• Proceedings of the KSME Conference
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• 2004.04a
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• pp.1-6
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• 2004

In this study, the intrinsic static/dynamic fracture toughness of Al 7175=T74 is evaluated from the apparent static/ dynamic toughness of notched specimen, The critical average stress fracture model is suggested to establish the relationship to predict the intrinsic fracture toughness from the apparent fracture toughness of a notched specimen. The critical average stress fracture model is established using the relation between the notch root radius and the effective distance calculated by finite element analysis. Also, effective distance is applied to estimate the failure criterion for the combustion pipe with notch. It is conclude that the true fracture toughness can be estimated from test results of apparent fracture toughness measured by using a notched specimen. Also, the effective In this study, the intrinsic static/dynamic fracture toughness of Al 7175=T74 is evaluated from the apparent static/ dynamic toughness of notched specimen, The critical average stress fracture model is suggested to establish the relationship to predict the intrinsic fracture toughness from the apparent fracture toughness of a notched specimen. The critical average stress fracture model is established using the relation between the notch root radius and the effective distance calculated by finite element analysis. Also, effective distance is applied to estimate the failure criterion for the combustion pipe with notch. It is conclude that the true fracture toughness can be estimated from test results of apparent fracture toughness measured by using a notched specimen. Also, the effective distance can be used to evaluate the failure criterion of structure with notch.

• Speech Sciences
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• v.10 no.2
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• pp.303-318
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• 2003

This paper attempts to investigate the tonal implementations of English stress clash, arguing that a preceding stress shifts leftward when two lexical stresses conflict across word boundaries or that H* and L* pitch accents are alternatively manifested on the stressed syllables, establishing intonational peak and valley contours. We claim that the H*/L* alternation might be a tonal strategy to avoid stress clash, and that pitch could be solely manipulated to display a rhythmic effect with maintaining lexical stress. In the experiment, we examined two-word combinations whose boundaries involve stress clash, and divided them into two categories. One has the preceding words involving a heavy syllable ahead of stress to guarantee the place for a shifting stress and the other, a light syllable, in which case stress shift is completely prevented. We analyzed the distribution of pitch accents in the word combinations, focusing on the pitch configurations in the cases where stress should not be shifted. Results show that approximately 50% of the stimuli show stress shift in the heavy syllable combinations of the preceding words; the preceding stress is moved leftward within the word. The other 50% and the light syllable combinations show various pitch accents patterns; H* and L* alternation, deaccentuation of either stressed syllable, or L-insertion between two H* pitch accents, etc. We interpret this as a rhythmic effect of tone to avoid stress clash and suggest that a true stress clash would be confined into cases without H*/L* contours.

• Journal of the Korean Data and Information Science Society
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• v.6 no.1
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• pp.73-83
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• 1995

We construct the approximate bootstrap confidence intervals for reliability (R) when the distributions of strength and stress are both normal. Also we propose percentile, bias correct (BC), bias correct acceleration (BCa), and percentile-t intervals for R. We compare with the accuracy of the proposed bootstrap confidence intervals and classical confidence interval based on asymptotic normal distribution through Monte Carlo simulation. Results indicate that the confidence intervals by bootstrap method work better than classical confidence interval. In particular, confidence intervals by BC and BCa method work well for small sample and/or large value of true reliability.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1358-1361
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• 2003

In this study, intrinsic static/dynamic fracture toughness of Al 7175-T74 are evaluated from the apparent static/dynamic toughness of notched specimen. The notch/crack critical average stress fracture model is suggested to establish the relationship to predict the intrinsic fracture toughness from the apparent fracture toughness of a notched specimen. The notch/crack critical average stress fracture model is established using the relation between the notch root radius and the effective distance calculated by finite element analysis. It is conclude that the true fracture toughness can be estimated from test results of apparent fracture toughness measured by using a notched specimen. Also, critical notch root radius can be predicted by notch/crack critical average stress fracture model.

• Proceedings of the Korean Geotechical Society Conference
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• 1994.03b
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• pp.3-12
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• 1994

Based on the shear failure mechanism, hydraulic fracturing criteria are extended to three dimensional stress state. According to the situation of the directions of borehole and major principal stress axes, three equations can be derived for three dimensional hydraulic fracturing problems. By comparing these equations, a single criterion is selected for hydraulic fracturing pressure in cohesive soils. The criterion is a function of maximum principal stress, minimum principal stress and soil parameters in UU conditions. The equation indicates that with any increase in maximim principal stress, hydraulic fracturing pressure decreases. In order to prove the integrity of the criteria, laboratory tests are performed on compacted cubical specimens using true a triaxial apparatus. The shape and direction of fractures are determined by injecting colored water after fracture initiation. It is found that the direction of fractures are perpendicular to the o1 plane.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.11a
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• pp.693-694
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• 2010

