• Structural Engineering and Mechanics
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• v.40 no.6
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• pp.867-883
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• 2011

Six reinforced concrete beam-column joint specimens were constructed and tested under reverse cyclic loading to failure. The six specimens were divided into three groups, each group representing a different joint design. The main objectives of this study are to investigate the response of joints with three different design, reinforcement detailing and beam strengths, and to evaluate and compare the responses of beam-column joints reinforced with traditional steel rebar and a recently proposed steel reinforcement called prefabricated cage system (PCS). Each of the three test specimen designs included equivalent amount of steel reinforcement and had virtually identical details. The results of the research show that the PCS reinforced joints had a slightly higher strength and significantly larger deformation capacity than the equivalent rebar reinforced joints.

• Steel and Composite Structures
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• v.32 no.1
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• pp.59-66
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• 2019

Hollow steel-reinforced concrete-filled GFRP tubular member is a new kind of composite members. Firstly set the mold in the GFRP tube (non-bearing component), then set the longitudinal reinforcements with stirrups (steel reinforcement cage) between the GFRP tube and the mold, and filled the concrete between them. Through the axial compression test of the hollow steel-reinforced concrete-filled GFRP tubular member, the working mechanism and failure modes of composite members were obtained. Based on the experiment, when the load reached the ranges of $55-70%P_u$ ($P_u-ultimate$ load), white cracks appeared on the surface of the GFRP tubes of specimens. At that time, the confinement effects of the GFRP tubes on core concrete were obvious. Keep loading, the ranges of white cracks were expanding, and the confinement effects increased proportionally. In addition, the damages of specimens, which were accompanied with great noise, were marked by fiber breaking and resin cracking on the surface of GFRP tubes, also accompanied with concrete crushing. The bearing capacity of the axially compressed components increased with the increase of reinforcement ratio, and decreased with the increase of hollow ratio. When the reinforcement ratio was increased from 0 to 4.30%, the bearing capacity was increased by about 23%. When the diameter of hollow part was decreased from 55mm to 0, the bearing capacity was increased by about 32%.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.27 no.1
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• pp.13-20
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• 1991

This paper describes the fish-density dependence of the mean backscattering strength with aggregations of encaged, free-swimming fish of known density in relation to the experimental verification of echo-integration technique for estimating the density of fish shoals. In this experiment, various numbers of gold crussian, Carassius burgeri burgeri, with a mean length of 18.5cm and a mean weight of 205.9g, were introduced into a net cage of approximately 0.76m super(3). During the backscattering measurements. the cage was suspended on the sound axis of the 50kHz transducer having a beam width of 33 degrees at -3dB downpoints. The volume backscattering strengths from fish aggregations were measured as a function of fish density. Data acquisition, processing and analysis were performed by means of the microcomputer-based sonar-echo processor including a FFT analyzer. The calibration of echo-sounder system was carried out at field with a steel ball bearing of 38mm in diameter having the target strength of -40.8dB. The dorsal-aspect target strengths on anesthetized specimens of gold crussian used in the cage experiment were measured and compared with the target strength predicted by the fish density-echo energy relationship for aggregations of free-swimming gold crussian in the cage. The results obtained can be summarized as follows: 1. The target strengths in the dorsal aspect on anesthetized specimens of gold crussian, with the mean length of 19.1cm and the mean weight of 210.5g, varied from -40.9dB to -44.8dB with a mean of -42.6dB. This mean target strength did not differ significantly from that predicted by the regression of echo energy on fish density of free-swimming gold crussian in the cage. It suggests that the target-strength measurements on anesthetized fish was valid and can be representative for live, free-swimming fish. 2. The relationship between mean backscattering strength(, dB) and distribution density of gold $crussian(\rho, $ fish/m super(3)) was expressed by the following equation; =-41.9+11 $Log(\rho)$ with a correlation coefficient of 0.97. This result support the existence of a linear relationship between fish density and echo energy, but suggest that this line has steeper slope than the regression by the theory of estimating the density of fish schools.

• Journal of the Korean Geotechnical Society
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• v.26 no.11
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• pp.111-123
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• 2010

The steel pipe of steel-concrete composite drilled shafts increases the pile strength and induces the ductile failure by constraining the deformation of the inner concrete. In this research, pile loading tests were performed to analyze the field applicability of a steel-concrete composite drilled shafts. The test ground consisted of 5~7 m thick soil underlying rock mass. The test piles consisted of two steel-concrete composite drilled shafts, which were the concrete filled steel pipe piles with the diameter of 0.508 m, and a concrete pile with the same diameter. The test results showed that the boundary between the upper steel composite section and the lower concrete section was structurally weak and needs to be reinforced by using a inner steel cage. If the boundary is located in deep depth, which is not influenced by lateral load, the allowable strength of the lower concrete section increases, so an economical design can be performed by increasing the design load of steel-concrete composite drilled shafts.

