• Structural Engineering and Mechanics
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• v.20 no.6
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• pp.695-712
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• 2005

Hybrid coupled shear walls in tall buildings are known as efficient structural systems to provide lateral resistance to wind and seismic loads. Multiple hybrid coupled shear walls throughout a tall building should be joined to provide additional coupling action to resist overturning moments caused by the lateral loading. This can be done using a coupling beam which connects two shear walls. In this study, experimental studies on the hybrid coupled shear wall were carried out. The main test variables were the ratios of coupling beam strength to connection strength. Finally, this paper provides background for rational design guidelines that include a design model to behave efficiently hybrid coupled shear walls.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.433-438
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• 2003

Structural steel/composite beams provide a viable alternative for coupling individual reinforced concrete wall piers. Well-established guidelines for shear links in eccentrically braced steel frames form the basis of current design guidelines. However, these provisions ignore the effects of nominally reinforced concrete encasement which typically surrounds the coupling beam, and are based on overly conservative assumed deformation demand. A coordinated analytical research program at here has focused on response of steel/composite coupling beams, their connections to reinforced concrete walls, and overall behavior of composite coupled wall systems. Using the results from this study, guidelines for proper design and detailing of steel/composite coupling beams and beam-wall connections have been developed. This paper summarizes the research program, and highlights the basic concepts, important findings, and recommendations.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.701-705
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• 2000

On the dynamic behavior of a simple beam subjected to an uniformly distributed tangential follower force, the influences of the velocities and magnitudes of a moving mass have been studied by numerical method. The instant amplitude of a simple beam is calculated and analyzed for each position of the moving mass represented by the time functions. The uniformly distributed tangential follower force is considered in its critical value of a simple beam, and four values of velocity is also chosen. Their coupling effects on the deflections of a simple beam are inspected too. When a moving mass moves after middle zone of a simple beam at the low velocities, its deflection is increased by the coupling of an uniformly distributed tangential follower force and moving mass.

• Journal of KSNVE
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• v.11 no.2
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• pp.257-264
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• 2001

In this research, piezoelectric smart structures are applied for SEA(Statistical Energy Analysis), which is well known approach for high frequency analysis. A new input power measurement based on piezoelectric electrical power measurement is proposed and compared with the conventional method in SEA. As an example, a simple aluminum beam on which piezoelectric actuator is attached is considered. By measuring the electrical impedance and electrical current of the piezoelectric actuator, the electrical power given on the actuator is found and this is In turn converted into the mechanical energy. From the measured value of the stored energy of the beam, the Internal loss factor is calculated and this value shows a good agreement with that given by the conventional method as well as the theoretical value. To compare the coupling loss factor, L-shape beam system which consists of a aluminum beam subsystem and a steel beam subsystem coupled by three pin is taken as second example. The input power and stored energy of each subsystem are found by the proposed approach. The coupling loss factor found by the electrical input power obtained from the piezoelectric actuator exhibits similar trend to the value found by the conventional method as well as the theoretical value. In conclusion, the use of SEA for high frequency application of piezoelectric smart structures is Possible. Especially, the input power that is essential for SEA can be found accurately by measuring the electrical input power of the piezoelectric actuator.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2002.11a
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• pp.293-296
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• 2002

In this paper, we proposed a beam tilting microstrip patch array antenna for the reception of satellite signals by using low cost copper etched polyester films and foams. The configuration and coupling mechanism of the proposed antenna are similar to the dipole Yagi-Uda antenna. It is composed of 3 layers of polyester films and three layers of foam. In order to prevent unwanted radiation and coupling loss by microstrip feeding networks and parasitic patches, a stacked layer with rectangular slots above the driver patch array is inserted. The 16${\times}$8 element microstrip Patch way antenna is Presented by experimental results. Its beam patterns are affected by many parameters such as sizes of the patches, gap between the patches. characteristics of the substrates, feeding method, etc. Owing to its complexities of various design parameters, both simulation and experiment were performed. The fabricated antenna received DBS signal from KOREASAT 3 by doing nothing but adjusting azimuth direction.

• Korean Journal of Optics and Photonics
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• v.3 no.4
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• pp.217-221
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• 1992

A micro lens system was designed for the modulator in optical fiber communication. One was the collimating lens which transferred the diffracted beam from optical fiber to the modulator. The other was the coupling lens which connected the modulated collimating beam to the optical fiber. The light source was He-Ne laser beam. The lens would be made of optical glass BK-7. We determined the tolerance of curvature radius, thickness and conic constant.

• Journal of electromagnetic engineering and science
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• v.10 no.4
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• pp.224-230
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• 2010

Wireless power transmission (WPT) is useful technology in near future. There are some kinds of the WPT technologies, WPT via radio waves, resonance coupling, and inductive. Especially the WPT via radio waves is used for multi-purposes from short range to long range application. However, unfortunately it is misunderstood that it is low efficiency and low power. In this paper, I show the theory of beam efficiency between transmitting antennas and receiving antennas and also show some high efficient applications of the WPT via radio waves. Especially, I pick up a wireless power charging system of an electric vehicle and show the experimental results. I show difference between the theory of beam efficiency and the experimental results of short range WPT. I indicate that reasons of poor beam efficiency in the experiment are (1) change of impedance caused by mutual coupling between transmitting antennas and receiving antennas, (2) oblique direction of microwave power to receiving antennas caused by short distance.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.850-853
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• 2006

This paper presents a primary study for a new method of enhancing measurement using impedance analysis method, which is widely used for structure health monitoring. Many of skyscrapers, bridges, tunnels, which have been built up several years, and nearly reached their operating life due to aging crack, material deterioration, and so on. therefore, the health monitoring technique has obtained considerable attention. The usage of the PZT sensor is proposed, and the coupling torque of bolt-connection overlapping beam is assumed. By using the torque wrench, it is easy to apply torque of different values to each bolt. The coupling torque is adjusted gradually from $3N{\cdot}m\;to\;0N{\cdot}m$ with the decrement of $1N{\cdot}m$. Simultaneously, the impedance peak variation is measured. The peak frequency variation can be determined through the change of bolt coupling torque.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.257-260
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• 2006

Coupled shear walls consist of two or more in-plane walls inter-connected with coupling beams. In order to effectively resist seismic loads, coupling beams must be sufficiently stiff, strong and posses a stable load-deflection hysteretic response. Much of requirements to the civil and building structures have recently been changed in accordance with the social and economic progress. Ductility of high performance fiber reinforced cementitious composites(HPFRCCs), which exhibit strain hardening and multiple crackling characteristics under the uniaxial tensile stress is drastically improved. This paper provides background for design guidelines that include a design model to calculate the shear strength of pseudo strain hardening cementitious composite steel coupling beam.

• Proceedings of the Korea Concrete Institute Conference
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• 2010.05a
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• pp.171-172
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• 2010

It includes that the evaluation of the degree of coupling between the shear walls and the coupling beams. It is demonstrated through a review of theoretical investigations of coupling beam behavior.