• Journal of the Computational Structural Engineering Institute of Korea
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• v.17 no.4
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• pp.413-421
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• 2004

In this paper, a structural analysis for the pressurized water reactor(PWR) spent nuclear fuel disposal canister which is deposited under the 500m deep underground is carried out to predict the creep deformation of the canister while the underground water and swelling bentonite pressure are applied on the canister. Usually the creep deformation may be caused due to the Pressure and the high heat applied to the canister even though additional external loads are not applied to the canister. These creep deformations depend on the time. In this paper, oかy the underground water and bentonite swelling Pressure are considered for the creep deformation analysis of the canister, because the heat distribution inside canister due the spent fuel is not simple and depends on time. A proper creep function is adopted for the creep analysis. The creep analysis is carried out during $10^8$ seconds. The creep analysis results show that the creep strains are very small and these strains occur usually in the lid and bottom of the canister not in the cast iron insert. A much smaller strain is found in the cast iron insert. Hence, the creep deformation doesn't affect the structural safety of the canister, and also the creep stress which shows the stress relaxation phenomenon doesn't affect the structural safety of the canister.

• Journal of the Korean Geotechnical Society
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• v.30 no.8
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• pp.13-24
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• 2014

A series of trapdoor model tests was systematically performed in order to investigate soil arching. The mobilized soil arching was clearly observed by change of the vertical earth pressure loaded on trapdoor of soil container box. A slow decent of the loading plate at the trapdoor results in loosening zone over the trapdoor and the stress in this loosening zone was transferred to the stationary zone in the vicinity of the trapdoor. In particular, it was observed that the vertical earth pressure rapidly decreased in the loosening zone and increased in the stationary zone at the trapdoor. Both the maximum decreasing rate of the vertical earth pressure in the loosening zone and the increasing rate of the vertical earth pressure in the stationary zone were not influenced by the ground density, but affected by the size of the trapdoor. The loosening zone could be defined by the elliptical configuration, in which the major axis was twice as long as the height of the loosening zone at the center of trapdoor and the minor axis was the same as the width of trapdoor. The height of loosening zone at the center of trapdoor was one and a half times as long as the width of trapdoor loading plate.

• Transactions of the Korean Society of Mechanical Engineers
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• v.12 no.3
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• pp.473-480
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• 1988

In this study, a method that can realize the effect of residual stresses on fatigue crack propagation has been proposed. This method requires that the relaxation quantities of residual stresses are measured by experimental method according to fatigue cycles and are employed to the experimental results of base materials by introducing the concept of superposition. SS41 material has been analyzed as an example. The results show that the relaxation factor of residual stresses for fatigue cycles is .alpha.$_{i}$= 1/0.6903+0.0380 $a_{I}$ the effective stress ratio for fatigue crack propagation length is ( $R_{eff}$)$_{i}$ = 1/1.1274+0.0118$_{I}$ and the fatigue crack propagation rate for relaxation quantities of residual stresses is (da/dN)$_{t}$ = 0.5 $K_{cf}$ - .DELTA.K/{1-1/1.1274+0.0118$_{ai}$ } $K_{cf}$ - .DELTA. K(da/dN), for stress ratio /R=0.5.io /R=0.5.5.

• Journal of Korean Association for Spatial Structures
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• v.10 no.3
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• pp.57-64
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• 2010

Uniaxial tensile tests of ETFE membrane are performed in this paper. Three kinds ETFE membrane with different thickness are used in the tests. The tensile strength, the tensile strain at break and the stress-strain curve are obtained from the tests. Futhermore, The cycle loading test of ETFE membrane is carried out through using different values of cycle stress. The residual strain, the relaxation of stress and the change of the elastic modulus of foil are investigated. In the creep test, three kinds of temperature (25, 40 and 60 $^{\circ}C$)and three kinds of stress(3,6and9 MPa) are set respectively and the creep time lasts 24 hours.

• Computational Structural Engineering
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• v.10 no.2
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• pp.131-138
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• 1997

This paper concerns the stress singularity at the interface corner of the viscoelastic adhesive layer bonded between rigid adherends, subjected to a uniform transverse tensile strain. The characteristic equation is derived in the Laplace transformed space, following Williams, and the transformed characteristic equation is inverted analytically into real time space for the viscoelastic model considered here. The order of the singularity is obtained numerically. The time-domain boundary element method is employed to investigate the nature of stresses along the interface. Numerical results show that the order of the singularity increases with time while the free-edge stress intensity factors are relaxed with time.

