• Proceedings of the KWS Conference
• /
• 2001.05a
• /
• pp.224-227
• /
• 2001

In this study, CT specimens were prepared hem ASTM SA516 which was used for pressure vessel plates for room and low temperature service. And we got the following characteristics from fatigue crack growth test carried out in the environment of room and low temperature at $25^{\circ}C$, -3$0^{\circ}C$, -6$0^{\circ}C$, -8$0^{\circ}C$, -l$0^{\circ}C$ and -l2$0^{\circ}C$ and in the range of stress ratio of 0.1, 0.3 by means of opening mode displacement. At the constant stress ratio, the threshold stress intensity factor range $\Delta K_{th}$ in the early stage of fatigue crack growth ( Region I ) and stress intensity factor range $\Delta$K in the stable of fatigue crack growth ( Region II) was increased in proportion to descend temperature. It assumed that the fatigue resistance characteristics and fracture strength at low temperature is considerable higher than that of room temperature in the early stage and stable of fatigue crack growth region. The straight line slope relation of logarithm da/dN - $\Delta$K in Region II, that is, the fatigue crack growth exponent m increased with descending temperature at the constant stress ratio. It assumed that the fatigue crack growth rate da/dN is rapid in proportion to descend temperature in Region H and the cryogenic-brittleness greatly affect a material with decreasing temperature.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
• /
• 2001.05a
• /
• pp.320-325
• /
• 2001

In this study, CT specimen were prepared from Pressure Vessel Steel which was used for pressure vessel plates for room and low temperature service. And we got the following characteristics from fatigue crack growth test carried out in the environment of room and low temperature at $25^{\circ}C$, -3$0^{\circ}C$, -6$0^{\circ}C$, -8$0^{\circ}C$, -10$0^{\circ}C$ and -12$0^{\circ}C$ and in the range of stress ratio of 0.05 and 0.3 by means of opening mode displacement. At the constant street ratio, the threshold stress intensity factor range ΔK$_{th}$ in the early stage of fatigue crack growth(Region I) and stress intensity factor range ΔK in the stable of fatigue crack growth(Region II) was increased in proportion to descend temperature. It assumed that the fatigue resistance characteristics and fracture strength at low temperature is considerable higher than that of room temperature in the early stage and stable of fatigue crack growth region. The straight line slope relation of logarithm do/dN -ΔK in RegionII, that is, the fatigue crack growth exponent m increased with descending temperature at the constant stress ratio. It was assumed that the fatigue crack growth rate do/dN is rapid in proportion to descending temperature in Region IIand the cryogenic-brittleness greatly affect a material with decreasing temperature.e.greatly affect a material with decreasing temperature.

• The Journal of Korean Academic Society of Nursing Education
• /
• v.10 no.1
• /
• pp.84-93
• /
• 2004

Purpose: This study was conducted to investigate the subjective degree of fatigue, the degree of fatigue depending on constitution, and the factors related to fatigue in middle-aged women. Method: Data were collected from 51 patients, registered at Oriental Medicine Hospital in J-city and K-city respectively. The instrument used in this study were the Multidimensional Assessment of Fatigue and the Questionnaire of Sasang Constitution Classification Ⅱ. Data analysis was done SPSS Result: The characteristics of constitution in middle-aged women could be divided into three: twenty six people of Soeumin, thirteen people of Taeumin, and twelve people of Soyangin. The degree of fatigue in middle-aged women: the average score 30.61 out of the total score 40. Subdivision of fatigue scores: common fatigue degree 7.71, distress due to fatigue 7.67, degree of daily activity fatigue 7.43, and fatigue frequency in the previous week 7.84. There were significant differences in the degree of fatigue depending on constitution in middle-aged women(p=.033). This study revealed weight, exercise, and drinking are important factors that can exert influence on the degree of fatigue. Also, there was a big difference in the degree of fatigue depending on constitution. Conclusion: In conclusion, fatigue is one of the difficult problems with middle-aged women. And this study revealed that change in the weight(especially loss of weight), physical exercise, and drinking are important factors that can exert influence on the degree of fatigue. Also, there was a big difference in the degree of fatigue depending on constitution. Therefore it is necessary to develop Korean nursing intervention to providing an appropriate environment where there is the harmony of the dual principles of the negative and positive, and patients can be taken care of properly.

• Proceedings of the KWS Conference
• /
• 2004.05a
• /
• pp.290-292
• /
• 2004

In this paper, static and fatigue load tests for the specimens, components and carbody were carried out to investigate the strength of welded joints in aluminum rolling stock. Tensile load test results showed that the static strength of welded joint for heat-treated alloys is reduced significantly and fatigue strengths are scattered by the welding imperfections. Component and whole carbody fatigue test results showed agreements with the design fatigue strength standards for specimens of same joint detail. Test results revealed that full penetration welding and strict management of welding procedure are crucial for securing strength of welded joint in aluminum carbody.

