• Steel and Composite Structures
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• 제36권2호
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• pp.163-177
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• 2020

Concentrically Braced Frames (CBFs) are commonly used in the construction of steel structures because of their ease of implementation, rigidity, low lateral displacement, and cost-effectiveness. However, the principal disadvantage of this kind of braced frame is the inability to provide deformation capacity (ductility) and buckling of bracing elements before yielding. This paper aims to present a novel Composite Buckling Restrained Fuse (CBRF) to be utilized as a bracing segment in concentrically braced frames that allows higher ductility and removes premature buckling. The proposed CBRF with relatively small dimensions is an enhancement on the Reduced Length Buckling Restrained Braces (RL-BRBs), consists of steel core and additional tensile elements embedded in a concrete encasement. Employing tensile elements in this composite fuse with a new configuration enhances the energy dissipation efficiency and removes the tensile strength limitations that exist in bracing elements that contain RL-BRBs. Here, the optimal length of the CBRF is computed by considering the anticipated strain demand and the low-cyclic fatigue life of the core under standard loading protocol. An experimental program is conducted to explore the seismic behavior of the suggested CBRF compare with an RL-BRB specimen under gradually increased cyclic loading. Moreover, Hysteretic responses of the specimens are evaluated to calculate the design parameters such as energy dissipation potential, strength adjustment factors, and equivalent viscous damping. The findings show that the suggested fuse possess a ductile behavior with high energy absorption and sufficient resistance and a reasonably stable hysteresis response under compression and tension.

• Fashion & Textile Research Journal
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• 제18권1호
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• pp.120-129
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• 2016

This study aimed to develop an optimal sizing system and a draping pattern for hip protector based on an analysis of anthropometric characteristics of Korean older women. A hip protector is a specialized form of pants or underwear containing pads along the outside of each hip. The 3D body scan data of Korean older women were analyzed to identify their anthropometric characteristics and a four-size system with 93% of population accommodation was developed by clustering analysis based on key dimensions derived from factor analysis. The sizing system consists of small/short, large/short, small/tall, and large/tall. A 3D physical model and hip pads were fabricated; then, a hip protector was draped on the 3D model and hip pads. The sizing system of hip protector was analyzed in terms of size and shape and a draping pattern was compared on back center, back side, front side, front center and pad. Lastly, the pattern deformation and clothing pressure were analyzed using the virtual clothing system CLO. Virtual system have disadvantage of not to suggest the objective value. In the future research the wearing comfort and impact absorption of the hip protector needs to be tested and then a hip protector design will be finalized by considering the hip protector's size, material, comfort testing results, aesthetic appeal, protection effectiveness, and practical utility of everyday use.

• Computers and Concrete
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• 제19권3호
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• pp.233-241
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• 2017

During the last two decades, CFRP have been extensively used for repair and rehabilitation of existing structures as well as in new construction applications. For rehabilitation purposes CFRP are currently used to increase the load and the energy absorption capacities and also the shear strength of concrete columns. Thus, the effect of CFRP confinement on the strength and deformation capacity of concrete columns has been extensively studied. However, the majority of such studies consider empirical relationships based on correlation analysis due to the fact that until today there is no general law describing such a hugely complex phenomenon. Moreover, these studies have been focused on the performance of circular cross section columns and the data available for square or rectangular cross sections are still scarce. Therefore, the existing relationships may not be sufficiently accurate to provide satisfactory results. That is why intelligent models with the ability to learn from examples can and must be tested, trying to evaluate their accuracy for composite compressive strength prediction. In this study the forecasting of wrapped CFRP confined concrete strength was carried out using different Data Mining techniques to predict CFRP confined concrete compressive strength taking into account the specimens' cross section: circular or rectangular. Based on the results obtained, CFRP confined concrete compressive strength can be accurately predicted for circular cross sections using SVM with five and six input parameters without spending too much time. The results for rectangular sections were not as good as those obtained for circular sections. It seems that the prediction can only be obtained with reasonable accuracy for certain values of the lateral confinement coefficient due to less efficiency of lateral confinement for rectangular cross sections.

