• Structural Engineering and Mechanics
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• v.89 no.4
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• pp.421-436
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• 2024

This research addresses experimentally the relationship between the excitation frequency and both hoop and axial wall stresses in a water storage tank. A low-density polyethylene tank with six different aspect ratios (water level to tank radius) was tested using a shake table. A laminar box with sand represents a soil site to simulate Soil-Structure Interaction (SSI). Sine excitations with eight frequencies that cover the first free vibration frequency of the tank-water system were applied. Additionally, Ricker wavelet excitations of two different dominant frequencies were considered. The maximum stresses are compared with those using a nonlinear elastic spring-mass model. The results reveal that the coincidence between the excitation frequency and the free-vibration frequency of the soil-tank-water system increases the sloshing intensity and the rigid-like body motion of the system, amplifying the stress development considerably. The relationship between the excitation frequency and wall stresses is nonlinear and depends simultaneously on both sloshing and uplift. In most cases, the maximum stresses using the nonlinear elastic spring-mass model agree with those from the experiments.

• Nuclear Engineering and Technology
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• v.56 no.2
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• pp.506-519
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• 2024

To simulate the verification process using materials from a decommissioned reactor, a mock-up of the bottom-mounted instrument nozzle in the Kori 1 reactor, where the nozzle was attached to a plate by J-groove dissimilar metal welding, was fabricated. The mock-up distortion was quantified by measuring the plate surface displacement after welding. The residual stresses formed on the support plate surface and the inner surface of the nozzle were then analyzed using the hole-drilling method, contour method, and neutron diffraction. Welding simulations were performed using a 3D finite element method to validate the measured results. The measured and computed stress distributions on the support plate exhibited reasonable agreement. Conversely, the stresses on the inside of the nozzle were found to have an indisputable difference in the contour method and neutron diffraction measurements, which demonstrated strong tensile and compressive hoop stresses, respectively. The possible origins of such differences were investigated and we have provided some suggestions for a precise evaluation in the simulation. This study is expected to be useful in future research on decommissioned reactors.

• Nuclear Engineering and Technology
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• v.55 no.12
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• pp.4647-4658
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• 2023

In this paper, elastic-plastic fracture mechanics analysis is performed to determine the critical crack sizes of the multipurpose canister (MPC) manufactured using austenitic stainless steel under dynamic loading conditions that simulate drop accidents. Firstly, dynamic finite element (FE) analysis is performed using Abaqus v.2018 with the KORAD (Korea Radioactive Waste Agency)-21 model under two drop accident conditions. Through the FE analysis, critical locations and through-thickness stress distributions in the MPC are identified, where the maximum plastic strain occurs during impact loadings. Then, the evaluation using the failure assessment diagram (FAD) is performed by postulating an external surface crack at the critical location to determine the critical crack depth. It is found that, for the drop cases considered in this paper, the principal failure mechanism for the circumferential surface crack is found to be the plastic collapse due to dominant high bending axial stress in the thickness. For axial cracks, the plastic collapse is also the dominant failure mechanism due to high membrane hoop stress, followed by the ductile tearing analysis. When incorporating the strain rate effect on yield strength and fracture toughness, the critical crack depth increases from 10 to 20%.

• Journal of the Earthquake Engineering Society of Korea
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• v.10 no.4 s.50
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• pp.85-94
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• 2006

In the design of bridge piers in seismic area, the ductility requirement is the most important factor. In order to enhance the seismic performance of RC columns, it is necessary to make the ductility of columns larger by covering RC columns with steel tubes or confining RC columns by arranging transverse reinforcements such as hoop ties closely. Using core steel composite columns is useful as one of the reinforcing RC columns. In this paper, quasi-static tests on concrete encased composite columns with single core steel or multiple steel elements were performed to investigate the seismic performance of the composite columns. Eight concrete-encased composite specimens were fabricated. The cross-sections of these specimens are composed of concrete-encased H-shaped structural steel columns and a concrete-encased circular tube with partial in-filled concrete. Test parameters were the amount of the transverse reinforcements, type and number of encased steel member. Through the tests, it was evaluated the ductility of SRC composite specimens. It has become clear from the test results that encased steel elements makes the deformation capacity of the columns to be larger. The displacement ductility and lateral strength of specimen with concrete-encased circular tube were indicated the biggest value.

