• Computers and Concrete
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• v.12 no.4
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• pp.499-518
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• 2013

Fiber reinforced polymer (FRP) jackets have been widely used as an effective tool for the strengthening and rehabilitation of concrete structures, especially damaged concrete columns. Therefore, a clear understanding of the compressive behavior of FRP-confined concrete is essential. The objective of this paper is to develop a simple efficient method for predicting the compressive strength, the axial strain at the peak stress, and the stress-strain relationship of FRP-confined concrete. In this method, a compressive strength model is established based on Jefferson's failure surface. With the proposed strength model, the strength of FRP-confined concrete can be estimated more precisely. The axial strain at the peak stress is then evaluated using a damage-based formula. Finally, a modified stress-strain relationship is derived based on Lam and Teng's model. The validity of the proposed compressive strength and strain models and the modified stress-strain relationship is verified with a wide range of experimental results collected from the research literature and obtained from the self-conducted test. It can be concluded that, as a competitive alternative, the proposed method can be used to predict the compressive behavior of FRP-confined concrete with reasonable accuracy.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.7
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• pp.1055-1063
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• 2001

When the interfacial crack of isotropic/orthotropic bi-materials is propagated with constant velocity along the interface, stress and displacement components are derived in this research. The dynamic photoelastic experimental hybrid method for the bimaterial is introduced. It is assured that stress components and dynamic photoelastic hybrid developed in this research are valid. Separating method of stress components is introduced from only dynamic photoelastic fringe patterns. Crack propagating velocity of interfacial crack is 69∼71% of Rayleigh wave velocity of epoxy resin. The near-field stress components of bonded interface of bimaterial are similar with those of pure isotopic material and two dissimilar isotropic bimaterials under static or dynamic loading, but very near-field stress components of bonded interface of bimaterial are different from those.

• The Journal of Korean Medicine
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• v.17 no.2 s.32
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• pp.277-290
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• 1996

This study was aimed to evaluate the anti-pain effect of Kamikuibitang in acetic acid method and the anti-ulceration effect of Kamikuibitang in indomethacin, aspirin and immobilization stress method in rats. The results were follows; 1. The anti-pain effects of Kuibitang and Kamikuibitang were decreased compared with those of control group. 2. In indomethacin and aspirin method, the anti-ulcerative effects of experimental groups were shown compared with those of control group. 3. In immobilization stress method, the anti-ulcerative effect of experimental groups was significantly shown compared with that of control group. 4. The serum gastrin levels of Kuibitang groups showed very significant decrease in indomethacin-induced and immobilization stress-induced ulcers. The serum gastrin levels of Kamikuibitang groups showed very significant decrease in indomethacin-induced, aspirin- induced and immobilization stress-induced ulcers. 5. The serum $V_{B12}$ levels of Kuibitang groups showed very significant increase in both indomethacin-induced and immobilization stress-induced ulcers. The serum $V_{B12}$ levels of Kamikuibitang groups showed significant increase in aspirin-induced and immobilization stress-induced ulcers whereas very significant increase in indomethacin-induced ulcer. According to the above results, it was concluded that Kamikuibitang had very significant anti-ulceration effect as well as anti-pain effect on gastric ulcer in rats.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.10
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• pp.1671-1677
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• 2001

Cracks at mechanical fastener holes usually nucleate as elliptical comer cracks at the faying surface of the mechanical joints and grow as elliptical arc through cracks. The weight function method for elliptical arc through cracks at mechanical fastener holes has been developed and verified in the part I of this study. In part H, applying the weight function method, the effects of the amount of clearance on the mixed-mode stress intensity (actors are investigated and the change of crack shape is predicted from the analysis for various crack shapes. The stress intensity factors leer inclined crack are analyzed and critical angle at which mode I stress intensity factor becomes maximum is determined.

• Journal of the Society of Naval Architects of Korea
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• v.51 no.1
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• pp.26-33
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• 2014

In this study, Non-load-carrying EH Grade steels in fillet welded joints were evaluated with both the hot spot stress method and the 1mm stress method. The thickness effect criterion for fatigue strength evaluation of welded of welded steel structures recommendations of the IIW was used to evaluate the fatigue strength of EH40 and EH36 and Both EH40 and EH36 have been compared with FAT 125 curve recommended in the IIW. Furthermore, fatigue strength of the welded tow and the ground conditions for Non-load-carrying EH36 based on the 1mm stress method has been discussed.

• Nuclear Engineering and Technology
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• v.54 no.12
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• pp.4481-4490
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• 2022

In this study, a new rupture disk corrosion test (RDCT) method was developed for real-time detection of stress corrosion cracking (SCC) initiation of Alloy 600 in a primary water environment of pressurized water reactors. In the RDCT method, one side of a disk specimen was exposed to a simulated primary water at high temperature and pressure while the other side was maintained at ambient pressure, inducing a dome-shaped deformation and tensile stress on the specimen. When SCC occurs in the primary water environment, it leads to the specimen rupture or water leakage through the specimen, which can be detected in real-time using a pressure gauge. The tensile stress applied to the disk specimen was calculated using a finite element analysis. The tensile stress was calculated to increase as the specimen thickness decreased. The SCC initiation time of the specimen was evaluated by the RDCT method, from which result it was found that the crack initiation time decreased with the decrease of specimen thickness owing to the increase of applied stress. After the SCC initiation test, many cracks were observed on the specimen surface in an intergranular fracture mode, which is a typical characteristic of SCC in the primary water environment.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.66-71
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• 2007

