• Journal of Satellite, Information and Communications
• /
• v.11 no.4
• /
• pp.107-113
• /
• 2016

In this paper, we suggest a design method of a wide-band Butler matrix working at 5.9 GHz for V2X communication antennas. Since V2X communication needs beam-forming and beam-steering antennas to make transportation systems, mobile comm platforms, saturated frequency-resources, and signal TX-and-RX smart, multi-functional, resolved, and efficient utmost, respectively, the proper Butler matrix and its radiating elements as a low-profile geometry are realized. The constitutive components of the basic Butler matrix of a narrow band are designed first. And then, it is extended to a wide-band version to make its frequency-shift less affected by the event of the antenna system being mounted on a car body. The beam-forming and beam-steering performance is presented as the common feature tagged along with the different bandwidths of the frequency responses as the comparison between the narrow- and wide-band cases.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.28 no.3
• /
• pp.259-266
• /
• 2015

In this paper, transverse shear spacing and effective depth of wide beams were considered as parameters to evaluate the shear capacity of wide beam according to transverse spacing of steel plates with openings in experimental way. The eight specimens were composed of: five specimens of shear reinforced by steel plates with openings and three non-reinforced specimens. Crack, failure mode, strain and load-displacement curve of specimens were analysed. Shear contribution of shear reinforcement is evaluated and maximum transverse spacing of shear reinforcement was proposed. Shear strength of the specimen that reinforced with three stirrup legs was higher than shear strength of the specimen that reinforced with two stirrup legs. And as the effective depth increased, shear strength was increased.

• Proceedings of the Korean Society of Laser Processing Conference
• /
• 1998.05a
• /
• pp.51-53
• /
• 1998

• The Journal of Sustainable Design and Educational Environment Research
• /
• v.10 no.2
• /
• pp.1-7
• /
• 2011

An experimental study to evaluate structural capacity of an embedded plate connected with prestressed concrete beam was performed. Embedded steel plates and prestressed concrete beam were connected with stud-bolts at the ends of concrete beam specimens. About 1,000 kN concentrated load was applied at 450mm away from the end of beam specimen. A 3,000 kN capacity static Oil-jack was used to direct concentrated load. The maximum strain of stud-bolt recorded $90{\times}10^{-6}$(mm/mm) and wide width cracks were not founded. Any falling failures of concrete and large deformations were not founded either between steel plate and prestressed concrete specimen. As a result, construction performance can be improved using this embedded steel plate connection system apply to large space educational facilities.

• Proceedings of the IEEK Conference
• /
• 2003.07a
• /
• pp.274-277
• /
• 2003

Millimeter-wave networking is composed of narrow beam link. High directivity of the beam provides either advantage or disadvantage in comparison with conventional wide-lobe microwave communications. In such networks, it is very substantial that beam connecting point to point is fixed in right direction. It is major requirement in the beam network to keep the beam in best direction. In this paper, We propose the method to find a best suited direction of the antenna's beam using the Genetic Algorithm in point-to-point link. Proposed method presume that each station knows his direction $\theta$$_1$,$\theta$$_2$ at every step of Genetic Algorithm, then it can be expected that GA is possible to search the ideal solution. Intensity of the received signal is evaluated by the multiplication of lengths to the point which the lobe meets with the horizontal line.

• Journal of Sensor Science and Technology
• /
• v.14 no.4
• /
• pp.225-230
• /
• 2005

This paper describes a novel tip position sensor made of a triangularly shaped piezoelectric PVDF (polyvinylidene fluoride) film for a cantilever beam. Due to the boundary condition of the cantilever beam and the spatial sensitivity function of the sensor, the charge output of the sensor is proportional to the tip position of the beam. Experimental results with the PVDF sensor were compared with those using two commercially available position sensors: an inductive sensor and an accelerometer. The resonance frequencies of the test beam, measured using the PVDF sensor, matched well with those measured with the two commercial sensors and the PVDF sensor also showed good coherence over wide frequency range, whereas the inductive sensor became poor above a certain frequency.

• Journal of the Korea Concrete Institute
• /
• v.17 no.1 s.85
• /
• pp.85-94
• /
• 2005

Post-tensioned Precast concrete System(PPS) consists of U-shaped precast wide beams and concrete column. The continuity of beam-column joint is provided with floor concrete cast on the PC shell beam and post-tensioning. The purpose of this paper is to evaluate the response of PPS interior beam-column joint subjected to cyclic lateral loading. To this end, an experimental investigation was performed with three half-scale specimens of interior connection. The design parameters are the amount of beam reinforcement placed inside the joint core. The test results showed that cracks were distributed well without my significant degradation of strength and ductility. Also, it was found that the prestressing may affect to alter the torsional crack angle. And the specimens sufficiently resist up to limiting drift ratio of 0.035 in accordance with the provisional by ACl of acceptance criteria for concrete special moment frames.

• Structural Engineering and Mechanics
• /
• v.19 no.5
• /
• pp.551-566
• /
• 2005

Using two different, but related approaches, an exact dynamic stiffness matrix for a two-part beam-mass system is developed from the free vibration theory of a Bernoulli-Euler beam. The first approach is based on matrix transformation while the second one is a direct approach in which the kinematical conditions at the interfaces of the two-part beam-mass system are satisfied. Both procedures allow an exact free vibration analysis of structures such as a plane or a space frame, consisting of one or more two-part beam-mass systems. The two-part beam-mass system described in this paper is essentially a structural member consisting of two different beam segments between which there is a rigid mass element that may have rotatory inertia. Numerical checks to show that the two methods generate identical dynamic stiffness matrices were performed for a wide range of frequency values. Once the dynamic stiffness matrix is obtained using any of the two methods, the Wittrick-Williams algorithm is applied to compute the natural frequencies of some frameworks consisting of two-part beam-mass systems. Numerical results are discussed and the paper concludes with some remarks.

• Structural Engineering and Mechanics
• /
• v.48 no.1
• /
• pp.93-102
• /
• 2013

An optimization work was developed in this work to provide design information for sandwich beam in civil engineering applications. This research is motivated by the wide-range applications of sandwich structures such as; slab, beam, girder, and railway sleeper. The design of a sandwich beam was conducted by using analytical and numerical optimization. Both analytical and numerical procedures consider the optimum design with structure mass objective minimization. Allowable deflection was considered as design constraints. It was found that the optimized core to the skins mass ratio is affected by the skin to core density and elastic modulus ratios. Finally, the optimum core to skin mass ratio cannot be constant for different skin and core materials.

• Proceedings of the KSME Conference
• /
• 2008.11a
• /
• pp.1727-1732
• /
• 2008

We present a facile, yet versatile carbon nanofabrication method using electron beam lithography and resist pyrolysis. Various resist nanopatterns were fabricated using a negative electron beam resist, SAL-601, and were then subjected to heat treatment in an inert atmosphere to obtain carbon nanopatterns. Suspended carbon nanostructures were fabricated by wet-etching of an underlying sacrificial oxide layer. Free-standing carbon nanostructures, which contain 122 nm-wide, 15 nm-thick, and 2 ${\mu}m$-long nanobridges, were fabricated by resist pyrolysis and nanomachining processes. Electron beam exposure dose effects on resist thickness and pattern widening were studied. The thickness of the carbon nanostructures was thinned down by etching with oxygen plasma. An electrical biosensor utilizing carbon nanostructures as a conducting channel was studied. Conductance modulations of the carbon device due to streptavidin-biotin binding and pH variations were observed.