• Steel and Composite Structures
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• v.11 no.4
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• pp.291-305
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• 2011

The new structure consisting of continuous compound spiral hoop reinforced concrete (CCSHRC)column and steel concrete composite (SCC) beam has both the advantages of steel structures and concrete structures. Two types of beam-to-column connections applied in this structural system are presented in this paper. The connection details are as follows: the main bars in beam concrete pass through the core zone for both types of connections. For connecting bar connection, the steel I-beam webs are connected by bolts to a steel plate passing through the joint while the top and bottom flanges of the beams are connected by four straight and two X-shaped bars. For bolted end-plate connection, the steel I-beam webs are connected by stiffened extended end-plates and eight long shank bolts passing through the core zone. In order to study the seismic behaviour and failure mechanisms of the connections, quasi-static tests were conducted on both types of full-scale connection subassemblies and core zone specimens. The load-drift hysteresis loops show a plateau for the connecting bar connection while they are excellent plump for bolted end-plate connection. The shear capacity formulas of both types of connections are presented and the values calculated by the formula agree well with the test results.

• Journal of Korean Association for Spatial Structures
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• v.21 no.3
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• pp.69-76
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• 2021

Precast concrete (PC) modules have been increased its use in modular buildings due to their better seismic performance than steel modules. The main issue of the PC module is to ensure structural performance with appropriate connection methods. This study proposed a PC modular beam system for simple construction and improved structural and splicing performance. This modular system consisted of modules with steel plates inserted, and it is easy to construct by bolted connection. The steel plates play the role of tensile rebar and stirrup, which has the advantage of structural performance. The structural performance of the proposed PC modular beam system was evaluated by flexural test on one reinforced concrete (RC) beam specimen consisting of a monolithic, and two PC specimens with the proposed PC modular beam system. The results demonstrated that the proposed PC modular beam system achieved approximately 86% of the structural performance compared to the RC monolithic specimen, with similar ductility of approximately 1.06 fold greater.

• Journal of Advanced Navigation Technology
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• v.27 no.5
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• pp.546-551
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• 2023

In this study, a beam steering measurement system was developed to perform functions such as far-field beam steering and near-field beam focusing for TX/RX modes in the near file of the AESA radar. The beam steering measurement system consists of a spherical near-field scanner, an antenna positioner, a near-field controller, a network analyzer, a radar control system, a verification radar, a simulated radio, and an AESA radar. Using the developed system, the characteristics of TX/RX patterns before and after installation of radome to AESA radar were measured, and the beam pattern was analyzed through conversion to far field-after near-field measurement.The boresight error of the radar antenna device was measured, and it was confirmed that the main lobes were formed the same before and after the simulated radar dome was mounted.

• Land and Housing Review
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• v.6 no.3
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• pp.129-138
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• 2015

The building structure in Korea is planned to maximize the use of space in recent. The hybrid OCB(Optimized Composite Beam) beam is developed to take advantage of using the space. The OCB beam is composed of the steel H-beam section reinforced by open strands in negative moment zone and the pretensioned PSC concrete section in positive zone. Flexural behavior of typical architectural hybrid OCB beam section was investigated by F.E.M. The 15m, 20m, 30m OCB models were tested on nonlinear material and geometry under static loading system. Following results are obtained from the analysis; 1)The OCB beam develop initial flexural cracking over full service loading. 2)Overall deflections of OCB beam under the service loads are less than those of the allowable limits in KCI Code(2012). 3)The ultimate load capacity get over the nominal strength of the OCB main section. The OCB beam is verified of structural reliability from the finite element analysis.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.44 no.4
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• pp.413-422
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• 2011

An improved split-beam transducer for a 50 kHz fish-sizing echo sounder was developed. The main objective of this study was to minimize the side lobe level in the beam pattern and the distance between acoustic centers for adjacent transducer quadrants in the geometrical arrangement of array elements while maintaining a given number of transducer elements and beam width. To achieve these goals, a 32-element planar array transducer ($6{\times}6$ array with one element in each corner missing) was designed using the Dolph-Chebyshev shading function to suppress side lobes in the array beam pattern and fabricated by arranging the inter-element spacing to be substantially equal to half the wavelength using the transducer element of 0.4 times the wavelength in diameter. The performance characteristics of this split-beam transducer were evaluated in the experimental water tank of $5m{\times}5m{\times}6m$ (length${\times}$height${\times}$width). In this study, the design goal of the beam width and side lobe level for transmitting a beam pattern was initially set at $21^{\circ}$ and -30 dB, respectively. However, the measured beam width at 3 dB was $21^{\circ}$ in both directions with side lobe levels of -24.7 dB in the horizontal plane and -25.6 dB in the vertical plane. The averaged beam width at -3 dB of the receiving beam patterns for four receiving quadrants was $31.4^{\circ}$. The transmitting voltage response was 161.5 dB (re $1{\mu}Pa$/V at 1 m) at 50.23 kHz with a bandwidth of 2.16 kHz, and the averaged receiving sensitivity for four receiving quadrants was -178.13 dB (re 1 V/${\mu}Pa$) at 49.8 kHz with a bandwidth of 2.64 kHz.