• Journal of the Korean Institute of Gas
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• v.15 no.6
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• pp.57-62
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• 2011

In this study, the optimized design for 130 liter storage fuel tank with 70MPa filling pressure has been investigated using a FEM technique and Taguchi design method. The strength safety of a composite fuel tank in which is fabricated by an aluminum liner of 6061-T6 material and carbon fiber wound composite layers of T800-24K has been analyzed based on the criterion of design safety of US DOT-CFFC and Korean Standard. The FEM computed results on the stress safety of 70MPa hydrogen gas tank were compared with a criterion of a stress ratio, 2.4 of US DOT-CFFC and Korean Standard, and indicated the safety. Thus, the optimized design elements based on the Taguchi's method were recommended as an aluminum liner thickness of 6.4mm, a carbon fiber laminate thickness in hoop direction of 31mm and a carbon fiber laminate thickness in helical direction of 10.2mm, which is represented by a design model of No. 5.

• Journal of the Korea institute for structural maintenance and inspection
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• v.9 no.2
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• pp.207-216
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• 2005

External confinement by CFS (Carbon Fiber Sheet) is a very effective retrofit method for the reinforced concrete columns subject to either static or seismic loads. For the reliable and cost-effective design of CFS, an accurate stress-strain model is required for CFS-confined concrete. In this paper, uniaxial compression test on short RC column with square section was performed. To evaluate the effect of confinement on the stress-strain relationship of CFS-confined concrete, CFS area ratio and tie area ratio are considered. Based on the experimental results, a stress-strain model is proposed for concrete confined by CFS wraps. In the development of the model, the method to compute the actual hoop strains in CFS jackets at the rupture was examined and resolved. Overall, the results of the model agree well with test data.

• Asian-Australasian Journal of Animal Sciences
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• v.30 no.9
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• pp.1358-1362
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• 2017

Objective: The objective of the present study was to compare growth performance of Berkshire purebred pigs (BB), Hereford (HB) and/or Tamworth (TB) sired Berkshire crossbred pigs reared in a hoop structure in two experiments. Methods: In the first experiment, BB was compared to TB while HB and TB were compared in the second. Body weights (BW) were recorded at 3 days of age and every 28 days from birth until 140 days of age. There was no significant difference between the BW of BB and TB, but HB was heavier than TB by 84 days of age. Least square means of average daily gain (ADG) were evaluated using one-way analysis of variance. Results: The mean parity (${\pm}$standard deviation) of the sows was $3.42{\pm}2.14$ and a total of 45 farrowing occurred from year 2012 to 2014. The mean number of total born, number born alive, number of mummies, and number weaned were $9.23{\pm}2.52$, $7.87{\pm}2.53$, $0.04{\pm}0.21$, and $5.94{\pm}2.74$, respectively. Parity did not have a significant effect on the growth performance of the pigs. For BB and TB, there was only one time frame in which there was a significant difference in the ADG: between 28 and 56 days of age. For HB and TB, the overall ADG of HB was significantly greater than the total ADG of TB. Conclusion: The breed of the sire did not affect the growth performance of the progeny between Berkshire purebreds and Tamworth${\times}$Berkshire crossbreds. The breed of the sire did have an effect between Hereford and Tamworth sired Berkshire crossbreds (p<0.05). The Hereford sired pigs were found to have increased growth performance compared to Tamworth sired.