• Journal of Environmental Health Sciences
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• 제8권1호
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• pp.31-43
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• 1982

Seventy-seven Mugil cephalus of spinal deformation, living in Hanam, Nogsan, and Myeongji area, the downstreams of the Nagdong River, were collected in order to determine their forms and the levels of heavy metal contamination between March and October, 1981. The specimens were examined by X-ray and content of cadmium, lead, copper, and zinc by atomic absorption spectrophotometer. The results were summarized as follows: 1. The rate of appearance of deformational fish to the total Mugil cephflus were 4.3% (13 fish), 5.7% (17 fish), relatively high in May and June (dry season). Meanwhile during March and October they were low by 1.0% (3 fish), 2.0% (6 fish). As far as the research areas are concerned, they appeared in larger numbers in downstreams than in upper streams Myeongji (39), Nogsan (25), and Hanam (13). 2. Concerning with fractured parts of vertebraes,86 percent (66 out of 77) had their caudal regions fractured and 72 percent (55) their first to seventh caudal regions fractured. 3. The average levels of cadmium, lead, copper, zinc detected from flesh were 0.26ppm, 2.06ppm, 6.35ppm, 0.85ppm on the other hand, they were 0.22ppm, 1.84ppm, 5.03ppm, 0.93ppm in normal fish. 4. The average levels of cadmium, lead, copper, zinc measured in the bones were 0.39ppm, 2.55ppm, 8.97ppm, 2.73ppm. Meanwhile, from normal fish they were 0.33ppm, 2.25ppm, 7.24ppm, 2.42ppm. 5. Compared with regional heavy metal contamination such as cadium, lead, zinc, Myeongji area had higher contamination content than Nogsan area Nogsan area than Hanam area. 6. Compared with heavy metal contamination level in their tissues, cadmium was highly found in bones Lead and copper were highly detected in viscera. Particularly in skeleton cadmium was 560 times, zinc 160 times in proportion to those in the downstreams of the Nagdong River.

• Journal of Korean Society of Steel Construction
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• 제15권5호통권66호
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• pp.561-570
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• 2003

This study evaluate the characteristics of stainless steel for the use of stainless steel tubes as structural members. The strength of stainless steel tube was compared with that of steel tube stub-columns through tensile experiment and compressed experiment. The selected experimental parameters were diameter (width)-thickness and section shape. The results of tests showed that stainless steel tubes could be predicted as superior to steel tubes in terms of tensile strength, yield ratio, elongation percentage, and absorption ability of energy. The yield strength of stainless steel tubes were found to be higher than the Korean Standards ($Fy=2.1tf/cm^2$) and the design strength of SIJ-ASD($Fy=2.4tf/cm^2$). It was also higher then the yield strength of steel tubes. The plastic deformation of stainless steel tubes was found to beto that of steel tubes.

• Environmental Analysis Health and Toxicology
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• 제20권1호
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• pp.13-21
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• 2005

The purpose of this study was to determine the effects of bisphenol A (BPA), which is known to have estrogenic activity, on the early development of medaka fish (Oryzias latipes). The fertilized eggs of medaka were treated with BPA at different concentrations for 3 weeks. Embryonic growth, deformation, hatching success, and gonadal differentiation were determined to observe the effects of this chemical. Also we tried to measure the estrogenic activity of bisphenol A using ELISA and RT-PCR methods. By using this techniques, we evaluated the induction of vitellogenin, an estrogen-regulated gene from the whole body-homogenates of larvae. At results, a reduced blood circulation was seen in embryos and peritoneal edema and hindrance of yolk-sac absorption were observed in larvae of treated group. However, BPA at the concentrations tested (2～200 ㎍/L) did not have severe adverse effects on the early life-stages. According to the observation of gonadal histology, inter-sex or sex -reversal was not found in all test fish. After the exposure was ended, vitellogenin mRNA and protein levels were measured in larvae and then their levels were found to be increased in treated group with 200㎍/L. These results indicate that BPA can induce the expression of vitellogenin in early life-stages as well as in adult male fish.

