• Journal of Korean Association for Spatial Structures
• /
• v.8 no.4
• /
• pp.91-100
• /
• 2008

In this study, the vibration control performance of high-rise building structures connected by a sky-bridge has been investigated. The philosophy of vibration control using sky-bridges is to allow structures with different dynamic characteristics to exert control forces upon one another through sky-bridges to reduce the overall responses of the system. The the high-rise building structure connected by sky-bridge with 49 and 42 stories was used in this study to investigate the displacement, acceleration, reaction of bearings and stress of sky-bridge by analytical methods. To this end, historical earthquakes, an artificial earthquake and wind force time histories obtained from wind tunnel tests were used. Based on the analytial results, the use of sky-bridge can be effective in reducing the structural responses of high-rise buildings against wind and seismic loads.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2010.05a
• /
• pp.109-110
• /
• 2010

A pedestrian UHPC cable-stayed bridge(Super Bridge I) of the KICT was completed as a test bed. A long-term monitoring system has been installed on the UHPC bridge in order to acquire all types of long-term data such as strain, acceleration, tension force, wind direction and speed, temperature, etc. This system will provide valuable database enabling to assess the long-term behavior of the UHPC pedestrian hybrid cable-stayed bridge. This database will be exploited for the evaluation of the mechanical characteristics and serviceability of the UHPC members so as to estimate the behavioral features of long-span hybrid cable stayed bridges.

• Proceedings of the KSR Conference
• /
• 2007.05a
• /
• pp.188-193
• /
• 2007

Airport railroad have required maximum design speed 120km/h and wind speed 50m/s condition as design item of airport railroad vehicles. To design and manufacture the vehicle satisfying these conditions, it must carry out the dynamic behaviors analysis such as hunting stability, ride comfort derailment ratio, unloading ratio and lateral force to meet the criterion described in Urban Railroad Act. Dynamic behaviors of vehicle have carried out using the multi-body dynamics simulation program(VAMPIRE). This paper presents the evaluation methods and criterion used to verify dynamic performance of airport railroad vehicle, and show the analysis results of vehicle dynamic simulation and the test results for vibration and ride comfort measured on running performance tests. As a results, each analysis results and test results meet the criterion described in Urban Railroad Act.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.23 no.2
• /
• pp.139-145
• /
• 2017

Recently, gusts, typhoon and tsunamis have been occurring more frequently around the world. In such an emergency situation, a moored vessel can be used to predict and analyze other vessel behavior, but if the mooring system is destroyed, marine casualties can occur. Therefore, it is necessary to determine quantitatively whether a vessel should be kept in the harbour or evacuate. In this study, moored ship safety in an exclusive wharf according to swell effects on motion and mooring load have been investigated using numerical simulations. The maximum tension exerted on mooring lines exceeded the Safety Working Load for intervals 12 and 15 seconds. The maximum bollard force also exceeded 35 tons (allowable force) in all evaluation cases. The surge motion criteria result for safe working conditions exceeded 3 meters more than the wave period 12 seconds with a wind speed of 25 knots. As a result, a risk rating matrix (risk category- very high risk, high risk and moderate risk) was developed with reference to major external forces such as wind force, wave height and wave periods to provide criteria for determining the control of capabilities of mooring systems to prevent accidents.

• Journal of Ocean Engineering and Technology
• /
• v.34 no.6
• /
• pp.394-405
• /
• 2020

To assess the station-keeping performance of floating structures in the Arctic region, the ice load should be considered along with other environmental loads induced by waves, wind, and currents. However, present methods for performance evaluation in the time domain are not effective in terms of time and cost. An ice load generation module is proposed based on the experimental data measured at the KRISO ice model basin. The developed module was applied to a time domain simulation. Using the results of a captive model test conducted in multiple directions, the statistical characteristics of ice loads were analyzed and processed so that an ice load corresponding to an arbitrary angle of the structure could be generated. The developed module is connected to commercial dynamic analysis software (OrcaFlex) as an external force input. Station-keeping simulation in the time domain was conducted for the same floating structure used in the model test. The mooring system was modeled and included to reflect the designed operation scenario. Simulation results show the effectiveness of the proposed ice generation module and its application to station-keeping performance evaluation. Considering the generated ice load, the designed structure can maintain a heading angle relative to ice up to 4°. Station-keeping performance is enhanced as the heading angle conforms to the drift direction. It is expected that the developed module will be used as a platform to verify station-keeping algorithms for Arctic floating structures with a dynamic positioning system.