• Advances in Computational Design
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• v.2 no.1
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• pp.57-69
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• 2017

The composite plate to upgrade structures and, in particular, to extend the lives of reinforced concrete beams has wide applications. One of the main aspects of the bonded strengthening technology is the stress analysis of the reinforced structure. In particular, reliable evaluation of the adhesive shear stress and of the stress in the composite plates is mandatory in order to predict the beam's failure load. In this paper, a finite element analysis is presented to calculate the stresses in the reinforced beam under mechanical loads. The numerical results was compared with the analytical approach, and a parametric study was carried out to show how the maximum stresses have been influenced by the material and geometry parameters of the composite beam.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.05a
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• pp.437-442
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• 2001

Recently, there have been increased much concerns about repair and rehabilitation works for aged concrete structures. In particular, it is known that due to repeated overburden vehicle there are significantly increasing number of aged concrete bridge slabs, which are strongly needed to construct and rehabilitate by innovative construction method. The objective of this research is to develop the new construction method of concrete slab in bridge structure, which can contribute to minimize the traffic congestion during the repair and rehabilitation works of aged concrete slab, and can also sufficiently assure the quality through the minimization of in-situ works at the site. I-beams with punch holes, which are substituted instead of main reinforcing steels in concrete slabs, will be manufactured in accordance with the specification in the factory. and will be preassembled into the Panel. After erecting the preassembled panels in the site, concrete will be poured into the slab panel. This research is to investigate physical properties of I-Beam with punch holes itself through static and fatigue test with rational numerical analysis Finally this research is to suggest reformed I-beam through the numerical analysis.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.60-63
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• 2004

The paper deals with the damage assessment of the concrete beam using static displacements and the flexural stiffness reduction of the beam was evaluated. Simply supported concrete beams were loaded at the mid-span, and the applied load level ranged $20\%,\;40\%,\;80\%$ of the flexural strength of the beam. When the displacements from the tests were increased more than $10\%$ of the initial values, flexural cracks occured. Judging from the observed cracks, damaged area of the beams were assumed and the stiffness reduction using the smeared-cracking concept was estimated to minimize the error between the test results and analytical results. Four stages of the behavior of a RC beam, which are uncracked, initial cracking, stabilized cracking and post-yielding, can be considered to assess the damage of RC beams. Main parameters for the assessment were cracking area and the stiffness reduction ratio. In each stage, damaged elements and their stiffness reduction were estimated to minimized the error.

• Proceedings of the Korea Concrete Institute Conference
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• 1995.04a
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• pp.311-318
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• 1995

Increases in strength and ductilities of steel fiber reinforced concrete(SFRC) under direct tension and compression result in improvements of flexural behavior of reinforced steel fibrous concrete beam(RSFCB) Use of hooked steel fibers in stead of round steel fibers enhances futher the structural porperties of a beam due to their greater mechanical bond resistance compared to that of round steel fibers. Flexural strength, initial stiffness ductility and failure mechani는 of RSFCB are dependent upon material and structural parameters and among which are the volume fraction of fibers, reinforcement ratio, and casting depth of SFRC in a beam section. The flexural behavior of RSFCB's are examined experimentally in this study and some conclusions are made regarding those effects of main material and structural parameters on the overall behavior of RSFCB.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.4
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• pp.206-215
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• 2002

It is to be classified into friendly environment and safety problems, as a main technology development of the recent automotive industry. As these tendency, lots of automobile companies focus on a reduction of fuel expenses and strengthen of crash safety using high strength steel. In this study advanced technologies such as tailored blanks, aluminum extrusion and high strength steel forming applied to bumper beam will be described. As a result of impact analysis and an actual impact test, in terms of beam performance and a possibility fur the mass production will be discussed.