safety of architecture. Pink-C and white-D were completely dehydroxylated when burnt at 800℃ for 1 hour and converted to metakaoline. The compressive strengths of specimens added calcined pink-C were lower than those of press molding mortar products inspire of calcining conditions. When white-D with calcined 800℃ and 1000℃ for 1 hour was mixed 30% in the weight ratio of cement, the specimens cured 28 days had 338㎏/㎠ and 347㎏/㎠ of compressive strengths respectively.