• Journal of the Korean Institute of Gas
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• v.16 no.6
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• pp.67-72
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• 2012

In this study, the leak-free performance and sealing endurance safety of CNG fueling nipple in which are related to the contact normal stress and equivalent true stress have been analyzed for CNG automobile using a finite element analysis. For the conventional circular o-rings and new double-lip o-rings with an initial compression rate of 15 percentages, the leak-free performance of double-lip o-rings with two contact sealing spots is 41% higher than that of the conventional circular o-rings with a contact sealing spot. The FEM computed results present that the leak-free endurance safety of double-lip o-rings with two contact sealing spots is 5% higher than that of the conventional circular o-rings for initial compression ratio of 15 percentages and a gas compression pressure of 8MPa. And, the maximum equivalent true stress of double-lip o-rings is 10.2% higher than that of the conventional circular o-rings for the leak-free endurance safety. This means that the double-lip o-ring may guarantee the extended sealing life compared to that of a conventional circular o-ring.

• Journal of Nutrition and Health
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• v.29 no.7
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• pp.788-805
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• 1996

This study was performed to investigate effects of examination-stress and protein supplementation on nitrogen metabolism and blood protein levels of Korean college students. Experiment was conducted at the beginning of a academic term and during midterm examination. During midterm examination, subjects were classified into two groups randomly : protein supplemental group(male n=6, female n=10) and placebo group(male n=4, female n=9). Protein capsules(2g/day) above 10% of indispensible amino acids requirement estimates were given to supplemental group for 10 days. At the begining of the term, male students(n=12) ingested 223.15mgN/kg/d, excreted 20.7mgN/kg/d in feces, and excreted 94.31mgN/kg/d in urine. Their apparent protein protein digestibility was 90.72%, true N balance was +100.11mgN/kg/d, and the mean maintenance N requirement of mixed Korena diet calculated was 112.13mgN/kg/d. Female students(n=19) ingested 171.44mgN/kg/d, excreted 22.13mgN/kg/d in feces, and excreted 122.92mgN/kg/d in urine. Their apparent protein digestibility was 86.76%, true N blance was + 18.39mgN/kg/d, and the mean maintenance N requirement calculated was 135.31mgN/kg/d. Blood levels of serum total protein, albumin, and BUN were within normal range. During midterm examination, fecal and urinary N excretions of female subjects(n=19) were increased, especially urea N markedly, and urea N/creatinine N ratio was augumented significantly. Apparent protein digestibility of male subjects(n=10) was decreased. Examination-stress showed 8.05mgN/kg/d (7.2%) increase of mean maintenance N requirement in male and 8.55mgN/kg/d(6.3%) increase in female students in comparison with that of the beginning of the term. Serum total protein and albumin levels showed no significant change, but serum transferrin level of female were decreased significantly. During midterm examination, females supplemented with protein capsules(2g/d)had no significant increase in fecal and urinary N excretions.

• Journal of the Microelectronics and Packaging Society
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• v.21 no.4
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• pp.125-131
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• 2014

In order to develop stretchable substrates for wearable packaging applications, the variation behavior of elastic modulus was evaluated for transparent PDMS Sylgard 184 and black PDMS Sylgard 170 as a function of the base/curing agent mixing ratio. Both for Sylgard 184 and Sylgard 170, the true elastic modulus evaluated on a true stress-true strain curve was higher more than two times compared to the engineering elastic modulus obtained from an engineering stres-sengineering strain curve, and their difference became larger with increasing the stiffness of the PDMS. Sylgard 184 exhibited a maximum engineering elastic modulus of 1.74 MPa and a maximum true elastic modulus of 3.57 MPa at the base/curing agent mixing ratio of 10. A maximum engineering elastic modulus of 1.51 MPa and a maximum true elastic modulus of 3.64 MPa were obtained for Sylgard 170 at the base/curing agent mixing ratio of 2.

• Nuclear Engineering and Technology
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• v.44 no.8
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• pp.953-960
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• 2012

This paper reports the irradiation effect on the deformation behavior and tensile fracture properties of A533B RPV steel. An inverse identification technique using iterative finite element (FE) simulation was used to determine those properties from tensile data for the A533B RPV steel irradiated at 65 to $100^{\circ}C$ and deformed at room temperature. FE simulation revealed that the plastic instability at yield followed by softening for higher doses was related to the occurrence of localized necking immediately after yielding. The strain-hardening rate in the equivalent true stress-true strain relationship was still positive during the necking deformation. The tensile fracture stress was less dependent on the irradiation dose, whereas the tensile fracture strain and fracture energy decreased with increasing dose level up to 0.1 dpa and then became saturated. However, the tensile fracture strain and fracture energy still remained high after high-dose irradiation, which is associated with a large amount of ductility during the necking deformation for irradiated A533B RPV steel.