• Asian-Australasian Journal of Animal Sciences
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• v.30 no.9
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• pp.1207-1214
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• 2017

Since the industrialization of swine production in the late 1900s, swine farms in the United States, as well as in Europe, have largely become consolidated. Pig farms became larger in size but fewer in number, with 91% of market pigs being produced by large operations with 5,000 or more pigs on-site in the US, and only 3% of the total utilized agricultural land representing organic farming. Such change in the market made it difficult for small farmers to stay competitive, forcing them to find alternative ways to reduce the cost of production and increase profit using the outdoor production system. In contrast to the indoor confinement system, outdoor production system uses pasture-based units and/or deep-bedded hoop structures that promote animal welfare and environmental sustainability with a lower capital investment. In accord with the growing concern for animal and environmental welfare and food safety by the consumers, small farmers practicing an outdoor production system are seeing increased opportunities for marketing their products in the pork niche market. Unlike the general belief that the reproductive and growth performance measures of the outdoor sows and piglets are poorer in comparison with the animals reared indoors, studies showed that there was no significant difference in the performance measures, and some traits were even better in outdoor animals. Improved reproductive and production traits can increase the sustainability of outdoor farming. Present study reviewed the recent studies comparing the performance measures, meat quality and health of indoor and outdoor animals, as well as the efforts to improve the outdoor production system through changes in management such as hut types and breed of animals.

• Advances in concrete construction
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• v.2 no.3
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• pp.177-192
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• 2014

One of the main applications of FRP composites is confining concrete columns. Hence identifying the cyclic and monotonic stress-strain behavior of confined concrete columns and the parameters influencing this behavior is inevitable. Two significant parameters affecting the stress-strain behavior are aspect ratio and corner radius. The present study aims to scrutinize the effects of corner radius and aspect ratio on different aspects of stress-strain behavior of FRP confined concrete specimens (rectangular, square and circular). Hence 44 FRP confined concrete specimens were tested and the results of the tests were investigated. The findings indicated that for specimens with different aspect ratios, the relationship between the ultimate stress and the corner radius is linear and the variations of the ultimate stress versus the corner radius decreases as a result of an increase in aspect ratio. It was also observed that increase of the corner radius results in increase of the compressive strength and ultimate axial strain and increase of the aspect ratio causes an increase of the ultimate axial strain but a decrease of the compressive strength. Investigation of the ultimate condition showed that the FRP hoop rupture strain is smaller in comparison with the one obtained from the tensile coupon test and also the ultimate axial strain and confined concrete strength are smaller when a prism is under monotonic loading. Other important results of this study were, an increase in the axial strain during the early stage of unloading paths and increase of the confining effect of FRP jacket with the increase and decrease of the corner radius and aspect ratio respectively, a decrease in the slope of reloading branches with cycle repetitions and the independence of this trend from the variations of the aspect ratio and corner radius and also quadric relationship between the number of each cycle and the plastic strain of the same cycle as well as the independence of this relationship from the aspect ratio and corner radius.

• Journal of the Korean Society of Costume
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• v.39
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• pp.139-166
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• 1998

This dissertation is to help understanding about the emergence of active children's clothes in the latter part of the 18th century in England. In previous ages children had not been look-ed upon as children, but as incomplete and in-ferior men and women, the costume of children had not been distinguishable from that of their elders. The early eighteenth-century chil-d could not play in comfort because they dressed like their parents. But in the third quarther of the eighteenth century children became free from their con-comfortable and became active. English chil-dren's clothes was prevailing even in Europe as well. In the background of this liberation, there were many enlightened ideas, such as philosophers of enlightenment, doctors, writers, educators. Among these John Locke and Jean Jacque Rousseau criticized openly about rampant fashion which was distorting the body by corset and hoop. Rousseau was the one who wrote$\boxDr$Emile$\boxUl$and played the most important role to free children from an old fashioned idea, and emphasized to bring up children by the natural process of mental and physical development as human beings are a part of nature. Fashion reflects politic, economic, social, ideology, culture of the days and these factor function to create fashion which shows“Time Spirit”.Children's clothes, like those of their parents, follow the fashion, but with a difference, the form of which varies with the attitude to the child. Thus this dissertation was to study in relation with the background of the times in the latter part of 18th century in England and Rousseau's Naturalism in connection with the emergence of active children's clothes. The result is that diffusion of the idea of freedom and equality, the growth of bourgeoisie, the development of clothing and tex-tile industry have influenced to the emergence of active children's clothes. Also a great deal of middle and high class parents devoted to their children's education and was influenced by Rousseau's Naturalism. Specially the bourgeoisie who made their fortune by their own effort were eager to educate their achievement and business by their children through education. This factor influenced to the children's clothes as well.