• Journal of the Korean Society of Safety
• /
• v.8 no.1
• /
• pp.59-63
• /
• 1993

It is very difficult to find not only optimized welding condition but also fatigue characteristics of the dissimilar weld. In this study. Low carbon steel (SS41) and austenitic stainless steel (STS304) were welded by GTAW welding with STS309 stainless wire rod and Single Edge Notch specimens were used for the examination of fatigue behavior on welding heat cycle. The fatigue crack growth rate in HAZ of SS41 was the highest. The second was in STS304 bond line and the lowest was in HAS of STS304.

• Journal of Korean Academy of Nursing
• /
• v.29 no.2
• /
• pp.248-257
• /
• 1999

The purpose of this study was to identify basic data for the health fare of normal pregnant women. The number of subjects was 779 pregnant women who received prenatal care in two University hospitals. The data, which were collected from June to October, 1998. and used the questionnaire “Symptom Table on Fatigue Perception” designed by the Research Committee of the Industial Fatigue in Hygienic. Association of Japan Industry. The collected data were scored by use of means and standard deviations according to the subjective symptoms of fatigue and each item as an independent variable was analysed by t-test and ANOVA test. The results are as follows : 1) Degree of subjective fatigue showed as an average of 1.81. Fatigue as physical symptoms had the highest score with 2.09. followed by neuro-sensory symptoms, 1.69 and psychological symptoms had the lowest score 1.66. 2) With the respect to the general characteristics of the subjects. there were statiscally significant difference in experience of pregnancy(t＝-2.286, p＝.023). wanted pregnancy(t＝-2.935, p＝.004), parity(t＝-2.429, p＝.015), sleeping time(F＝3.478, p＝.031). and presence of other child(t＝2.347, p＝0.19).

• Proceedings of the Korea Concrete Institute Conference
• /
• 1992.10a
• /
• pp.161-166
• /
• 1992

In this paper, the effect of compressive strength on the fatigue behavior of plain concrete was studied. The fatigue behavior of plain concrete in uniaxial compression is somewhat affected by the compressive strength of the concrete. Concrete cylindrical specimens(100$\times$200mm) with compressive strength of 265kg/$\textrm{cm}^2$, 530kg/$\textrm{cm}^2$ , 860kg/$\textrm{cm}^2$ and 1053kg/$\textrm{cm}^2$ were tested and analyzed on the fatigue strength, In addition to fatigue strength, the deformation characteristics of the concrete subjected to fatigue loading was investigated. The fatigue strength was decreased for the high-strength concrete. The deformation studies indicated that the irrecoverable strain in normal strength concrete is greater than that in high strength concrete.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.25 no.1
• /
• pp.161-167
• /
• 2001

The overhead transmission wires operating both at warm temperature and tighten state for a long period of time in a power transmission plant are degraded by air pollution, wind, creep and slip between steel wire and aluminium conductor. The objective of this study is to investigate to investigate the characteristics of fatigue properties with tension and bending loading of a high carbon steel wire. The fatigue behaviors have been carried out by tension-tension, 4 points bending and 3 points bending loading. In the present study, a conventional fatigue strengths between 4 points bending and tension-tension fatigue were determined by Gerber, Sorderberg and Goodmans theory and we investigated S-N diagram for bending and tensile loading.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 1997.04a
• /
• pp.143-149
• /
• 1997

the horizontal corrosion fatigue tester has been developed for investigating environmental strength. Using this tester, we investigated about corrosion fatigue caracteristic for A106 GrB steel weldments in 3.5% synthetic seawater and room temperature. Considered parameter is only frequency of 1,3 and 5Hz. and Corrosion fatigue crack length was measured by DC potential difference method. From the results, we could find that the horizontal corrosion fatiued tester could be well applied to estimation of fatigue strength. and In case of 5Hz, corrosion fatigue crack growth path of A106 GrB steel weldment was transgranular, and of 1 and 3Hz showed that transgranular and intergranular was mixed. Also, Corrosion fatigue crack growth caracteristic values estimated in each frequency were C=9.33 x 10-9 and m=2.93 in 1Hz, C=9.77x10-10 and m=3.47 in 3Hz, C=1.02x10-10 and m=4.05 in 1Hz

• Journal of Ocean Engineering and Technology
• /
• v.20 no.5 s.72
• /
• pp.82-88
• /
• 2006

This assessment is concerned with the fatigue strength of the tendon porch found in TLP. Lorge-scale fatigue tests with models constructed at 30% the size of the real structures have been carried out to investigate the fatigue behavior of the API 2W Grade 50 steel recently produced by POSCO. The fatigue life for the present test models was obtained based on the concept of nominal stress. A comparison of the present test results with those obtained by a numerical approach based on the structural analysis results has showngood agreement. The present results were also compared with the design curves in DnV RP-C203.