• Journal of the Korean Society for Nondestructive Testing
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• v.28 no.2
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• pp.125-130
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• 2008

A spherical indentation has been proposed as a nondestructive method of measuring local residual stress field in laser-voided joints. The apparent yield strengths interpreted from the spherical indentation data of as-welded cutting wheel were compared with the intrinsic yield strengths measured at nearly equivalent locations in annealed wheel. Their difference along the distance from the welding line is welding stress distribution because the intrinsic yield strength is invariant regardless of the elastic residual stress. The spherical indentations show that the laser-welded diamond cutting wheel displays a 10 min-wide distribution of the welding residual stress and has peak compressive and tensile stresses in the shank and tip regions, respectively.

• Journal of the Korean GEO-environmental Society
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• v.15 no.7
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• pp.23-30
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• 2014

This paper deals with the characteristics of deformation of the underground corrugated steel plate culverts constructed in the areas where the minimum depth of within 1.5 m soil cover is not secured in the bottom of highways. The underground corrugated steel plate culverts at shallow depth are often designed and constructed with the consideration of the minimum depth of soil cover according to the design standards, which was made in order to minimize any deformation. Additionally, if under unfavorable conditions, slabs are set up for stress relaxation to disperse and minimize the weight of loads transferred to the corrugated steel plate culverts. Nevertheless, if the underground corrugated steel plate culverts are built in areas where the minimum depth of soil cover inevitably cannot be secured, there may occur some deformation. In this paper, a research was carried out to identify the characteristics of deformation in areas where the minimum depth of soil cover is not secured. The result shows that there existed the deterioration of pavement and in its smoothness around the corners of slabs for stress relaxation. To this end, this paper studied the structural stability of the underground corrugated steel plate culverts established in the areas with no minimum depth of soil cover secured, with the consideration of causes and solutions of pavement deterioration.

• Journal of the Korean Society of Food Science and Nutrition
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• v.42 no.3
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• pp.421-426
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• 2013

We evaluated physical properties such as density, compressive characteristics, irrecoverable work, and stress relaxation of red pepper powder with different particle sizes. The particle sizes showed a normal distribution in size, with a particle size of $150{\sim}600{\mu}m$ accounting for 70.95% of the particles in the Hanbando cultivar and 82.21% in the Cheongyang cultivar. Loose bulk density ranged between 0.34 and $0.45g/cm^3$, while tapped bulk density ranged between 0.43 and $0.56g/cm^3$. The Hausner ratio was highest (1.531) at a particle size below $150{\mu}m$ in the Cheongyang cultivar. The compressibility and compression ratios were 0.001351~0.004383 and 1.0062~1.0265, respectively. Irrecoverable work ranged between 69.16% and 90.24%. The $K_2$ value and stress relaxation characteristics were greatest (1.74 and 44.92%, respectively) at particle sizes of $300{\sim}425{\mu}m$ in the Cheongyang cultivar. The dynamic angle of repose was $32.84-49.84^{\circ}$. Overall, particle sizes below $150{\mu}m$ had the highest compactibility, cohesiveness, and transformation.

• Journal of the Korean Society of Food Science and Nutrition
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• v.40 no.4
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• pp.599-605
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• 2011

This study investigated the physical properties of red pepper powders according to cultivation area and variety. Values for density, compressive characteristics, dynamic angle, irrecoverable work, and stress relaxation were analysed. Loose bulk density ranged between 0.40 and 0.50 g/$cm^3$, and tapped bulk density ranged between 0.49 and 0.67 g/$cm^3$. The highest Hausner ratio was 1.369 for PRmanitta cultivated in Eumseong and the lowest value of was 0.194 for Buchon cultivated in Yeongyang. Compressibility ranged between 0.0046 and 0.0092. The highest compression ratio was 1.040 for Myeongjak cultivated in Suwon, and the lowest value was 1.007 for Buchon cultivated in Yeongyang. Dynamic angles ranged between 35.14 and $41.70^{\circ}$. The highest irrecoverable work value was 79.9% for PRmanitta cultivated in Eumseong and the lowest value was 67.9% for Nokgwang cultivated in Suwon. The greatest $k_2$ and relaxation values of stress relaxation characteristics were 1.56 and 42.03%, respectively, for Cheongyang cultivated in Yeongyang.

• Journal of Korean Tunnelling and Underground Space Association
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• v.19 no.5
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• pp.733-747
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• 2017

In the shallow tunnel, the surrounding ground could be loosened and deformed, which could be the cause of stress change in the ground. Terzaghi has clarified the development of a ground arching induced by the deformation of a tunnel crown in the trap door tests. However, he considered only the case in which that the tunnel crown deformed uniformly. He did not consider the effect of deformation shapes. Therefore, the relation between the shape of the ground relaxation above the tunnel crown and the deformation shape of the tunnel crown is not clear yet. In this study, model tests were performed for the three types of the tunnel crown, such as uniform, concave and convex shapes. As results, it was found that the vertical load would be transferred in various types depending on the deformation shapes of the tunnel crown.