• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.1888-1890
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• 2000

This paper describes the analysis results for the protection of lightning surge at 154 kV substation. We found that the surge arrester is needed at the inlet structure. The maximum overvoltage is about 1,500 kV at the circuit breaker without the surge arrester at the inlet structure. This value can be lower than 600 kV by installing the surge arrestor at the inlet structure. In addition to the incoming surge from transmission line, the shield wire should be considered to prevent the shielding failure by the direct lightning stroke.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.6
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• pp.115-122
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• 2012

The purpose of this study is to optimize the design of the jack-up platform for 5MW offshore wind turbine system. Considering all the environmental loads such as currents, waves, winds and so on, the members of structures have been designed and optimized based on the AISC and API-RP-2A to be within the allowable stress even in the most critical and severe condition. In addition to the above strength check of structural members, the joint punching shear check and the hydrostatic collapse check are also performed where they are required for the design. The design life of the jack-up platform is 50 years for the static strength check and the fatigue design life is 100 years including to the DFF(Design Fatigue Factor) of 2.0 to have enough stability and workability for the design optimization.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2013.05a
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• pp.162-163
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• 2013

A temporary work are lifting equipment that tower crane or lift, and temporary architectures that office building and storage in construction site. And it is main construction work that built and used temporarily like to a scaffolding, a walk plate, and a formwork. This study is to adjust breakdown structure of temporary work to introduce technical tendency. With a site manager, it is collected a detailed statement and compared. As a result to break down a tendency that temporary equipment, additional function, and direct work of temporary technique, first, existing detail technical indexes that group I, group J, group K, and group L are classified. Second, due to set up and manage to main agents in case of existing detail technical indexes that B1, B2, it is not wrong to classify. But, it is somewhat different, and therefore adjust it to same level. Finally, as a technical tendency that temporary equipment, additional function, and direct work of temporary technique, it is adjusted the others.

• Smart Structures and Systems
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• v.10 no.4_5
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• pp.443-458
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• 2012

The structural health monitoring (SHM) benchmark study on optimal sensor placement problem for the instrumented Canton Tower has been launched. It follows the success of the modal identification and model updating for the Canton Tower in the previous benchmark study, and focuses on the optimal placement of vibration sensors (accelerometers) in the interest of bettering the SHM system. In this paper, the sensor placement problem for the Canton Tower and the benchmark model for this study are first detailed. Then an information entropy based sensor placement method with the purpose of damage detection is proposed and applied to the benchmark problem. The procedure that will be implemented for structural damage detection using the data obtained from the optimal sensor placement strategy is introduced and the information on structural damage is specified. The information entropy based method is applied to measure the uncertainties throughout the damage detection process with the use of the obtained data. Accordingly, a multi-objective optimal problem in terms of sensor placement is formulated. The optimal solution is determined as the one that provides equally most informative data for all objectives, and thus the data obtained is most informative for structural damage detection. To validate the effectiveness of the optimally determined sensor placement, damage detection is performed on different damage scenarios of the benchmark model using the noise-free and noise-corrupted measured information, respectively. The results show that in comparison with the existing in-service sensor deployment on the structure, the optimally determined one is capable of further enhancing the capability of damage detection.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2004.11a
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• pp.174-181
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• 2004

We will introduce a method of construction of super-block curtain wall applied to Tower Palace III which is the highest high-rise complex building in Korea. Up-up method is utilized on Tower Palace III to shorten the term of works and it is that the curtain walls for the belt wall part are installed after the rests. The belt wall structure increases the horizontal structural stiffness of the building. The method of construction of super-block curtain wall is developed and used to raise and install the curtain wails of the belt wall floor. It is that the large block of curtain walls corresponding to three stories is fabricated on the ground in advance and the block is installed at a time by a tower crane. Specialized installing equipment :,s newly developed and applied to install the super-block. curtain wail. The curtain wall of the upper floor of the belt wall part is installed after the super-block. The installing equipment for this floor is developed utilizing a mini excavator and vacuum suctions. The application of this method had made it possible to omit the setting up the scaffold and financial profits such as the shortening of the terms of works was realized. The safety of works was secured and the productivity was also improved.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.3
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• pp.1764-1769
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• 2014

Numerical investigations have been conducted on the junction that connect the multi-tubular section and the single shell section in order to evaluate applicability of hybrid sections in wind turbine towers instead of conventional single shell towers. Major characteristics in structural details include extension of multi-tubular member into shell end section, installation of wing stiffeners, and different layout of floor beams. Elastic and nonlinear incremental analyses were conducted to examine stress concentration patterns and ultimate behaviors, respectively. Based on evaluation of structural performance due to vertical and horizontal forces, it has been confirmed that installation of floor beams and wing stiffeners sensitively affect ultimate strength of global wind tower.