Isochromatics obtained from photoelastic experiment shows the stress distributions of full field of a structure under a load. Therefore stress distributions of the structure can be read at a glace through isochromatics. Many experimental data are obtained from isochromatics. And then, the various photoelastic experimental hybrid methods have been developed. Until now, monochromatic light has been used for photoelastic experimental hybrid method. Therefore the photoelastic experimental hybrid method used until now is called the photoelastic experimental hybrid method for black and white isochromatics. When stresses are analyed by photoelastic experimental hybrid method, many experimental data are needed. Therefore some fringe orders of isochromatics are needed for the photoelastic experimental hybrid method for white and black isochromatics. Therefore in this paper, the photoelastic experimental hybrid method for color isochromatics is developed. In this case, two fringe orders are enough for the experimental data of photoelastic experimental hybrid method for color isochromatics. Applying the method to stress concentration problems, its validity is confirmed. In the precision, the photoelastic experimental hybrid method for color isochromatics is better than the photoelastic experimental hybrid method for white and black isochromatics when fringe orders of isochromatics are few. When fringe orders are few, the photoelastic experimental hybrid method for color isochromatics can be used to analyze stress through few fringe orders of isochromatics.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.3 s.174
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• pp.743-751
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• 2000

Because welding residual stress is formidable result in electric resistance spot welding process, and it detrimentally affect to fatigue crack initiation and growth at nugget edge of spot welded la p joints, it should be considered in fatigue analysis. Thus, accurate prediction of residual stress is very important. In this study, nonlinear finite element analysis on welding residual stress generated in process of the spot welding was conducted, and their results were compared with experimental data measured by X-ray diffraction method. By using their results, the maximum principal stress considered welding residual stress at nugget edge of the spot welded lap joint subjected to tension-shear load was calculated by superposition method. And, the $\Delta$P- $N_f$ relations obtained through fatigue, tests on the IB-type spot welded lap joints was systematically rearranged with the maximum principal stress considered welding residual stress. From the results, it was found th2at fatigue strength of the IB-type spot welded lap joints could be systematically and more reasonably rearranged by the maximum principal stress($\sigma$1max-res considered welding residual stress at nugget edge of the spot welding point.

• Research in Community and Public Health Nursing
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• v.12 no.3
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• pp.732-745
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• 2001

This study attempted to identify obese students' stress and coping method in middle and high schools. The data were collected from the total of 600 obese students from middle and high schools in Pusan. The author used a convenience sampling method. The data collection was done from March 2 to April 30. 2001. The analysis of the data was done with SPSS Win(10.0) for descriptive statistics. t-test. and ANOVA. The instrument used for the obese students' stress and coping method was a questionnaire developed by Kim. Yi-Soon and Kim. Young-Hae(200l). The tool was composed of 65 items (33stress items: 32coping method items) with the five-point Likert scale. The results were as follow: 1. The average score of stress was 2.49 (SD = .86) points in the male students. and 2.83(SD= .86) points in the female students. The subcategories were: (outward appearance), (boyfriend/girlfriend), (occurrence of an outbreak of a disease), (relationship within the family), (an obese appearance), (difficulty in exercise). The highest degree of stress came from 'an obese appearance' for the male students (mean=2.64. SD=0.87) and (mean=2.64. SD=0.87) for the female students. 2. The subcategories of the coping method were: (be concerned about other matters), (recreation activities), (self-violence), (relaxation), (hobby activities), (avoid a situation), (communication), (music), (negative behavior), (positive thinking). The highest degree of coping method were (recreation activities) in the male students (mean=3.07. SD=0.86) and (music) in the female students (mean=3.47. SD=1.01). 3. The results comparing stress with demographic variables were significant for gender (t=7.010. p=0.000). grades at school (F=2.918. p=0.02l), degree of obesity (F=5.205. p=0.006). grades (F=2.550. p=0.027). standard of living(F=8.277. p=0.000). the state of health (F=2.882, p=0.022), relationship with the father (F=4.790, p=0.001), relationship with the mother (F=6.080, p=0.000), and the educational level of the father (F=3.192, p=0.013). 4. The results comparing the coping method with demographic variables were significant for gender (t=4.597. p=0.000). These findings contribute to the understanding of the degree of stress and the type of coping methods of obese students in middle and high schools. Therefore, the result of this study aids in an effective nursing intervention to improve the mental health program for the obese.

• Journal of Korean Tunnelling and Underground Space Association
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• v.9 no.3
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• pp.275-286
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• 2007

In construction of a structure in underground space, in-situ stress in rock mass has great effect on the stability of the structure. Especially, the direction and magnitude of rock stress have influence on the excavation method, the choice of support and reinforcement method for establishing the stability of tunnel. Therefore, it is very important to consider the characteristics of in-situ stress in rock mass for tunnel stability analysis. In this study, a reasonable design method for underground structure was reviewed through the case study for tunnel design considering in-situ rock stress. For this purpose, the estimation for SRF (Stress Reduction Factor) as input parameter in rock classification using Q-System and the assesment for tunnel support were studied. Also, considering the characteristics of in-situ rock stress such as the magnitude of K and the direction of principal stress, the parameter studies for tunnel stability analysis were carried out. An improved method was proposed for obtaining the better results in the tunnel stability analysis.