• Journal of Power System Engineering
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• v.5 no.4
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• pp.67-73
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• 2001

Recently the steel parts used at automobiles are required to be used under high stress more than ever before in need of the weight down. To achieve this requirement of a high strength steel, it must be necessary to decrease inclusion content and surface defect as like decarburization, surface roughness etc.. In this study, the surface conditions are measured to know the influence on fatigue properties by two cases of two-stage shot peening iud single-stage shot peening for two kinds of spring steel(SUP7, SAE9254). This study shows the outstanding improvement of fatigue properties at the case of two-stage shot peening in the rotary bending fatigue test and this is assumed to be from decreasing the surface roughness unchanging the surface hardness increasing the compressive residual stress. Results also show fatigue failures originated at inclusion near surface, and this inclusion type is turned out to be a alumina of high hardness.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2001.05a
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• pp.338-343
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• 2001

Recently the steel parts used at automobiles are required to be used under high stress more than ever before in need of the weight down. To achieve this requirement of a high strength steel, it must be necessary to decrease inclusion content and surface defect as like decarburization, surface roughness etc., In this study, the surface conditions are measured to know the influence on fatigue properties by two cases of shot peening of two-stage shot peening and single-stage shot peening. And for this study, two kinds of spring steel(SAE 9254, DIN 50CrV4) are made. This study shows the outstanding improvement of fatigue properties at the case of two-stage shot peening in the rotary bending fatigue test and this is assumed to be from (1) on low stress condition, the single stage shot peening is not affected by nonmetallic inclusion under metal. (2) it is possible that the two-stage shot peening increases the fatigue life and the high stress, but, that is affected by nonmetallic inclusion under metal. (3) so far, beeasily 50CrV4 have made high stress. But, results also show fatigue failures originated at inclusion near surface, and this inclusion type is turned out to be a alumina of high hardness.

• Journal of Nutrition and Health
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• v.29 no.1
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• pp.32-40
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• 1996

To investigate the effect of dietary docosahexaenoic acid(DHA) and environmental enrichment on brain fatty acid composition and acetylcholinesterase(AChE) activity, two groups of was fed isocaloric diets containing 10 or 12% dietary lipids for 7 weeks. A third group was fed 10% (w/w) dietary lipids with supplemented 2% DHA-rich fish oil. Each diet group was housed either in a stainless steel cage individually or in a large enriched cage with toys where 7 rats were kept together. The fatty acid composition of plasma and brain was significantly affected by dietary lipid composition but not by environmental enrichment. Fish oil supplementation significanlty decreased plasma levels of monounsaturated fatty acids(MUFA) and increased polyunsaturated fatty acids(PUFA). Fish oil supplemented groups also maintained lower plasma n-6 fatty acids and higher n-3 fatty acids levels than unsupplemented groups. The fish oil supplementation significantly decreased arachidonic acid and increased eicosapentaenic, docosapentaenoic acids, and DHA in brain fatty acid composition. In addition, brain DHA level in supplemented groups tended higher than the unsupplemented. Brain, AChE activity significantly increased by the environmental enrichment but not by the fish oil supplementation. These finding suggest that the 2% fish oil (0.57% DHA & 0.31% EPA, per diet weigth) supplementation is enough to accumulate n-3 fatty acids and to change the n-6 n-3 ratio in brain and environmental enrichment might promote the learning ability.

• Korean Journal of Veterinary Research
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• v.29 no.1
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• pp.51-55
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• 1989

A survey on the prevalence of internal parasites in the laboratory rats in the Chonnam and Kyunggi areas was carried out. A total of 208 rats was selected for necropsy and the parasites were collected from the organs and the fecal samples. The infection rate of the internal parasites was high as 63.9% and eight species of parasites were identified. Among the species identified A tetraptera(21.6%) and H diminuta(20.7%) appeared with relatively higher infection rates than any other species identified. A significant difference in numbers of parasites was recognized between the regions as 8 species in Chonnam and 4 species in Kyunggi. The laboratory rats reared in stainless steel cage showed the higher infection rate than those in polycarbonate cage, with some exception in H spumosa and H nana. In this survey T crassicauda was firstly in the laboratory rats in Korea.

• International conference on construction engineering and project management
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• 2005.10a
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• pp.1187-1192
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• 2005

Approximately 25% of military establishments became superannuated to unable perform their function, and it influences on the environment by construction wastes and the waste of national budget, as there is no rational and objective standard even though old facilities have been replaced through modernization project. Therefore, it has been searched to introduce industrial building system that can cope with the new building-construction and transference for the improvement of existing military establishments. However, as there is no economical estimation standard for practical use, industrial building-construction is still remaining at the initial stage, and the study is insufficient too. So. in this study, I would like to develope LCC cost model for rational LCC comparative analysis between industrial construction system (Modular) and existing reinforced concrete structure and cage, and to evaluate economical efficiency through case analysis.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.2D
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• pp.277-285
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• 2008

X-ray images are wildly used in medical applications, and these can be more efficiently find scoliosis which is appearing during the growth of human skeleton than others. This research is focused on the calibration of X-ray image and three-dimensional coordinate determination of objects. Three-dimensional coordinate of objects taken by X-ray are determined by two step procedure. Firstly, interior and exterior orientation parameters are determined by camera calibration using Primary Calibration Object (PCO) which has two sides with embedded radiopaque steel ball. Secondly, calibration cage coordinates which is composed of two acrylic sheets that are perpendicular to X-ray source are determined by the parameters. Three-dimensional coordinates of calibration cage determined by photogrammetric technique are compared with that of Coordinate Measuring Machine (CMM). Though the accuracy analysis, X direction which is parallel to X-ray source error values are relatively higher than those of Y and Z directions. But, the accuracies of Y and Z axis are approximately -3 mm to 3 mm. From the research results, it is considered that photogrammetric technique is applied to determine three-dimensional coordinates of patients or assist to make medical devices.