• Journal of the wind engineering institute of Korea
• /
• v.22 no.4
• /
• pp.155-161
• /
• 2018

In modern society, damage caused by strong winds such as typhoons is expected to increase due to urbanization and global warming. In order to test the reinforcement performance of the newly developed window protection device, two-point force test and uniformly distributed load test were carried out on non-reinforced plate glass. It reinforcement performance of the window protection device was evaluated based on the flexural performance improvement. The analytical performance of the window protection device was evaluated by analysis using differential equations of elastic loading method and deflection curve and Midas-Gen. First, the analytical window protection device was evaluated by formulae derived using differential equations of elastic loading and deflection curve. The validity of the derived formulae investigated by comparing the maximum deflection of the central part of the plate with the experimental value and the theoretical value at maximum load. Then the results were compared with those by finite element FE method using Midas-Gen. Under the experimental conditions, with the window protection device, stress reduction effect up to 40% and deflection reduction up to 71.4% under the same load were obtained. It was also found that it is advantageous to perform the FE analysis using the plate element when the performance is evaluated because the error of FE analysis result using plate elements is far less than that using beam elements.

• International Journal of Naval Architecture and Ocean Engineering
• /
• v.5 no.2
• /
• pp.263-276
• /
• 2013

Most yacht sails are made of thin fabric, and they have a cambered shape to generate lift force; however, their shape can be easily deformed by wind pressure. Deformation of the sail shape changes the flow characteristics over the sail, which in turn further deforms the sail shape. Therefore, fluid-structure interaction (FSI) analysis is applied for the precise evaluation or optimization of the sail design. In this study, fluid flow analyses are performed for the main sail of a 30-foot yacht, and the results are applied to loading conditions for structural analyses. By applying the supporting forces from the rig, such as the mast and boom-end outhaul, as boundary conditions for structural analysis, the deformed sail shape is identified. Both the flow analyses and the structural analyses are iteratively carried out for the deformed sail shape. A comparison of the flow characteristics and surface pressures over the deformed sail shape with those over the initial shape shows that a considerable difference exists between the two and that FSI analysis is suitable for application to sail design.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.20 no.2
• /
• pp.125-134
• /
• 2016

In order to improve seismic safety of nuclear power plant (NPP) structures in high seismicity area, seismic isolation system can be adapted. In this study, friction pendulum system (FPS) is used as the seismic isolation system. According to Coulomb's friction theory, friction coefficient is constant regardless of bearing pressure and sliding velocity. However, friction coefficient under actual situation can be changed according to bearing pressure, sliding velocity and temperature. Seismic responses of friction pendulum system with constant friction and various velocity-dependent friction are compared. The velocity-dependent friction coefficients of FPS are varied between low-and fast-velocity friction coefficients according to sliding velocity. From the results of seismic analysis of FPS with various cases of friction coefficient, it can be observed that the yield force of FPS becomes larger as the fast-velocity friction coefficient becomes larger. Also, the displacement response of FPS becomes smaller as the fast-velocity coefficient becomes larger.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.17 no.1
• /
• pp.298-303
• /
• 2016

Owing to the advantages of reduced weight and wind effect, the space-framed towers that consist of vertical and horizontal members of circular hollow tubular sections have been adopted widely for various purposes. It is critical to guarantee the strengths of tubular joints where vertical and horizontal members are connected structurally to make the entire space-framed system behave as a single tower structure. In this study, a strength evaluation was conducted for T-type tubular joints subjected to the concurrent action of compression and bending. Three of the available design codes, i.e., AISC, Eurocode 3, ISO 19902 were investigated and a design equation was suggested for an ultimate strength interaction between the axial force and bending moment based on nonlinear finite element analyses by selecting the slenderness ratios at the joints as major parameters.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.15 no.1
• /
• pp.49-55
• /
• 2009

Typhoons are usually influencing at least 3 or 4 times per year in Korean peninsula and they accompanied with strong winds and heavy rains and then brought tremendous loss of properties and lives. Especially typhoon "MAEMI" resulted in a lot of marine accidents of vessels such as sinking, stranding, collision etc. at anchoring or on berthing in pier. If the typhoon comes up to expected area influencing the incidents, the vessel tries to escape from the route of typhoon or anchor in sheltering anchorage. However, consideration of the anchoring or judgement of ship's safety against strong winds is decided only by the experience of operators without detail evaluation of the safety. Therefore, this paper evaluated the safety of T.S. HANBADA by comparing the external forces with the holding powers. Furthermore, based on this evaluation, the anchoring manual was produced for the maximum endurable wind velocity, the general precautions and the actions taken on the ship with steps.