• Smart Structures and Systems
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• v.6 no.3
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• pp.183-196
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• 2010

Monitoring and economical design of alternative energy generators such as wind turbines is becoming increasingly critical; however acquisition of the dynamic output data can be a time-consuming and costly process. In recent years, low-cost wireless sensors have emerged as an enabling technology for structural monitoring applications. In this study, wireless sensor networks are installed in three operational turbines in order to demonstrate their efficacy in this unique operational environment. The objectives of the first installation are to verify that vibrational (acceleration) data can be collected and transmitted within a turbine tower and that it is comparable to data collected using a traditional tethered system. In the second instrumentation, the wireless network includes strain gauges at the base of the structure. Also, data is collected regarding the performance of the wireless communication channels within the tower. In both turbines, collected wireless sensor data is used for off-line, output-only modal analysis of the ambiently (wind) excited turbine towers. The final installation is on a turbine with embedded braking capabilities within the nacelle to generate an "impulse-like" load at the top of the tower. This ability to apply such a load improves the modal analysis results obtained in cases where ambient excitation fails to be sufficiently broad-band or white. The improved loading allows for computation of true mode shapes, a necessary precursor to many conditional monitoring techniques.

• Wind and Structures
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• v.15 no.4
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• pp.331-343
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• 2012

Thunderstorm downbursts are responsible for numerous structural failures around the world. The wind characteristics in thunderstorm downbursts containing vortex rings differ with those in 'traditional' boundary layer winds (BLW). This paper initially performs an unsteady-state simulation of the flow structure in a downburst (modelled as a impinging jet with its diameter being $D_{jet}$) using a computational fluid dynamics (CFD) method, and then analyses the pressure distribution on a solar updraft tower (SUT) in the downburst. The pressure field shows agreement with other previous studies. An additional pair of low-pressure region and high-pressure region is observed due to a second vortex ring, besides a foregoing pair caused by a primary vortex ring. The evolutions of pressure coefficients at five orientations of two representative heights of the SUT in the downburst with time are investigated. Results show that pressure distribution changes over a wide range when the vortices are close to the SUT. Furthermore, the fluctuations of external static pressure distribution for the SUT case 1 (i.e., radial distance from a location to jet center x=$D_{jet}$) with height are more intense due to the down striking of the vortex flow compared to those for the SUT case 2 (x=$2D_{jet}$). The static wind loads at heights z/H higher than 0.3 will be negligible when the vortex ring is far away from the SUT. The inverted wind load cases will occur when vortex is passing through the SUT except on the side faces. This can induce complex dynamic response of the SUT.

• Magazine of the Korea Concrete Institute
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• v.20 no.6
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• pp.28-35
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• 2008

The Burj Dubai Project will be the tallest structure ever built by man; when completed the tower will be more than 700 meter tall and more than 160 floors. While the early integration of aerodynamic shaping and wind engineering considerations played a major role in the architectural massing and design of this multi-use/residential tower, where mitigating and taming the dynamic wind effects was one of the most important design criteria, the material selection for the structural systems of the tower was also a major consideration and required detailed evaluation of the material technologies and skilled labor available in the market at the time Concrete was selected for its strength, stiffness, damping, redundancy, moldability, free fireproofing, speed of construction, and cost effectiveness. In addition, the design challenges of using concrete for the design of the structural system components will be addressed. The focus on this paper will also be on the early planning of the concrete works of the Burj Dubai Project.

• Structural Engineering and Mechanics
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• v.57 no.5
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• pp.951-968
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• 2016

Long-span cross-strait bridges extending into deep-sea waters are exposed to complex marine environments. During the construction stage, the flexible freestanding bridge towers are more vulnerable to environmental loads imposed by wind and wave loads. This paper presents an experimental investigation on the dynamic responses of a 389-m-high freestanding bridge tower model in a test facility with a wind tunnel and a wave flume. An elastic bridge model with a geometric scale of 1:150 was designed based on Froude similarity and was tested under wind-only, wave-only and wind-wave combined conditions. The dynamic responses obtained from the tests indicate that large deformation under resonant sea states could be a structural challenge. The dominant role of the wind loads and the wave loads change according to the sea states. The joint wind and wave loads have complex effects on the dynamic responses of the structure, depending on the approaching direction angle and the fluid-induced vibration mechanisms of the waves and wind.