• Journal of the Korea institute for structural maintenance and inspection
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• 제19권6호
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• pp.10-17
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• 2015

In this study, to examine seismic reinforcement effect of a school building constructed prior to application of seismic design, a Double I-type damper supported by wall was installed to perform comparative analysis on existing non-seismic designed RC frame. As a result of experiment, while non-seismic designed specimen showed rapid reduction in strength and brittle shear destruction as damages were focused on top and bottom of left and right columns, reinforced specimen showed hysteretic characteristics of a large ellipse with great energy absorption ability, exhibiting perfectly behavior with increased strength and stiffness from damper reinforcement. In addition, as a result of comparing stiffness reduction between the two specimens, specimen reinforced by shear wall type damper was effective in preventing stiffness reduction. Energy dissipation ability of specimen reinforced by Double I-type damper was about 3.5 times as high as energy dissipation ability of non-reinforced specimen. Such enhancement in energy dissipation ability is considered to be the result of improved strength and deformation.

• Steel and Composite Structures
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• 제37권2호
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• pp.175-191
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• 2020

In this article, for the first time, the seismic behavior of elliptic-braced moment resisting frame (ELBRF) is assessed through a laboratory program and numerical analyses of FEM specifically focused on the development of global- and local-type failure mechanisms. The ELBRF as a new lateral braced system, when installed in the middle bay of the frames in the facade of a building, not only causes no problem to the opening space of the facade, but also improves the structural behavior. Quantitative and qualitative investigations were pursued to find out how elliptic braces would affect the failure mechanism of ELBRF structures exposed to seismic action as a nonlinear process. To this aim, an experimental test of a ½ scale single-story single-bay ELBRF specimen under cyclic quasi-static loading was run and the results were compared with those for X-bracing, knee-bracing, K-bracing, and diamond-bracing systems in a story base model. Nonlinear FEM analyses were carried out to evaluate failure mechanism, yield order of components, distribution of plasticity, degradation of structural nonlinear stiffness, distribution of internal forces, and energy dissipation capacity. The test results indicated that the yield of elliptic braces would delay the failure mode of adjacent elliptic columns and thus, help tolerate a significant nonlinear deformation to the point of ultimate failure. Symmetrical behavior, high energy absorption, appropriate stiffness, and high ductility in comparison with the conventional systems are some of the advantages of the proposed system.

• Transactions of the Korean Society of Mechanical Engineers A
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• 제35권9호
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• pp.1021-1026
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• 2011

Structural impact problems are becoming increasingly important for a modern defense industry, high-speed transportation, and other applications because of the weight reduction with high strength. In this study, a numerical investigation on the impact fracture behavior of aluminum plates was performed under various projectile conditions such as nose shapes, velocities, and incidence angles. In order to reduce the iterative numerical analysis, the Latin Square Method was employed. The influence factor was then determined by an FE analysis according to the conditions. The results were evaluated by means of a statistical significance interpretation using variance assessment. It was shown that the velocity and incidence angle can be the most important influence factors representing the impact absorption energy and plastic deformation, respectively.

• Korean Journal of Food Science and Technology
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• 제37권5호
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• pp.763-767
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• 2005

Effect of ${\alpha}-amylase$ and various emulsifiers on characteristics of bread dough were examined. Fungal or bacterial ${\alpha}-amylase$ and various emulsifiers including monoglyceride (MG), sodium stearoyl-2-lactylate (SSL), and diacetyltartaric acid ester of mono- and diglycerides (DATEM) were added to bread dough both individually and as mixtures. Rheological characteristics of various bread doughs were examined through falling number, farinograph, alveograph, and rapid visco analysis. Results obtained showed falling number decreased via degradation of starch by ${\alpha}-amylase$. In farinogram, addition of ${\alpha}-amylase$ and emulsifiers in dough decreased consistency, water absorption, mechanical tolerance index, and dough development time. Farinogram characteristic was improved by adding SSL+MG to dough formula. Similar to farinogram addition of ${\alpha}-amylase$ and emulsifiers in alveogram of dough decreased overpressure, extensibility, swelling index, and deformation energy. Whereas addition of ${\alpha}-amylase$ did not affect pasting temperature, viscosity of dough tended to decrease.